1^4^Ackerly,D D^Coleman,J S^Morse,S R^Bazzaz,F A^1992^1^CO2 and Temperature Effects on Leaf Area Production in Two Annual Plant Species^2^73^^1260-1269^^^^^^^^^^3^^^^^^^^^^^Abutilon theophrasti/Amaranthus retroflexus;sϝ_ZÀ}&>!&&C^1^Ecology[PQR&Dt&"O&\&D t&Du&|Au&|But&|tV2r^ZYXA^1^We studied leaf area production in two annual plant species, _Abutilon theophrasti_ and _Amaranthus retroflexus_, under three day/night temperature regimes (18/14C, 28/22C, and 28/31C) and two concentrations of carbon dioxide (400 and 700 uL/L). The production of whole-plant leaf area during the first 30 d of growth was analyzed in terms of the leaf initiation rate, leaf expansion, individual leaf area, and, in _Amaranthus_, production of branch leaves. Temperature and CO2 inf% luenced leaf area production through stem (the plastochron index), and through shifts in the relationship between whole-pl) ant leaf area and the number of main stem nodes. In _Abutilon_, leaf initiation rate was highest at 38C, but area of indi- vidual leaves was greatest at 28C. Total leaf area was greatly reduced at 18C due to slow leaf initiation rates. Elevate0 d CO2 concentration increased leaf initiation rate at 28C, resulting in an increase in whole-plant leaf area. In _Amarant3 hus_, leaf initiation rate increased with temperature, and was increased by elevated CO2 at 28C. Individual leaf area wasA greatest at 28C, and was increased by elevated CO2 at 28C but decreased at 38C. Branch leaf area displayed a similar response to CO2, but was greater at 38C. Overall, whole-plant leaf area was slightly increased at 38C relative to 28C, aDnd elevated CO2 levels resulted in increased leaf area at 28C but decreased leaf area at 38C. The effects on leaf area cTlosely parallel rates of biomass accumulation in the same experiment, suggesting that responses of developmental processesW to elevated CO2 and interacting factors may play an important role in mediating effects on plant growth.uPVښ*[2^1^Acock,B^1990^3^Effects of CO2 on Photosynthesis, Plant Growth and Other Processes^Impact of CO2, Trace Gases, and Clim^ate Change on Global Agriculture^American Society of Agronomy^Madison, Wisconsin^45-60^^^^^^^ASA Special Publication No. 53^^^^^^^^^^^^^^^^^^^^^^^^Kimball,BA^Rosenberg,NJ^Allen,LH,Jri&4t tCVt\ut t1TtJctPt=Vtb3^3^Acock,B^Acock,M C^Pasternak,D^1990^1^Interactions of CO2 Enrichment and Temperature on Carbohydrate Production and Acciumulation in Muskmelon Leaves^3^115^^525-529^^^^^^^^^^7^^^^^^^^^^^muskmelon/Cucumis meloL. XX B~. CC^5^J. Amer. Soc. Hort. Sci.6&P& &&&@&& S~X؊}ǀtttttmA^5^We examined how temperature and stage of vegetative growth affect carbohydrate production and accumulation in _Cucumisu melo_ L. 'Haogen' grown at various CO2 concentrations ([CO2]). Carbohydrate production was measured by net assimilation rate either on a leaf-area basis (NARa) or a leaf dry-weight basis (NARw); carbohydrate accumulation was measured by leaf sxtarch plus sugar content. Twenty-four- and 35-day-old muskmelon plants were grown for 11 days in artificially lighted cabinets at day/night temperatures of 20/20 or 40/20C and at [CO2] of 300 or 1500 uL/L. NARa and NARw both increased with increasing [CO2], but the CO2 effect was smaller at low temperature, especially for plants at the later stage of vegetative growth. NARw was a better indicator of total dry-weight gain than was NARa. Both suboptimal temperatures and CO2 enrichment caused carbohydrates to accumulate in the leaves at both stages of vegetative growth. NARw was correlated negatively with !leaf starch plus sugar content. The rate of decrease in NARw with increasing leaf starch plus sugar content was significan"tly greater for CO2-enriched plants. Leaf starch plus sugar content >0.03 to 0.04 kg/kg of leaf residual dry weight at the# end of a dark period may indicate that temperature is suboptimal for growth. Plants grown at the same temperature had hig$her leaf starch plus sugar content if they were CO2-enriched than if grown in ambient [CO2], suggesting that an optimal temperature for growth in ambient [CO2] may be suboptimal in elevated [CO2].@&&2'&>tQ3&6S~&Dt tS~ &4^4^Acock,B^Acock,M C^Reddy,V R^Baker,D N^1985^5^The Simulation, with GLYCIM, of Soybean Crops Grown in the Field and at V'arious CO2 Concentrations in Open-top Chambers during 1982^U.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S(. Dept. of Agriculture, Agric. Res. Serv., Washington, D.C^^^^^^^^^^^^^^^^^^^^^^^^soybean^^011 in Green Report Series^Response of Vegetation to Carbon Dioxide^^S~@&tG;u:&>u&>#w&uS~Z&S~@&uC*5^7^Acock,B^Baker,D N^Reddy,V R^McKinion,J M^Whisler,F D^Del Castillo,D^Hodges,H F^1982^5^Soybean Responses to Carbon Diox+ide: Measurement and Simulation 1981^U.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture,, Agric. Res. Serv., Washington, D.C^^^^^^^^^^^^^^^^^^^^^^^^soybean/Glycine max^^004 in Green Report Series^Response of Vegetation to Carbon Dioxide^^ Dioxide^^~uG~us~~ -6Z~\~D ^~D\DD~$s~^RV.6^2^Acock,B^Allen,LH,Jr^1985^3^Crop Responses to Elevated Carbon Dioxide Concentrations^Direct Effects of Increasing Carbo/n Dioxide on Vegetation^Dept. of Energy, Carbon Dioxide Research Division^Washington, D.C.^53-97^^^^^^^DOE/ER-0238^^^^^^^^^^^^^^^^^^^^^^^^Strain,BR^Cure,JD~DDDь\s"6N~D${6N~|>N~6N~&&t 8& 17^2^Acock,B^Pasternak,D^1986^3^Effects of CO2 Concentration on Composition, Anatomy, and Morphology of Plants^Physiology, 2Yield and Economics^CRC Press, Inc.^Boca Raton, Florida^41-52^^^^II^^Carbon Dioxide Enrichment of Greenhouse Crops^^^^12^^^^^^^^^^^^^^^^^^^^^Enoch,HZ^Kimball,BAl,B A &Dt&T&D@t&Dt&tr v &Du &t⇨uZX4A^11^In summary, we can say that species differ in their response to high CO2. Plants which are using CAM are relatively u5nresponsive. Other plants with the C4 pathway show modest dry weight gains but large reductions in transpiration rate. Pla6nts which only have the C3 pathway, or well-watered CAM plants which are behaving like C3 plants, exhibit modest reduction7s in transpiration rate and large gains in dry weight, resulting in a variety of changes in plant composition, anatomy, an8d morphology. We know too little to even begin dividing C3 species into response groups. However, we can describe a typica9l or average response as follows. All organs on the plants become heavier with roots gaining proportionally more dry weigh:t than stems, and stems more than leaves. The additional dry matter in the root is mainly used to increase root length wit;h very little going to increase the density of the root tissue. Additional dry matter going to the stem causes increases ir which is probably greater than can be explained by the increase in number of mesophyll cell layers, although no one has  ?even done a definitive experiment on this. Finally, there is an increase in starch accumulating in the leaves which, depen@ding on the circumstances, can be very large. Branch and tiller numbers are frequently increased, as are the number of flowers. Either the weight or number of individual fruits is increased.8s@+CJJXS28+@I[WPS3B8^5^Acock,B^Reddy,V R^Hodges,H F^Baker,D N^McKinion,J M^1985^1^Photosynthetic Response of Soybean Canopies to Full-Season !Carbon Dioxide Enrichment^4^77^^942-947^^^^^^^^^^15^^^^^^^^^^^soybean/Glycine maxx(L.) Merr.T_PSQV5Y: |<C^13^Agron. J.5&|Du=:u2&L F&< t:T13^Y[XPSQR&tt2N$:T15:$EA^13^Global atmospheric CO2 concentration ([CO2]) is increasing as a result of the burning of fossil fuels. At present the+Fre is little information about how agronomic crops will respond to future high [CO2]. To investigate the basic process thaGt will be most affected, soybean canopies were continuously exposed to various [CO2] and photosynthetic rates were measure-Hd throughout the growing season. Soybean was grown to physiological maturity in sunlit controlled-environment chambers in 9ICO2 concentrations of 330, 450, 600 and 800 uL/L. Carbon dioxide fluxes were measured on the canopies at 15-min intervals Jevery day and used to calculate photosynthetic and respiration rates. Gross photosynthetic rate increased with each increm<Kent in [CO2] regardless of stage of development, but there was considerable day-to-day and seasonal variation. Seasonal chCLanges in photosynthetic rate were associated with developmental changes in the crop. Photosynthetic rates were low during Mearly vegetative development, even after the canopy had closed, but increased threefold just before flowering to reach a pGNeak during flowering at stage R2. They then decreased by 30% or more until just before the start of pod expansion (R3) whePOn a 45% increase occurred. Thereafter, photosynthetic rates decreased slowly and continuously to final harvest. The daily Pcurves of photosynthetic rate _vs._ photosynthetic photon flux density were further analyzed to determine canopy light utiSQlization efficiency () and canopy conductance to CO2 transfer (). Plants grown in 800 uL/L [CO2] had a value of that a\Rveraged about 40% higher than that for plants grown in 330 uL/L and a value of that averaged about 24% lower for the seaSson. Differences in between these treatments were significant throughout the season, while initial differences in betw_een treatments became less obvious after late vegetative growth stage VII.2t&G2t&G3t&G 3 t&GjU9^7^Acock,B^Reddy,V R^Whisler,F D^Baker,D N^McKinion,J M^Hodges,H F^Boote,K J^1983^5^The Soybean Crop Simulator GLYCIM: MoVdel Documentation^U.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture, Agric. Res. Serv.m$w, Washington, D.C^^^^^^^^^^^^^^^^^^^^^^^^soybean/Glycine max^^002 in Green Report Series^Response of Vegetation to Carbon {X10^7^Acock,B^Reddy,V R^Del Castillo,D^Hodges,H F^Baker,D N^McKinion,J M^Whisler,F D^1983^5^Soybean Responses to Carbon DioYxide: Measurement and Simulation 1982^U.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of AgriculturZe, Agric. Res. Serv., Washington, D.C^^^^^^^^^^^^^^^^^^^^^^^^soybean/Glycine max^^008 in Green Report Series^Response of Vegetation to Carbon Dioxide^^ Dioxide^^ PSQRVU3MUEU?EU tsJ tE t%r\11^2^Acock,B^Trent,A^1991^5^The Soybean Crop Simulator GLYCIM: Documentation for the Modular Version 91^U.S. Dept. of Ener]gy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture, Agric. Res. Serv., Washington, D.C^^^^^^^^^^^^^^^^^^^^^^^^soybean/Glycine max^^017 in Green Report Series^Response of Vegetation to Carbon Dioxide^^ Dioxide^^t-< t(< t#<t<_12^3^Aizawa,K^Nakamura,Y^Miyachi,S^1985^1^Variation of Phosphoenolpyruvate Carboxylase Activity in _Dunaliella_ Associated` with Changes in Atmospheric CO2 Concentration^128^26^^1199-1203^^^^^^^^^^21^^^^^^^^^^^Dunaliella tertiolecta/Dunaliella bioculata/Dunaliella viridis/Porphyridium cruentumm3 tփs<3;rr;r@uBy ^YCC^19^Plant Cell Physiol.&g RQ&g0uYZPSQRVWSsu^&wv&w&G'u։S&&G [P&GcA^19^In _Dunaliella tertiolecta_, _D. bioculata_ and _D. viridis_ the activities of phosphoenolpyruvate carboxylase and cadrbonic anhydrase were higher in the cells grown in ordinary air (low-CO2 cells) than in those grown in air enriched with 1e-5% CO2 (high-CO2 cells), whereas in _Porphyridium cruentum_ R-1 there was no difference in phosphoenolpyruvate carboxylasfe activity between these two types of cells. Apparent Km (NaHCO3) values for photosynthesis in low-CO2 cells of all speciegs tested were smaller than those in high-CO2 cells. Most of the 14C was incorporated into 3-phosphoglycerate, sugar mono- hand di-phosphates during the initial periods of photosynthetic NaH14CO3-fixation, indicating that both types of cells in _D. tertiolecta_ are C3 plants.y ^3 twPSQRVWb3ۊ@ ^r%2&N3ɾ &j13^3^Akey,D H^Kimball,B A^Mauney,J R^1988^1^Growth and Development of the Pink Bollworm,_ Pectinophora gossypiella_ (Lepidkoptera: Gelechiidae), on Bolls of Cotton Grown in Enriched Carbon Dioxide Atmospheres^6^17^^452-455^^^^^^^^^^24^^^^^^^^^^^cotton/Gossypium hirsutummL. FQnYsS&&W&O[ & u6& u & u &O$&O$0^NtsFC^22^Environ. Entomol.42҃t#2ᰀtt^Y PQVPQVrʚd${su^YXSnA^22^The pink bollworm, _Pectinophora gossypiella_ (Saunders), was reared on the bolls of cotton plants grown in CO2-enricohed (649 uL/L) and ambient (371 uL/L) chambers and in two open field plots, one with free-air CO2 enrichment (522 uL/L) anpd one without enrichment (ambient CO2, 360 uL/L). The effects of increased CO2 levels on growth and development were examiqned. There was no difference in pupal weights of pink bollworm raised on CO2-enriched cotton compared with those raised onr ambient CO2 cotton (26.80 versus 26.64 mg, respectively). Also, there was no difference in developmental time (21-27 d). sAnalysis of percent seed damage by larvae showed no differences between CO2-enriched and ambient CO2 cotton. These resultst were attributed to the nutritional qualities of the seed remaining the same (specifically the carbon:nitrogen ratio) despite CO2 and photosynthetic changes in the plant.t,ltr_r t _ F F ]_Y[XZR2Rv14^2^Akey,D H^Kimball,B A^1989^1^Growth and Development of the Beet Armyworm on Cotton Grown in an Enriched Carbon Dioxide Atmosphere^7^14^^255-260^^^^^^^^^^27^^^^^^^^^^^cotton/Gossypium hirsutummL.^€~ t2tĚ__rFlC^25^Southwestern Entomol.GDLVydr%^F FuPbkPr*X=o&+15^1^Allen,L H,Jr^1991^3^Effects of Increasing Carbon Dioxide Levels and Climate Change on Plant Growth, Evapotranspiration, and Water Resources^Managing Water Resources in the West under Conditions of Climate Uncertainty; 1990 Nov. 14-16; Scot-tsdale, Arizona^National Academy Press^Washington, D.C.^101-147^^^^^^^^^^^^^^^^^^^^^soybean/Glycine max^^^^^^^^^^Committee on Climate Uncertainty and Water Resources Management8r>u&]&Ùt+016^1^Allen,L H,Jr^1992^1^Free-Air CO2 Enrichment Field Experiments: An Historical Overview^8^11^^121-134^^0;9u;>t;&SC^29^Crit. Rev. Plant Sci.=?Nv;5u;6t.`T5633҇13tC9;]_^Y[V u u17^1^Allen,L H,Jr^1990^1^Plant Responses to Rising Carbon Dioxide and Potential Interactions with Air Pollutants^9^19^^15-?34^^^^^^^^^^333v&D u3&\ &t VvK^6Hdؿ9Vv&\&]&\%]E&| t&&D &d &t fKC^31^J. Environ. Qual. &DE&DE&]Y]&D2 W> uv&t&| uuK6H]3&t t@[WA^31^As global population increases and industrialization expands, carbon dioxide (CO2) and toxic air pollutants can be exNpected to be injected into the atmosphere at increasing rates. This analysis reviews a wide range of direct plant responseds to rising CO2, increasing levels of gaseous pollutants, and climate change, and potential interactions among the factors. Although several environmental interactions on stomata and foliage temperatures are reviewed briefly, a comprehensive refview of effects of potential climatic change on plants is not a major objective of this analysis. Research shows that elevwated CO2 increases photosynthetic rates, leaf area, biomass, and yield. Elevated CO2 also reduces transpiration rate per uznit leaf area, but not in proportion to reduction of stomatal conductance, because foliage temperature tends to rise. With increasing leaf area and foliage temperature, water use per unit land area is scarcely reduced by elevated CO2. Increases in photosynthetic water-use efficiency are caused primarily by increased photosynthesis rather than reduced transpiration. Gaseous pollutants (O3, SO2, NOx, H2S) affect plants adversely primarily by entry through the stomata. An example calculation showed that reduction in stomatal conductance by doubled CO2 could potentially reduce the effects of ambient O3 and SO2 by 15%. However, information on the interaction of CO2 and air pollutants is scanty. More research is needed on these interactions, because regional changes in air pollutants are occurring concurrently with global changes in CO2.o4:r$18^2^Allen,L H,Jr^Beladi,S E^1990^5^Free-Air CO2 Enrichment (FACE): Analysis of Gaseous Dispersion Arrays for the Study of Rising Atmospheric CO2 Effects on Vegetation. 1983-1989 Progress Report^U.S. Dept. of Energy, Carbon Dioxide Research Div#6ision, and U.S. Dept. of Agriculture, Agric. Res. Serv., Washington, D.C^^^^^^^^^^^^^^^^^^^^^^^^^^057 in Green Report Seri19^4^Allen,L H,Jr^Bisbal,E C^Campbell,W J^Boote,K J^1990^1^Carbon Dioxide Effects on Soybean Developmental Stages and Expansive Growth^10^49^^124-131^^^^^^^^^^37^^^^^^^^^^^soybean/Glycine maxx(L.) Merr.ZSQRVW5NP9RTr>wC^35^Soil and Crop Sci. Soc. Fla. Proc.dfd؉=ԉ?ԸbءhYj]l n[oWpXqYrZsVtA^35^Crop productivity is expected to increase as atmospheric carbon dioxide (CO2) continues to rise. The purpose of this paper is to examine the response of soybean [_Glycine max_ (L.) Merr., cv. Bragg] stages of development and plant size to CO2 concentration during four experiments (1981-1984) in outdoor controlled-environment chambers. Attached lysimeters contained Arredondo fine sand (loamy, siliceous, hyperthermic Grossarenic Paleudult). Air temperature and dewpoint temperature were controlled to common set-points within each year with CO2 concentration being the treatment variable among chambers. Vegetative and reproductive developmental stages were determined at frequent intervals during each experiment. Growth parameters of mainstem height, total mainstem plus branch stem length, number of mainstem nodes with branches, mainstem diameter, and leaf areas were measured during at least one experiment. Vegetative stages progressed slightly faster and the final number of nodes was slightly greater with increased CO2 concentration. All size parameters clearly increased with increasing CO2 concentration. Growth responses per unit CO2 concentration change were greater over the subambient range (160 to 330 umol/mol) than over the superambient range (330 to 990 umol/mol). For soybean, plant expansive growth will increase as atmospheric CO2 continues to rise, whereas direct effects of CO2 (without interaction of potential climatic changes) will have little effect on phenology.X[1ș&X[&X[+ڋȋ&X[ȋ&X[ȋ&X[##&X[320^4^Allen,L H,Jr^Bisbal,E C^Boote,K J^Jones,P H^1991^1^Soybean Dry Matter Allocation under Subambient and Superambient Levels of Carbon Dioxide^4^83^^875-883^^^^^^^^^^40^^^^^^^^^^^soybean/Glycine maxx (L.) Merr.ƀt҃C^38^Agron. J.ڒt ҃>tƀt҃ǀt t t tA^38^Rising atmospheric carbon dioxide concentration [CO2] is expected to cause increases in crop growth and yield. The objective of this study was to investigate effects of subambient, as well as superambient, [CO2] on soybean [_Glycine max_ (L.) Merr.] dry matter production and allocation for two reasons: to assess response of plants to prehistoric as well as fu-ture expected CO2 levels and to increase confidence in [CO2] response curves by imposing a wide range of [CO2] treatments. Soybean was grown in outdoor, sunlit, controlled-environment chambers at CO2 levels of 160, 220, 280, 330, 660, and 990 u0mol (CO2)/mol (air). Total dry matter growth rates during the linear phase of vegetative growth were 5.0, 8.4, 10.9, 12.5,= 18.2, and 20.7 g/m2/d for the above respective [CO2]. Samples taken from 24 to 94 d after planting showed that the percentage of total plant mass in leaf trifoliates decreased with increasing [CO2] whereas the percentage in structural componen@ts (petioles and stems) increased. At final harvest the respective [CO2] treatments resulted in 38, 53, 62, 100, 120 and 9K2% seed yield with respect to the 330 umol/mol treatment. Total dry weight responses were similar. Late season spider mite damage of the 990 and 280 umol/mol treatments reduced yields. These data confirm not only that rising CO2 should increaseO plant growth, but also that plant growth was probably seriously limited by atmospheric [CO2] in preindustrial revolution \times back to the previous global glaciation.E~ tM&%E &!E ]EWn*_ub21^8^Allen,L H,Jr^Boote,K J^Jones,J W^Mishoe,J W^Jones,P H^Vu,C V^Valle,R^Campbell,W J^1982^5^Effects of Increased Carbon _Dioxide on Photosynthesis and Agricultural Productivity of Soybeans. 1981 Progress Report^U.S. Dept. of Energy, Carbon Diobxide Research Division, and U.S. Dept. of Agriculture, Agric. Res. Serv., Washington, D.C^^^^^^^^^^^^^^^^^^^^^^^^soybean/Glycine max^^003 in Green Report Series^Response of Vegetation to Carbon Dioxide^^ Dioxide^^PSQRVWU&>&[22^10^Allen,L H,Jr^Boote,K J^Jones,J W^Mishoe,J W^Jones,P H^Vu,C V^Valle,R R^Campbell,W J^Harris,P R^Heimburg,K F^1984^5^Effects of Increased Carbon Dioxide and Water Stress Interactions on Photosynthesis, Transpiration, and Productivity of Soybeans. 1983 Progress Report^U.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture, Agric. Res. Serv., Washington, D.C^^^^^^^^^^^^^^^^^^^^^^^^soybean/Glycine max^^014 in Green Report Series^Response of Vegetation to Carbon Dioxide^^n Dioxide^^&dGs6 ~| ~X u tt%523^8^Allen,L H,Jr^Boote,K J^Jones,J W^Jones,P H^Valle,R R^Acock,B^Rogers,H H^Dahlman,R C^1987^1^Response of Vegetation to Rising Carbon Dioxide: Photosynthesis, Biomass, and Seed Yield of Soybean^11^I^^1-14^^^^^^^^^^45^^^^^^^^^^^soybean/Glycine maxx (L.) Merr.H122ɿr@>' %5F %'F fP %YF_^[r;C^43^Global Biogeochem. Cycles&v = u Ms鉅Wf22sv>W>tsNV A^43^Elevated carbon dioxide throughout the lifespan of soybean causes an increase in photosynthesis, biomass, and seed yield. A rectangular hyperbola model predicts a 32% increase in soybean seed yield with a doubling of carbon dioxide from 315 to 630 ppm and shows that yields may have increased by 13% from about 1800 A.D. to the present due to global carbon dioxide increases. Several other sets of data indicate that photosynthetic and growth response to rising carbon dioxide of many species, including woody plants, is similar to that of soybean. Calculations suggest that enough carbon could be sequestered annually from increased photosynthesis and biomass production due to the rise in atmospheric carbon dioxide from 315 ppm in 1958 to about 345 ppm in 1986 to reduce the impact of deforestation in the tropics on the putative current flux of carbon from the biosphere to the atmosphere.FȉF̉F҉FЉF։F@FʉF΋3FƋ1FvĿc$6F~6F624^7^Allen,L H,Jr^Boote,K J^Jones,J W^Mishoe,J W^Jones,P H^Valle,R R^Bisbal,E C^1985^5^Subambient and Superambient Carbon Dioxide Effects on Growth, Nonstructural Carbohydrates, Biochemistry of Photosynthesis and Transpiration of Soybeans. 1984 Progress Report^U.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture, Agric. Res. Serv.," Washington, D.C^^^^^^^^^^^^^^^^^^^^^^^^soybean/Glycine max^^031 in Green Report Series^Response of Vegetation to Carbon D25^2^Allen,L H,Jr^Boote,K J^1992^3^Vegetation, Effect of Rising CO2^Encyclopedia of Earth System Science^Academic Press, Inc.^New York^409-416^^^^4^^^^^^^^^^^^^^^^^^^^^^Ƅ_^mcwW u^NV t7rp^_N]ҍ^^^^^^^^^^^^^^^^^^^^^^^^^Shands,WE^Hoffman,JSNV^ t 닋^Ftr&E-26^4^Allen,L H,Jr^Drake,B G^Rogers,H H^Shinn,J H^1992^1^Field Techniques for Exposure of Plants and Ecosystems to Elevated CO2 and Other Trace Gases^8^11^^85-119^^0~tF܉FtF׈c DŽ[Ƅ_.&t ^N&fnC^49^Crit. Rev. Plant Sci.fN6v t2J*r+*W%5)55%N%NW 27^5^Allen,L H,Jr^Valle,R R^Mishoe,J W^Jones,J W^Jones,P H^1990^1^Soybean Leaf Gas Exchange Responses to CO2 Enrichment^10^49^^192-198^^^^^^^^^^53^^^^^^^^^^^soybean/Glycine maxx (L.) Merr.[^6:s.S^r[[ a6:rad6:r F\C^51^Soil and Crop Sci. Soc. Fla. Proc.NV*6 _ZY[^K}M3ێF&Cu OFQu!3c 3VȉFƋ]28^5^Allen,L H,Jr^Vu,J C V^Valle,R R^Boote,K J^Jones,P H^1988^1^Nonstructural Carbohydrates and Nitrogen of Soybean Grown `under Carbon Dioxide Enrichment^12^28^^84-94^^^^^^^^^^56^^^^^^^^^^^soybean/Glycine maxx (L.) Merr.c 3 t<3eC^54^Crop Sci.c 3^ t<N剕A?qoc 35 t 3#, uJGusc 3 tgA^54^Carbon dioxide (CO2) concentration has been rising in the atmosphere for over a century. This study was conducted to determine the effects of anticipated future levels of CO2 on nonstructural carbohydrates and N of soybean [_Glycine max_ (jL.) Merr. cv. Bragg]. Plants were grown at Gainesville, FL from seed to maturity in six sunlit, controlled-environment chaumbers that maintained CO2 at 330, 330, 450, 600, 800, and 800 umol (CO2)/mol (air). Attached lysimeters contained Arredondyo fine sand (loamy, siliceous, hyperthermic Grossarenic Paleudult). Leaflet blades were sampled five times per day at 48 a{nd 69 d after planting (DAP). At 48 DAP, average daytime starch conc. of leaflets increased with increasing CO2 from 85 g/|kg of dry wt at 330 umol/mol to 205 g/kg at 800 umol/mol. On each date, the daytime rate of starch accumulation combined over all CO2 treatments was 6 g/kg. Specific leaf weight increased significantly throughout the day both at 48 (0.64 g/m2/h) and 69 DAP (0.29 g/m2/h). Total Kjeldahl N (TKN) conc., expressed on a g/m2 basis, showed no change over the day. Total final dry wt increased 18, 34, and 54% at 450, 600 and 800 umol/mol, respectively. The TKN harvested per plant increased 25, 26 and 45% in the 450, 600 and 800 umol/mol CO2 treatments, respectively. Plants in the 450 umol/mol CO2 treatment partitioned more biomass to seed than the other CO2 treatments. With that exception, we saw no great differences among treatment partitioning at final harvest, and thus interpret the main effect of CO2 enrichment to be enhanced photoassimilation by soybean canopies while maintaining consistent allometric relationships of the plants.&>&2&e%_ZY[QRW&L29^3^Allen,S G^Idso,S B^Kimball,B A^1990^1^Interactive Effects of CO2 and Environment on Net Photosynthesis of Water-Lily^13^30^^81-88^^^^^^^^^^59^^^^^^^^^^^Nymphaea marliac/water lilyy6&r+3ɿ & GGr&>&2>s&M'C^57^Agric. Ecosystems Environ.r&>&22&&8\ t&M'^_ZY[XPQRVWU&@&|&D2&d&L&A^57^Water-lily (_Nymphaea marliac_) plants were grown out of doors in 570-L stock tanks contained in plastic-walled, open-topped CO2-enrichment chambers continuously supplied with either 640 or 340 (ambient) uL CO2/L air. Net photosynthesis (Pn) of water-lily leaves in each CO2 treatment was measured hourly between 0800 and 1600 h MST on 26 October and 10 and 24 November 1987. Air temperature and net solar radiation were measured at the same time. The 3 days on which Pn was measured provided an air temperature range of 10.3-33.2C and a net solar radiation range of 30-659 W/m2. Significant linear relationships were established between Pn and air temperature and Pn and net solar radiation for both CO2 treatments. Significant interactive effects of CO2 and air temperature and CO2 and net solar radiation were also found to affect Pn. In conditions generally unfavorable for Pn (low light and low temperature), there was no difference in Pn rate between the two CO2 treatments. In conditions that were favorable for Pn (high light and high temperature), however, Pn in the 640 uL CO2/L air treatment was as much as 60% greater than in the ambient CO2 treatment.t Zrs Z>Xs3]_^YPSUC30^4^Allen,S G^Idso,S B^Kimball,B A^Anderson,M G^1988^1^Relationship between Growth Rate and Net Photosynthesis of _Azolla_ in Ambient and Elevated CO2 Concentrations^13^20^^137-141^^^^^^^^^^62^^^^^^^^^^^Azolla pinnataa~F33ɋ^V3C^60^Agric. Ecosystems Environ.6F߹d dÉF_^ZY[XVWu23 uφ ++r r; A^60^_Azolla pinnata_ was grown out-of-doors at Phoenix, AZ, U.S.A. in open-topped plastic-walled chambers supplied with e ither 340 or 640 uL CO2/L air. Net photosynthesis and growth rate were measured weekly between September 1985 and May 1986 and a significant (P<0.01) positive correlation was established between these two parameters in both CO2 environments. Regression coefficients for the linear regression of growth rate onto net photosynthesis were not significantly different in the two CO2 environments, indicating that the rate of growth per unit of CO2 uptake is not influenced by an atmospheric C O2 concentration-environment interaction.F&FF tFF 7X7XÚ${Ú${ÚO${Ú31^3^Alpert,P^Warembourg,F R^Roy,J^1992^1^Transport of Carbon among Connected Ramets of _Eichhornia crassipes_ (Pontederiaceae) at Normal and High Levels of CO2^14^78^^1459-1466^^^^^^^^^^65^^^^^^^^^^^Eichhornia crassipes/water hyacinth/water hyacinth66u6r9S^[r t!"C266:|S^[rT^]_YZ[PSRU2666aC^63^Amer. J. Bot.&"]Z[XPQV&=t&|t&\&"${ ^YXPSQWU싏a&;MuEX&:Mu;A^63^The floating stoloniferous plant, _Eichhornia crassipes_, has high rates of productivity and rapidly invades new site+s. Because the transport of carbon among connected ramets in known to increase the growth of clonal plants, we asked whether there is intraclonal carbon transport in _E. Crassipes_. Because net photosynthesis of _E. Crassipes_ is significantly .higher at high levels of atmospheric CO2, we also asked if high CO2 can change patterns of carbon transport in ways that m<ight modify clonal growth. We exposed individual ramets within groups of connected ramets to 14-CO2 for 15-45 min and measured the distribution of 14-C in the group after 4 days of growth at 350, 700, 1,400, or 2,800 uL/L CO2. At 350 uL/L CO2, @a parent ramet exported approximately 10% of the 14-C that it assimilated to its first rooted offspring ramet. The offspriMng exported a similar percentage of the 14-C it assimilated toward the parent; two-thirds of this 14-C was retained by the parent, and one-third moved into new offspring of the parent. In all ramets, imported carbon moved into leaves as well asP roots. At the higher levels of CO2, the percentage of assimilated carbon exported from a parent ramet to the leaf blades ^of its first offspring was lower by half. High CO2 had little other effect on carbon transport. _E. crassipes_ maintains b idirectional transport of carbon between ramets even under uniform and favorable environmental conditions and when externabl CO2 levels are very high.LD0D~t!tu t t5*s =uoF]ZXSVb腚r.&6n"32^2^Alscher,G^Krug,H^1989^1^On-line Control of CO2 Enrichment in Protected Cultivation^15^248^^321-327^^^^^^^^^^68^^^^^^^^^^^lettuce/Lactuca sativaa L.]^_ZY[XPSQRWVU这s&>t,&M&&] 2&=&E t&E u &e|rStrr C^66^Act. Hort.}0&O &E't&E' uS&2&a [0rsF]^_ZY[XPWUr&;>s&e{%A^66^As a base for experiments on CO2 on-line control the CO2 fluxes in greenhouses are simulated and potential control st&rategies presented. Some approaches are tested, others outlined for discussion. Preliminary experiments with lettuce were 'performed with CO2 supply depending on wind velocity and irradiance. Additionally, intermittent CO2 application was tested(. Results indicate that the efficiency of CO2 enrichment varies relying on season and year. If planted in October cutting )off CO2 supply led to extended growth periods with increased energy demands. If planted in January no significant differen*ces in growing periods occurred between constant CO2 treatments, intermittent CO2 supply and cutting off due to wind velocity and irradiance, except differences to the control. Simulations for optimizing CO2 on-line control are in progress.33^1^Amthor,J S^1991^1^Respiration in a Future, Higher-CO2 World^16^14^^13-20^^^^^^^^^^711 tTdؾDu&E&M#C^69^Plant, Cell and EnvironmentHr~r: sF ]^_ZY[XRPWVU˷r觔r&6&D&t&t:ŷrsF.A^69^Apart from its impact on global warming, the annually increasing atmospheric [CO2] is of interest to plant scientists/ primarily because of its direct influence on photosynthesis and photorespiration in C3 species. But in addition, 'dark' r0espiration, another major component of the carbon budget of higher plants, may be affected by a change in [CO2] independen1t of an increase in temperature. Literature pertaining to an impact of [CO2] on respiration rate is reviewed. With an incr2ease in [CO2], respiration rate is increased in some cases, but decreased in others. The effects of [CO2] on respiration r3ate may be direct or indirect. Mechanisms responsible for various observations are proposed. These proposed mechanisms rel4ate to changes in: (1) levels of nonstructural carbohydrates, (2) growth rate and structural phytomass accumulation, (3) c5omposition of phytomass, (4) direct chemical interactions between CO2 and respiratory enzymes, (5) direct chemical interac6tions between CO2 and other cellular components, (6) dark CO2 fixation rate, and (7) ethylene biosynthesis rate. Because a7 range of (possibly interactive) effects exists, and present knowledge is limited, the impact of future [CO2] on respirati8on rate cannot be predicted. Theoretical considerations and types of experiments that can lead to an increase in the understanding of this issue are outlined.5 ƚe,sG*"P7 e,sG t[2 *3>et:6bt)F:34^3^Amthor,J S^Koch,G W^Bloom,A J^1992^1^CO2 Inhibits Respiration in Leaves of _Rumex crispus_ L^17^98^^757-760^^^^^^^^^^74^^^^^^^^^^^Rumex crispus/curly dockdock^_+rXr ^o]^ZY[XˉF SVWPR2@t<u23 t 2$6F_^,C^72^Plant Physiol.b& t̀u4: Nt @suFu^~[XPSRUbۀt.0.=A^72^Curly dock (_Rumex crispus_ L.) was grown from seed in a glasshouse at an ambient CO2 partial pressure of about 35 pa>scals. Apparent respiration rate (CO2 efflux in the dark) of expanded leaves was then measured at ambient CO2 partial pres?sure of 5 to 95 pascals. Calculated intercellular CO2 partial pressure was proportional to ambient CO2 partial pressure in@ these short term experiments. The CO2 level strongly affected apparent respiration rate: a doubling of the partial pressuAre of CO2 typically inhibited respiration by 25 to 30%, whereas a decrease in CO2 elicited a corresponding increase in res!Bpiration. These responses were readily reversible. A flexible, sensitive regulatory interaction between CO2 (a byproduct o*f respiration) and some component(s) of heterotrophic metabolism is indicated.^_Y;w+PRVW363^VF-D35^4^Anderson,I H^Dons,C^Nilsen,S^Haugstad,M K^1985^1^Growth, Photosynthesis and Photorespiration of _Lemna gibba_: Respon0Ese to Variations in CO2 and O2 Concentrations and Photon Flux Density^18^6^^87-96^^^^^^^^^^77^^^^^^^^^^^Lemna gibba/duckwe3edd2F xd }2hZ-$d<(  D 6 _PSQRWV ;C^75^Photosynth. Res....&ˆFFFsvFVNF^rr^ Ffu8t2FvBtOfF6HA^75^Dry weight and Relative Growth Rate of _Lemna gibba_ were significantly increased by CO2 enrichment up to 6000 uL CO2AI/L. This high CO2 optimum for growth is probably due to the presence of nonfunctional stomata. The response to high CO2 waDJs less or absent following four days growth in 2% O2. The Leaf Area Ratio decreased in response to CO2 enrichment as a resGKult of an increase in dry weight per frond. Photosynthetic rate was increased by CO2 enrichment up to 1500 uL CO2/L duringL measurement, showing only small increases with further CO2 enrichment up to 5000 uL CO2/L at a photon flux density of 210JM umol/m2/s and small decreases at 2000 umol/m/s. The actual rate of photosynthesis of those plants cultivated at high CO2 XNlevels, however, was less than the air grown plants. The response of photosynthesis to O2 indicated that the enhancement oOf growth and photosynthesis by CO2 enrichment was a result of decreased photorespiration. Plants cultivated in low O2 prod[uced abnormal morphological features and after a short time showed a reduction in growth. t_:guZguRF?t;w uEFkQ36^1^Andersson,N E^1991^1^The Influence of Constant and Diurnally Changing CO2 Concentrations on Plant Growth and Development^19^66^^569-574^^^^^^^^^^80^^^^^^^^^^^Ficus benjamina/Rosa hybridaa&}D&=tv:/#:v*tmFC^78^J. Hort. Sci.^XPQRVWF~FFًLNLNLNLN^&2N&>N F&E'@tFVF m;VrTA^78^Plants of _Ficus benjamina_ and miniature rose (_Rosa hybrida_ cv. Red Minimo) were grown under four CO2 treatments. UTwo had constant CO2 levels (600 and 900 ppm) and the other two had diurnal changes in CO2 levels, one increasing from 600V to 1500 ppm and one decreasing from 1500 to 600 ppm, each in four steps of 300 ppm during the day-time. In all treatmentsW 900 ppm CO2 was maintained during the night when supplementary light was used, except in the treatment with constant 600 Xppm where 600 ppm was also continued throughout the night. Plant growth was monitored under both decreasing and increasingY natural daylength and irradiance. The tallest plants and greatest increment in height for _Ficus_ occurred with plants grZown under constant CO2 concentration at 900 ppm. In both experiments with miniature roses the number of flower buds was si[gnificantly increased under diurnally changing CO2 concentration or when the CO2 level was constant at 600 ppm compared with a constant 900 ppm. Time to flowering was decreased by constant CO2 at 900 as compared with the other treatments.I.:]37^6^Andre,M^Cotte,F^Gerbaud,A^Massimino,D^Massimino,J^Richaud,C^1989^1^Effect of CO2 and O2 on Development and Fructification of Wheat in Closed Systems^124^9^^(8)17-(8)28^^^^^^^^^^83^^^^^^^^^^^Triticum aestivum/wheat^^^^^^^um aestivum L./whme that physiological evidence indicates the CCM is approaching maximal activity. Glycolate DH activity in 24 hour air-ad`A^81^The cultivation of wheat (_Triticum aestivum_ L.) was performed in controlled environment chambers with the continuouas monitoring of photosynthesis, dark respiration, transpiration and main nutrient uptakes. A protocol in twin chambers wasb developed to compare the specific effects of low O2 and high CO2. Each parameter is able to influence photosynthesis but cdifferent effects are obtained in the development, fructification and seed production, because of the different effects ofd each parameter on the ratio of reductive to oxidative cycle of carbon. The first main conclusion is that low level of O2,e at the same rate of biomass production, strongly acts on the rate of ear appearance and on seed production. Ear appearancfe was delayed and seed production reduced with a low O2 treatment (about 4%). The O2 effect was not mainly due to the reprgession of the oxidative cycle. The high CO2 treatment (700 to 900 uL/L) delayed ear appearance by 4 days, but did not reduhce seed production. High CO2 treatment also reduced transpiration by 20%. Two hypotheses were proposed to explain the similarities and the difference in the O2 and CO2 effects on the growth of wheat.r &W&GN3zr rr rFF^r transfer and then declines to the original level within 48 hours. The decline in PGPase activity begins at about the tik38^2^Andre,M^Du Cloux,H^1993^1^Interaction of CO2 Enrichment and Water Limitations on Photosynthesis and Water-Use Efficie ncy in Wheat^20^31^^103-112^^^^^^^^^^86^^^^^^^^^^^wheat/Triticum aestivumm L.2&3ҁ~|u &L&L&;Lt&RC^84^Plant Physiol. Biochem.OIr`t\RQ&Gt&WNYZr;&G&g}r( t~\u%6:"6:nA^84^Wheat plants (_Triticum aestivum_ L. cv. Capitole) were grown in twin closed growth chambers with continuous monitoriong of CO2 and water exchanges. During the vegetative stage the effect of CO2 enrichment, from 330 to 660 uL/L, was studiedp under an irradiance of 660 uE/m2/s with an optimum watering. Comparisons were made with successive experiments in which d!qaily water supply was fixed to a fraction (0.62-0.5-0.25) of the maximal transpiration of previous experiments. In a well 1rwatered canopy, the doubling of CO2 decreased transpiration by only 8%. Water use efficiency was increased (factor 1.45) msainly by the stimulation of photosynthesis. Under restricted water supply, photosynthesis of plants was more limited than 4ttranspiration. The inhibition of photosynthesis and the increase of water use efficiency can be predicted by a simple diffAuusion model applied to the response curve of photosynthesis to CO2, measured on canopy in standard conditions of watering.v The main hypothesis is that the equivalent stomatal conductance is reduced proportionally to the water availability, withDwout closure by patching. Under enriched CO2, the same reduction of leaf surface by water limitation was observed. PhotosynRxthesis was less affected. Therefore, water use efficiency was again increased. Doubling CO2 concentration can compensate fyor water stress inhibition on CO2 assimilation. That model also predicts interactions of CO2 and water stress observed on Uzwater-use-efficiency which was increased by a factor up to 5 in comparison with well-watered plants in standard atmospheref. The implications of this study on global change models are discussed.&&G^SRYԡ[ tgb&y >^Ԛ(6: |39^3^Andre,M^Du Cloux,H^Richaud,C^1986^3^Wheat Response to CO2 Enrichment: CO2 Exchanges, Transpiration and Mineral Uptakej}s^Controlled Ecological Life Support System: CELLS '85 Workshop^AMES Research Center^Moffett Field, California^405-428^^^^x^^^1985 July 16-19, NASA Report TM88215^^^^^^^^^^^^^^wheat/Triticum aestivum^^^^^^^^^^MacElroy,R^Martello,NV^Smernoff,D,DlXrq&GF&&G!_rY&ON&WVxXrBF t3ɋ^t XFFN^ t XFF t X|40^7^Andre,M^Ducloux,H^Richaud,C^Massimino,D^Daguenet,A^Massimino,J^Gerbaud,A^1987^1^Etude des Relations entre Photosynthese Respiration, Transpiration et Nutrition Minerale chez le Ble^124^7^^(4)105-(4)114^^^^^^^^^^90^^^^^^^^^^^wheat/Triticum aestivum^^^^^^^Triticum aestivum L.]Xse k xX^Y[F 7  F 7  >m^^^^^ Adv. Space Res. ',, &A^88^La croissance du Ble _Triticum aestivum_ a ete etudiee en environnement controle et ferme pendant une periode de 70 jours. Les echanges gazeux (Photosynthese, Respiration) hydriques (Transpiration) et al consommation en elements mineraux (Azote, Phosphore, Potassium) ont ete mesures en continu. On prsentera les relations dynamiques observees entre les differentes fonctions physiologiques, d'une part sous l'influence de la croissance et d'autre part en reponse a des modifications de l'environnement. L'influence de la teneur en CO2 pendant la croissance (teneur normale ou doublee) sera mise en evidence. In French.'-.---4,%%%%%%//,&l(l(l(l(l(l(l(l(l(l(l(l(l(l(l(l(l(l(l(l(l(l(l(l(l(l(l(41^5^Andreeva,T F^Strogonova,L E^Voevudskaya,S Yu^Maevskaya,S N^Cherkanova,N N^1989^1^Effect of Enhanced CO2 Concentration on Photosynthesis, Carbohydrate and Nitrogen Metabolism, and Growth Processes in Mustard Plants^21^36^^40-48^^^^^^^^^^93^^^^^^^^^^^mustard/Brassica junceaa L.bC    ! V~C^91^Fiziol. Rast.U(sp10h12vsb3T&d@E%-12345X@PJL RDYMSG DISPLAY = "" %-12345Xerences*p1005Xwhich*p1132Xcan*p1210A^91^We investigated prolonged (8- to 10-day) influence of enhanced carbon dioxide content (0.03-0.05%) in the air on photosynthesis of mustard plants (_Brassica juncea_ L.), on their carbohydrate and nitrogen metabolism, and on the course of growth processes. Considerable attention is devoted to the question of the effect of leaf starch excess on the rate of photosynthesis. It is demonstrated that mustard plants in the vegetative phase of growth under conditions of enhanced CO2 concentration in the air exhibit higher pure productivity of photosynthesis and a higher rate of photosynthesis than in plants growing at normal CO2 content in the atmosphere. Increase of apparent photosynthesis is realized without supplementary synthesis of fraction I protein. Increase in the rate of photosynthesis is accompanied by intensification of nitrogen metabolism, increase of growth, and accumulation of biomass. An excess of assimilates in the form of starch accumulates in the chloroplasts (25% of leaf dry mass at 27/24). Starch content increases significantly in plants grown under conditions of reduced temperature compared with ones grown at a higher temperature (34.4% of leaf dry mass at 20/17 as compared with 20.1% at 32/27). It is concluded that high starch content in the leaves is not a cause of photosynthesis suppression. Decline of photosynthesis is observed only when the starch excess disturbs structure of the chloroplasts.))42^1^Apel,P^1989^1^Influence of CO2 on Stomatal Numbers^22^3^^72-74^^^^^^^^^^96^^^^^^^^^^^Phaseolus vulgaris/Vicia faba/Lycopersicon esculentum/Acer pseudoplatanus/Triticum aestivum/Hordeum vulgare/Secale cereale/Avena sativa/Zea mays/bean/broad bean/tomato/sycamore maple/wheat/barley/rye/oat/cornmaple/wheat/barley/rye/oat/cornTUPPPUUUUUUUUUUC^94^Biol. PlantarumUUUUUUUUUUUUUUUUUUUUUUUUUUUUEDDDDDDDDDEDDDDDDDDDTDDDDDDDDDDDDDDDDP A^94^From nine different plant species grown at 1500 cm3/m3 CO2 five responded with a significant increase in stomatal numbers per mm2 as compared with plants grown under normal air conditions. Within a collection of twelve french bean cultivars remarkable cultivar differences with regard to the CO2 enhancement effect on stomatal numbers was found. 43^1^Arnone,J A,III^1988^6^Photosynthesis, Carbon Allocation, and Nitrogen Fixation in Red Alder^^Yale University^^Doctora(l Dissertation^^^Dissertation Abstracts Vol.50:08-B, p.3244 (96 pp.)^^^^^^^98^^^^^^^^^^^Alnus rubra/red alderalderA^97^Research reported in the three sections of this dissertation addresses the problem of the effect of potentially high *carbon costs of nitrogen fixation by alder-Frankia symbioses on host plant biomass productivity. Effects of root nodulatio7n and nitrogen fixation on plant biomass productivity and allocation patterns were evaluated by growing inoculated and uninoculated red alder seedlings in atmospheres containing ambient (350 uL/L) and elevated (650 uL/L) levels of CO2, with and: without combined nitrogen (20 mg/L NH4NO3) supplied in modified N-free Hoagland's nutrient solution. Effect of nodulationD, CO2 enrichment, substrate nitrogen, and the feedback interaction on early seedling development and aboveground and belowground growth were also tested using the same plant material. Root:shoot ratios for plants in all treatments decreased oveHr the course of the experiment. This occurred more rapidly in nodulated plants and was attributed to more rapid attainmentU of balanced root:shoot growth. This and evidence supporting the hypothesis that whole plant internal carbon/nitrogen balance regulated aboveground and belowground growth is presented and discussed.X44^2^Arnone,J A,III^Gordon,J C^1990^1^Effect of Nodulation, Nitrogen Fixation and CO2 Enrichment on the Physiology, Growth` and Dry Mass Allocation of Seedlings of _Alnus rubra_ Bong^23^116^^55-66^^^^^^^^^^101^^^^^^^^^^^Alnus rubrara Bong.C^99^New Phytol.cA^99^Inoculated and uninoculated _Alnus rubra_ Bong. seedlings were grown for 47 days in atmospheres containing ambient (3t50 uL CO2/L) and elevated (650 uL CO2/L) levels of CO2, with and without combined nitrogen (20 mg/L) supplied as ammonium nitrate. Five plants from each treatment were harvested 15, 30, and 47 days after exposure to CO2 treatments began. Evidenwce for the presence of a positive feedback loop between nitrogen fixation and photosynthesis was observed in nodulated plants growing at elevated CO2. These plants had greater whole-plant photosynthesis and nitrogenase activity, leaf area and nitrogen content, as well as nodule and plant dry mass, relative to nodulated plants grown at ambient CO2 and non-nodulated plants grown at both CO2 levels. This feedback may be an important way in which the potential carbon drain of nitrogen fixation on the host plant could be compensated; increased nitrogen availability resulting in stimulated leaf area growth and whole-plant photosynthesis. The relative amount of dry mass allocated to below ground decreased for all seedlings over time, and the amount allocated above ground increased. This shift in allocation occurred slowly and at a constant rate in non-nodulated plants and more rapidly and abruptly when plants were nodulated. The proportion of dry mass allocated below ground was consistently greater in non-nodulated plants grown at high CO2. Dry mass partitioning among other organs was not directly affected by nodulation, CO2 enrichment, or other treatment interactions.45^1^Arp,W J^1991^1^Effects of Source-Sink Relations on Photosynthetic Acclimation to Elevated CO2^16^14^^869-875^^^^^^^^^C^102^Plant Cell Environ. 8GA^102^While photosynthesis of C3 plants is stimulated by an increase in the atmospheric CO2 concentration, photosynthetic capacity is often reduced after long-term exposure to elevated CO2. This reduction appears to be brought about by end product inhibition, resulting from an imbalance in the supply and demand of carbohydrates. A review of the literature revealed that the reduction of photosynthetic capacity in elevated CO2 was most pronounced when the increased supply of carbohydrates was combined with small sink size. The volume of pots in which plants were grown affected the sink size by restricting root growth. While plants grown in small pots had a reduced photosynthetic capacity, plants grown in the field showed no reduction or an increase in this capacity. Pot volume also determined the effect of elevated CO2 on the root:shoot ratio--the root:shoot ratio increased when root growth was not restricted and decreased in plants grown in small pots. The data presented in this paper suggest that plants growing in the field will maintain a high photosynthetic capacity as the atmospheric CO2 level continues to rise.    ^10404     46^1^Arp,WJ^1991^6^Vegetation of a North American Salt Marsh and Elevated Atmospheric Carbon Dioxide^^Centrale Huisdrukkerij Vrije Universiteit, Amsterdam^^Doctoral Dissertation^^^^^^^^^^^^^^^^^^^^^Distichlis spicata/Spartina patens/Scirpus olneyi^^^^^eyi        47^2^Arp,W J^Drake,B G^1991^1^Increased Photosynthetic Capacity of _Scirpus olneyi_ after 4 Years of Exposure to Elevated CO2^16^14^^1003-1006^^^^^^^^^^108^^^^^^^^^^^sedge/Scirpus olneyiyi C^106^Plant Cell Environ. A^106^While a short-term exposure to elevated atmospheric CO2 induces a large increase in photosynthesis in many plants, long-term growth in elevated CO2 often results in a smaller increase due to reduced photosynthetic capacity. In this study,  it was shown that, for a wild C3 species growing in its natural environment and exposed to elevated CO2 for four growing (seasons, the photosynthetic capacity has actually increased by 31%. An increase in photosynthetic capacity has been observ +ed in other species growing in the field, which suggests that photosynthesis of certain field grown plants will continue t /o respond to elevated levels of atmospheric CO2.a d h? 548^5^Arp,W J^Drake,B G^Pockman,W T^Curtis,P S^Whigham,D F^1993^1^Interactions between C3 and C4 Salt Marsh Plant Species d 9uring Four Years of Exposure to Elevated Atmospheric CO2^123^104/105^^133-143^^^^^^^^^^111^^^^^^^^^^^Spartina patens/Scirp =us olneyi/Distichlis spicata^^^^^&s4&s) ي54t "k)9 &s43kean variety was more promoted by CO2 enrichment than by NO3-N application, while that of the wild one was enhanced by NO3- @A^109^Elevated atmospheric CO2 is known to stimulate photosynthesis and growth of plants with the C3 pathway but less of p Jlants with the C4 pathway. An increase in the CO2 concentration can therefore be expected to change the competitive interactions between C3 and C4 species. The effect of long term exposure to elevated CO2 (ambient CO2 concentration + 340 umol C NO2/mol) on a salt marsh vegetation with both C3 and C4 species was investigated. Elevated CO2 increased the biomass of the W C3 sedge _Scirpus olneyi_ growing in a pure stand, while the biomass of the C4 grass _Spartina patens_ in a monospecific Zcommunity was not affected. In the mixed C3/C4 community the C3 sedge showed a very large relative increase in biomass in elevated CO2 while the biomass of the C4 species declined. The C4 grass _Spartina patens_ dominated the higher areas of th ]e salt marsh, while the C3 sedge _Scirpus olneyi_ was most abundant at the lower elevations, and the mixed community occup jied intermediate elevations. _Scirpus_ growth may have been restricted by drought and salt stress at the higher elevations, while _Spartina_ growth at the lower elevations may be affected by the higher frequency of flooding. Elevated CO2 may af mfect the species distribution in the salt marsh if it allows _Scirpus_ to grow at higher elevations where it in turn may a vffect the growth of _Spartina_.is required $ Error: 80286 or higher CPU is required $ 49^1^Artus,N N^1990^1^Two Mutants of _Arabidopsis thaliana_ That Become Chlorotic in Atmospheres Enriched with CO2^16^13^^ y575-580^^^^^^^^^^114^^^^^^^^^^^Arabidopsis thalianana L.2꤀DF>?a꤀DpF>?꤀D C^112^Plant Cell Environ.DWPP^WWP^#d":ffp d#d:ZA^112^Two nonallelic, nuclear recessive mutants of _Arabidopsis thaliana_ (L.) Heynh. which become chlorotic when grown in  an atmosphere enriched to 20,000 cm3 CO2/m3 have been isolated. For one of the mutants, chlorosis begins at the veins and  gradually spreads to the interveinal regions. A minimum photon flux density of ca 50 umol/m2/s is required for this response. For the other mutant, the yellowing is independent of the light intensity and begins at the basal regions of the leav es and spreads to the tips. The injurious effects of CO2 seem to be restricted to photosynthetic tissues, since root elong ation and callus growth were not inhibited by a high atmospheric CO2 concentration for either mutant. Neither mutant became chlorotic in a low O2 atmosphere that suppressed photorespiration as effectively as the elevated CO2 does. Thus, the mut ations do not impose a requirement for photorespiration. The possibilities that the high CO2-sensitive phenotypes are caus ed by an effect of CO2 in stomata, on ethylene synthesis, or on mineral uptake are discussed but are considered unlikely.50^3^Ashenden,T W^Baxter,R^Rafarel,C R^1992^1^An Inexpensive System for Exposing Plants in the Field to Elevated Concentra tions of CO2^16^15^^365-372^^^^^^^^^^11717SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS C^115^Plant Cell Environ.SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS A^115^An inexpensive, potentially mobile field exposure system is described which may be easily constructed by a small wor kshop. It may be operated as an open-top with a frustum or covered with a polycarbonate 'lid'. The system is cost-effective for CO2 exposure work because the small size allows provision of CO2-enriched atmospheres over prolonged periods at rela tively low cost. A preliminary assessment of the chambers has been made and concentrations can be maintained at +/- 6% for  a target atmosphere of 680 cm3/m3 CO2 under normal operating conditions. Other chamber environmental conditions are reported.SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS            ! " # % & ) * + , - . 0 1 2 3 4 7 ; @  E F G H J K L M N O Q R S T V W X Y Z [ \ ] ^ _ a b c d e f g h j k l m n o p q r v w x y z { | } ~   51^1^Aston,A R^1984^1^The Effect of Doubling Atmospheric CO2 on Streamflow: a Simulation^24^67^^273-280^^^^^^^^^^1200t C^118^J. Hydrol. &Yt 8r>u&]&Ùt+ A^118^There is a potential for atmospheric CO2 to rise four- or six-fold, and at some time in the foreseeable future a dou bling of stomatal resistance seems, on present evidence, to be inevitable. A distributed deterministic process model was used to simulate the effects of changed stomatal resistance on streamflow of a 5-ha experimental catchment and a large (417  km2) water-supply area. The results indicated that we can expect streamflow to increase from 40 to 90% as a consequence of doubling of atmospheric CO2 concentration.Y]&D2 W> uv&t&| uuK6H]3&t t@[W 52^1^Austin,M P^1992^1^Modelling the Environmental Niche of Plants: Implications for Plant Community Response to Elevated CO2 Levels^25^40^^615-630^^^^^^^^^^123^^^^^^^^^^^Eucalyptus fastigatataK<}EE&&dFV&&`FV C^121^Aust. J. Bot.^NV;u;rEEEE3F^NV;u;֋NV;u;֋F^;u; u  A^121^No simple natural gradients in CO2 concentration exist for testing predictions about changes in plant communities in  response to elevated CO2. However indirect effects of CO2 via temperature increases can be tested by reference to natural  analogues. Physiologists, vegetation modellers of climate change and community ecologists assume very different temperature responses for plants. Physiologists often assume a skewed non-monotonic curve with a tail towards low temperatures, for est modellers using FORET type models, a symmetric curve, and community ecologists a skewed response with a tail towards h #igh temperatures. These assumptions are reviewed in relation to niche theory, and recent propositions concerning the continuum concept. Confusion exists between the different approaches over the shape of response curves to temperature. Distinctions need to be made between responses due to growth (physiological response), potential fitness (fundamental niche) and observed performance (realised niche). These types of response should be quantified and related to each other if process-models are to be tested for predictive success by reference to naturally occurring communities and temperature gradients. An / example of a statistical method for quantifying the realised environmental niche response of a species to temperature is provided. It is based on generalised linear modelling (GLM) of presence/absence data on _Eucalyptus fastigata_ for 8377 si 3tes in southern New South Wales, Australia. Seven environmental variables or factors are considered: mean annual temperatu >re, mean annual rainfall, mean monthly solar radiation, topographic position, rainfall seasonality, lithology, and soil; nutrient status. The temperature response is modelled by a _Beta_-function, log _y + a + alpha_ log _(t - a) + sigma_ log _ A(b - t)_, where _t_ is temperature and letters are parameters. The probability of occurrence is shown to be a skewed funct Jion of mean annual temperature. Any process-models of climate change for vegetation incorporating temperature changes due to elevated CO2 must be capable of generating such realised environmental niche responses for species.YPSQRVWUt M53^1^Badger,M^1992^1^Manipulating Agricultural Plants for a Future High CO2 Environment^25^40^^421-429^^^^^^^^^^12626 P C^124^Aust. J. Bot.&ur N?&^XW>~;6w*r&2r _ A^124^This paper discusses the potential ways in which C3 plant performance may benefit from a future high-CO2 environment!. These include increases in the efficiencies for light, nitrogen and water utilisation, particularly at elevated temperat b"ures, resulting from the improvement which will occur in the performance of the primary carboxylating enzyme, Rubisco. How n#ever, while growth experiments at elevated CO2 indicate that C3 plants show stimulation of dry matter accumulation, the po$tential gains are greatly ameliorated by a redistribution of plant resources. This primarily occurs via a reduction in the q% leaf area ratio which offsets increases in the net assimilation rate. In addition, there may be an overcommitment of nitr y&ogen in key photosynthetic components such as Rubisco and the thylakoid electron transport system. It is concluded that pl'ants may not be genetically adapted to optimise their growth and performance at elevated CO2 and that consideration should }( be given to exploring avenues for manipulating plants for more optimal responses. Targets for improvement of growth at el )evated CO2 include (1) altering source-sink relations; (2) improving the redistribution of nitrogen between the photosynth*etic machinery and the rest of the plant; and (3) changing the response of stomata to CO2 and humidity to increase water-u se efficiency even further than is currently predicted.tƀt҃ǀt t t t 54^1^Baille,A^1989^1^Greenhouse Microclimate and Its Management in Mild Winter Climates^15^246^^23-36^^28Xr uC^127^Act. Hort.\&Q9r J9rK&2Q &79rY5O&r9rr9rr֊9rϊ8rr .55^2^Bailly,J^Coleman,J R^1988^1^Effect of CO2 Concentration on Protein Biosynthesis and Carbonic Anhydrase Expression in _Chlamydomonas reinhardtii_^17^87^^833-840^^^^^^^^^^131^^^^^^^^^^^Chlamydomonas reinhardtiiiidu&^_X. ,C^129^Plant Physiol.rdۉsW3PWPryd3ҹd4Xך؇6F_ tы:_QrFw33ɋ&:w 1A^129^The effect of external inorganic carbon (Ci) concentrations on protein biosynthesis and carbonic anhydrase (CA) mRNA2 abundance were examined in the eukaryotic alga _Chlamydomonas reinhardtii_. Transfer of high CO2 (5%) grown algae to air 3levels of CO2 resulted in the transitory synthesis of two polypeptides of approximately 49,000 and 52,000 daltons as well 4as prolonged synthesis and accumulation of the 37,000 dalton CA monomer and an unidentified 20,000 dalton polypeptide. The5 gene coding for carbonic anhydrase was isolated from a genomic expression library and subjected to restriction endonuclea 6se analysis. Southern blot analysis of chromosomal DNA indicates that only a single copy of the gene is present. The 2.5 k 7ilobase DNA fragment hybridizes specifically to a 1.4 kilobase transcript in RNA isolated from air-grown cells and from ce 8lls grown on 5% CO2 that have been exposed to air levels of CO2. Maximum mRNA abundance was observed after 1 to 3 hours of 9 exposure to air. Transfer of air-grown cells to a high CO2 environment resulted in the elimination of the CA transcript a:fter 60 minutes of exposure. Changes in CA transcript abundance in response to external Ci concentrations occurred in the presence or absence of light. & tG4&_&&c&[ }r4Fr ^r$s^r&>&F^2 <56^2^Baker,R G E^Boatman,D J^1990^1^Some Effects of Nitrogen, Phosphorus, Potassium and Carbon Dioxide Concentration on th=e Morphology and Vegetative Reproduction of _Sphagnum cuspidatum_ Ehrh^23^116^^604-611^^^^^^^^^^134^^^^^^^^^^^Sphagnum cus pidatumum Ehrh.ZY[XSRQU&DžOv&t%&%N.P&%&!Y&Q&!U&tD&!vP&+Uy&!& /C^132^New Phytol.&UY&Q&U&!v]YZ[PSQRVW&6&[ oskF^Nc&E%t@A^132^Five experiments are described which were designed to investigate the effects of varying the concentrations of nitra Ate, phosphate, potassium and carbon dioxide in the culture solution on the morphology and vegetative reproduction of _Spha Bgnum cuspidatum_ Ehrh. The plants were grown axenically from spores sown on agar containing inorganic salts and then transCferred to aqueous culture solutions through which air containing enhanced concentrations of carbon dioxide was passed. In Dthree of the experiments the plants were grown in a balanced inorganic salt solution at various dilutions and in two of th Eese the concentration of carbon dioxide in the gas bubbled through the solution was varied. The concentrations of nitrogenF, phosphorus and potassium were varied independently and in combination in the remaining experiments while the concentrati Gon of carbon dioxide was kept constant. In some of the experiments the minimum concentrations of nitrogen and potassium su Hpplied were considerably below the minimum average concentrations recorded in rain but the minimum concentration of phosph Iorus supplied was within the upper part of the range recorded in rain. Within the ranges supplied the concentrations of al Jl three elements and of carbon dioxide affected interfascicle length and vegetative reproduction (innovation formation) bu t it was concluded that the element limiting innovation formation in natural conditions is phosphorus.2~FU&E0 %L57^3^Baldocchi,D D^White,R^Johnston,J W^1989^1^A Wind Tunnel Study to Design Large, Open-top Chambers for Whole-tree Pollu 'tant Exposure Experiments^27^39^^549-1556^^^^^^^^^^13737F։F@FʉF΋3FƋ1FvĿc$6F~6F6 3>C^135^JapcaFF-]6F^3&E&E&E&E &E&E"tQ!&E(&E*%&E,&E._ZY[XPSQRVW F 6OA^135^A wind tunnel study was conducted to determine the optimal design features of a large, open-top chamber, as needed f 8Por pollution exposure studies on mature trees. An optimally-designed, open-top chamber must minimize the incursion of ambi GQent air through its opening and maintain a uniform treatment concentration throughout the chamber. The design features of Rinterest are the diameter and height of the chamber and the deflection angle and opening size of any frustum that may be m JSounted on top of a model chamber. Design specifications depend on the turbulence regime about the chamber, which is influe ZTnced by the nature of the surrounding vegetation. Consequently, our investigation was performed on scale-model, open-top cUhambers in a wind tunnel populated with a model coniferous forest. Turbulence measurements demonstrated the similarity bet ]Vween the turbulence regime of the model and a natural forest. A hydrocarbon tracer was injected into the wind tunnel flow kWto characterize chamber performance. The main design features of open-top chambers are the velocity of air exiting throughX the top and the relationship between the length scale of the turbulence and the diameter of the chamber opening. As exit nYvelocities increase, the proportion of eddies with sufficient force to penetrate into the chamber decrease. Therefore, for qZ equal volumetric air flows, smaller opening sizes increase the exit velocities and reduce the number and extent of ambien t[t air incursions. Almost total exclusion of ambient air is achieved as the exit velocity of the air exceeds the magnitude \of one standard deviation of the vertical wind velocity measured at the chamber top. The incursion of ambient air is also w]reduced when the diameter of the chamber opening is smaller than the characteristic length scale of the turbulence, a meas |^ure of mean eddy size. Frusta deflect air flow over the chamber. Three prototypes, with 30-, 45- and 60-degree angles were _ tested. A 30-degree frustum slightly improves the performance of the chamber and is more effective in preventing ambient `air from entraining into the chamber opening than frusta with either a 45- or 60-degree angle. A flatter frustum allows fo ar a smoother transition in the wind velocity streamline and is less apt to cause wake turbulence, as is the case with stee bper frusta. Knowledge of the turbulence characteristics of plant canopies are readily available in the literature and can caid scientists and engineers in designing the optimal chamber and frusta dimensions for their particular application. Ther efore, the empirical approach to chamber design can be avoided, and substantial savings can be realized.[uS^v58^2^Ball,M C^Munns,R^1992^1^Plant Responses to Salinity under Elevated Atmospheric Concentrations of CO2^25^40^^515-525^^ MC^138^Aust. J. Bot.QNv^Ft6FN6FFvY[XPSQRV6@t%KKwtMt c gA^138^This review explores effects of elevated CO2 concentrations on growth in relation to water use and salt balance of hhalophytic and non-halophytic species. Under saline conditions, the uptake and distribution of sodium and chloride must be iregulated to protect sensitive metabolic sites from salt toxicity. Salt-tolerant species exclude most of the salt from the j transpiration stream, but the salt flux from a highly saline soil is still considerable. To maintain internal ion concent krations within physiologically acceptable levels, the salt influx to leaves must match the capacities of leaves for salt s ltorage and/or salt export by either retranslocation or secretion from glands. Hence the balance between carbon gain and th me expenditure of water in association with salt uptake is critical to leaf longevity under saline conditions. Indeed, one nof the striking features of halophytic vegetation, such as mangroves, is the maintenance of high water use efficiencies co oupled with relatively low rates of water loss and growth. These low evaporation rates are further reduced under elevated CpO2 conditions. This, with increased growth, leads to even higher water use efficiency. Leaves of plants grown under elevat qed CO2 conditions might be expected to contain lower salt concentrations than those grown under ambient CO2 if salt uptake r is coupled with water uptake. However, salt concentrations in shoot tissues are similar in plants grown under ambient ands elevated CO2 conditions despite major differences in water use efficiency. This phenomenon occurs in C3 halophytes and in t both C3 and C4 non-halophytes. These results imply shoot/root communication in regulation of the salt balance to adjust t uo environmental factors affecting the availability of water and ions at the roots (salinity) and those affecting carbon gain in relation to water loss at the leaves (atmospheric concentrations of water vapour and carbon dioxide).DF&DF& ^^^^^^^^14040F{s& 2& ؋&^&\^FlOriF22賱rX؋&&tt 2&&2&e'_ZYSQRWr$3ɿ & GGr&>&2&e%_ZY[QRW&L {A^141^Australia produced $2.7 billion worth of forest products in 1983-84 but a further $1.3 billion worth, principally so |ftwood, were imported. Because of this ever increasing demand for softwood, there is a move away from utilization of nativ }e hardwoods and by 2020 AD, when the atmospheric CO2 concentration is likely to be greater than 450 ppmv, 75% of forest pr~oducts are projected to come from coniferous plantations. This move towards _Pinus radiata_ is a result of both demand for  softwood and lack of indepth investigations of the potential of Australian native species, particularly eucalypts, for plantation forestry. _Pinus radiata_ is the major plantation softwood in southern Australia and is presently grown at sites where phosphorus deficiency and repeated episodes of drought are common. Consequently, we are investigating the growth res ,ponse of pines to elevated CO2 at a range of phosphorus and water levels. When phosphorus was adequate, doubling CO2 conce /ntration more than doubled the rate of photosynthesis and increased the total plant dry weight by about 40%. However, ther Pe was no response when phosphorus was deficient. In contrast, there was a slightly higher response under simulated drought conditions. A further possible effect of rising CO2 levels is that the climatic range of _P. radiata_ may be altered due Tto a reduction in water use or an increase in the drought tolerance of the trees. We found that CO2 enrichment did not aff dect either of these factors but the water-use efficiency was increased when phosphorus was adequate. All families of _P. radiata_ do not respond to CO2 enrichment in the same manner. In a study investigating the response of four families to ele gvated CO2 at two phosphorus levels, we have identified a considerable variation between the families in their response to pCO2 and phosphorus. To date our studies have indicated that the projected increase in atmospheric CO2 levels is likely to have a significant influence on the productivity of Australia's _P. radiata_ plantations. But this will only occur if phos tphorus fertilization is adequate. If the rise in CO2 results in climatic change the range of _P. radiata_ may be even furt her restricted because there will be no concomitant decrease in water use or increase in drought tolerance. There is an urgent need for complementary studies of the response of Australian native species to elevated CO2 at realistic levels of ph osphorus and water to enable more accurate prediction of the productivity and water use of Australian native forests and e ucalyptus plantations.]ZY[_^F&FF tFF 7X7XÚ${Ú${ÚO${Ú%;60^2^Baron,J J^Gorski,S F^1986^1^Response of Eggplant to a Root Environment Enriched with CO2^28^21^^495-498^^^^^^^^^^2058 eC^143^HortSci.t &\?2A'&L&8t&W326 rJ& rA&9s"s5ʋF3${r)&F |rv&<3 62^2^Barson,M M^Gifford,R M^1990^3^Carbon Dioxide Sinks: The Potential Role of Tree Planting in Australia^Greenhouse and Energy^CSIRO^Australia^433-443^^^^^^^^^^149^^^^^^^^^^^^^^^^^^^^^Swain,DJ9;5_^Y[ˀ>@ t>@ u A^148^Reforestation has been suggested as a possible policy option at several recent international 'greenhouse effect' for ums. The issue of deforestation/reforestation may be the subject of a protocol for which detailed arrangements will be developed following the establishment of a non-obligatory Framework Convention on Climate Change in the early 1990's. Althoug h forestry cannot in principle offer a permanent solution to continuous emission of CO2 from fossil fuel burning, its expa nsion could assist in slowing down net emissions. This would 'buy time' to reduce rates of CO2 emission and to develop strategies to adapt to global atmospheric and climate change. A simple model is developed to explore the dynamics of carbon s equestration by new forest plantations. The areal extent of land suitable for reforestation is also examined. It is concluded from one optimistic scenario that a program of planting 40,000 ha/y of new forest onto non-forested land could, after 20 y absorb about 5-12 Mt (C) p.a. (7-17 per cent 1987-88 total Australian emissions) as long as planting at that rate continued.F&9&uHr~r: sF ]^_ZY[XRPWVU˷r觔r&6&D&t&t:ŷrsFA^151^Increasing atmospheric carbon dioxide concentrations present a novel resource condition for plant communities. In or der to understand and predict how plant community structure and function may be altered in a high CO2 world, we need to understand how interactions among neighboring plants within a community will alter the growth and reproduction of component species. Because CO2 is readily diffusible, plants have little influence on the CO2 acquisition of their neighbors, except . within particularly dense canopies. Thus, plants seldom compete directly for CO2. Rather, CO2 availability is likely to alter plant-plant interactions indirectly through its effects on plant growth and competition for other resources. As a con 2sequence, competitive outcome under elevated CO2 atmospheres within even simple systems is not easy to predict. For example, under some conditions, C4 species in competitive assemblages have improved competitive ability relative to C3 competito 5rs as a result of CO2 enrichment, contrary to expectations based on their photosynthetic pathways. It is now clear that in Bdividually grown plants can differ substantially from those within mono- or multispecific stands in response to CO2 enrichment. At present, our understanding of how stands of interacting plants modify the availability of CO2 and other resources E is incomplete. We urgently need information about how elevated CO2 atmospheres influence stand formation and population d Synamics, specifically with regard to the identities, numbers, sizes and reproductive fitnesses of individuals within singl Ue and multiple species stands, if we are to make multi-generational predictions concerning the fate of populations and communities in an elevated CO2 world.t̀u4: Nt @suFu^~[XPSRUbۀt.0. Y353r^^]Z[XˉFV&<uFQr&<t&<u r E4:^V&<uF#r&<t&<u `r 4:^65^2^Bazzaz,F A^Garbutt,K^1988^1^The Response of Annuals in Competitive Neighborhoods: Effects of Elevated CO2^2^69^^937-9 \46^^^^^^^^^^156^^^^^^^^^^^Ambrosia artemisiifolia/Abutilon theophrasti/Amaranthus retroflexus/Setaria faberiiSetaria fabe erii Herm.^_ZY[XPQVWUd&>u6 hA^154^Four members of an annual community were used to investigate the effects of changing neighborhood complexity and inc xreased CO2 concentration on competitive outcome. Plants were grown in monoculture and in all possible combinations of two, three, and four species in CO2-controlled growth chambers at CO2 concentrations of 350, 500, and 700 uL/L with ample mois {ture and high light. Species responded differently to enhanced CO2 level. Some species (e.g., _Abutilon theophrasti_) had increased biomass with increasing CO2, while others (e.g., _Amaranthus retroflexus_) had decreased biomass with increasing CO2 concentration. In mixtures, species tended to interact strongly, and, in some cases, the interaction canceled out the  effects of CO2. Furthermore, there were clear differences in species behavior in different competitive neighbors. In gene ral, competitive arrays that had C3 species depressed the response of C4 species, especially _Amaranthus_. _Ambrosia artemisiifolia_ was the strongest competitor in the assemblage. Strong statistical interactions between CO2 and the identity of  the competing species in mixtures were found to be primarily due to the as yet unexplained response of plants with CO2 at  500 uL/L. The potential effects of CO2 on community structure could be profound, particularly at the intermediate levels of CO2 that are predicted to be reached during the first half of the next century.PSQV &}tGt)< u!&2&A 66^1^Bazzaz,F A^1990^1^The Response of Natural Ecosystems to the Rising Global CO2 Levels^30^21^^167-196^^58_rtDޚ C^157^Ann. Rev. Ecol. Syst.dPSQRVWtE&4u ?u<6}t~tGXv3ҋF&;uGG t uB:67^4^Bazzaz,F A^Ackerly,D D^Woodward,F I^Rochefort,L^1992^1^CO2 Enrichment and Dependence of Reproduction on Density in an Annual Plant and a Simulation of Its Population Dynamics^31^80^^643-651^^^^^^^^^^161^^^^^^^^^^^Abutilon theophrasti^^^^^C^159^J. Ecol.Q t t:YXPW&2&E:G _XPSQVW<f&}D&=tv:/#:v*t A^159^1. Populations of an annual plant, _Abutilon theophrasti_, were grown at four densities (100, 500, 1500 and 4000/m2)  and two CO2 concentrations (350 and 700 uL/L) to examine the influence of CO2 environment on density-dependent patterns o f demography and reproduction. Variables measured included survivorship, proportion of plants flowering and fruiting, numb er of fruiting individuals, number of seeds per individual, total seed production per population, mean seed mass, and germination of seeds produced in each environment. 2. All variables, except the number of fruiting individuals, declined with increasing density, and at the highest density no individuals set seed. The number of fruiting individuals was highest at a density of 500/m2. In the elevated CO2 environment, survivorship was significantly reduced but the proportion of plants flowering and fruiting and the number of fruiting individuals in each population all increased. Total population seed prod uction was higher in the elevated CO2 environment at all densities, although the differences were not significant. Significant effects of CO2 concentration were observed only for population-level variables, but not for mean individual fecundity  or seed size. Seed germination declined with increasing maternal density, and no germination was recorded for seeds produ ced at 1500 /m2. 3. Simple models of population dynamics, utilizing difference equations, were constructed to examine potential population-level consequences of these density and CO2 effects. In the absence of a persistent seed pool, the simula ted populations exhibited damped or stable oscillations under low germination values, but displayed non-cyclic ('chaotic') oscillations or went extinct for higher germination due to the complete failure of seed-set at high density. Because of its higher fecundity, the elevated-CO2 population generally exhibited greater oscillations, and the critical germination value at which the simulated populations went extinct was much lower for the elevated-CO2 than for the ambient-CO2 population.ˉN rB_r=&G &8r*&&3Ћ"r3 F&8Et &MN&M0&&O&G{r68^3^Bazzaz,F A^Coleman,J S^Morse,S R^1990^1^Growth Responses of Seven Major Co-occurring Tree Species of the Northeastern  United States to Elevated CO2^32^20^^1479-1484^^^^^^^^^^164^^^^^^^^^^^American beech/Fagus grandifolia/paper birch/Betula papyrifera/black cherry/Prunus serotina/white pine/Pinus strobus/red maple/Acer rubrum/sugar maple/Acer saccharum/eastern hemlock/Tsuga canadensis./eastern hemlock/Tsuga canadensis (L.) Carr.2ˉN0urI rA&G &C^162^Can. J. For. Res.3 F&8Et A&M&M0&&O&G$r &W&GN3zr rr rFFA^162^We examined how elevated CO2 affected the growth of seven co-occurring tree species: American beech (_Fagus grandifolia_ Ehrh.), paper birch (_Betula papyrifera_ Marsh.), black cherry (_Prunus serotina_ Ehrh.), white pine (_Pinus strobus_ L.), red maple (_Acer rubrum_ L.), sugar maple (_Acer saccharum_ Marsh.), and eastern hemlock (_Tsuga canadensis_ (L.) Carr.). We also tested whether the degree of shade tolerance of species and the age of seedlings affected plant responses to enhanced CO2 levels. Seedlings that were at least 1 year old, for all species except beech, were removed while dormant fr%om Harvard Forest, Petersham, Massachusetts. Seeds of red maple and paper birch were obtained from parent trees at Harvard& Forest, and seeds of American beech were obtained from a population of beeches in Nova Scotia. Seedlings and transplants were grown in one of four plant growth chambers for 60 d (beech, paper birch, red maple, black cherry) or 100 d (white pin*e, hemlock, sugar maple) under CO2 levels of 400 or 700 uL/L. Plants were then harvested for biomass and growth determinat2ions. The results showed that the biomass of beech, paper birch, black cherry, sugar maple, and hemlock significantly increased in elevated CO2, but the biomass of red maple and white pine only marginally increased in these conditions. Furtherm5ore, there were large differences in the magnitude of growth enhancement by increased levels of CO2 between species, so it; seems reasonable to predict that one consequence of rising levels of CO2 may be to increase the competitive ability of some species relative to others. Additionally, the three species exhibiting the largest increase in growth with increased CO>2 concentrations were the shade-tolerant species (i.e., beech, sugar maple, and hemlock). Thus, elevated CO2 levels may enHhance the growth of relatively shade-tolerant forest trees to a greater extent than growth of shade-intolerant trees, at least under the light and nutrient conditions of this experiment. We found no evidence to suggest that the age of tree seedKlings greatly affected their response to elevated CO2 concentration.6&&G^SRYԡ[ tgb&y >^Ԛ(6: S69^2^Bazzaz,F A^Fajer,E D^1992^1^Plant Life in CO2-Rich World^33^266^^68-74^^66SRb&y >^Ԛ(6: u eԋ_CC^165^Sci. Amer.u_ԋw+e+my+e+mԋw+_+kZ[nNV t~hZuNc+_@Fa+e@FW70^3^Bazzaz,F A^Garbutt,K^Williams,W E^1985^3^Effect of Increased Atmospheric Carbon Dioxide Concentration on Plant Communfities^Direct Effects of Increasing Carbon Dioxide on Vegetation^U.S. Dept. of Energy, Carbon Dioxide Research Division^Washington, D.C.^155-204^^^^^^^DOE/ER-0238^^^^^^^^^^^^^^^^^^^^^^^^Strain,BR^Cure,J D @^~t ;c u>i uc i71^3^Bazzaz,F A^Garbutt,K^Williams,W E^1985^5^The Effect of Elevated Atmospheric CO2 on Plant Communities^NTIS, U.S. Dept.q of Commerce, Springfield, Virginia^^^^^^^^^^^^^^^^^^^^^^^^^^TR023 in Yellow Report Series^DOE/EV/04329-5^Dept. of Energy, Carbon Dioxide Research Division^de Research Division^ ',, &t72^4^Bazzaz,F A^Garbutt,K^Reekie,E G^Williams,W E^1989^1^Using Growth Analysis to Interpret Competition between a C3 and a C4 Annual under Ambient and Elevated CO2^34^79^^223-235^^^^^^^^^^171^^^^^^^^^^^Abutilon theophrasti/Amaranthus retroflexusroflexus L.  (((0)9))))))(((((())))")*-*Y*L)&&&&&&&&&&'<'C^169^Oecologiap([(B(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p( /.,,,,, , , , , ,,,A^169^Detailed growth analysis in conjunction with information on leaf display and nitrogen uptake was used to interpret c ompetition between _Abutilon theophrasti_, a C3 annual, and _Amaranthus retroflexus_, a C4 annual, under ambient (350 uL/L ) and two levels of elevated (500 and 700 uL/L) CO2. Plants were grown both individually and in competition with each othe r. Competition caused a reduction in growth in both species, but for different reasons. In _Abutilon_, decreases in leaf a rea ratio (LAR) were responsible, whereas decreased unit leaf rate (ULR) was involved in the case of _Amaranthus_. Mean ca nopy height was lower in _Amaranthus_ than _Abutilon_ which may explain the low ULR of _Amaranthus_ in competition. The decrease in LAR of _Abutilon_ was associated with an increase in root:shoot ratio implying that _Abutilon_ was limited by competition for below ground resources. The root:shoot ratio of _Amaranthus_ actually decreased with competition, and _Amaranthus_ had a much higher rate of nitrogen uptake per unit of root than did _Abutilon_. These latter results suggest that _Amaranthus_ was better able to compete for below ground resources than _Abutilon_. Although the growth of both species was reduced by competition, generally speaking, the growth of _Amaranthus_ was reduced to a greater extent than that of _Abutilon_. Regression analysis suggests that the success of _Abutilon_ in competition was due to its larger starting capital (seed size) which gave it an early advantage over _Amaranthus_. Elevated CO2 had a positive effect upon biomass in _Amaranthus_, and to a lesser extent, _Abutilon_. These effects were limited to the early part of the experiment in the case of the individually grown plants, however. Only _Amaranthus_ exhibited a significant increase in relative growth rate (RGR). In spite of the transitory effect of CO2 upon size in individually grown plants, level of CO2 did effect final biomass of competitively grown plants. _Abutilon_ grown in competition with _Amaranthus_ had a greater final biomass than _Amaranthus_ at ambient CO2 levels, but this difference disappeared to a large extent at elevated CO2. The high RGR of _Amaranthus_ at elevated CO2 levels allowed it to overcome the difference in initial size between the two species.ddd' 73^1^Beer,S^1986^3^The Fixation of Inorganic Carbon in Plant Cells^Physiology, Yield, and Economics^CRC Press, Inc.^Boca Raton, Florida^3-11^^^^II^^Carbon Dioxide Enrichment of Greenhouse Crops^^^^173^^^^^^^^^^^^^^^^^^^^^Enoch,H^Kimball,B AB AA^172^The initial fixation of atmospheric inorganic carbon (CO2) in plant cells is carried out via either the C3 or C4 pathway. The first step of the C3 pathway is the fixation of CO2 by a five-carbon compound to yield two molecules of PGA (a three-carbon compound). PGA is subsequently reduced to form sugars. In the so-called C3 plants, this is the only pathway fo r incorporation of CO2. The enzyme (RuBPcase) catalyzing CO2 fixation in the C3 pathway may also act as an oxygenase. When! doing so, glycolate (a two-carbon compound) is formed together with PGA, and there is no net carbon gain of the process. "In the further metabolism of glycolate, CO2 is released. This is called photorespiration and its rate is, in contrast to m#itochondrial or dark respiration, strongly enhanced by O2 and light. In the C4 pathway, atmospheric CO2 is fixed, via the $enzyme PEPcase, by a three-carbon compound to yield one molecule of malate or aspartate (four-carbon compounds). In C4 pla%nts, this occurs in mesophyll cells. Malate or aspartate is then transported to bundle sheath cells where it is decarboxyl&ated, and the released CO2 is refixed via the C3 pathway. There is no apparent photorespiration in C4 plants, because CO2 'levels in the vicinity of RuBPcase are probably elevated and any CO2 released from the bundle sheath cells is efficiently (refixed via PEPcase in the mesophyll cells. In CAM plants, atmospheric CO2 is fixed into malate during the night while the) decarboxylation and refixation of CO2 occurs in the daytime. The C4 pathway provides C4 and CAM plants with an efficient *carbon-capturing system complementing the basic C3 pathway. In C4 plants this leads to a higher net CO2 incorporation rate+ than in C3 plants under high light and temperature regimes such as are found in the tropics. In CAM plants it allows for  nightly CO2 fixation in arid climates where opening of stomates during the day would cause excessive water loss..74^2^Beerling,D J^Chaloner,W G^1993^1^The Impact of Atmospheric CO2 and Temperature Change on Stomatal Density: Observatio+ns from _Quercus robur_ Lammas Leaves^35^71^^231-235^^^^^^^^^^176^^^^^^^^^^^Quercus roburur L.C^174^Ann. Bot..1A^174^A comparative study of leaves formed on shoots during the spring and summer (lammas) of _Quercus robur_ from three c92ontrasting geographical locations (Cardiff, Durham and London) gives a measure of the effect of temperature on stomatal de3nsity. This is of value in attempting to distinguish the effects of CO2 and temperature on observed stomatal density chang<4es under different CO2 and temperature conditions through the Quaternary. These leaves of normal and lammas shoots will haF5ve developed under similar CO2 levels but different environmental temperatures. Our results demonstrate that leaves formed6 under the warmer summer temperatures had reduced stomatal densities and indices from all sites, compared with their sprinI7g counterparts. This trend was also detected from measurements of spring and summer leaves made upon herbarium material coS8llected from the same tree in 1840. The results suggest that for _Q. robur_ temperature overrides the influence of irradia9nce intensity and small seasonal (75^2^Beerling,D J^Chaloner,W G^1993^1^Stomatal Density Responses of Egyptian _Olea europaea_ L. Leaves to CO2 Change Since 1327 BC^35^71^^431-435^^^^^^^^^^179^^^^^^^^^^^Olea europaea/olivelive~/C^177^Ann. Bot.AA^177^We have attempted to separate the effects of CO2 and temperature change on stomatal density by examining ancient leaBf material of _Olea europaea_ L. The distribution of this species is confined to a Mediterranean type climate, so that _O.C europaea_ leaves of different ages will have formed under similar temperatures but different CO2 levels over the last 300D0 years. Stomatal density measurements have been made upon leaves of _O. europaea_ originating from King Tutankhamun's tomEb dating from 1327 BC, and have been compared with values obtained from Egyptian _O. europaea_ material dating from pre-33F2 BC, 1818 and 1978 AD. Together, the four dates provide a record of how the plant has responded to increases in atmospherGic CO2 concentration during that time. The results demonstrate that in accordance with similar studies examining the stomaHtal density response of plants over three time scales (hundreds, thousands and tens of thousands of years) stomatal densitIy falls as CO2 levels increase. Since we have examined a natural system with leaves developing under similar environmentalJ temperatures the results confirm observations from experimental studies in which plants were grown under the same temperature but different CO2 regimes.      L76^6^Beerling,D J^Chaloner,W G^Huntley,B^Pearson,J A^Tooley,M J^Woodward,F I^1992^1^Variations in the Stomatal Density of M_Salix herbacea_ L. under the Changing Atmospheric CO2 Concentrations of Late- and Post-glacial Time^36^336^^215-224^^^^^^^^^^182^^^^^^^^^^^Salix herbaceaea L.?C^180^Phil. Trans. R. Soc. Lond. B.PA^180^The rapidly rising CO2 concentration of the past 200 years has been shown to be accompanied by a fall in stomatal deQnsity in the leaves of temperate trees. The present study attempts to investigate the relationship of atmospheric CO2 chanRge and stomatal density in the arctic-alpine shrub, _Salix herbacea_, over the longer time span of 11,500 years offered byS fossil leaves from post-glacial deposits. Comparisons of fossil material from Scotland and Norway are made with leaves frTom living populations growing in Austria, Greenland and Scotland. The Austrian material, from an altitudinal gradient betwUeen 2000 and 2670 m above sea level, gives added comparisons of contemporary differences of CO2 partial pressure with altiVtude. The results of our investigation indicate, rather surprisingly, that the rising CO2 concentration of the past 11,500W years has been accompanied by an increase in the stomatal density of _S. herbacea_ in contrast to the shorter-term observXations on the herbarium material of temperate trees. The most likely explanation appears to centre on the temperature and Ywater availability of the early post-glacial environment overriding the effect of the lower CO2 regime. However, the scaleZ of the time interval involved may also be significant. Natural selection over the 11,500 year period concerned may have f[avoured a different response to what is, in effect, an acclimatory response observed in trees within the period of rapid CO2 rise of the past 200 years..ۘ* xZ'3*p*@@ ]77^2^Beeson,R C,Jr^Graham,M E D^1991^1^CO2 Enrichment of Greenhouse Roses Affects Neither Rubisco nor Carbonic Anhydrase Activities^3^116^^1040-1045^^^^^^^^^^2059^^^^^^^^^^^Rosa hybrida/rose^^^^^  WordPerfect NC^183^J. Amer. Soc. Hort. Sci.  6.0     `78^2^Bellamy,L A^Kimball,B A^1986^3^CO2 Enrichment Duration and Heating Credit as Determined by Climate^Physiology, Yield,"a and Economics^CRC Press, Inc.^Boca Raton, Florida^168-197^^^^II^^Carbon Dioxide Enrichment of Greenhouse Crops^^^^186^^^^%^^^^^^^^^^^^^^^^^Enoch,HZ^Kimball,B AB A   (cA^185^To determine if it is economical to invest in CO2 enrichment equipment, a detailed economic analysis considering the4d increases in income and operating expenses should be performed. The procedure for such an analysis is straightforward (e.eg., Chapter 13) but it is necessary to make estimates of the percent increase in yield, the amount of CO2 used, and of any7f reduction in heating energy requirements resulting from a combustion-type CO2 generator. For any given greenhouse and croBgp, these three factors will vary with the local climate and in particular, with the outside air temperature, and global soEhlar radiation. It is practical to enrich with CO2 only while a greenhouse is closed and not ventilated. Therefore, CO2 enrPiichment duration equals day length minus ventilation time. Using Kimball's MEB program curves were generated which show thUje ventilation time fraction a 0.05 m3/m2/s capacity (47 greenhouse volume changes per hour) fan would need to operate to mYkaintain a given set point temperature as a function of transmitted solar radiation for various ambient air temperatures. S^limilar curves were generated showing the heating credit from a CO2 generator rated at 42.5 W/m2 (CO2 output 9.5 g/m2/h). Hbmourly solar radiation and temperature data for days typical of each month of the year for six climate regions were generatned using simple models from values of monthly mean minimum and maximum temperatures and mean total daily global radiation.eo Such data should be available nearby to most greenhouse locations. The hourly climate data for each of the typical monthlqpy days were used in conjunction with the ventilation time fraction curves to compute the ventilation requirement throughouqt the year for six locations--Oslo, Norway; De Bilt, Netherlands; Milan, Italy; Columbus, Ohio, U.S.; Tokyo, Japan; Tel Avuriv, Israel. The number of hours at which the greenhouse operated in five ventilation classes (0%, 0 to 20%, 20 to 50%, 50 sto 100%, 100%) for a 30C ventilation temperature setpoint were plotted. For all sites except Tel Aviv, enrichment is possxtible throughout the whole day during winter. At Oslo, a greenhouse can remain unventilated and enriched for up to 7 monthsu of the year. The areas in each ventilation class were measured to estimate the corresponding annual number of hours of povssible CO2 enrichment. From these CO2 enrichment duration values, the required amounts of CO2 can be estimated. The amountw of solar radiation received by the crop during each of the ventilation classes was also determined, so that the percent ixncrease in yield due to CO2 enrichment could be calculated. A greenhouse in Oslo can remain closed and CO2 enriched for 79y% of the total annual daylight hours, yet only 51% of the total radiation is received by the crop during this time. Using zthe assumption that yield is directly proportional to transmitted solar radiation, yields with and without CO2 enrichment {were compared for the six locations to assess the effect of climate on percent yield increase. Annual yields could be incr|eased 2% at Tel Aviv and 26% at Oslo if enrichment is limited to when the greenhouse remains completely closed. If CO2 is }pulsed into the greenhouse between intervals of fan operation, these CO2 response values can increase to 22 and 48%, respe~ctively. The effects on CO2 enrichment duration of using 'hot' CO2 from a combustion-type generator rather than 'cold' CO2 from other sources were computed for the Tel Aviv location. Using a 27C greenhouse air temperature for the ventilation setpoint, average daily CO2 enrichment duration (0% ventilation) was 4.0 hr during the winter using cold CO2, but decreased to 2.6 hr with hot CO2. Finally, the annual heating credit was determined for each of the six locations for 15C day heating setpoint, and the annual and winter savings in heating energy requirements were tabulated. The proportion of annual CO2 enrichment duration (0% ventilation) that was heating credit time ranged from 49% for Oslo to 8% for Tel Aviv."\79^2^Bentley,B L^Johnson,N D^1990^3^Plants as Food for Herbivores: The Roles of Nitrogen Fixation and Carbon Dioxide Enrichment^Plant-Animal Interactions: Evolutionary Ecology in Tropical and Temperate Regions^John Wiley & Sons, Inc.^^257-272^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^Price,PW^Lewinsotin,TM^Fernandes,GW^Benson,WWZi~~0XCF@80^2^Berntson,G M^Woodward,F I^1992^1^The Root System Architecture and Development of _Senecio vulgaris_ in Elevated CO2 and Drought^37^6^^324-333^^^^^^^^^^190^^^^^^^^^^^Senecio vulgaris^dpD$NsLp'oy!oF>^C^188^Funct. Ecol.d>$"8>F"dZz+!p'd#C@dd#CC$dCC+a *FS3A^188^1. The impact of elevated CO2 and drought on the architecture and development of root systems of _Senecio vulgaris_ was examined and implications for water and nutrient uptake discussed. Plants were grown in miniature rhizotrons to non-destructively monitor the development of roots _in situ_ at both an elevated (700 umol/mol) and ambient (350 umol/mol) atmospheric CO2 concentration and high or low supply of water. 2. CO2 and water had a significant impact on the way that _S. vulgaris_ root systems filled the soil matrix. Elevated CO2 resulted in more branched, longer root systems that foraged through larger volumes of soil. Under elevated CO2 and a low water supply, root systems had branching and foraging patterns and root length similar to those grown under ambient CO2 with a high water supply. 3. Overall, water had a more pronounced impact on the growth rate of _S. vulgaris_ roots than did CO2. The density of rooting remained unchanged across all treatments. Thus, under elevated CO2 the intensity of foraging _S. vulgaris_ root systems might be unchanged while the extent of  foraging by these root systems, as indicted by the horizontal spread of roots, may be increased.$ 6Fi?5T5Zr4581^1^Besford,R T^1990^1^The Greenhouse Effect: Acclimation of Tomato Plants Growing in High CO2, Relative Changes in Calvin Cycle Enzymes^38^136^^458-463^^^^^^^^^^192^^^^^^^^^^^Lycopersicon esculentum^^^^^^WO6P|PPGQNQQQ R"/ A^191^Tomato plants (cv. Findon Cross) were grown in a normal concentration of CO2 (approximately 340 vpm) or in elevated CO2 (1000 vpm) with a 12 h photoperiod of 400 umol quanta/m2/s, PAR. The activities of three Calvin cycle enzymes, RuBPco !(E.C. 4.1.1.39), 3 phosphoglyceric acid phosphokinase (E.C. 2.7.2.3) and NADP-dependent glyceraldehyde 3-phosphate dehydro6genase (E.C. 1.2.1.13) were determined in extracts from the unshaded 5th leaf during leaf development. RuBPco activity was reduced in the high-CO2 grown leaves at 60% expansion compared with leaves grown in 340 vpm CO2, but there were no appare9nt differences in the other two Calvin cycle enzymes at this stage of expansion. With subsequent leaf development in high FCO2 there was an accelerated decline in all three enzyme activities. The loss of RuBPco activity was studied further by raising antibodies to RuBPco and the large subunit of RuBPco (LSU) was detected in electroblotted crude extracts from normalI and high-CO2 grown plants. This specific immunoassay estimated a 75% reduction of LSU in the high-CO2 grown leaf at full Wexpansion.Xu7vX7vX7vX7vX7vX7vX7vX<8vX8vXvXvXvX7vXLvX]vXbvXlvXwvXvXvXvX4vXKvXRvXXvXvXvX[82^1^Besford,R T^1993^1^Photosynthetic Acclimation in Tomato Plants Grown in High CO2^123^104/105^^441-448^^^^^^^^^^195^^^^^^^^^^^Lycopersicon esculentum/tomato^^^^^^^^^^vX+vX+vX+vX+vX+vX+vX+vX+vX+vX,vX,vX,vX ,vX&,vX2,vXe,vX^wth and dinitrogen fixation in the vegetative growth stage were examined. 1. The whole plant weight of the cultivated soyb_A^193^The effects of prolonged CO2 enrichment of tomato plants on photosynthetic performance and Calvin cycle enzymes, including the amount and activity of ribulose-1,5-bisphosphate carboxylase (RuBPco), were determined. Also the light-saturatebd rate of photosynthesis (Pmax) of the 5th leaf throughout leaf development was predicted based on the amount and kineticso of RuBPco. With short-term CO2 enrichment, i.e. only during the photosynthesis measurements, Pmax of the young leaves did not increase while the leaves reaching full expansion more than doubled their net rate of CO2 fixation. However, with lonrger-term CO2 enrichment, i.e. growing the crop in high CO2, the plants did not maintain this photosynthetic gain. Compared| with leaves of plants grown in normal ambient CO2 the high CO2-grown leaves, when almost fully expanded, contained only about half as much RuBPco protein and Pmax in 300 and 1000 vpm CO2 was similarly reduced. The loss of RuBPco protein may be a factor associated with the accelerated fall in Pmax since Pmax was close to that predicted from the amount and kinetics of RuBPco assuming RuBP saturation. Acclimation to high CO2 is fundamentally different from acclimation to high light. In contrast to acclimation to high light, acclimation to high CO2 does not usually involve an increase in photosynthetic machinery so the synthesis and maintenance costs (as indicate by the dark respiration rate) are generally lower..0S183^2^Besford,R T^Hand,D W^1989^1^The Effects of CO2 Enrichment and Nitrogen Oxides on some Calvin Cycle Enzymes and Nitrite Reductase in Glasshouse Lettuce^39^40^^329-336^^^^^^^^^^198^^^^^^^^^^^Lactuca sativa L.N~C^196^J. Exp. Bot.A^196^Glasshouse lettuce (cvs Pascal and Talent) was grown during late autumn and early winter in an atmosphere polluted with nitrogen oxides (NOx) generated from direct-fired natural gas burners used for CO2 enrichment and warm air heating (high CO2 + NOx treatment). Concentrations of 0.3-0.4 vpm NOx were detected during the daytime when near 3-fold CO2 enrichment (1000 vpm) was practised without heating. In cold weather, the CO2 and NOx levels were dependent on the amount of heating required to maintain minimum temperatures of 5C (night) and 7C (day). Concentrations of between 2000-5000 vpm CO2 and 1-2.5 vpm NOx were recorded at night during an intensely cold period in early January just prior to sampling for leaf enzymes. The plants were compared with those grown in unpolluted atmospheres with either a natural (340 vpm) or an enriched level (1000 vpm) of CO2. Pascal grown in elevated CO2 had less activity per g fresh weight of RuBPc (E.C. 4.1.1.39), 3PGA phosphokinase (E.C. 2.7.2.3) and NADP-G3P dehydrogenase (E.C 12.1.13) than plants grown in a normal ambient CO2 atmosphere. The cytoplasmic enzyme PEPc (E.C. 4.1.1.31) was not significantly affected by the pure CO2 enrichment. With high CO2 + NOx the activities of the Calvin cycle enzymes were restored to values close to those present in non-enriched plants, while the activity of PEPc was increased. The activity of nitrite reductase (NiR) (E.C. 1.7.7.1) was increased in Pascal and Talent by high CO2 + NOx. Immunoblotting techniques were used to show that the increase in activity of this enzyme was accompanied by an increase in the steady state concentration of the protein. Only one molecular form of NiR was detected by immunoblotting, and it would appear that the 'induction' of NiR activity resulted from increased net enzyme synthesis rather than activation of pre-existing enzyme. At the time of sampling no visible damage by high CO2 and NOx was evident and the lack of symptoms may have been associated with the enhanced levels of nitrite reductase in these cultivars.84^3^Besford,R T^Ludwig,L J^Withers,A C^1990^1^The Greenhouse Effect: Acclimation of Tomato Plants Growing in High CO2, Photosynthesis and Ribulose-1, 5-_Bis_phosphate Carboxylase Protein^39^41^^925-931^^^^^^^^^^201^^^^^^^^^^^Lycopersicon esculentumumC^199^J. Exp. Bot.A^199^Tomato plants were grown in solution culture in a controlled environment at 20C with a 12 h photoperiod of 400 umol# quanta/m2/s PAR with either normal ambient CO2, approximately 340 vpm, or with 1000 vpm CO2. The short- and long-term eff/ects of CO2 enrichment on photosynthesis were determined together with the levels of ribulose-1,5-_bis_phosphate carboxyla3se (RuBPco) EC. 4.1.1.39 protein and activity throughout leaf development of the unshaded 5th leaf above the cotyledons. T6he high CO2 concentration during growth did not appreciably affect the rate of leaf expansion or final leaf area but did iBncrease the fresh weight per unit area of leaf. With short-term CO2 enrichment, i.e. only during the photosynthesis measurements, the light-saturated photosynthetic rate (Pmax) of young leaves did not increase while those reaching full expansioFn more than doubled their net rate of CO2 fixation. However, with longer term CO2 enrichment, i.e. growing the crop in higUh CO2, the plants did not maintain this photosynthetic gain. While the CO2 concentration during growth did not affect the peak in Pmax measured in 300 vpm CO2 or Pmax measured in 1000 vpm CO2, RuBPco protein or its activity, the subsequent ontoXgenetic decline in these parameters was greatly accelerated by the high CO2 treatment. Compared with plants grown in normal ambient CO2 the high CO2 grown leaves, when almost fully expanded, contained only approximately half as much RuBPco prot[ein and Pmax in 300 vpm CO2 and Pmax in 1000 vpm CO2 were similarly reduced. The loss of RuBPco protein may be a major facetor associated with the accelerated fall in Pmax since it was close to that predicted from the amount and kinetics of RubBPco assuming RuBP saturation. In the oldest leaves examined grown in high CO2 additional factors may be limiting photosynthhesis since RuBPco kinetics marginally overestimated Pmax in 300 vpm CO2 and the initial slope of photosynthesis in responrse to intercellular CO2 was also less than expected from the extractable RuBPco.@@ @ @ WPCs85^5^Betsche,T^Morin,F^Cotte,F^Gaugain,F^Andr,M^1989^3^Gas Exchanges, Chlorophyll _a_ Fluorescence, and Metabolite Levelsu in Leaves of _Trifolium subterraneum_ during Long-term Exposure to Elevated CO2^Progress in Photosynthesis Research, Proc|. VIIIth International Congress on Photosynthesis, Stockholm, Sweden, 1989^^^^^^^^^^^^^203^^^^^^^^^^^Trifolium subterraneuA^202^High CO2 stimulates photosynthesis of C3-plants initially, but then photosynthesis often declines and undesirable effects such as excessive starch accumulation and yellowing of leaves can occur. Results from chlorophyll _a_ fluorescence measurements and metabolite determinations indicate that high CO2 can perturb photosynthesis probably on the level of phosphate recycling. We propose that the absence of photorespiration in high CO2 causes phosphate deficiency in the chloroplast stroma and a low phosphorylation potential in the cytosol. Both conditions favour the synthesis of starch.86^1^Bhattacharya,N C^1992^3^Prospects of Agriculture in a Carbon Dioxide-enriched Environment^A Global Warming Forum: Scientific, Economic and Legal Overview^CRC Press, Inc.^Boca Raton, Florida^^^^^^^^^^^205^^^^^^^^^^^^^^^^^^^^^Geyer,R AA^204^The CO2 concentration in the atmosphere is steadily increasing. It has been predicted that it will double the preindustrial level (270 umol/mol) by the year 2080. Investigations conducted on different food and fiber crops in response to elevated CO2 in phytotrons, glasshouses, open-top chambers, SPAR units, and Face environments have generally showed increases in growth and yields of most of the crops, although some plants responded negatively to increased concentrations of CO2. The increased growth of plants in a CO2-enriched environment may rapidly deplete nutrients from the soil and consequently, positive effects of CO2 may not persist under low fertility levels. Similarly, interactive effects of high CO2 with high temperature may not be good for all plant species because of specific temperature requirements for each plant. In certain cases, plants may remain vegetative at high temperatures throughout the growth cycle. Therefore, cropping patterns may have to be modified with the increase in atmospheric temperature in the future world of high CO2. Interestingly, water use efficiency of plants in a CO2-enriched environment may have beneficial effects in tropical and subtropical regions of the world where water is limited for crop production. Elevated CO2 in the atmosphere results in increased concentrations of carbohydrates and 'dilution' of other metabolites such as chlorophyll, proteins, amino acids, carotene and reduced nutrients in plant tissues. Increasing atmospheric CO2 may alter plant/herbivore interactions. The impact of leaf-eating herbivores may increase as the level of atmospheric CO2 rises. Furthermore, C3 weeds may grow faster than C4 crops of agricultural importance in a CO2-enriched environment, and vice versa. In unmanaged ecosystems, these effects of elevated CO2 may cause marked changes.SUP\WP{WPC}.DLN\WP{WPC}.DLNWP}WPC{.GMKWP}WPC{.GKGMK.EXEC:\WP60\WP.FIL87^4^Bhattacharya,N C^Bhattacharya,S^Strain,B R^Biswas,PK^1989^1^Biochemical Changes in Carbohydrates and Proteins of Sweet Potato Plants (_Ipomoea batatas_ [L.] Lam.) in Response to Enriched CO2 Environment at Different Stages of Growth and Development^38^135^^261-266^^^^^^^^^^208^^^^^^^^^^^Ipomoea batatas/sweet potatosweet potatoo;5Hs8C^206^J. Plant Physiol.ggHP;5H8000A^206^Sweet potato (_Ipomoea batatas_ [L.] Lam., cv. Georgia Jet) plants were grown at different CO2 concentrations (350, 675 and 1000 umol/mol) in controlled environment conditions. The effect of CO2 enrichment on carbohydrate concentrations i n leaves, stems, roots and tubers at different stages of growth and development were investigated. The glucose, sucrose and starch concentrations in leaves increased during 0-35 days after planting as compared to stems and roots receiving incre ased CO2 concentrations. However, starch and glucose concentrations increased significantly in tubers during the 50-65 day interval which corresponded with rapid growth of tubers at high CO2 concentrations. Increasing CO2 concentrations did not raise the protein content of leaves, roots or tubers at any stages of growth and development. CO2 enrichment increased the soluble protein concentration in stems during the 20-50 day growth interval which subsequently decreased at maturity.88^5^Bhattacharya,N C^Bhattacharya,S^Strain,B R^Biswas,P K^Tolbert,M E M^1986^3^An Insight into the Mechanism of Auxin Action in Rooting Hypocotyl Cuttings of _Impatiens balsamina_ Grown in Phytotron under Enriched CO2 Environment^Proc., Thirte"enth Annual Meeting; 3-7 Aug. 1986; St. Petersburg Beach, Florida^Plant Growth Regulator Society of America, Department of( Citrus^Lake Alfred, Florida^92^^^^^^^^^^^^^^^^^^^^^Impatiens balsamina^^^^^^^^^^Wilson,WCWC\WPC60DOS\,89^3^Bhattacharya,N C^Bhattacharya,S^Strain,B R^1989^1^Isozyme Polymorphism during Rooting at Elevated CO2^28^24^^302-305^6^^^^^^^^^212^^^^^^^^^^^Impatiens balsaminana L.  """ RE:C^210^HortSci.HERC.VRSS0HGC 720x348 Monochromed>9A^210^The effects of CO2 enrichment and IAA on adventitious root formation of hypocotyl cuttings of _Impatiens balsamina_ FL. 'Camellia' were examined. Root numbers increased significantly at 675 and 1000 uL CO2/L compared to 350 uL/L. In the prIesence of IAA, the number of roots increased at 675 and 1000 uL CO2/L and the effect was most pronounced with 5 ug IAA/ml ]at 675 uL CO2/L. IAA-treated cuttings, compared to those in deionized water, exhibited slightly increased intensities of s ome of the isoperoxidases coinciding with root initiation and development in a CO2-enriched atmosphere. The data also indi`cate that at least two isozymes of peroxidase are associated with root development.VWPMAIN.WPBWPGEDIT.WPBn 90^5^Bhattacharya,N C^Biswas,P K^Bhattacharya,S^Sionit,N^Strain,B R^1985^1^Growth and Yield Response of Sweet Potato to Atmospheric CO2 Enrichment^12^25^^975-981^^^^^^^^^^215^^^^^^^^^^^sweet potato/Ipomoea batatasas (L.) Lam.z*WdWdWdqC^213^Crop Sci.   |A^213^Tuber growth of sweet potato (_Ipomoea batatas_) is a sink that may be limited by source capacity under present ambient CO2 levels. Hence, sweet potato may demonstrate more response to predicted increases in atmospheric CO2 than many other annual plants. The present investigation was undertaken to determine the long-term effects of CO2 enrichment on some physiological parameters, growth, and yield, as well as on the source-sink relationship in sweet potato at different stages of growth. Plants of the cultivar Georgia Jet were grown from stem cuttings in a mixture of gravel and vermiculite in controlled environment chambers at 350, 675, and 1000 uL/L CO2 and were irrigated with one-half strength Hoagland's solution. The temperature was 28C during 14-h days and 20C during 10-h nights. The length of main stem, total branch length, number of branches, and leaf area were increased for plants grown at 675 or 1000 uL/L CO2. The production of total dry matter of plants increased at each harvest interval in response to CO2 enrichment but it was greatest in 1000 uL/L CO2. Specific leaf weight also increased with increased CO2 concentration. The number and diameter of tubers increased at high CO2 concentration. At the final harvest, the dry weight of roots and tubers increased 1.8 and 2.6 times in plants grown at 675 and 1000 uL/L CO2, respectively, compared to those grown at 350 uL/L CO2. Carbon dioxide enrichment resulted in the modulation of sink capacity to enhance the production of tubers in sweet potato.[GH 1:&1:1: 1:1:1:^91^5^Bhattacharya,N C^Ghosh,P P^Bhattacharya,S^Hileman,D R^Biswas,P K^1988^1^Effects of Abscisic Acid on Rooting Stem Cuttings of Sweet Potato in Open Top Chambers under Enriched CO2 Environment^22^30^^204-209^^^^^^^^^^218^^^^^^^^^^^sweet potato/Ipomoea batatasas (L.) Lam.:/:/:_$` /: /:^/:/:/:&/: /:/:/:_/:/: C^216^Biol. PlantarumL0:[L0:L0:q`) :] :Q :>:`M T\::Y::[::Z::::::::::S::d:A^216^Ten centimeter long stem cuttings of sweet potato (_Ipomoea batatas_ L. cv. Georgia Jet) with intact apex and leaves were cultured in distilled water as well as in varying concentrations of abscisic acid (ABA) in open top chambers at 364,! 438 and 666 cm3/m3 CO2. Low concentration of ABA promoted rooting and elongation of roots at 364 cm3/m3 CO2 while rooting" was suppressed at enriched levels of CO2. However, biomass production in shoots and roots was higher in 666 than in 364 cm3/m3 CO2.b ?=:"?=:+-$3:2:,:/:5: 8:&: ):H8s8se9s=s =s=$92^6^Bhattacharya,N C^Hileman,D R^Ghosh,P P^Musser,R L^Bhattacharya,S^Biswas,P K^1990^1^Interaction of Enriched CO2 and Wa%ter Stress on the Physiology of and Biomass Production in Sweet Potato Grown in Open-top Chambers^16^13^^933-940^^^^^^^^^^221^^^^^^^^^^^sweet potato/Ipomoea batatas^^^^^.) Lam.=gggh~iik&' C^219^Plant Cell Environ.)0  <O$H Mk<=l=== = >@H>^>[I O O O1=>>0(A^219^The objective of this study was to investigate the effects of water stress in sweet potato (_Ipomoea batatas_ L. [La)m.] 'Georgia Jet') on biomass production and plant-water relationships in an enriched CO2 atmosphere. Plants were grown in* pots containing sandy loam soil (Typic Paleudult) at two concentrations of elevated CO2 and two water regimes in open-top+ field chambers. During the first 12 d of water stress, leaf xylem potentials were higher in plants grown in a CO2 concent,ration of 438 and 666 umol/mol than in plants grown at 364 umol/mol. The 364 umol/mol CO2 grown plants had to be rewatered- 2 d earlier than the high CO2-grown plants in response to water stress. For plants grown under water stress, the yield of. storage roots and root:shoot ratio were greater at high CO2 than at 364 umol/mol; the increase, however, was not linear w/ith increasing CO2 concentrations. In well-watered plants, biomass production and storage root yield increased at elevated CO2, and these were greater as compared to water-stressed plants grown at the same CO2 concentration.[ 193^4^Bhattacharya,S^Bhattacharya,NC^Biswas,P K^Strain,B R^1985^1^Response of Cow Pea (_Vigna unguiculata_ L.) to CO2 Enric$2hment Environment on Growth, Dry-matter Production and Yield Components at Different Stages of Vegetative and Reproductive Growth^40^105^^527-534^^^^^^^^^^224^^^^^^^^^^^cowpea/Vigna unguiculatata L..rrr?08ś@כH㛀08'&C^222^J. Agric. Sci. Camb.azmkWPCC60XX.DTL 5A^222^This study examines the effects of increased atmospheric carbon dioxide concentrations on vegetative and reproductiv*6e growth and partitioning of biomass during pod and seed development of cow pea in controlled environment chambers at 350,37 675, and 1000 uL CO2/L. The length of main stem and branches, the number of leaves and branches, and leaf area were all g8reater at high CO2 than at low CO2 concentration. The appearance of flowers was 10-12 days earlier in high CO2 than in amb89ient CO2 atmosphere. The senescence of leaves started about 7 days earlier in plants grown at 675 and 1000 uL CO2/L than i=:n those grown at 350 uL CO2/L. The rate of leaf senescence was more rapid in 1000 uL/L than in 675 uL CO2/L. The dry weigh@;t of roots, stems and leaves increased with CO2 enrichment, being greater in 675 uL/L than in 1000 uL CO2/L. Plants grown ent caused a significant increase in the total number and weight of seeds as well as pods, it did not affect the ratio of ?seed dry weight to the total dry weight of above-ground plant parts (harvest index). It is concluded from the present inveN@stigation that CO2 enrichment significantly enhanced vegetative as well as reproductive growth resulting in the increase i`n yield and early plant maturation in this leguminous crop.B94^3^Bhattacharya,S^Bhattacharya,NC^Strain,B R^1985^1^Rooting of Sweet Potato Stem Cuttings under CO2-enriched Environmentc and with IAA Treatment^28^20^^1109-1110^^^^^^^^^^227^^^^^^^^^^^sweet potato/Ipomoea batatasas (L.)n3C^225^HortSci.EA^225^Stem cuttings of sweet potato (_Ipomoea batatas_ L. 'Georgia Jet') with intact apex and leaves were cultured in wateqFr or in different concentrations of IAA and were maintained in controlled environment chambers at 350, 675, or 1000 ppm CO~G2. The temperature was 20C during a 14-hr day and 14 during a 10-hr dark period. The photosynthetic photon flux density Hwas 550 umol/s/m2 (27.7 mol/m2/day). Elevated CO2 concentrations stimulated the production of roots in the presence of IAA, and this effect was more pronounced at 675 ppm than at 1000 ppm CO2 atmosphere.J95^4^Bhattacharya,S^Eatman,J F^Biswas,P K^Tolbert,M E M^1988^1^CO2 Enrichment and its Relationship to Bioconversion of CelKlulosic Biomass of Sweet Potato (_Ipomoea batatas_ L.) into Fermentable Sugars^41^15^^259-268^^^^^^^^^^230^^^^^^^^^^^sweet potato/Ipomoea batatas^^^^^.)CC^228^BiomassNA^228^Sweet potatoes (_Ipomoea batatas_ L. (Lam.) 'Georgia-Jet') were grown in open field plots and open top chambers at COO2 concentrations of 354, 531, 506 and 659 uL/L for 90 days. The leaves and stems after the harvest were used as substratePs for the production of fermentable sugars. Elevated CO2 concentrations increased the cellulose content of stems, being moQst pronounced at 506 uL/L. Hemicellulose content of leaves and stems as well as lignin content of stems decreased as a resRult of CO2 enrichment. The increase in cellulosic biomass in plants grown in CO2 enriched environment resulted in increaseSd conversion of cellulose into fermentable sugars. The saccharification was greater in stems than in leaves. It was also fTound that chemical pretreatment of stems and leaves enhanced the enzymatic hydrolysis and the yields of glucose were higher than those from untreated stems and leaves.V96^7^Biswas,P K^Hileman,D R^Allen,J R^Bhattacharya,N C^Lu,J Y^Pace,R D^Rogers,H H^1985^5^Field Studies of Sweet Potatoes aWnd Cowpeas in Response to Elevated Carbon Dioxide^U.S. Dept. of Energy, Carbon Dioxide Research Division, Washington, D.C.X, and Tuskegee University, Tuskegee, Alabama^^^^^^^^^^^^^^^^^^^^^^^^sweet potato/cowpea/Ipomoea batatas/Vigna unguiculata^^022 in Green Report Series^Response of Vegetation to Carbon Dioxide^^^^on Dioxide^^!~(TZ97^7^Biswas,P K^Hileman,D R^Bhattacharya,N C^Ghosh,P P^Bhattacharya,S^Johnson,J H^Mbikayi,NT^1986^5^Growth, Yield and Plan[t Water Relationships in Sweet Potatoes in Response to Carbon Dioxide Enrichment^U.S. Dept. of Energy, Carbon Dioxide Rese\arch Division, Washington, D.C., and Tuskegee University, Tuskegee, Alabama^^^^^^^^^^^^^^^^^^^^^^^^sweet potato/Ipomoea batatas^^030 in Green Report Series^Response of Vegetation to Carbon Dioxide^^Dioxide^^ioxide^^^98^1^Black,C C,Jr^1986^3^Effects of CO2 Concentration on Photosynthesis and Respiration of C4 and CAM Plants^Physiology, Y_ield, and Economics^CRC Press, Inc.^Boca Raton, Florida^29-40^^^^II^^Carbon Dioxide Enrichment of Greenhouse Crops^^^^234^^^^^^^^^^^^^^^^^^^^^Enoch,HZ^Kimball,BAAB AddU<k d f e h g j i < @)yaA^233^With C4 plants, CO2 enrichment will have a small, probably less than 25%, enhancement of plant growth or biomass probduction. However, water use efficiency will increase severalfold with a doubling or tripling of air CO2 levels. With CAM pclants, CO2 enrichment should be done at night. Little daytime CO2 uptake occurs in most CAM plants, but enrichment late ind the day and at night likely will be beneficial to growth. No long-term growth work has been done with CO2 enrichment and the production of CAM plants, but the available research indicates night enrichment should be beneficial.f99^4^Bolin,B^Doos,BR^Jager,J^Warrick,RA^1986^2^The Greenhouse Effect, Climatic Change, and Ecosystems^John Wiley & Sons^New York^^Y^^^^^^^^^^^^^^^^^^^^^^^^^^͊G{Íۍh100^3^Boone,M Y L^Rickman,R W^Whisler,F D^1990^1^Leaf Appearance Rates of Two Winter Wheat Cultivars under High Carbon Dioxide Conditions^4^82^^718-724^^^^^^^^^^238^^^^^^^^^^^wheat/Triticum aestivumum L.W#WLWpH8o LC^236^Agron. J.&7*x`GnQJ()HP LaserJet 4              kA^236^The mechanisms describing leaf appearance and tillering are vital to the modeling of wheat canopy development. How t lhese two factors will be affected by increasing global atmospheric [CO2] in cool or warm climates is not fully understood.m Two southeastern USA adapted wheat (_Triticum aestivum_ L.) cultivars, Coker 762 and Stacy, were grown under nearly nonlinmiting conditions including elevated [CO2] (600 uL/L) and under six air temperature regimes (ranging from 4/-1 to 18/7C do/night and progressively increasing to 16/4 to 29/18C d/night during the season) to observe leaf and tiller appearance ra%ptes and to compare tillering rates to those predicted by the Fibonacci series as approximated by Binet's equation. Both cuqltivars exhibited an abrupt one-time change in their phyllochron interval for all six temperatures. This change occurred j)rust prior to double ridge formation. The vegetative growth phase phyllochron interval of the two cultivars was significant2sly different only in the 21/10C temperature treatment. In the two lowest temperature treatments (16/4 and 18/7C), the cutltivars differed in phyllochron interval during the reproductive growth phase. The tillering rate of wheat followed closel6y the theoretical development predicted by Binet's equation during the vegetative phase of development.Av101^2^Bottner,P^Couteaux,M M^1991^3^Effect of Plant Activity on Decomposition: Soil-plant Interactions in Response to Incrweasing Atmospheric CO2 Concentration^Ecosystem Research Report No.1, Decomposition and Accumulation of Organic Matter in TDxerrestrial Ecosystems: Research Priorities and Approaches; 1991 Sept. 2-4; Doorwerth, The Netherlands^^^^^^^^^^^^^^^^^^^^^M^^^^^^^^^^^^^van Breemen,N@H'@@5z102^2^Bottner,P^Couteaux,M M^1992^3^Reponse de la Matiere Organique des Sols^Les Recherches en France sur les Ecosystemes PForestiers^Ministere de l'Agriculture et de la Foret^Paris^25-26^^^^^^^^^^241^^^^^^^^^^^^^^^^^^^^^Landmann,GF XA^240^In French.4(P-'0(#(#  h)}103^3^Bottomley,P A^Rogers,H H^Prior,S A^1993^1^NMR Imaging of Root Water Distribution in Intact _Vicia faba_ L. Plants in] Elevated Atmospheric CO2^16^16^^335-338^^^^^^^^^^244^^^^^^^^^^^Vicia faba/broad bean beaneiC^242^Plant Cell Environ.A^242^The effect of elevated atmospheric CO2 on water distribution in the intact roots of _Vicia faba_ L. bean seedlings ghrown in natural soil was studied noninvasively with proton (1-H) nuclear magnetic resonance (NMR) imaging. Exposure of 24-od-old plants to atmospheric CO2 enriched air at 675 cm3/m3 produced significant increase in water imaged in upper roots, hypogeal cotyledons and lower stems in response to a short-term drying-stress cycle. Above ground, drying produced negligibrle stem shrinkage and stomatal resistance was unchanged. In contrast, the same drying cycle caused significant depletion o|f water imaged in the same upper root structures in control plants subject to ambient CO2 (350 m3/m3), and stem shrinkage and increased stomatal resistance. The results suggest that inhibition of transpiration caused by elevated CO2 does not ne~cessarily result in attenuation of water transport from lower root structures. Inhibition of water loss from upper roots and lower stem in elevated CO2 environments may be a mitigating factor in assessing deleterious effects of greenhouse changes on crops during periods of dry climate.US , 104^1^Bouwman,A F^1990^2^Soils and the Greenhouse Effect^John Wiley & Sons, Ltd.^New York^^N^^^^^^^^^105^1^Bowes,G^1991^1^Growth at Elevated CO2: Photosynthetic Responses Mediated through Rubisco^16^14^^795-806^^^^^^^^^^248~C^246^Plant Cell Environ.A^246^The global uptake of CO2 in photosynthesis is about 120 gigatons (GT) of carbon per year. Virtually all passes through one enzyme, ribulose bisphosphate carboxylase/oxygenase (rubisco), which initiates both the photosynthetic carbon reduction, and photorespiratory carbon oxidation, cycles. Both CO2 and O2 are substrates; CO2 also activates the enzyme. In C3 plants, rubisco has a low catalytic activity, operates below its Km(CO2), and is inhibited by O2. Consequently, increases in the CO2/O2 ratio stimulate C3 photosynthesis and inhibit photorespiration. CO2 enrichment usually enhances the productivity of C3 plants, but the effect is marginal in C4 species. It also causes acclimation in various ways: anatomically, morphologically, physiologically or biochemically. So, CO2 exerts secondary effects in growth regulation, probably at the molecular level, that are not predictable from its primary biochemical role in carboxylation. After an initial increase with CO2 enrichment, net photosynthesis often declines. This is a common acclimation phenomenon, less so in field studies, that is ultimately mediated by decline in rubisco activity, though the RuBP/Pi-regeneration capacities of the plant may play a role. The decline is due to decreased rubisco protein, activation state, and/or specific activity, and it maintains the rubisco fixation and RuBP/Pi-regeneration capacities in balance. Carbohydrate accumulation is sometimes associated with reduced net photosynthesis, possibly causing feedback inhibition of the RuBP/Pi-regeneration capacities, or chloroplast disruption. As exemplified by field-grown soybeans and salt marsh species, a reduction in net photosynthesis and rubisco activity is not inevitable under CO2 enrichment. Strong sinks or rapid translocation may avoid such acclimation responses. Over geological time, aquatic autotrophs and terrestrial C4 and CAM plants have genetically adapted to a decline in the external CO2/O2 ratio, by the development of mechanisms to concentrate CO2 internally; thus circumventing O2 inhibition of rubisco. Here rubisco affinity for CO2 is less, but its catalytic activity is greater, a situation compatible with a high-CO2 internal environment. In aquatic autotrophs, the CO2 concentrating mechanisms acclimate to the external CO2, being suppressed at high CO2. It is unclear, whether a doubling in atmospheric CO2 will be sufficient to cause a de-adaptive trend in the rubisco kinetics of future C3 plants, producing higher catalytic activities.qWP_WP_US^^^^^^^^^^^^^^^^ WPCH_*.WPMM&M&@*.WPBWPGEDIT.WPB < >   106^3^Bowes,G^Rowland-Bamford,A J^Allen,LH,Jr^1990^3^Regulation of Rubisco Activity of Carboxyarabinitol-1-Phosphate and Elevated Atmospheric CO2 in Rice and Soybean Cultivars^^Kluwer Academic Publishers^The Netherlands^399-402^^^^III^^Current Research in Photosynthesis^^^^250^^^^^^^^^^^rice/Oryza sativa/soybean/Glycine max^^^^^^^^^^Baltscheffsky,My,MA^249^The degree of rubisco dark inhibition not only shows species, but also intercultivar, and development differences. As with total activity, rubisco activation is developmentally influenced; so for rice, assays of whole leaf extracts integrate various rubisco states. The growth CO2 and temperature have interactive effects on the activity, activation, and dark inhibition of rice rubisco. Detrimental temperature effects on total rubisco activity may be compounded by elevated atmospheric CO2. $107^2^Bowman,W D^Strain,B R^1987^1^Interaction between CO2 Enrichment and Salinity Stress in the C4 Non-halophyte _Andropogon glomeratus_ (Walter) BSP^16^10^^267-270^^^^^^^^^^253^^^^^^^^^^^Andropogon glomeratusus (Walter) BSP൧,:'C^251^Plant Cell Environ.:^:: :: :Q:Q::4A^251^Increasing atmospheric CO2 may result in alleviation of salinity stress in salt-sensitive plants. In order to assess the effect of enriched CO2 on salinity stress in _Andropogon glomeratus_, a C4 non-halophyte found in the higher regions 7of salt marshes, plants were grown at 350, 500 and 650 cm3/m3 CO2 with 0 or 100 mol/m3 NaCl watering treatments. IncreasesB in leaf area and biomass with increasing CO2 were measured in salt-stressed plants, while decreases in these same parameters were measured in non-salt-stressed plants. Tillering increases substantially with increasing CO2 in salt-stressed planEts, resulting in the increased biomass. Six weeks following initiation of treatments, there was no difference in photosyntRhesis on a leaf area basis with increasing CO2 in salt-stressed plants, although short-term increases probably occurred. Stomatal conductance decreased with increasing CO2 in salt-stressed plants, resulting in higher water-use efficiency, and mUay have improved the diurnal water status of the plants. Concentrations of Na+ and Cl- were higher in salt- stressed plantls, while the converse was found for K+. There were no differences in leaf ion content between CO2 treatments in the salt-stressed plants. Decreases in photosynthesis in salt-stressed plants occurred primarily as a result of decreased internal (onon-stomatal) conductance.3*2 z108^1^Bown,A W^1985^1^CO2 and Intracellular pH^16^8^^459-465^^^^^^^^^^25656wp_wp_XX.qrsC^254^Plant Cell Environ.~DP@-5jx"}A^254^The experimental determination of cytoplasmic and vacuolar pH values is discussed. Despite variation in these values evidence indicates that intracellular pH values are normally regulated within narrow limits. The regulatory mechanisms proposed involve the metabolic consumption of OH- and the active efflux of H+. The evidence for intracellular pH modification in response to CO2 hydration and the production of HCO3- and H+ is examined. Theoretical calculations and experimental data indicate that CO2 concentrations as high as 5% will lower intracellular pH. Conversely, variation in CO2 levels around atmospheric concentrations is unlikely to perturb intracellular pH. High CO2 levels are found in bulky tissues, and flooded root systems. Evidence is presented that the slow diffusion of dissolved CO2 compared to gaseous CO2 results in its accumulation. It is proposed that the accumulation of respiratory CO2 may reduce intracellular pH values when plant tissues, cells or protoplasts are maintained in a liquid culture medium. Finally, the possible role of dark CO2 fixation and organic acid synthesis in the regulation of intracellular pH is examined. PPT:S+;V6WUlWJQQQYXZZY[ZY\X.YY&R@ R@R109^1^Bravdo,B^1986^3^Effect of CO2 Enrichment on Photosynthesis of C3 Plants^Physiology, Yield, and Economics^CRC Press, Inc.^Boca Raton, Florida^13-27^^^^II^^Carbon Dioxide Enrichment of Greenhouse Crops^^^^^^^^^^^^^^^^^^^^^^^^^Enoch,HZ^Kimball,BA AB AtI110^3^Breen,P J^Hesketh,J D^Peters,D B^1986^1^Field Measurements of Leaf Photosynthesis of C3 and C4 Species under High Irradiance and Enriched CO2^42^20^^281-285^^^^^^^^^^260^^^^^^^^^^^Glycine max/soybean/Gossypium hirsutum/cotton/Phaseolus vulgaris/bean/Vigna unguiculata/cowpea/Amaranthus hybridus/pigweednthus hybridus L./pigweedC^258^Photosynthetica 03C^264^Tree Phsiol.wxyz{|}~N113^1^Brown,K R^1989^6^Effects of Nitrogen Availability and Atmospheric Carbon Dioxide Enrichment on Growth, Water Use, and Nutrition of Seedlings of Boreal Trees^^University of Alberta^^Doctoral Dissertation^^^Dissertation Abstracts Vol. 50:07Q-B, p.2703^^^^^^^267^^^^^^^^^^^Populus tremuloides/Picea glauca*$*$*$*$*$*$*$*$*$*$*$*$*))))-7  #$##$!#bA^266^Seedlings of two boreal tree species were studied. _Populus tremuloides_ dominates early successional, relatively fertile sites; _Picea glauca_ dominates later successional sites with slower rates of nutrient turnover. Seedlings were growen for 100 days at ambient (350 uL/L) or high (750 uL/L) levels of atmospheric CO2 and fertilized with high-N (15.5 mM-N, mledium-N (1.55 mM-N), or low-N (0.155 mM-N) solutions. High CO2 increased leaf and total mass of high-N _Picea_, and root moass of low-N _Picea_ after 100 days. High CO2 increased mass, height, and leaf area of _Populus_ at 30 days in the high-N sregime, at 40 days in the medium-N regime, and at 60 days in the low-N regime; in each treatment, effects did not persist to the following harvest. High CO2 accelerated the time-dependent decreases in concentrations of N and P (all N treatmentsw) and Ca and Mg (high-N and medium-N treatments) to deficient levels, preventing the continuation of growth enhancement. In a second experiment, the effects of CO2 enrichment to 650 uL/L were examined with plant N concentrations held constant at high or low levels using the relative addition technique of nutrient supply. In the high-N regime, elemental concentrations were higher in _P. tremuloides_ than in _P. glauca_ and were unaffected by CO2 enrichment. Relative growth rates (RGR) and net assimilation rates (NAR) of _Picea_ (high-N regime) and of _Populus_ (high-N, low-N) increased with CO2 enrichment. The absolute effect of CO2 enrichment on NAR increased with foliar N content and was greater in _Populus_ at a given foliar concentration of N. Nitrogen status had greater effects on root:shoot ratios of _Picea_ than of _Populus_; CO2 enrichment did not affect root:shoot ratios in either species. High CO2 reduced transpiration by 60% in _Populus_ under both N regimes, but did not affect transpiration by _Picea_. Nitrogen productivity of _Populus_ may have increased with CO2 enrichment. Thus, methods of nutrient supply may affect plant nutrient status over time and therefore affect plant response to CO2 enrichment. The effect of CO2 enrichment increases with nutrient status and is potentially greater in early successional boreal trees, given adequate nutrient supplies..HA:\COVER.LTR 114^2^Brown,K^Higginbotham,K O^1986^1^Effects of Carbon Dioxide Enrichment and Nitrogen Supply on Growth of Boreal Tree Seedlings^43^2^^223-232^^^^^^^^^^270^^^^^^^^^^^Picea glauca/white spruce/Populus tremuloides/aspenremuloides Michx./aspenC^268^Tree Physiol.bA^268^The effects of two levels of atmospheric carbon dioxide (350 uL/L, 750 uL/L) and three levels of nitrogen (15.5 mM, 1.55 mM, 0.155 mM N) on biomass accumulation and partitioning were examined in aspen (_Populus tremuloides_ Michx.) and white spruce (_Picea glauca_ (Moench) Voss) seedlings grown in controlled environment rooms for 100 days after germination. Nitrogen supply had pronounced effects on biomass accumulation, height, and leaf area of both species. Root weight ratio of white spruce was significantly increased at the lowest level of nitrogen, whereas RWR of aspen did not change much with increasing levels of nitrogen. Carbon dioxide enrichment significantly increased (1) the leaf and total biomass of spruce seedlings grown in the high-N regime, (2) the RWR of seedlings in the medium-N regime, and (3) the root biomass of seedlings in the low-N regime after 100 days. Carbon dioxide enrichment of aspen temporarily increased biomass and height in all three nitrogen regimes. Root, stem, and leaf mass, height, and leaf area of aspen were increased only at the 30-day harvest in the high-N treatment and at 50 and 60 days in the low-N treatment. Height, stem biomass, and leaf biomass of aspen se edlings were significantly increased by CO2 enrichment after 40 days in the medium-N treatment. These effects did not persist, possibly because of the onset of mineral nutrient supply limitations with increasing plant size.*.vrs*.irs*.arsst 115^4^Brugink,G T^Wolting,H G^Dassen,J H A^Bus,V G M^1988^1^The Effect of Nitric Oxide Fumigation at Two CO2 Concentration s on Net Photosynthesis and Stomatal Resistance of Tomato (_Lycopersicon lycopersicum_ L. cv. Abunda)^23^110^^185-191^^^^^^^^^^273^^^^^^^^^^^Lycopersicon lycopersicumum L.r7:u7:{7: i7:l7: o7:H$3:%0:$3:C^271^New Phytol. >* -[](      ?* -[]      Ӗ'0( A^271^Net photosynthesis of 5-week-old tomato plants (_Lycopersicon lycopersicum_ L. cv. Abunda was measured in clean air or with NO fumigation, for five consecutive days under simulated winter glasshouse conditions: temperature 22C, VPD 0.4 kPa, irradiance 30 W/m2 and daylength 8-9 h. NO concentrations applied were 0 or 1 uL/L in combination with CO2 concentrations of 350 or 1000 uL/L. A reduction in net photosynthesis due to NO became apparent in the third day of measurement. On the fifth day this reduction was 38% of the control at 350 uL/L CO2 and 24% at 1000 uL/L CO2. The increase in photosynthesis due to CO2 enrichment was initially 50%; this effect was strongly reduced after 5 d in the presence of NO. Plants did no"t recover in the dark after the daily fumigation treatment, the level to which photosynthesis was reduced at the end of th5e day being the level at which it started the next day. The decrease in photosynthesis could not be explained by an increa9sed stomatal resistance, and the plants did not show visible symptoms of injury. Practical implications of the results are< discussed.*A)$Fn\RI ^jL8Wm=`p  ^?116^5^Brugnoli,E^Hubick,K T^von Caemmerer,S^Wong,S C^Farquhar,G D^1988^1^Correlation between the Carbon Isotope Discrimination in Leaf Starch and Sugars of C3 Plants and the Ratio of Intercellular and Atmospheric Partial Pressures of Carbon DioBxide^17^88^^1418-1424^^^^^^^^^^276^^^^^^^^^^^Populus nigra/Populus deltoides/Gossypium hirsutum/Phaseolus vulgaris^^^^^ulKgaris L. "#$%'0$*06<jqx    !"$%&(),-.2O~^-O C^274^Plant Physiol.ii_WA^274^Carbon isotope discrimination ([delta]) was analyzed in leaf starch and soluble sugars, which represent most of the recently fixed carbon. Plants of three C3 species (_Populus nigra_ L. x _P. deltoides_ Marsh., _Gossypium hirsutum_ L. andZ _Phaseolus vulgaris_ L.) were kept in the dark for 24 hours to decrease contents of starch and sugar in leaves. Then gas d!exchange measurements were made with constant conditions for 8 hours, and subsequently starch and soluble sugars were extrh"acted for analysis of carbon isotope composition. The ratio of intercellular, _Pi_, and atmospheric, _Pa_, partial pressur#es of CO2 was calculated from gas exchange measurements, integrated over time and weighted by assimilation rate, for compal$rison with the carbon isotope ratios in soluble sugars and starch. Carbon isotope discrimination in soluble sugars correlat%ted strongly (_r_=0.93) with _Pi/Pa_ in all species, as did delta in leaf starch (_r_=0.84). Starch was found to contain s&ignificantly more 13C than soluble sugar, and possible explanations are discussed. The strong correlation found between [dx'elta] and _Pi/Pa_ suggests that carbon isotope analysis in leaf starch and soluble sugars may be used for monitoring, indi(rectly, the average of _Pi/Pa_ weighted by CO2 assimilation rate, over a day. Because _Pi/Pa_ has a negative correlation w)ith transpiration efficiency (mol CO2/mol H20) of isolated plants, delta in starch and sugars may be used to predict diffe*rences in this efficiency. This new method may be useful in ecophysiological studies and in selection for improved transpiration efficiency in breeding programs for C3 species.ms*xR+xr+o*--+=<=>~~ ===/c~<~>`:~^,117^2^Bugbee,B G^Salisbury,F B^1988^1^Exploring the Limits of Crop Productivity. I. Photosynthetic Efficiency of Wheat in High Irradiance Environments^17^88^^869-878^^^^^^^^^^279^^^^^^^^^^^wheat/Triticum aestivumum L.C^277^Plant Physiol.svvyyyyyyyy/A^277^The long-term vegetative and reproductive growth rates of a wheat crop (_Triticum aestivum_ L.) were determined in t0hree separate studies (24, 45, and 79 days) in response to a wide range of photosynthetic photon fluxes (PPF, 400-2080 mic1romoles per square meter per second; 22-150 moles per square meter per day; 16-20-hour photoperiod) in a near-optimum, con2trolled-environment. The CO2 concentration was elevated to 1200 micromoles per mole, and water and nutrients were supplied3 by liquid hydroponic culture. An unusually high plant density (2000 plants per square meter) was used to obtain high yiel4ds. Crop growth rate and grain yield reached 138 and 60 grams per square meter per day, respectively; both continued to in5crease up to the highest integrated daily PPF level, which was three times greater than a typical daily flux in the field.6 The conversion efficiency of photosynthesis (energy in biomass/energy in photosynthetic photons) was over 10% at low PPF 7but decreased to 7% as PPF increased. Harvest index increased from 41 to 44% as PPF increased. Yield components for primar8y, secondary, and tertiary culms were analyzed separately. Tillering produced up to 7000 heads per square meter at the hig9hest PPF level. Primary and secondary culms were 10% more efficient (higher harvest index) than tertiary culms; hence cult:ural, environmental, or genetic changes that increase the percentage of primary and secondary culms might increase harvest; index and thus grain yield. Wheat is physiologically and genetically capable of much higher productivity and photosynthetic efficiency than has been recorded in a field environment.^YXSQ|r-D t'ttD dDDD\[DD\=118^1^Bunce,J A^1993^1^Effects of Doubled Atmospheric Carbon Dioxide Concentration on the Responses of Assimilation and Co>nductance to Humidity^16^16^^189-197^^^^^^^^^^282^^^^^^^^^^^Amaranthus hypochondriacus/amaranth/Dactylis glomerata/orchard grass/Glycine max/soybean/Helianthus annuus/sunflowerus annuus L./sunflowerSQRWttd\ t9 t43ɋDp${s -C^280^Plant Cell Environ.${"rfD${s DFE>tf>u_rZ:t!A&E%:uAFD!AA^280^Experiments were performed to determine if growth at elevated partial pressure of CO2 altered the sensitivity of leaBf water vapour conductance and rate of CO2 assimilation to the leaf-to-air difference in the partial pressure of water vapCour (delta w). Comparisons were made between plants grown and measured at 350 and 700 uPa/Pa partial pressure of CO2 for aDmaranth, soybean and sunflower grown in controlled environment chambers, soybean grown outdoors in pots, and orchard grass!E grown in field plots. In amaranth, soybean and orchard grass, both the absolute and the relative sensitivity of conductan)Fce to delta w at the leaf surface were less in plants grown and measured at elevated CO2. In sunflower, there was no changGe in the sensitivity of conductance to delta w for the two CO2 partial pressures. Tests in soybeans and amaranth showed th-Hat the change in sensitivity resulted from elevated CO2 during the measurement of the delta w response. Assimilation rate 7Iof CO2 was not altered by delta w in amaranth, which has C4 metabolism. In sunflower, the assimilation rate of plants grow;Jn and measured at elevated CO2 was insensitive to delta w, consistent with the response of assimilation rate to intercelluFKlar CO2 partial pressure in the prevailing range. In soybean, the sensitivity of assimilation rate to delta w was not diffLerent between CO2 treatments, in contrast to what would be expected from the response of assimilation rate to intercellulaJr CO2 partial pressure.P/V~ u^\SF[s\_^Y[VFDDD*^QVW|VH ^XN119^1^Bunce,J A^1992^1^Light, Temperature and Nutrients as Factors in Photosynthetic Adjustment to an Elevated Concentration of Carbon Dioxide^44^86^^173-179^^^^^^^^^^285^^^^^^^^^^^soybean/Glycine max/sugar beet/Beta vulgarisBeta vulgaris L.v[?C^283^Physiol. Plant.}PSQRV1S׍v6F;ED;|D;E| D;E2N^ZY[XPSQRVWˋ׋1Q_3XXpQA^283^The short-term stimulation of the net rate of carbon dioxide exchange of leaves by elevated concentrations of CO2 usRually observed in C3 plants sometimes does not persist. Experiments were conducted to test whether the patterns of responssSe to the environment during growth were consistent with the hypothesis that photosynthetic adjustment to elevated CO2 conc{Tentration is due to (1) feedback inhibition or (2) nutrient stress. Soybean [_Glycine max_ (L.) Merr. cv. Williams] and suUgar beet (_Beta vulgaris_ L. cv. Mono Hye-4) were grown from seed at 350 and 700 uL/L CO2 at 20 and 25C, at a photon flux~V density of 0.5 and 1.0 mmol/m2/s and with three nutrient regimes until the third trifoliate leaf of soybean or the sixth Wleaf of sugar beet had finished expanding. Net rates of CO2 exchange of the most recently expanded leaves were then measurXed at both 350 and 700 uL/L CO2. Plants grown at the elevated CO2 concentration had net rates of leaf CO2 exchange which wYere reduced by 33% in sugar beet and 23% in soybean when measured at 350 uL/L CO2 and when averaged over all treatments. NZegative photosynthetic adjustment to elevated CO2 concentration was not greater at 20 than at 25C, was not greater with l[imiting nutrients. Furthermore, in soybean, negative photosynthetic adjustment could be induced by a single night at eleva\ted CO2 concentration, with net rates of CO2 exchange the next day equal to those of leaves of plants grown from seed at t]he elevated concentration of CO2. These patterns do not support either the feedback-inhibition or the nutrient-stress hypothesis of photosynthetic adjustment to elevated concentrations of CO2.8HĉtH**tGtq_120^1^Bunce,J A^1990^1^Short- and Long-Term Inhibition of Respiratory Carbon Dioxide Efflux by Elevated Carbon Dioxide^35^65^^637-642^^^^^^^^^^288^^^^^^^^^^^tomato/soybean/Lycopersicon esculentum/Glycine max/Amaranthus hypochondriacus/amaranthahondriacus L./amaranthߒ@uu>Ru N Hrvq֒t֒ttQL u5tKX>Ru$Vrz jOC^286^Ann. Bot.֒t ֈu rG u@t>t֒t.:#t<ֈt>at->aucA^286^Dark carbon dioxide efflux rates of recently fully expanded leaves and whole plants of _Amaranthus hypochondriacus_ dL., _Glycine max_ (L.) Merr., and _Lycopersicon esculentum_ Mill. grown in controlled environments at 35 and 70 Pa carbon edioxide pressure were measured at 35 and 70 Pa carbon dioxide pressure. Harvest data and whole-plant 24-h carbon dioxide efxchange were used to determine relative growth rates, net assimilation rates, leaf area ratios, and the ratio of respiratigon to photosynthesis under the growth conditions. Biomass at a given time after planting was greater at the higher carbon hdioxide pressure in _G. max_ and _L. esculentum_, but not the C4 species, _A. hypochondriacus_. Relative growth rates for ithe same range of masses were not different between carbon dioxide treatments in the two C3 species, because higher net asjsimilation rates at the higher carbon dioxide pressure were offset by lower leaf area ratios. Whole plant carbon dioxide ekfflux rates per unit of mass were lower in plants grown and measured at the higher carbon dioxide pressure in both _G. maxl_ and _L. esculentum_, and were also smaller in relation to daytime net carbon dioxide influx. Short-term responses of resmpiration rate to carbon dioxide pressure were found in all species, with carbon dioxide efflux rates of leaves and whole plants lower when measured at higher carbon dioxide pressure in almost all cases.o121^1^Bunce,J A^1992^1^Stomatal Conductance, Photosynthesis and Respiration of Temperate Deciduous Tree Seedlings Grown Ouptdoors at an Elevated Concentration of Carbon Dioxide^16^15^^514-549^^^^^^^^^^291^^^^^^^^^^^Acer rubrum/Acer saccharinum/Quercus prinus/Quercus robur/Malus domestica^^^^^estica Borkh.^^^^^/Malus domestica Borkh.3 3 " The increase by CO2 enrichment was remarkable in the cultivated soybean variety and was negligible in the wild one. In bsA^289^Seedlings of temperate deciduous tree species were grown outdoors at ambient and at an elevated concentration of car%tbon dioxide to examine how aspects of their gas exchange would be altered by growth at elevated carbon dioxide concentrati4uon. Leaf conductances to water vapour and net carbon dioxide exchange rates were determined periodically near midday. Wholve-plant carbon dioxide efflux rates in darkness were also determined. The stomatal conductance of leaves of plants grown a7wnd measured at 700 cm3/m3 carbon dioxide did not differ from that of plants grown and measured at 350 cm3/m3 in _Malus dom@xestica_, _Quercus prinus_ and _Quercus robur_ at any measurement time. In _Acer saccharinum_, lower conductances occurred yfor plants grown and measured at elevated carbon dioxide concentration only at measurement temperature above 33C. PhotosyCznthetic adjustment to elevated carbon dioxide concentration was evident only in _Q. robur_. All species examined had lower rates of dark respiration per unit of mass when grown and measured at elevated carbon dioxide concentration.S N|122^2^Bunce,J A^Caulfield,F^1991^1^Reduced Respiratory Carbon Dioxide Efflux During Growth at Elevated Carbon Dioxide in TPhree Herbaceous Perennial Species^35^67^^325-330^^^^^^^^^^294^^^^^^^^^^^Dactylis glomerata/Lolium perenne/Medicago sativa~o sativa L.&g7`V4 e*<^' ,sSt Npu 6 dcU6W6 N|uF u <2tR`C^292^Ann. Bot. |u: t: ta` t< s< uf<ua`2V8V3)t$:lUA^292^Long-term effects of elevated carbon dioxide on respiration were investigated in _Dactylis glomerata_, _Lolium perenne_ and _Medicago sativa_ in controlled environment chambers, and in _D. glomerata_ and _M. sativa_ in field plots. PlantsX were grown at 35 and 70 Pa carbon dioxide pressure. Dark carbon dioxide efflux rates were determined for whole plants dur`ing the first 40 d of growth in the controlled environment chambers, and for the ecosystems during the first year of growtdh in the field. Elevated carbon dioxide increased the rate of biomass accumulation in all species. In controlled environmetnts, efflux rates per unit of biomass were 30-40% lower in the elevated carbon dioxide treatment in _L. perenne_ and _ M. sativa_ at similar relative growth rates. In _D. glomerata_, efflux rates did not differ between treatments, but relative wgrowth rate was 50% higher at the elevated carbon dioxide. In the field, _M. sativa_ plots at elevated carbon dioxide had 15% less carbon dioxide efflux per unit of ground area, in spite of greater biomass production. Plots with _D. glomerata_ had equal rates of carbon dioxide efflux, but the plot with elevated carbon dioxide had higher biomass production. Thus, in all cases respiratory carbon dioxide efflux was reduced at elevated carbon dioxide, at least relative to the biomass accumulated.Ku譗Ž&Ku**P+s3SRZ[r: [=^v${DD_^ZY[X& þLss123^1^Burch,D W^1986^3^Economics of CO2 Enrichment in Greenhouses^Physiology, Yield, and Economics^CRC Press, Inc.^Boca Raton, Florida^199-209^^^^II^^Carbon Dioxide Enrichment of Greenhouse Crops^^^^296^^^^^^^^^^^^^^^^^^^^^Enoch,H Z^Kimball,B AB At;\s;TvS..G._.G[WS_&EG?[o_G?_S..o._.[PRWs#;A^295^The economic feasibility of any long-term commitment of capital is dependent on initial capital cost and further input/output relationships and prices which normally cannot be known in advance, but about which in many instances, it may seem reasonable to surmise. In the case of CO2 enrichment of the greenhouse atmosphere, the factors of primary importance are (1) the added market value of the crop due to CO2 enrichment, (2) the cost of CO2 and other expenses, (3) any heating or tax credits, and (4) the cost of equipment and terms of financing. A comprehensive equation was presented for projecting cash flow for several years, and a criteria equation was presented to determine the internal rate of return. A numerical example illustrated use of the equation. Prospects appear to be favorable for profitability of CO2 enrichment in cold climates, where it is a recommended practice. However, costs and incremental value of production may vary widely, particularly as ventilation requirements increase in warmer climates, so each case should be examined on an individual basis. The economic analysis equations presented here offer a satisfactory framework for case-by-case evaluations of the profitability of CO2 enrichment. Moreover, they can be used to compare alternative methods of financing and even to compare the attractiveness of an investment in CO2 enrichment relative to investments in other greenhouse equipment or to investments in financial instruments.EE_^ZRR3QWVO${sE tFF!Df~~=u124^4^Burger,J^Miyachi,S^Galland,P^Senger,H^1988^1^Quantum Requirements of Photosynthetic Oxygen Evolution and 77K Fluorescence Emission Spectra in Unicellular Green Algae Grown under Low-and High-CO2-Conditions^45^101^^229-232^^^^^^^^^^299^^^^^^^^^^^Dunaliella tertiolecta/Chlamydomonas reinhardtii/Chlorella vulgaris/Chlorella pyrenoidosasaX_[tE=t}C^297^Bot. Act.WF.sr#+f~Ў.sr vF*s_^Ss[4555l5t5|555 5A^297^Quantum requirements of photosynthetic oxygen evolution at 682 nm and fluorescence spectra at liquid nitrogen temperature (77K), were investigated in _Dunaliella tertiolecta_, _Chlamydomonas reinhardtii_ C-9, _Chlorella vulgaris_ 11 g, _Chlorella vulgaris_ C3, and _Chlorella pyrenoidosa_ 8b grown under low- and high-CO2 conditions. _Dunaliella_, _Chlamydomonas_ and _C. vulgaris_ 11 g show higher quantum requirements and a higher ratio of F710-740/F680-695 fluorescence when grown under low-CO2 conditions, indicating a change in excitation energy distribution towards PS-I. In _C. pyrenoidosa_ the quantum requirement for low-CO2 grown cells is higher than in high-CO2 grown cells, but there was practically no change in the fluorescence ratio. In _C. vulgaris_ C3, the quantum requirements of low- and high-CO2 grown cells are the same, but the fluorescence ratio is higher in high-CO2 grown cells than in low-CO2 grown cells. These results indicate that most of th.e low-CO2 grown cells require more PS-I light than high-CO2 grown cells. It is possible that this energy is used for cyclic electron flow. In _C. vulgaris_ C3, a mechanism may exist for excitation energy distribution which leads to the same qua0ntum requirements under low- and high-CO2 conditions.t.L8E~rntsM^tF.T8]ZrJPsM}t&125^4^Burnett,R B^Chaudhuri,U N^Kanemasu,E T^Kirkham,M B^1985^5^Sorghum at Elevated Levels of CO2^U.S. Dept. of Energy, CaCrbon Dioxide Research Division, Washington, D.C^^^^^^^^^^^^^^^^^^^^^^^^sorghum/Sorghum bicolor^^024 in Green Report SeriesG^Response of Vegetation to Carbon Dioxide^^n Dioxide^^s~'~t"& "" _G+vFyv2FRf126^3^Butler,G D^Kimball,B A^Mauney,J R^1986^1^Populations of _Bemisia tabaci_ (Homoptera: Aleyrodidae) on Cotton Grown inJ Open-top Field Chambers Enriched with CO2^6^15^^61-63^^^^^^^^^^303^^^^^^^^^^^Gossypium hirsutum/cottonottonNuFWC^301^Environ. Entomol.^V؃Xv}Ws~FFVVVVSF؊'~t& "" B;Vr3A^301^Atmospheric CO2 levels are anticipated to rise from the current ambient level of ca. 350 uL/L to 500-600 uL/L in the[ next 50 to 75 years. Plant scientists are artificially enhancing the CO2 environment of crop plants to increase photosyntnhesis, which is currently limited by inadequate levels of CO2. It is not known how increases of CO2 might affect consumers in the food chain. Population levels of sweetpotato whitefly (SPWF), _Bemisia tabaci_ (Gennadius), were assessed with stiqcky traps placed in a field experiment wherein cotton was grown in open-top field chambers that were enriched with CO2 at }levels approaching 200% ambient concentration levels. Although trapping started at the first of June, only an occasional SPWF was caught until early August. At that time populations began to increase at an exponential rate similar to that observed in commercial cotton fields in Arizona and California in previous years. There was no difference in rate of buildup of SPWF in ambient and CO2-enriched chambers in either wet or dry irrigation treatment. Thus, it seems that raised CO2 levels, either natural or artificial, do not affect SPWF populations.n^~uă~uߋ_^ZYQRVWF P tN127^2^Byrd,G T^Brown,R H^1989^1^Environmental Effects on Photorespiration of C3-C4 Species. I. Influence of CO2 and O2 during Growth on Photorespiratory Characteristics and Leaf Anatomy^17^90^^1022-1028^^^^^^^^^^306^^^^^^^^^^^Flaveria trinervia/Flaveria floridana/Flaveria pringlei/Festuca arundinacea/Panicum milloides/Panicum laxum;z9&EvC\rC^304^Plant Physiol.Nr3ۉ\\6tC&]&E 3]^[UW~N m_]UW~N [V_]VUP&5D &EPDPA^304^The possibility of altering CO2 exchange of C3-C4 species by growing them under various CO2 and O2 concentrations was examined. Growth under CO2 concentrations of 100, 350 and 750 micromoles per mole had no significant effect on CO2 exchange characteristics or leaf anatomy of _Flaveria pringlei_ (C3), _Flaveria floridana_ (C3-C4), or _Flaveria trinervia_ (C4). Carboxylation efficiency and CO2 compensation concentrations in leaves of _F. floridana_ developed under the different CO2 concentrations were intermediate to _F. pringlei_ and _F. trinervia_. When grown for 12 days at an O2 concentration of 20 millimoles per mole, apparent photosynthesis was strongly inhibited in _Panicum milloides_ (C3-C4) and to a lesser degree in _Panicum laxum_ (C3). In _P. milloides_, acute starch buildup was observed microscopically in both mesophyll and bundle sheath cells. Even after only 4 days exposure to 20 millimoles per mole O2, the presence of starch was more pronounced in leaf cross-sections of _P. milloides_ compared to those at 100 and 210 millimoles per mole. Even though this observation suggests that _P. milloides_ has a different response to low O2 with respect to translocation of photosynthate or sink activity than C3 species, the concentration of total available carbohydrates increased in shoots of all species by 33% or more when grown at low O2. This accumulation occurred even though relative growth rates of _Festuca arundinacea_ (C3) and _P. milloides_ grown for 4 days at 210 millimoles per mole O2, were inhibited 83 and 37%, respectively, when compared to plants grown at 20 millimoles per mole O2.AvO${ssG gO ]Z[XSQWVr; t!tDTG t128^2^Campagna,M A^Margolis,H A^1989^1^Influence of Short-term Atmospheric CO2 Enrichment on Growth, Allocation Patterns, and Biochemistry of Black Spruce Seedlings at Different Stages of Development^32^19^^773-782^^^^^^^^^^309^^^^^^^^^^^Picea mariana/black sprucek spruce;6wG ;6vG;6w G ;6wZO2 Du#D;6wD;6v;6w D;6w C^307^Can. J. For. Res.3^ZYlo>u>g7tS~P2ANr.=NDCdDGgN@A^307^Black spruce seedlings (_Picea mariana_ Mill.) were exposed to either elevated (1000 ppm) or ambient (340 ppm) atmospheric CO2 levels at different stages of seedling development over a winter greenhouse production cycle. Seedlings germinated in early February and were placed in CO2 chambers for either 3 or 6 weeks during March, April, May, or August. Total seedling biomass increased under high CO2 conditions for the March, April, and May stages of development, but showed no sig nificant response in August. The greater part of the CO2 response occurred during the second 3 weeks of exposure in March and April but during the first 3 weeks of exposure in May. In September, those seedlings exposed to CO2 in April and May had 30 and 14%, respectively, greater biomass than control seedlings, but seedlings from the other stages of development no longer had significant differences remaining from the CO2 treatment. This suggests that it could be very efficient to give a short well-timed CO2 pulse at the beginning of the production cycle in hopes of producing a size difference that is maintained throughout the remainder of the greenhouse production cycle under ambient levels of CO2. Short-term exposure to elevated CO2 also increased the ratio of shoot dry weight to total height for the March, April, and May stages of development. The ratio of total nonstructural carbohydrates to free amino acids was negatively correlated (_r2_=0.98) with the allo(cation of new growth between shoots and roots as measured by the allocation coefficient, _k_ (milligrams shoot growth per milligram root growth). As seedlings developed along their seasonal growth cycle, ratios of total nonstructural carbohydra*tes to free amino acids increased and the values for _k_ decreased. The effect of CO2 enrichment on these two factors is d4iscussed. Monitoring total nonstructural carbohydrate and free amino acid concentrations in foliage could have potential as a method to predict the percentage of carbon allocation to root systems of entire forest stands as well as of individual7 tree seedlings.E3*^PsVv^r(D9DtL3ۏDD_ZY333=tӓS\^XP&P u $D D <129^2^Campbell,D E^Young,R^1986^1^Short-term CO2 Exchange Response to Temperature, Irradiance, and CO2 Concentration in Strawberry^18^8^^31-40^^^^^^^^^^312^^^^^^^^^^^strawberry/Fragaria ananassasah/D&Pt P&`X&V&T ?C^310^Photosynth. Res.BE@EsaSRWD Au#rPsD t ڻDE${PQA33X&\D t"3ro&`A^310^Relative importance of short-term environmental interaction and preconditioning to CO2 exchange response was examined in _Fragaria ananassa_ (strawberry, cv. Quinault). Tests included an orthogonal comparison of 15 to 60-min and 6 to 7-h exposures to different levels of temperature (16 to 32C), photosynthetically active radiation (PAR, 200 to 800 uE/m2/s), nand CO2 (300 to 600 uL/L) on successive days of study. Plants were otherwise maintained at 21C, 300 uE/m2/s PAR and 300-3q60 uL/L CO2 as standard conditions. Treatment was restricted to the mean interval of 14 h daily illumination and the firstz 3-4 days of each test week over a 12-week cultivation period. CO2 exchange rates were followed with each step-change in e|nvironmental level including ascending/descending temperature/PAR within a test period, initial response at standard conditions on successive days of testing, and measurement at reduced O2. Response generally supported prior concepts of leaf biochemical modeling in identifying CO2 fixation as the major site of environmental influence, while overall patterns of whole plant CO2 exchange suggested additional effects for combined environmental factors and preconditioning. These included a positive interaction between temperature and CO2 concentration on photosynthesis at high irradiance and a greater contribution by 'dark' respiration at lower PAR than previously indicated. The further importance of estimating whole plant CO2 exchange from repetitive tests and measurements was evidenced by a high correlation of response to prior treatment both during the daily test period and on consecutive days of testing. Xu$0<0tu s݃ tu Dr130^1^Caporn,S J M^1989^1^The Effects of Oxides of Nitrogen and Carbon Dioxide Enrichment on Photosynthesis and Growth of Lettuce (_Lactuca sativa_ L.)^23^111^^473-481^^^^^^^^^^315^^^^^^^^^^^lettuce/Lactuca sativava L.EuQR2;EEZY WC^313^New Phytol.E_E!tQRe!C@@E! u.F3҇ڋUE +E srO t 3ƒE!u/211^3^Eng,R Y N^Tsujita,M J^Grodzinski,B^1985^1^The Effects of Supplementary HPS Lighting and Carbon Dioxide Enrichment on the Vegetative Growth, Nutritional Status and Flowering Characteristics of _Chrysanthemum morifolium_ Ramat^19^60^^389-395^^^^^^^^^^521^^^^^^^^^^^Chrysanthemum morifolium/chrysanthemumum ;wHH.-u؋.&.-.&-!$ C^519^J. Hort. Sci.a XPSQPSQd;u> 7uEtudtY[XPQdt a$:tdd under the CO2 regime predicted for the year 2050) and Q-700/350 (the quotient of present yield predicted for a doubling of ambient CO2 concentration). Values of Q-540/350 for whole-plant dry weight ranged from below 1.01 to 1.49, the upper values being at least similar in magnitude to those already observed in C3 crops. The mean value of whole-plant Q-700/350 for 11 species of near-competitive strategy was 1.43. Four species of stress-tolerant or ruderal strategy had a mean Q-700/350 of only 1.05. High CO2 responsiveness was common only within the competitive strategy and its close relations. The fitted Q-540/350 for species of the pure strategy was 1.38. In the centre of the strategic range the fitted value was 1.12, and at the far extreme, the value for species of ruderal or stress-tolerant strategy was only 1.03.Individual leaf area waA^313^The response of glasshouse crops to the nitrogen oxide pollutants which may be generated during enrichment with CO2 has been studied in controlled environments. Lettuce (_Lactuca sativa_ L. cv. Ambassador) was grown in air containing either low CO2 (380 umol/mol), high CO2 (1200 umol/mol), or high CO2 plus oxides of nitrogen (NOx). Carbon dioxide enrichment increased the rate of emergence and expansion of leaves and the growth of young plants. Addition of NOx (2 umol/mol NO and c. 0.5 umol/mol NO2) to CO2-enriched air significantly reduced the yield, compared with the 'clean', high CO2 treatment, without producing visible symptoms of toxicity. Fumigation of single plants in high CO2 with NOx rapidly inhibited photosynthesis per unit leaf area. This did not appear to be due to a reduction in stomatal conductance. Removal of NOx from the  atmosphere caused a rapid and complete recovery in the rate of photosynthesis. Studies were made of the effects of growing plants for long periods in atmospheres containing high CO2 and NOx on the photosynthetic capacity of single leaves when m% easured in NOx-free air. The decrease in photosynthetic rate as the fourth leaf aged occurred earlier in plants grown in C O2-enriched air than in those from the low CO2 treatment. Leaves which developed in the CO2-enriched air containing NOx di* d not suffer any long-term damage to photosynthetic activity in comparison with those of the 'clean' high CO2. In mature l4eaves the principal long-term effect of enrichment (with or without NOx) was to reduce the rate of photosynthesis in saturating CO2. In contrast, there was less effect on the rate of photosynthesis in low CO2. The absence of a long-term effect 7of NOx on the photosynthetic capacity suggested that photosynthesis by the lettuce crop will be inhibited only during the Ctransient periods of NOx accumulation in the glasshouse.131^3^Caporn,S J M^Mansfield,T A^Hand,D W^1990^1^The Critical Influence of Temperature on the Inhibition of PhotosynthesisG by Oxides of Nitrogen in Lettuce^15^268^^103-110^^^^^^^^^^318^^^^^^^^^^^lettuce/Lactuca sativavaTC^316^Act. Hort.A^316^The photosynthetic response of lettuce to the oxides of nitrogen (NOx) generated during enrichment with CO2 has beenX studied at different temperatures. The steady rates of net photosynthesis of lettuce fell within several minutes followinjg the addition of nitric oxide to the cuvette. This did not appear to have been caused by a reduction in the stomatal conductance. Removal of the pollutant gas resulted in a rapid and complete recovery in the rate of photosynthesis. Gas exchangme by a small stand of lettuce was measured in a novel growth chamber with fine thermal control. In high CO2 (1000 vpm) andv at 16, 10 and 6C a transient fumigation with 2.0 vpm NO reduced CO2 uptake by 7, 11 and 29% respectively. Deposition of zNO into the canopy was 46% less at 6 than at 16C. Uptake of the pollutant, therefore, did not explain the increased inhibition of photosynthesis. The greater damage at low temperature may be due to a reduced capacity to metabolize some toxic products of NOx assimilation. Methods of CO2 enrichment which vent the flue gases from the burners directly into the glasshouse air may not be entirely suitable for winter crops grown at low temperatures.wL TUU132^3^Caporn,S J M^Mansfield,T A^Hand,D W^1991^1^Low Temperature-enhanced Inhibition of Photosynthesis by Oxides of Nitrogen in Lettuce (_Lactuca sativa_ L.)^23^118^^309-313^^^^^^^^^^321^^^^^^^^^^^lettuce/Lactuca sativava L.)yC^319^New Phytol.Gddd?()"A^319^The response of photosynthetic gas exchange to oxides of nitrogen (NOx) was studied in leaves of lettuce (_Lactuca s#ativa_ L.) at different temperatures. Exposure to high concentrations (e.g. 1.3 umol NOx/mol), similar to those often foun$d in commercial glasshouses, caused a rapid inhibition of the net assimilation of CO2. This appeared to be by a direct eff%ect on photosynthesis rather than by a change in the stomatal conductance. In ambient CO2 (345 umol/mol), the percentage i&nhibition at 10 and 5C was approximately 3x and 5x, respectively, that measured at 20C. This effect of temperature also 'occurred when measured in CO2 enriched air (1050 umol/mol), which would normally accompany NOx in a glasshouse. The extent( of photosynthetic inhibition caused by NOx was, however, always less in high than in low CO2. The results suggest that wh)en burning fuel to raise the CO2 concentration and heat the glasshouse air, growers should avoid generating high concentrations of NOx in conditions of low temperature.HP LaserJet 4              +133^2^Carlson,T N^Bunce,J A^1991^3^The Effect of Atmospheric Carbon Dioxide Doubling on Transpiration^Tenth Conference on ,Biometeorology and Aerobiology and the Special Session on Hydrometeorology; 1991 Sept. 10-13; Salt Lake City, Utah^American Meteorological Society^Boston, Massachusetts^196-199^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^Preprint Volume.134^2^Challa,H^Schapendonk,A H C M^1986^3^Dynamic Optimization of CO2 Concentration in Relation to Climate Control in Gree/nhouses^Physiology, Yield, and Economics^CRC Press, Inc.^Boca Raton, Florida^147-160^^^^II^^Carbon Dioxide Enrichment of Greenhouse Crops^^^^^^^^^^^^^^^^^^^^^^^^^Enoch,H Z^Kimball,B AB A1135^4^Chaudhuri,U N^Burnett,R B^Kanemasu,E T^Kirkham,M B^1986^5^Effect of Elevated Levels of CO2 on Winter Wheat under Two2 Moisture Regimes^U.S. Dept. of Energy, Carbon Dioxide Research Division, Washington, D.C^^^^^^^^^^^^^^^^^^^^^^^^wheat/Triticum aestivum^^029 in Green Report Series^Response of Vegetation to Carbon Dioxide^^^^` 4136^4^Chaudhuri,U N^Burnett,R B^Kirkham,M B^Kanemasu,E T^1986^1^Effect of Carbon Dioxide on Sorghum Yield, Root Growth, and Water Use^46^37^^109-122^^^^^^^^^^327^^^^^^^^^^^sorghum/Sorghum bicoloror (L.) Moench C^325^Agric. For. Meteorol.223'7A^325^The concentration of atmospheric carbon dioxide (CO2) is rising. The effect of higher than ambient levels of CO2 on 8plants grown in the sub-humid central Great Plains of the U.S.A. has not been investigated. Therefore, an experiment was c9onducted at Manhattan, Kansas, to study the effect of elevated levels of CO2 on grain sorghum [_Sorghum bicolor_ (L.) Moen:ch]. During the summer of 1984, the sorghum was grown in rhizotrons in which root and shoot growth could be monitored thro;ughout the growth cycle. The tops of the plants were enclosed in plastic chambers, which contained one of four concentratiile depths, root numbers and weights were higher at elevated CO2 than at ambient CO2. However, water use per unit dry matt8?er of leaf, stem, root, and grain was decreased 13, 30, 31 and 29%, respectively, in plants grown at 795 uL/L CO2 compared@ to plants at 330 uL/L CO2. Although elevated CO2 levels increased the stomatal resistance and leaf temperature, an increa;se in leaf area indices resulted in a lower canopy resistance.$F B137^4^Chaudhuri,U N^Burnett,R B^Kanemasu,E T^Kirkham,M B^1987^5^Effect of Elevated Levels of CO2 on Winter Wheat under Two>C Moisture Regimes^U.S. Dept. of Energy, Carbon Dioxide Research Division, Washington, D.C^^^^^^^^^^^^^^^^^^^^^^^^wheat/TriCticum aestivum^^040 in Green Report Series^Response of Vegetation to Carbon Dioxide^^^^E138^3^Chaudhuri,U N^Kanemasu,E T^Kirkham,M B^1989^5^Effect of Elevated Levels of CO2 on Winter Wheat under Two Moisture ReFFgimes^U.S. Dept. of Energy, Carbon Dioxide Research Division, Washington, D.C^^^^^^^^^^^^^^^^^^^^^^^^wheat/Triticum aestivVum^^050 in Green Report Series^Response of Vegetation to Carbon Dioxide^^^^d., H139^3^Chaudhuri,U N^Kirkham,M B^Kanemasu,E T^1990^1^Carbon Dioxide and Water Level Effects on Yield and Water Use of WinteYr Wheat^4^82^^637-641^^^^^^^^^^332^^^^^^^^^^^wheat/Triticum aestivumum L.g5C^330^Agron. J..KA^330^Increasing levels of atmospheric CO2 may have major effects on yield and water use of winter wheat (_Triticum aestiviLum_ L.). The objective was to determine the effect of elevated levels of CO2 on grain yield and water use from planting toM harvest under two water levels. 'Newton' winter wheat was grown in the field under ambient (340 uL/L) and elevated levelslN (485, 660, and 825 uL/L) of CO2, during three growing seasons, in 16 underground boxes (77 cm long, 37 cm wide, and 180 coOm deep) containing a Muir silt loam (fine-silty, mixed, mesic Cumulic Haplustoll). Water in half of the boxes was maintainPed at 0.38 m3/m3 (high water level) and in the other half between 0.14 to 0.25 m3/m3 (low water level). Boxes were weighedQ in the fall and spring to determine the amount of water use by transpiration. Plastic chambers (121 by 92 by 168 cm) coveRred the boxes to maintain different CO2 levels. Grain yield of the high-water-level wheat grown under ambient CO2 was abouSt the same as the grain yield of low-water-level wheat grown at the highest level of CO2 (825 uL/L) (3-yr means: 725 and 7T07 g/m2, respectively). Similar results were obtained for yield components (spike number, spike weight, kernels/spike, andU kernel weight). High-water-level wheat grown with 825 uL/L CO2 transpired more water than low-water-level wheat grown undVer ambient levels of CO2 (3-yr means: 453 and 370 L/m2, respectively). Under high and low water levels, 29 and 31% less waWter was required, respectively, to produce a gram of grain when the CO2 concentration was raised from ambient to 825 uL/L. Results show that the water requirement of wheat is reduced by about 30% by elevated (1.4 times present ambient) CO2.Y140^3^Chaudhuri,U N^Kirkham,M B^Kanemasu,E T^1990^1^Root Growth of Winter Wheat under Elevated Carbon Dioxide and Drought^12^30^^853-857^^^^^^^^^^335^^^^^^^^^^^wheat/Triticum aestivumum L.IC^333^Crop Sci.\A^333^With the atmospheric concentration of CO2 increasing, it is important to know how this will affect crop growth. The ]objective of this study was to determine the effect of enriched CO2 on root growth of winter wheat (_Triticum aestivum_ L.^ 'Newton') under both well-watered and dry conditions. The wheat was grown for 3 yr in 16 plastic chambers (121 by 92 by 1_68 cm) in the field under ambient CO2 (340 uL/L) and elevated levels of CO2 (485, 660, and 825 uL/L). Each chamber was pla`ced over an underground box (77 by 37 cm at the top; 180 cm deep) containing a Muir silt loam (fine-silty, mixed, mesic Cuamulic Haplustoll). The boxes could be pulled out of the ground for observation of the roots. Half of the boxes were maintabined at field capacity (0.38 m3/m3) (well-watered or not stressed plants) and half between 0.14 to 0.25 m3/m3 (drought-strcessed plants). At harvest, root dry weights at different depths and stem dry weight were determined. Roots of plants grownd under the three elevated levels of CO2 penetrated to the maximum depth of observation (176 cm) before roots of plants groewn under the ambient level. At harvest, the difference in root growth between elevated and ambient levels of CO2 was most fpronounced at the top level (0- to 10-cm depth). Roots of drought-stressed plants grown with 825 uL/L CO2 had a greater drgy weight than roots of well-watered plants grown with ambient CO2. The ratio of root to stem weight usually showed no trenhd (neither increase or decrease) with increasing CO2 concentration. Total dry weight at harvest of well-watered roots grow)in at ambient CO2 (3-yr mean: 118 g/m2) was similar to that of drought-stressed roots grown at the highest level of CO2 (3-jyr mean: 123 g/m2). The results indicated that high CO2 (825 uL/L) can compensate for restrictions in root growth by droug,ht.WPxx.LEXWPSP60xx.DTL8141^2^Chaves,M M^Pereira,J S^1992^1^Water Stress, CO2 and Climate Change^39^43^^1131-1139^^^^^^^^^^33838൧,:ZC^336^J. Exp. Bot.:&: :^:: :: :Q:Q::;nA^336^Climate change may bring about increased aridity of large areas of Europe. Higher temperatures, larger water deficitLos and high light stress are likely to occur in conjunction with elevated atmospheric CO2. This raises the question whetherp a high CO2 concentration in the atmosphere can compensate for the decrease in carbon gain in water-stressed plants. The pOqrocesses which determine dry matter production and the ways they are affected by soil water deficits are discussed. It is Wrnow well established that in most species and under most circumstances stomata are the main limiting factor to carbon uptaske under water deficit, the photosynthetic machinery being highly resistant to dehydration. However, when other stresses aZtre superimposed, a decline in photosynthetic capacity may be observed. In the short term, under drought conditions, the inducrease in CO2 in the atmosphere may diminish the importance of stomatal limitation for carbon assimilation, inhibit photorvespiration, stimulate carbon partitioning to soluble sugars and increase water-use efficiency. Some recent evidence seems gwto indicate that under conditions of high irradiance, plants growing at elevated CO2 may develop protection towards photoixxnhibition, which might otherwise result in significant losses in plant production under stress conditions. In the longer tyerm though, a negative acclimation of photosynthesis appears to occur in many species, an explanation for which still need|zs to be clearly identified. Similarly, the effects of extended exposure to elevated CO2 under arid conditions are not know{n. Plant production is more closely related to the integral of photosynthesis over time and total foliage area than to the| instantaneous rates of the photosynthetic process. Water deficits result in more respiratory losses. However, experimenta}l as well as simulatory evidence suggests that doubling CO2 concentration in the air may improve carbon assimilation and c~ompensate partially for the negative effects of water stress even if we assume a down-regulation of the photosynthetic process as a result of acclimation to elevated CO2. % _2L,0"142^2^Chen,J J^Sung,J M^1990^1^Gas Exchange Rate and Yield Responses of Virginia-type Peanut to Carbon Dioxide Enrichment^12^30^^1085-1089^^^^^^^^^^341^^^^^^^^^^^peanut/Arachis hypogaeaea L.lC^339^Crop Sci.A^339^Poor seed fill and resultant seed-coat shriveling occur commonly on Virginia-type peanut (_Arachis hypogaea_ L.) grown in Taiwan. The phenomenon may be linked to the limitation in photosynthate supply at seed filling. The objective of this study was to evaluate the effect of CO2 enrichment (1000 uL CO2/L) and depegging on CO2 exchange rate (CER) and yield responses of pot-grown Virginia-type peanut. Carbon dioxide enrichments were applied to the plants at pod filling. Depegging effect was examined contrasting the controls and the plants maintaining 38 to 40 pegs throughout the growing period. The results indicated that short-term CO2 enrichment (CO2 treatment for 10 d) improved leaf and canopy CER. Long-term CO2 enrichment (CO2 treatments throughout pod filling) tended to ease leaf ribulose 1,5-bisphosphate carboxylase/oxygenase (rubisco) and chlorophyll (chl) deteriorations. Electrophoresis patterns of leaf soluble protein extracts confirmed this finding. Seed yield per plant was increased with high CO2 treatment applied at seed-filling period, but the production of marketable seeds was improved only in the plants receiving CO2 and depegging treatments. The poor seed-fill characteristic observed in Virginia-type peanut is attributed to excessive sink load and low canopy CER.WPXX.ICR.143^3^Chu,C C^Coleman,J S^Mooney,H A^1992^1^Controls of Biomass Partitioning between Roots and Shoots: Atmospheric CO2 Enrichment and the Acquisition and Allocation of Carbon and Nitrogen in Wild Radish^34^89^^580-587^^^^^^^^^^344^^^^^^^^^^^radish/Raphanus sativus/Raphanus raphanistrum?-DT! @-DT!@ߓi>*?UUUUC^342^Oecologiaw )VD Jb0@P;f?&{?9B.?XoR>op|?? 8o?@?QBqq?A^342^The effects of CO2 enrichment on plant growth, carbon and nitrogen acquisition and resource allocation were investigated in order to examine several hypotheses about the mechanisms that govern dry matter partitioning between shoots and roots. Wild radish plants (_Raphanus sativus x raphanistrum_) were grown for 25 d under three different atmospheric CO2 conc entrations (200 ppm, 330 ppm and 600 ppm) with stable hydroponic 150 umol/L nitrate supply. Radish biomass accumulation, photosynthetic rate, water use efficiency, nitrogen per unit leaf area, and starch and soluble sugar levels in leaves incre ased with increasing atmospheric CO2 concentration, whereas specific leaf area and nitrogen concentration of leaves signif icantly decreased. Despite substantial changes in radish growth, resource acquisition and resource partitioning, the rate at which leaves accumulated starch over the course of the light period and the partitioning of biomass between roots and s hoots were not affected by CO2 treatment. This phenomenon was consistent with the hypothesis that root/shoot partitioning is related to the daily rate of starch accumulation by leaves during the photoperiod, but is inconsistent with hypotheses suggesting that root/shoot partitioning is controlled by some aspect of plant C/N balance. 144^2^Coleman,J S^Bazzaz,F A^1992^1^Effects of CO2 and Temperature on Growth and Resource Use of Co-occurring C3 and C4 Annuals^2^73^^1244-1259^^^^^^^^^^347^^^^^^^^^^^Amaranthus retroflexus/Abutilon theophrastiti !C^345^Ecology)A)%%P;2 ,A^345^We examined how CO2 concentrations and temperature interacted to affect growth, resource acquisition, and resource a 0llocation of two annual plants that were supplied with a single pulse of nutrients. Physiological and growth measurements =were made on individuals of _Abutilon theophrasti_ (C3) and _Amaranthus retroflexus_ (C4) grown in environments with atmospheric CO2 levels of 400 or 700 uL/L and with light/dark temperatures of 28/22 or 38/31C. Elevated CO2 and temperature A treatments had significant independent and interactive effects on plant growth, resource allocation, and resource acquisi Qtion (i.e., photosynthesis and nitrogen uptake), and the strength and direction of these effects were often dependent on p Tlant species. For example, final biomass of _Amaranthus_ was enhanced by elevated CO2 at 28 but was depressed at 38. For i _Abutilon_, elevated CO2 increased initial plant relative growth rates at 28 but not at 38, and had no significant effects on final biomass at either temperature. These results are interpreted in light of the interactive effects of CO2 and t memperature on the rates of net leaf area production and loss, and on net whole-plant nitrogen retention. At 28C, elevated | CO2 stimulated the initial production of leaf area in both species, which led to an initial stimulation of biomass accumulation at the higher CO2 level. However, in elevated CO2 at 28, the rate of net leaf area loss for _Abutilon_ increased w hile that of _Amaranthus_ decreased. Furthermore, high CO2 apparently enhanced the ability of _Amaranthus_ to retain nitro gen at this temperature, which may have helped to enhance photosynthesis, whereas nitrogen retention was unaffected in _Ab utilon_. Thus, at 28, final biomass of _Abutilon_ was not stimulated in a high CO2 environment whereas the final biomass of _Amaranthus_ was. At 38, _Abutilon_ had slightly reduced peak leaf areas under elevated CO2 in comparison to ambient C O2 grown plants, but increased rates of photosynthesis per unit leaf area early in the experiment apparently compensated f or reduced leaf area. For _Amaranthus_ at 38, peak leaf area production was not affected by CO2 treatment, but the rate of net leaf area loss hastened under elevated CO2 conditions and was accompanied by substantial reductions of whole-plant n itrogen content and leaf photosynthesis This may have led to the reduced biomass accumulation of high CO2 grown plants tha t we observed during the last 30 d of growth. Plants of both species grown in elevated CO2 exhibited reduced tissue-specific rates of nitrogen absorption, increased plant photosynthetic rate per unit of conductance, and increased initial alloca tion of biomass to roots, irrespective of temperature. Plants of both species grown under an elevated temperature regime h ad substantially decreased reproductive allocation, increased allocation to stem biomass, and increased plant water flux at both CO2 treatments. The age of plants also affected our interpretations of plant responses to CO2 and temperature treat ments. For example, significant effects of CO2 treatment on the growth of _Abutilon_ were evident early, prior to the init iation of flowering, when nitrogen availability would have been highest and pot space would not have been limited. Nevertheless, the opposite was true for _Amaranthus_, in which significant effects of CO2 treatment on plant growth were not dete ctable until the final 30 d of the experiment. Elevated CO2 interacted with temperature to affect plant productivity in di fferent ways than would have been predicted from plant responses to elevated CO2 alone. Furthermore, a majority of the interactive effects of CO2 concentration and temperature on plant growth could be interpreted in light of their effects on th e rates of net leaf area production and loss, nitrogen retention, and, to a lesser degree, photosynthesis and resource par titioning.145^4^Coleman,J S^Rochefort,L^Bazzaz,F A^Woodward,F I^1991^1^Atmospheric CO2, Plant Nitrogen Status and the Susceptibility  of Plants to an Acute Increase in Temperature^16^14^^667-674^^^^^^^^^^350^^^^^^^^^^^Abutilon theophrasti/Amaranthus retro flexus/Sinapis alba/white mustard./white mustardNG=C^348^Plant Cell Environ. A^348^Elevated levels of CO2 in the atmosphere are expected to affect plant performance and may alter global temperature p atterns. Changes in mean air temperatures that might be induced by rising levels of CO2 and other greenhouse gases could also be accompanied by increased variability in daily temperatures such that acute increases in air temperature may be more  likely than at present. Consequently, we investigated whether plants grown in a CO2 enriched atmosphere would be differen tly affected by a heat shock than plants grown at ambient CO2 levels. Plants of a C3 annual (_Abutilon theophrasti_), a C3 annual crop (_Sinapis alba_) and a C4 annual (_Amaranthus retroflexus_) were grown from seed in growth chambers under eit!her 400 or 700 cm3/m3 CO2, and were fertilized with either a high or low nutrient regime. Young seedlings of _S. alba_, as well as plants of all species in either the vegetative or reproductive phase of growth were exposed to a 4-h heat shock i!n which the temperature was raised an additional 14-23C (depending on plant age). Total biomass and reproductive biomass !were examined to determine the effect of CO2, nutrient and heat shock treatments on plant performance. Heat shock, CO2, and nutrient treatments, all had some significant effects on plant performance, but plants from both CO2 treatments responde!d similarly to heat shocks. We also found, as expected, that plants grown under high CO2 had dramatically decreased tissue N concentrations relative to plants grown under ambient conditions. We predicted that high-CO2-grown plants would be more! susceptible to a heat shock than ambient-CO2-grown plants, because the reduced N concentration of high-CO2-grown plants c!!ould result in the reduced synthesis of heat shock proteins and reduced thermotolerance. Although we did not examine heat shock proteins, our results showed little relationship between plant nitrogen status and the ability of a plant to tolerat!%e an acute increase in temperature.!-"146^3^Combe,L^Bertolini,J M^Quetin,P^1990^1^Growth and Photosynthesis of CO2-enriched Primrose^15^268^^55-62^^^^^^^^^^353^C^351^Act. Hort.!0A^351^_Primula obconica_ potted plants were cultivated in a glasshouse at normal (350 +/- 50 uL/L) or enriched (800 +/- 10!;0 uL/L) CO2 concentration in the air. Final growth and yield were measured: fresh and dry matter were significantly increa!>sed by CO2-enrichment (+94% and +77% respectively). Similarly leaf number increased but flower number did not. Plant quality was better. Net CO2-gas exchange rates were measured on a small population (10 pots =30 plants =1 m2) in a growth chamb!Aer where irradiance and CO2 could be controlled. Net photosynthesis curves were the same for both control and enriched pla!Mnts: there was no CO2 adaptive effect. The effect of temperature (14C and 18C) on photosynthesis was not significant. At!Q high irradiance (450 uE PAR/m2/s) and low CO2 concentration (<350 uL/L) some plants sets displayed lowered photosynthesis rate, probably due to photoinhibition. Ageing (5 to 13 weeks after transplantation) caused a reduction of photosynthesis !Trate except at 350 uL/L. Hence CO2-enrichment should be applied preferably at the beginning of cultivation.OPQRSTU![53Z[\]^_`abcdefghijklmnopqrstuvwxyz{|}~147^2^Combe,L^Kobilinsky,A^1985^1^Effet de la Fumure Carbonee sur la Photosynthese de Radis (_Raphanus sativus_) en Serre !^en Hiver^42^19^^550-560^^^^^^^^^^356^^^^^^^^^^^radish/Raphanus sativusus L.HIJKLPQRSTUVWXY[\]cdefg!kC^354^Photosynthetica!"#)/5;?hiopvw}~  #'*+/013   A^354^Carbon dioxide dependence of net photosynthetic rate [_Pn_(C) curves] was studied in _Raphanus sativus_ L. plants gr!nown in a greenhouse with and without CO2 enrichment [ca. 1000 and 350 cm3 (CO2)/m3] for a week. _Pn_ decreased with increa!}sing plant age (6 to 23 d); the decrease was higher under lower irradiance (_I_). CO2 concentration did not modify the age effect on _Pn_. When _I_ (400-700 nm) increased from 200 to 270 umol/m2/s (average of three days before the _Pn_ measurem!ent), _Pn_ increased unless the plants were very young (6d). The effect of _I_ was higher in old plants and under CO2 enri!chment. CO2 enrichment induced a higher decrease in _Pn_ under low _I_ and in older plants. The CO2 enrichment effect appeared only after more than one day of treatment. After the enrichment had been stopped, the effect persisted for at least o!ne day and disappeared 3 d after the treatment had been stopped. In French.  _ %(B1AC)+,97"8!:abcdef!148^1^Conroy,J P^1992^1^Influence of Elevated Atmospheric CO2 Concentrations on Plant Nutrition^25^40^^445-456^^^^^^^^^^35!C^357^Aust. J. Bot.ssvvyyyyyyyy!A^357^The rising levels of atmospheric CO2 are likely to increase biomass production of C3 species in both natural and managed ecosystems because photosynthetic rates will be higher. The greatest absolute increase in productivity will occur whe!n nitrogen and phosphorus availability in the soil is high. Low nitrogen does not preclude a growth response to high CO2, !whereas some C3 species fail to respond to high CO2 when phosphorus is low, possibly because insufficient phosphorus is av!ailable to maintain maximum photosynthetic activity at high CO2. C3 plants response to high CO2 because the flux of carbon! through the photoreductive cycle is increased and photorespiration is suppressed. This change in metabolism appears to al!ter the foliar nutrient concentration required to promote maximum productivity (critical concentration). Higher phosphorus! concentrations are needed at elevated CO2, whereas the nitrogen requirement is reduced by CO2 enrichment. Since critical !concentrations are used to evaluate nutrient status of crop and forest species and to manage fertiliser programs, they wil!l need reassessing as the atmospheric CO2 concentration rises. Another consequence of the altered nutrient requirement at high CO2 is that the nitrogen concentrations of foliage, roots and grain are consistently lower in plants grown at elevate"d CO2, irrespective of availability of nitrogen in the soil. In natural ecosystems,the lower nitrogen to carbon ratio of t" he litter may alter rates of nutrient cycling. For farmers, the rising CO2 concentrations could cause the reductions in grain nitrogen, and therefore protein content. This could have important implications for baking quality of hard wheats as w"ell as affecting the nutrient value of grain such as rice.QR\ t= t83ɋDp${s\${H${s D): "959r%D\T L+ً\rju;vSB!Yr[TD${sPVWNfE9NsN3Ҵ?!rQ3YF;149^3^Conroy,J^Barlow,E W^Bevege,D I^1986^1^Response of _Pinus radiata_ Seedlings to Carbon Dioxide Enrichment at Differen"t Levels of Water and Phosphorus: Growth, Morphology and Anatomy^35^57^^165-177^^^^^^^^^^362^^^^^^^^^^^Pinus radiatata D.C^360^Ann. Bot.rڋFD TD)D~t )FfLT NVB!TL\~tV39NsNQAY^3@!r\L "#A^360^Eight week old seedlings of _Pinus radiata_ D. Don, grown at three levels of phosphorus, were subjected to three wat"&ering regimes and to CO2 concentrations of either 330 or 660 uL/L for 22 weeks. Carbon dioxide enrichment increased total dry weight by an average of 30 per cent. In phosphorus deficient seedlings the increase was only 13 per cent, whereas unde"+r water stress it was 38 per cent. The NAR responded similarly to CO2. The number, length, diameter and specific weight of"4 the needles was also increased by CO2 enrichment, the effect being reduced by phosphorus deficiency but not by water stress. The increase in needle diameter was due to an increase in cell size rather than cell number. It may be inferred that i"8ncreases in the yield of field grown _P. radiata_ will occur even at sites where water limits growth. However, there is li"Attle possibility of improving growth where phosphorus deficiency is chronic.>it$\Wi2P򮿪_rѾi t Don* u+O~ z]_^ZY[XPSQRV!F:u&$,A<w:!!:u&B6!-r=tFF<tִ;!ssN V!"D 150^5^Conroy,J P^Kuppers,M^Kuppers,B^Virgona,J^Barlow,E W R^1988^1^The Influence of CO2 Enrichment, Phosphorus Deficiency "L and Water Stress on the Growth, Conductance and Water Use of _Pinus radiata_ D. Don^16^11^^91-98^^^^^^^^^^365^^^^^^^^^^^Pi"Onus radiata/Monterey pine^^^^^pine~ u^\SF[s\_^Y[VFDDD*^QVW|VH ^"T C^363^Plant Cell Environ.OXssD*_^Y˚6F5>5u 7:s5ˀ>5t5u7:58ui.NǠ8H"XA^363^Seedlings of _Pinus radiata_ D. Don were grown in growth chambers for 22 weeks with two levels of phosphorus, under "`either well-watered or water-stressed conditions at CO2 concentrations of either 330 or 660 mm3/dm3. Plant growth, water use efficiency and conductance were measured and the relationship between these and needle photosynthetic capacity, water u"cse efficiency and conductance was determined by gas exchange at week 22. Phosphorus deficiency decreased growth and foliar"s surface area at both CO2 concentrations; however, it only reduced the maximum photosynthetic rates of the needles at 660 mm3 CO2/dm3 (plants grown and measured at the same CO2 concentration). Water stress reduced growth and foliar surface area"u at both CO2 concentrations. Increases in needle photosynthetic rates appeared to be partly responsible for the increased "growth at high CO2 where phosphorus was adequate. This effect was amplified by accompanying increases in needle production. Phosphorus deficiency inhibited these responses because it severely impaired needle photosynthetic function. The relativ"e increase in growth in response to high CO2 was higher in the periodically water-stressed plants. This was not due to the" maintenance of cell volume during drought. Plant water use efficiency was increased by CO2 enrichment due to an increase "in dry weight rather than a decrease in shoot conductance and, therefore, transpirational water loss. Changes in needle conductance and water use efficiency in response to high CO2 were generally in the same direction as those at the whole plan"t level. If the atmospheric CO2 level reaches the predicted concentration of 660 mm3/dm3 by the end of the next Century, t"hen the growth of _P. radiata_ will only be increased in areas where phosphorus nutrition is adequate. Growth will be increased in drought-affected regions but total water use is unlikely to be reduced.tH**tGtq"151^3^Conroy,J P^Milham,P J^Barlow,E W R^1992^1^Effect of Nitrogen and Phosphorus Availability on the Growth Response of _"Eucalyptus grandis_ to High CO2^16^15^^843-847^^^^^^^^^^368^^^^^^^^^^^Eucalyptus grandis^^^^^Ї:XUs t'${r 3 C^366^Plant Cell Environ.uu>Ru N Hrvq֒t֒ttQL u5tKX>Ru$Vrz j""A^366^The response of _Eucalyptus grandis_ seedlings to elevated atmospheric CO2 concentrations was examined by growing se"#edlings at either 340 or 660 umol CO2/mol for 6 weeks. Graded increments of phosphorus and nitrogen fertilizers were added$ to a soil deficient in these nutrients to establish if the growth response to increasing nutrient availability was affect"%ed by CO2 concentration. At 660 umol CO2/mol, seedling dry weight was up to five times greater than at 340 umol CO2/mol. T"&he absolute response was largest when both nitrogen and phosphorus availability was high but the relative increase in dry 'weight was greatest at low phosphorus availability. At 340 umol CO2/mol and high nitrogen availability, growth was stimula"(ted by addition of phosphorus up to 76 mg/kg soil. Further additions of phosphorus had little effect. However, at 660 umol) CO2/mol, growth only began to plateau at a phosphorus addition rate of 920 mg/kg soil. At 340 umol CO2/mol and high phosp*horus availability, increasing nitrogen from 40 to 160 mg/kg soil had little effect on plant growth. At high CO2, growth r+eached a maximum at between 80 and 160 mg nitrogen/kg soil. Total uptake of phosphorus was greater at high CO2 concentrati# ,on at all fertilizer addition rates, but nitrogen uptake was either lower or unchanged at high CO2 concentration except at- the highest nitrogen fertilizer rate. The shoot to root ratio was increased by CO2 enrichment, primarily because the spec# .ific leaf weight was greater. The nitrogen and phosphorus concentration in the foliage was lower at elevated CO2 concentra#/tion partly because of the higher specific leaf weight. These results indicate that critical foliar concentrations current# 0ly used to define nutritional status and fertilizer management may need to be reassessed as the atmospheric CO2 concentration rises.3 3##2152^4^Conroy,J P^Milham,P J^Mazur,M^Barlow,E W R^1990^1^Growth, Dry Weight Partitioning and Wood Properties of _Pinus radi#-ata_ D. Don after 2 Years of CO2 Enrichment^16^13^^329-337^^^^^^^^^^371^^^^^^^^^^^Pinus radiatata X&A^2054^Leaf conductance of eggplant (_Solanum melongena_ L., cv. Cosmos) was measured comparatively in two glasshouse comp#/5A^369^Advanced selections (families 20010 and 20062) of _P. radiata_ D. Don were exposed to either 340 or 660 umol CO2/mol#46 for 2 years to establish if growth responses to high CO2 would persist during the development of woody tissues. The exper7iment was carried out in glasshouses and some of the trees at each CO2 concentration were subjected to phosphorus deficien#78cy and to periodic drought. CO2 enrichment increased whole-plant dry matter production irrespective of water availability,#C9 but only when phosphorus supply was adequate. The greatest increase occurred during the exponential period of growth and :appeared to be tied to increased rates of photosynthesis, which caused accelerated production of leaf area. The increase i#G;n whole-plant dry matter production was similar for both families; however, family 20010 partitioned larger amounts of dry#Q< weight to the trunks than family 20062, which favoured the roots and branches. Wood density was generally increased by el=evated CO2 and for family 20010 this increase was due to thickening of the tracheid walls. Tracheid length was similar at #T>both CO2 levels but differed between families. These results suggest that, as the atmospheric CO2 concentration rises, fie#e?ld-grown _P. radiata_ should produce more dry weight at sites where phosphorus is not acutely deficient, even where drough#h@t limits growth; however, increases in wood production are likely only for genotypes which continue to partition at least #{the same proportion of dry weight to wood in the trunk.ing failed, F7 exits WP without saving.&%˜.8%X.6%XSQRVWB153^4^Conroy,J P^Milham,P J^Reed,M L^Barlow,E W^1990^1^Increases in Phosphorus Requirements for CO2-Enriched Pine Species^#~17^92^^977-982^^^^^^^^^^374^^^^^^^^^^^Pinus radiata/Pinus caribaea^^^^^baea0%s$<u:;Ouu3YSQRVW.;0# C^372^Plant Physiol.&E_^ZY[t..%؋>AuڎۋAu ڋ&;]vB&U&EA^372^_Pinus radiata_ D. Don (half-sib families 20010 and 20062) and _Pinus caribaea_ var hondurensis (an open-pollinated #Ffamily) were grown for 49 weeks at seven levels of phosphorus and at CO2 concentrations of either 340 or 660 microliters p#Ger liter, to establish if the phosphorus requirements differed between the CO2 concentrations and if mycorrhizal associatiHons were affected. When soil phosphorus availability was low, phosphorus uptake was increased by elevated CO2. This may ha#Ive been related to changes in mycorrhizal competition. When the phosphorus concentration in the youngest fully expanded ne#Jedles was above 600 milligrams per kilogram the shoot weight of all pine families was greater at high CO2 due to increasesK in rates of photosynthesis. More dry weight was partitioned to the stems of _P. radiata_ family 20010 and _P. caribaea_. #LAt foliar phosphorus concentrations above 1000 milligrams per kilogram (_P. radiata_) and 700 milligrams per kilogram (_P.#M caribaea_), growth did not increase at 340 microliters of CO2 per liter. Soluble sugar levels in the same needles mirroreNd the growth response, but the starch concentration declined with increasing phosphorus. At 660 microliters of CO2 per lit#Oer, shoot weight and soluble sugar concentrations were still increasing up to a foliar P concentration of 1800 milligrams #Pper kilogram for _P. radiata_ and 1600 milligrams per kilogram for _P. caribaea_. The starch concentration did not declineQ. These results indicate that higher foliar phosphorus concentrations are required to realize the maximum growth potential# of pines at elevated CO2.t!+ X *N1:XUSQVF2&t+FuUNF $?eC^378^Plant Physiol.6F| t{^FE;FtQ t.L8E~rntsM^tF.T8]ZrJPsM}t&kA^378^Needles from phosphorus deficient seedlings of _Pinus radiata_ D. Don grown for 8 weeks at either 330 or 660 uL CO2/$DlL displayed chlorophyll _a_ fluorescence induction kinetics characteristic of structural changes within the thylakoid chlo$Pmroplast membrane, _i.e._, constant yield fluorescence (Fo) was increased and induced fluorescence ([Fp-Fi]/Fo) was reducedn. The effect was greatest in the undroughted plants grown at 660 uL CO2/L. By week 22 at 330 uL CO2/L acclimation to P def$Soiciency had occurred as shown by the similarity in the fluorescence characteristics and maximum rates of photosynthesis of$cp the needles from the two P treatments. However, acclimation did not occur in the plants grown at 660 uL CO2/L. The light qsaturated rate of photosynthesis of needles with adequate P was higher at 660 uL CO2/L than at 330 uL CO2/L, whereas photo$frsynthesis of P deficient plants showed no increase when grown at the higher CO2 concentration. The average growth increase$qs due to CO2 enrichment was 14% in P deficient plants and 32% when P was adequate. In drought stressed plants grown at 330 $ttuL CO2/L, there was a reduction in the maximal rate of quenching of fluorescence (Rq) after the major peak. Constant yieldu fluorescence was unaffected but induced fluorescence was lower. These results indicate that electron flow subsequent to p$xvhotosystem II was affected by drought stress. At 660 uL CO2/L this response was eliminated showing that CO2 enrichment imp$wroved the ability of the seedlings to acclimate to drought stress. The average growth increase with CO2 enrichment was 37% in drought stressed plants and 19% in unstressed plants.x;r ƋFF1 y~2]_^Y[XPSQVWUz%7$y156^4^Conroy,J P^Virgona,J M^Smillie,R M^Barlow,E W^1988^1^Influence of Drought Acclimation and CO2 Enrichment on Osmotic $zAdjustment and Chlorophyll _a_ Fluorescence of Sunflower during Drought^17^86^^1108-1115^^^^^^^^^^383^^^^^^^^^^^sunflower/Helianthus annuususۿ+tUP3Ҿ.rAF&u9VvtF&;v F&;Dr^&;\s&\^&D#+ҏw3;sX@Ⰻ$iC^381^Plant Physiol.+t03Ҿr &T&t&u;VrV;VrV@Ӌ+t+3Ҿ}r&T&D u;VrV;Vr$}A^381^Osmotic adjustment occurred during drought in expanded leaves of sunflowers (_Helianthus annuus_ var Hysun 30) which$~ had been continuously exposed to 660 microliters CO2 per liter or had been previously acclimated to drought. The effect was greatest when the treatments were combined and was negligible in nonacclimated plants grown at 340 microliters CO2 per $liter. The concentrations of ethanol soluble sugars and potassium increased during the drought but they did not account fo$r the osmotic adjustment. The delay in the decline in conductance and relative water content and in the loss of structural integrity with increasing drought was dependent on the degree of osmotic adjustment. Where it was greatest, conductance f$ell from 5.8 millimeters per second on the first day of drought to 1.3 millimeters per second on the fourth day and was ap$proximately the same level on the eighth day. The relative water content remained constant at 85% for three days and fell to 36% on the sixth day. There was no evidence of leaf desiccation even on the eighth day. In contrast, the conductance of$ leaves showing minimal adjustment fell rapidly after the first day of drought and was negligible after the fourth, at whi$ch time the relative water content was 36%. By the sixth day of drought, areas near the margins of the leaves were desicca$ting and the plants did not recover upon rewatering. Despite the differences in the rate of change of conductance and relative water content during drought, photosynthetic electron transport activity, inferred from measurements of chlorophyll _$a_ fluorescence _in vivo_ and PSII activity of isolated thylakoids, remained functional until desiccation occurred.G$157^1^Cooper,C F^1986^1^Carbon Dioxide Enhancement of Tree Growth at High Elevations^48^231^^859^^^^^^^^^^386^^^^^^^^^^^bristlecone pine/limber pineneRU|w LAvO${ssG gO ]Z[XSQWVr; t!tDTG t${C^384^Sciencew ;GsC ux&O;r;rO ;w;w O+G3GW+GW^_Y[QGWGD TD% A^384^Technical comment.O =tOO Y.I7PS6u7;:~r 6Gu( t<w 2H؊6;Ut % 158^3^Coudret,A^Ferron,F^Laffray,D^1985^1^High CO2 Partial Pressure Effects on Dark and Light CO2 Fixation and Metabolism %is _Vicia faba_ Leaves^18^7^^115-126^^^^^^^^^^389^^^^^^^^^^^Vicia faba^^^^^.=NDCdDGgN@C^387^Photosynth. Res.FC*XY^PV>Du4FDIDCDDD dD*r 5**^X6 H؀>!u&165^4^Curtis,P S^Balduman,L M^Drake,B G^Whigham,D F^1990^1^Elevated Atmospheric CO2 Effects on Belowground Processes in C3 and C4 Estuarine Marsh Communities^2^71^^2001-2006^^^^^^^^^^407^^^^^^^^^^^Scirpus olneyi/Spartina patens/Distichlis spica&C^405^EcologyuC"r>0 &&3&& H&&&&t 3Ҍ^s^YXPS6D36;Dt[&t&A^405^Belowground carbon allocation is a major component of a plant's carbon budget, yet relatively little is known about the response of roots to elevated atmospheric CO2. We have exposed three brackish marsh communities dominated by perennial& macrophytes to twice ambient CO2 concentrations for two full growing seasons using open top chambers. One community was d&ominated by the C3 sedge _Scirpus olneyi_, one was dominated by the C4 grass _Spartina patens_, and one was a mixture of _&S. olneyi_, _S. patens_, and _Distichlis spicata_, a C4 grass. Root and rhizome growth were studied in the 2nd yr of expos&ure by measuring growth into peat cores previously excavated and refilled with sphagnum peat devoid of roots. Growth under" elevated CO2 resulted in an 83% increase in root dry mass per core in the _Scirpus_ community. Those roots were also sign"ificantly lower in percentage of nitrogen than roots from ambient-grown plants. There was no effect of elevated CO2 on roo"t growth or nitrogen content in the _Spartina_ community or in the C4 component of the mixed community.^ZY[XWu1 r,"ta^^^^ƀt8 Ur  _SQR6>Du.6>Et&&Etu wrC sZY[6>DtPS!166^5^Curtis,P S^Drake,B G^Leadley,P W^Arp,W J^Whigham,D F^1989^1^Growth and Senescence in Plant Communities Exposed to Elevated CO2 Concentrations on an Estuarine Marsh^34^78^^20-26^^^^^^^^^^410^^^^^^^^^^^Scirpus olneyi/Spartina patens/Distichlis spicatata~&&U&eF&E_^ZY[XQVW6D6D+t u_^YÀ> uuu tsC^408^Oecologiaut!&> u&>u&t^YXSQRVW 6DH rGEFN6 EuVI6 #SA^408^Three high marsh communities on the Chesapeake Bay were exposed to a doubling in ambient CO2 concentration for one growing season. Open-top chambers were used to raise CO2 concentrations ca. 340 ppm above ambient over monospecific communigties of _Scirpus olneyi_ (C3) and _Spartina patens_ (C4), and a mixed community of _S. olneyi_, _S. patens_, and _DistichlWis spicata_ (C4). Plant growth and senescence were monitored by serial, nondestructive censuses. Elevated CO2 resulted in increased shoot densities and delayed senescence in the C3 species. This resulted in an increase in primary productivity in _S. olneyi_ growing in both the pure and mixed communities. There was no effect of CO2 on growth in the C4 species. Thes&re results demonstrate that elevated atmospheric CO2 can cause increased aboveground production in a mature, unmanaged ecos3ystem.&Ì 6;Ds & 6D !&&6+wvـPX^V&H 167^3^Curtis,P S^Drake,B G^Whigham,D F^1989^1^Nitrogen and Carbon Dynamics in C3 and C4 Estuarine Marsh Plants Grown under% Elevated CO2 _in situ_^34^78^^297-301^^^^^^^^^^413^^^^^^^^^^^Scirpus olneyi/Spartina patens/Distichlis spicatata2%C^411^Oecologia[P&}t0&Eu%t&&Ur6 Et6 E&XPSRVW6 E6& Er<6 Eu96& E%* A^411^Carbon dioxide concentrations were elevated in three estuarine communities for an entire growing season. Open top ch$e ambers were used to raise CO2 concentrations ca. 336 ppm above ambient in monospecific communities of _Scirpus olneyi_ (C3#) and _Spartina patens_ (C4), and a mixed community of _S. olneyi_, _S. patens_ and _Distichlis spicata_ (C4). Nitrogen and carbon concentration (% wt) of aboveground tissue was followed throughout growth and senescence. Green shoot %N was reduced and %C was unchanged under elevated CO2 in _S. olneyi_. This resulted in a 20%-40% increase in tissue C/N ratio. There was no effect of CO2 on either C4 species. Maximum aboveground N (g/m2) was unchanged in _S. olneyi_, indicating that increased productivity under elevated CO2 was dependent on reallocation of stored N. There was no change in the N recovery efficiency of _S. olneyi_ in pure stand and a decrease in the mixed community. Litter C/N ratio was not affected by elevated CO2 suggesting that decomposition and N mineralization rates will also remain unchanged. Continued growth responses to elevated CO2 could, however, be limited by the ability of _S. olneyi_ to increase the total aboveground N pool.G_[ 168^2^Curtis,P S^Teeri,J A^1992^1^Seasonal Responses of Leaf Gas Exchange to Elevated Carbon Dioxide in _Populus grandidentata_^32^22^^1320-1325^^^^^^^^^^416^^^^^^^^^^^Populus grandidentatata Michx.4E4Eێ8E&C;,Ev{QEg u C^414^Can. J. For. Res.E-[Z&t2E&&1SREE2E&&& & &!Z["aˋD`EYA^414^Rising atmospheric carbon dioxide concentrations may have important consequences for forest ecosystems. We studied above- and below-ground growth and leaf gas exchange responses of _Populus grandidentata_ Michx. to elevated CO2 under natural forest conditions over the course of a growing season. Recently emerged _P. grandidentata_ seedlings were grown in native, nutrient-poor soils at ambient and twice ambient (707 ubar (1 bar=100 kPa)) CO2 partial pressure for 70 days in open-top chambers in northern lower Michigan. Total leaf area and shoot and root dry weight all increased in high CO2 grown plants. Photosynthetic light and CO2 response characteristics were measured 28, 45, and 68 days after exposure to elevated CO2. In ambient grown plants, light saturated assimilation rates increased from day 28 to day 45 and then declined at day 68 (15 September). This late-season decline, typical of senescing _Populus_ leaves, was due both to a decrease in the initia!l slope of the net CO2 assimilation versus intercellular CO2 partial pressure relationship and to decreased CO2 saturated "assimilation rates. Specific leaf nitrogen (mg N/cm2 leaf area) did not change during this period, although leaf carbon co#ntent and leaf weight (mg/cm2) both increased. In ambient grown plants stomatal conductance also declined at day 68. In co$ntrast, plants grown at elevated CO2 showed no late-season decline in photosynthetic capacity or changes in leaf weight, s%uggesting a delay in senescence with long-term exposure to high CO2. High CO2 grown plants also maintained photosynthetic &sensitivity to increasing Ci throughout the exposure period, while ambient CO2 grown plants were insensitive to Ci above 4'00 ubar on day 68. These results indicate the potential for direct CO2 fertilization of _P. grandidentata_ in the field and provide evidence for a new mechanism by which elevated atmospheric CO2 could influence seasonal carbon gain. @ 169^1^Dahlman,R C^1993^1^CO2 and Plants: Revisited^123^104/105^^339-355^^^^^^^^^^419^^^^^^^^^^^^^^^^arecharacteristicwne_ _max_ L. Merr. cv. Tamahomare) were subjected to CO2 enrichment and/or NO3-N application (50 and 300 ppm), and the gro+A^417^The decade-long USA research program on the direct effects of CO2 enrichment on vegetation has achieved important mi,lestones and has produced a number of interesting and exciting findings. Research beginning in 1980 focused on field exper-iments to determine whether phenomena observed in the laboratory indeed occurred in natural environments. The answer is ye.s. Data obtained from numerous field studies show mixed response of crop and native species to CO2 enrichment however. Nea/rly all experiments demonstrate that plants exhibit positive gain when grown at elevated CO2; although the magnitude varie0s greatly. Most crop responses range from 30 to 50% increase in yield. Results from long-term experiments with woody speci1es and ecosystems are even more variable. Huge growth responses (100 to nearly 300% increase relative to controls) are rep2orted from several tree experiments and the salt-marsh ecosystem experiment. Other results from experiments with woody spe3cies and the tundra ecosystem suggest little or no effect of CO2 on physiology, growth or productivity. Numerous studies o4f the physiology of the CO2 effect are continuing in attempts to understand controlling mechanisms and to explain the vari5able growth responses. Particular emphasis needs to be given to physiological measures of interactions involving the CO2 e6ffect and other environmental influences, and to the wide-ranging observations of photosynthesis acclimation to CO2. Prospects for future research are identified.proximatedwiththehelpofthelognormalfunction.MatveyevYu8170^3^Dahlman,R C^Strain,B R^Rogers,H H^1985^1^Research on the Response of Vegetation to Elevated Atmospheric Carbon Dioxide^9^14^^1-8^^^^^^^^^^422^^^^^^^^^^^^^eview/agriculture/ecosystem level CO2 responsesationcoefficientsfordifferentlC^420^J. Environ. Qual.btainedthatallowonetojudgeaboutbaricandpressureformationsrelatedtocloudfieldformati;A^420^The global rise in atmospheric CO2 is an established phenomenon. Irrespective of whether a CO2-induced climate changease the rate of photosynthesis. Quantitative information on the CO2-induced growth response for field situations is neede?d for assessments of (i) possible benefits to agriculture, (ii) the amount of fossil C that can be sequestered by CO2-acce@lerated growth of the biosphere, and (iii) unknown or unidentified effects of CO2 on the physiology, structure, and functiAon of plants and ecosystems. Along with knowledge of CO2 effects on climate and other factors, information on direct plantB effects will be used in comprehensive evaluations of policy options related to increasing atmospheric CO2. Herein, a discCussion of the plan by the U.S. Department of Energy (DOE) to address the CO2 problem is presented along with research results from two programs, one agricultural and the other ecological.ocontainsinformationonoptical,electricalandradiatE171^2^Davis,T D^Potter,J R^1989^1^Relations between Carbohydrate, Water Status and Adventitious Root Formation in Leafy PeFa Cuttings Rooted under Various Levels of Atmospheric CO2 and Relative Humidity^44^77^^185-190^^^^^^^^^^425^^^^^^^^^^^Pisum sativumum L.ngrad,p.3749.Resultsofexperimentalresearchofhighlevelcloudmicrostructure P-(4 c9C^423^Physiol. Plant.rologicalObservatoryduringthe80iesarereviewed.ItisshownthattheparticlesizespectrumIA^423^Three levels of atmospheric CO2 and 2 levels of relative humidity (RH) during the rooting period were tested for theJir effect on several factors presumed to influence adventitious root formation in leafy pea (_Pisum sativum_ L. cv. AlaskaK) cuttings. Compared to normal CO2 levels (350 uL/L), neither 1800 nor 675 uL/L CO2 affected the rooting percentage or theL number of roots per cutting. However, 1800 uL/L CO2 increased root and shoot dry weight, root length, carbohydrate levelsM in the base of the cuttings and water potential (w) of cuttings compared to normal levels of CO2. Compared to 87% RH, 55N% RH decreased all of the above parameters, including the number of roots per cutting. A polyvinyl chloride antitranspiranOt (which partially blocks stomata and slows photosynthesis) applied simultaneously with 87% RH increased w and root lengtPh but lowered all of the other above parameters, compared to 87% RH without antitranspirant. Increasing current photosynthQate (products of photosynthetic activity after excision), carbohydrate, or w either alone or together was associated withR increased root system size but not necessarily with increased rooting percentage or root number. The data are consistent Swith a hypothesis that the number of roots per cutting increased with increasing current photosynthate and carbohydrate unTtil some other factor became limiting. Also, the effect of w on rooting percentage and root number was mediated through its effect on current photosynthate and carbohydrate.orcalculatingsmallanglescatteringoncirruscloudparticlesisshV172^2^de Bruin,H A R^Jacobs,C M^1993^1^Impact of CO2 Enrichment on the Regional Evapotranspiration of Agro-ecosystems, a Theoretical and Numerical Modelling Study^123^104/105^^307-318^^^^^^^^^^428^^^^^^^^^^^^^^^^rd,theaveragevaluesoffull)A^1073^A wild soybean variety (_Glycine_ _soja_ Sieb. and Zucc. line Nakei-No. 1) and a cultivated soybean variety (_GlyciYA^426^This paper gives a brief overview of factors determining evapotranspiration of vegetated surfaces. It indicates whicZh of these factors are sensitive to CO2 enrichment. A qualitative analysis is presented of the impact of large scale clima[te changes. Data in literature indicate that the surface resistance of vegetated areas may change within the range -25% an\d +50% if the atmospheric CO2-concentration doubles. The impact of such changes on regional scale transpiration is evaluat]ed using a numerical model in which the interaction between the evapotranspiration and the Planetary Boundary Layer is acc^ounted for. It is concluded that the impact of CO2 enrichment on the transpiration at the regional scale is relatively sma_ll for aerodynamically smooth surfaces (between +7% and -11%). For aerodynamically rough surfaces the effects are somewhat larger (between +15% and -21%).scalestructureandinparticularonthoseofitscharacteristicswhichaffecttheproca173^2^de Cortzar,V G^Nobel,P S^1990^1^Worldwide Environmental Productivity Indices and Yield Predictions for a CAM Plant,s _Opuntia ficus-indica_, Including Effects of Doubled CO2 Levels^46^49^^261-279^^^^^^^^^^431^^^^^^^^^^^Opuntia ficus-indicGC^429^Agric. For. Meteorol.uscloudparticles.RadiationPropertiesofCirrusClouds.Moscow,6572.AnensemblemethoddA^429^The productivity of _Opuntia ficus-indica_ was predicted for 253 regions on a worldwide basis using data from 1464 weeather stations within 60 of the equator. First, the climatic data were used to calculate daily values of a PAR index, a ftemperature index and a water index. These indices, each of which has a maximum value of unity when that environmental facgtor is not limiting net CO2 uptake by _O. ficus-indica_ over a 24-h period, were multiplied together to give an environmenhtal productivity index, which indicates how the three environmental factors limit net CO2 uptake and hence productivity. Tihe photosynthetically active radiation (PAR) index for a canopy of closely spaced plants that have a high productivity perj unit ground area was >/= 0.20 for 25% of the earth's land surface. The temperature index annually was >/= 0.50 for 81% ofk the earth's land surface, indicating that local temperatures do not greatly limit net CO2 uptake by this species. The watler index was >/= 0.50 for 79% of the earth's surfaces for _O. ficus-indica_ which exhibits Crassulacean acid metabolism wimth its accompanying high water-use efficiency. Predicted productivities for _O. ficus-indica_ without irrigation were at lneast 10 metric tons/ha/y, the value for many important annual agronomic crops, for 41% of the earth's land area. Irrigatioon increased such high productivity regions to 77% of the earth's land surface area within 60 of the equator. For simulatipons that included the worldwide changes in PAR, temperature and rainfall patterns that will most likely accompany a doubliqng in the ambient CO2 level, the high productivity of 10 tons/ha/y was predicted to occur for 54% of the earth's land surfrace area. Under elevated CO2, the predicted productivity of _O. ficus-indica_ increased for most of the U.S.A. and a productivity of 32 tons/ha/y was predicted for western South America.ividualparticle.Itsapplicationforcalculatingsmallacateringoncirruscloudparticlesisshownandatypicalexamplecharacterizingthephysicsoftheprocessisconsideru174^4^Del Castillo,D^Acock,B^Reddy,V R^Acock,M C^1989^1^Elongation and Branching of Roots on Soybean Plants in a Carbon Dioxide-Enriched Aerial Environment^4^81^^692-695^^^^^^^^^^434^^^^^^^^^^^soybean/Glycine maxax (L.) Merr.ingincrease.ThbC^432^Agron. J.resultsintheappearanceofnoiseintheangularbehaviorofscatteringintensity.IndicatrixmaximadecxA^432^Plants grown in high CO2 concentrations ([CO2]) often have a higher root weight than those grown in low [CO2]. It isy usually assumed that the plants with this extra root weight can explore a greater volume of soil and will, therefore, havze more water available to them. To test this assumption, soybean [_Glycine max_ (L.) Merr. cv. Forrest] plants were grown {in outdoor, sunlit plant-growth chambers in [CO2] of 330, 450, 600, and 800 uL/L throughout the growing season. The soil c|ontainers in the growth chambers had a glass side and new root growth appearing at the glass was measured and marked two o}r three times each week. Root weight at the end of the season (93 d after emergence) was 26 to 31% higher in [CO2]-enriche~d chambers compared with the 330 uL/L treatment, and cumulative root length was approximately proportional to [CO2]. However, CO2 treatment did not affect the rate of elongation of individual root axes. Instead, there was a significant linear increase in the number of actively growing roots with increased [CO2]. Plants grown in 800 uL/L had 65% more actively growing roots than plants grown in 330 uL/L. Thus, growing a plant in high [CO2] enabled it to explore a given volume of soil more thoroughly, but did not increase the volume of soil explored.cordingsfortheBlind.Ihave35daysofunusedconsul175^5^Delgado,E^Azcon-Bieto,J^Aranda,X^Palazon,J^Medrano,H^1992^1^Leaf Photosynthesis and Respiration of High CO2-grown Tobacco Plants Selected for Survival under CO2 Compensation Conditions^17^98^^949-954^^^^^^^^^^437^^^^^^^^^^^tobacco/Nicotiana tabacum^^ L. % GV 04#fU> AvC^435^Plant Physiol.anovWP( U$  HP LaserJeA^435^Four self-pollinated, doubled-haploid tobacco, (_Nicotiana tabacum_ L.) lines (SP422, SP432, SP435, and SP451), selected as haploids by survival in a low CO2 atmosphere, and the parental cv Wisconsin-38 were grown from seed in a growth room kept at high CO2 levels (600-700 parts per million). The selected plants were much larger (especially SP422, SP432, and SP451) than Wisconsin-38 nine weeks after planting. The specific leaf dry weight and the carbon (but not nitrogen and sulfur) content per unit area were also higher in the selected plants. However, the chlorophyll, carotenoid, and alkaloid contents and the chlorophyll _a/b_ ratio varied little. The net CO2 assimilation rate per unit area measured in the growth room at high CO2 was not higher in the selected plants. The CO2 assimilation rate _versus_ intercellular CO2 curve and the CO2 compensation point showed no substantial differences among the different lines, even though these plants were selected for survival under CO2 compensation point conditions. Adult leaf respiration rates were similar when expressed per unit area but were lower in the selected lines when expressed per unit dry weight. Leaf respiration rates were negatively correlated with specific leaf dry weight and with the carbon content per unit area and were positively correlated with nitrogen and sulfur content of the dry matter. The alternative pathway was not involved in respiration in the dark in these leaves. The better carbon economy of tobacco lines selected for low CO2 survival was not apparently related to an improvement of photosynthesis rate but could be related, at least partially, to a significantly reduced respiration (mainly cytochrome pathway) rate per carbon.WPSQW3&/&߁DLuY[XW,3 u<u uN;t |\t|176^5^Delgado,E^Parry,M A J^Lawlor,D W^Keys,A J^Medrano,H^1993^1^Photosynthesis, Ribulose-1,5-_bis_phosphate Carboxylase and Leaf Characteristics of _Nicotiana tabacum_ L. Genotypes Selected by Survival at Low CO2 Concentrations^39^44^^1-7^^^^^^^^^^440^^^^^^^^^^^tobacco/Nicotiana tabacumum L.Q&E>DuDD>6D_u&E6D&E8D~t&E9D3&2G*C^438^J. Exp. Bot.>Du4>t*7 jN< tF_rFNdpRr#6D8D:D6.]>!<uI!.>. from field cores appears to be related to the annual cycle of net photosynthesis in _S_. _alterniflora_._.A^441^The response of _Plantago major_ ssp. _pleiosperma_ plants, grown on nutrient solution in a climate chamber, to a doubling of the atmospheric CO2 concentration was investigated. Total dry matter production was increased by 30% after 3 weeks fo exposure, due to a transition stimulation of the relative growth rate (RGR) during the first 10 days. Thereafter RGR returned to the level of control plants. Photosynthesis, expressed per unit leaf area, was stimulated during the first two weeks of the experiment, thereafter it dropped and nearly reached the level of the control plants. Root respiration was not affected by increased atmospheric CO2 levels, whereas shoot, dark respiration was stimulated throughout the experimental period. Dry matter allocation over leaves stems and roots was not affected by the CO2 level. SLA was reduced by 10%, which can partly be explained by an increased dry matter content of the leaves. Both in the early and later stages of the experiment, shoot respiration accounted for a larger part of the carbon budget in plants grown at elevated atmospheric CO2. Shifts in the total carbon budget were mainly due to the effects on shoot respiration. Leaf growth accounted for nearly 50% of the C budget at all stages of the experiment and in both treatments.D:r@Dr0D@r%3:|. 178^2^den Hertog,J^Stulen,I^1990^3^The Effects of an Elevated Atmospheric CO2-concentration on Dry Matter and Nitrogen Allocation^The Greenhouse Effect and Primary Productivity in European Agro-ecosystems; 5-10 April 1990; Wageningen, The Netherlands^Pudoc^Wageningen^27-30^^^^^^^^^^^^^^^^^^^^^Plantago major/broadleaf plantain/Urtica dioica/stinging nettle^^^^^^^^^^Goudriaan,J^van Keulen,H^van Laar,HHar,H H`Z[X4:rFFr7DNDVr,DXr$DRrDPDTrD^r D`179^3^DeWitt,C A^Waldron,R E^Lambert,J R^1983^5^Effects of Carbon Dioxide Enrichment on Nitrogen Fixation in Soybeans 1982^U.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture, Agric. Res. Serv., Washington, D.C^^^^^^^^^^^^^^^^^^^^^^^^soybean/Glycine max^^010 in Green Report Series^Response of Vegetation to Carbon Dioxide^^ Dioxi180^3^Dietz,K-J^Schreiber,U^Heber,U^1985^1^The Relationship between the Redox State of Q(A) and Photosynthesis in Leaves a"t Various Carbon-dioxide, Oxygen and Light Regimes^51^166^^219-226^^^^^^^^^^448^^^^^^^^^^^Helianthus annuus/Fagus sylvatic!C^446^Planta W -,&-&-    13AugustA^446^The response of chlorophyll fluorescence elicited by a low-fluence-rate modulated measuring beam to actinic light and to superimposed 1-s pulses from a high-fluence-rate light source was used to measure the redox state of the primary acceptor, Q(A) of photosystem II in leaves which were photosynthesizing under steady-state conditions. The leaves were exposed to various O2 and CO2 concentrations and to different energy fluence rates of actinic light to assess the relationship between rates of photosynthesis and the redox state of Q(A). Both at low and high fluence rates, the redox state of Q(A) was little altered when the CO2 concentration was reduced from saturation to about 600 uL/L although photosynthesis was decreased particularly at high fluence rates. Upon further reduction in CO2 content the amount of reduced Q(A) increased appreciably even at low fluence rates where light limited CO2 reduction. Both in the presence and in the absence of CO2, a more reduced Q(A) was observed when the O2 concentration was below 2%. Q(A) was almost fully reduced when leaves were exposed to high fluence rates under nitrogen. Even at low fluence rates, Q(A) was more reduced in shade leaves of _Asarum europaeum_ and _Fagus sylvatica_ than in leaves of _Helianthus annuus_ and _Fagus sylvatica_ grown under high light. Also, in shade leaves the redox state of Q(A) changed more during a transition from air containing 350 uL/L CO2 to CO2-free air than in sun leaves. The results are discussed with respect to the energy status and the CO2-fixation rate of leaves.181^1^Dons,C^1988^1^Effects of Long-Term CO2 Enrichment under Different Irradiance Regimes on Growth and Photosynthesis in _Lemna gibba_^42^22^^328-334^^^^^^^^^^451^^^^^^^^^^^Lemna gibba/duckweeded@C^449^PhotosyntheticaQV @srDD Ƈ؉D^YV6؋D؋D@s^SW^ج<#t uA^449^Cultivation in CO2-enriched air increased the growth rate of _Lemna gibba_ only when day/night light cycling was used. Starch content increased with CO2 enrichment and irradiance (_I_). Reduced CO2 assimilation and growth in plants grown under high continuous _I_ and CO2-enriched air may be due to high starch levels. Changes in leaf area ratio and dry mass content were associated with increased starch content. Also morphological changes occurred in high-CO2-grown plants.O&182^1^Doorduin,J C^1990^1^Effects of CO2 and Plant Density on Growth and Yield of Glasshouse Grown Freesias^15^268^^171-177^^^^^^^^^^454^^^^^^^^^^^freesiaia9b6S~6H~>g7t2ɆkN>g7~g7H~fNkH~S~F2):&C^452^Act. Hort.NˀNPSQVWu >utV t *&G uF t3ޚ-Tr7&&2'3& lA^452^It has been demonstrated for many glasshouse crops that increasing the CO2 concentration leads to improved quality and yield, while concentrations below the ambient level lead to loss of quality and yield. Relatively few experimental data are known for freesia in this area and on freesia holdings CO2 enrichment is applied only to a limited extent. For this reason in an experiment 4 CO2 concentrations were combined with 4 plant densities to investigate the effect of CO2 on quality and yield of the cultivar 'Blue Heaven'. The CO2 concentrations realised were 265, 360, 560 and 860 ppm. Plant densities were 57, 78, 100 and 121 corms per net square metre. The concentration of 265 ppm resulted in a 20% lower yield of stems, corms and cormlets and a reduction of stem quality as compared to 360 ppm. Increasing the concentration to 560 ppm resulted in a 20% higher yield and an improved quality as compared to 360 ppm. Levels exceeding 560 ppm did not improve yield or quality. Higher plant densities did not give higher yields but evidently reduced quality. Vase life was not affected by differences in CO2 concentrations or plant densities.҆t€t%3: rƾ €t3 184^3^Downton,W J S^Grant,W J R^Chacko,E K^1990^1^Effect of Elevated Carbon Dioxide on the Photosynthesis and Early growth of Mangosteen (_Garcinia mangostana_ L.)^53^44^^215-225^^^^^^^^^^460^^^^^^^^^^^mangosteen/Garcinia mangostanana L.| tC^458^Scientia Hortic.^[XÃ'X'PPSVȚTr>et ȚTs^[Xr/' PSVȚT^[Xr''A^458^The Mangosteen is a potentially important new crop for tropical northern Australia if its long establishment time can be substantially reduced. The effect of enriching the atmosphere with up to 1000 ubar CO2 on the growth and photosynthesis of mangosteen seedlings was examined over the course of a year in an attempt to accelerate early plant development. It was initially found to be necessary to reduce photon irradiance from 450 to 200 umol photons/m2/s (400-700 nm) to overcome photoinhibition of photosynthesis, and to reduce CO2 from 1000 to 800 ubar to encourage greening of newly formed leaves. A major effect of CO2 enrichment was to stimulate earlier lateral branching which accelerated the development of leaf area and plant carbon gain. Photosynthetic rates of mangosteen leaves were found to be very low and the 800-ubar CO2 atmosphere increased CO2 fixation by 40-60% compared to control leaves measured at 400 ubar CO2. As a result, total plant dry weigh t increased by 77%. The stimulatory effect of CO2 was greatest on root and stem dry weight, which doubled. Although a smal ler proportion of dry weight was partitioned into leaves compared with control plants, CO2 enrichment increased average le af size by about 10%, specific leaf dry weight by 17% and total leaf area by 28%. By comparison, plants from the same apom ictic seedling population grown under shadehouse conditions in Darwin, Australia, developed more slowly, consistent with d escriptions in the literature, and were substantially smaller and lower in dry weight compared to the plants grown under c ontrolled conditions, even in the absence of CO2 enrichment, and had not developed lateral branches by harvest time. Reaso ns for this difference are suggested which may enable improvement of the early growth of mangosteen plants under field nursery conditions..F;Vw r;FsFVF;Vr w;FvFV;ׁw ;ՁwgvD FFDFV+FVD 185^1^Doyle,T W^1987^3^Seedling Response to CO2 Enrichment under Stressed and Non-stressed Conditions^Proceedings of the I nternational Symposium on Ecological Aspects of Tree Ring Analysis^NTIS^Springfield, Virginia^494-500^^^^^^^^^^462^^^^^^^^^^^loblolly pine/sweetgum/Liquidambar styraciflua/Pinus taeda^^^^^^^^^^Jacoby,GC^Hornbeck,JWck,JWW\D sse A^461^Loblolly pine and sweetgum seedlings were obtained from a Duke University phytotron study, where three groups were g rown in different atmospheres of CO2 (i.e., 350, 500, 650 ppmv). Seedlings were grown over three growing seasons, and incl uded a set of water-stressed and non-stressed individuals. X-ray densitometry was used to evaluate growth and density char acteristics of the wood samples. Cross-sectional discs of these samples were radiographed and scanned with a microdensitom eter to determine ring width, area, density and mass for each growth year. Results indicated significant differences in wo od production (ring width, area and mass) between the lowest treatment of CO2 (350 ppmv) and the higher concentration (500  and 650 ppmv) treatments. While only a few density parameters demonstrated significant changes with increasing CO2, almos t all showed a systematic increase in density with increasing CO2 concentration. Ring area and mass displayed the greatest  degree of change between treatments. Induced drought effects appeared only to strengthen the CO2-growth association. Thes e findings suggest that naturally stressed trees are also likely to exhibit some growth effect with increasing atmospheric  CO2. And because the greatest margin of response existed between 350 and 500 ppmv, this study emphasizes the importance a nd need to determine growth responses at preindustrial era CO2 concentrations in order to more accurately identify the postulated 'fertilizer' effect on modern forests.:^Z[XQ= sȸ3YV&&Ie;:^PRI#:r<&E&U& 186^1^Drake,B G^1992^1^A Field Study of the Effects of Elevated CO2 on Ecosystem Processes in a Chesapeake Bay Wetland^25^40^^579-595^^^^^^^^^^465^^^^^^^^^^^Spartina patens/Scirpus olneyi/Distichlis spicataasBY[QRUt}&C^463^Aust. J. Bot.&@u& t22H   &@XV *\*FJ^#:ZYUu@ A^463^Open top chambers are being used in a long-term project to determine the effects of elevated CO2 on ecosystem proces ses on a Chesapeake Bay wetland. Three communities are studied: mono-specific stands of the C3 sedge, _Scirpus olneyi_, an d the C4 grass, _Spartina patens_, and a mixed community of these two species and the C4 grass, _Distichlis spicata_. Trea tment began in the spring of 1987 and will continue through the 1994 growing season. During the first 4 years of exposure,  elevated CO2 had the following effects on mono-specific stands of the C3 sedge, _Scirpus olneyi_: increased quantum yield and photosynthetic capacity, reduced dark respiration, increased numbers of shoots, roots and rhizomes, reduced nitrogen !concentration of all tissues, increased nitrogen fixation and increased ecosystem carbon accumulation. In a mixed communit "y of the sedge and C4 grass species, _Spartina patens_ and _Distichlis spicata_, biomass of the C3 component increased ove #r 100% and this was accompanied by decreased biomass in the C4 component of the community. Elevated CO2 reduced water loss $, increased water potential and delayed senescence in all three species. Many factors contributed to CO2 stimulated carbon % accumulation in the plant community dominated by the C3 sedge, _Scirpus olneyi_, including: sustained high photosynthetic & capacity, decreased respiration, delayed senescence, and allocation of the additional carbon to roots and rhizomes. The c 'omplex interaction of these diverse responses suggests that the rising atmospheric CO2 may have a significant impact on ecosystem processes. GZ_YRVWB&wtr!:s>u>u>u>9t} e,s )187^6^Drake,B^Arp,W^Curtis,P S^Leadley,P W^Sager,J^Whigham,D^1986^5^Effects of Elevated CO2 on Chesapeake Bay Wetlands. I. * Description of the Study Site^U.S. Dept. of Energy, Carbon Dioxide Research Division, Washington, D.C^^^^^^^^^^^^^^^^^^^^!/^^^^Spartina patens/Distichlis spicata/Scirpus olneyi^^034 in Green Report Series^Response of Vegetation to Carbon Dioxide ,188^6^Drake,B G^Arp,W^Craig,J^Curtis,P S^Leadley,P W^Whigham,D^1987^5^Effects of Elevated CO2 on Chesapeake Bay Wetlands. -II. Gas Exchange and Microenvironment in Open Top Chambers^U.S. Dept. of Energy, Carbon Dioxide Research Division, Washing .ton, D.C^^^^^^^^^^^^^^^^^^^^^^^^Scirpus olneyi/Spartina patens/Distichlis spicata^^038 in Green Report Series^Response of Vegetation to Carbon Dioxide^^3\$${_^ZX_^ZXQVu<u3ɴ@9:s:s :s tFFuȊ 0189^12^Drake,B G^Arp,W J^Balduman,L^Curtis,P S^Johnson,J^Kabara,D^Leadley,P W^Pockman,W T^Seliskar,D^Sutton,M L^Whigham,D^ 1Ziska,L^1989^5^Effects of Elevated CO2 on Chesapeake Bay Wetlands. IV. Ecosystem and Whole Plant Responses. April-November 2 1988^U.S. Dept. of Energy, Carbon Dioxide Research Division, Washington, D.C^^^^^^^^^^^^^^^^^^^^^^^^Scirpus olneyi/Sparti 3na patens/Distichlis spicata/Glycine max/soybean/Lycopersicon esculentum/tomato/Manihot esculentum/Amaranthus hypochondria 4cus/amaranth/Acacia mangium/Ficus obtusifolia/Paspallum conjugatum/Pharus latifolia/Psychotria limonensis/Tabebuia rosea^^051 in Green Report Series^Response of Vegetation to Carbon Dioxide^^arbon Dioxide^^]] EtwM M Et 6190^12^Drake,B G^Arp,W J^Balduman,L^Cousimano,R^Dacey,J^D'Abundo,D^Hogan,K^Long,S^Pockman,W T^Utley,P^Villegas,A C^Whigham 7,D^1990^5^Effects of Elevated Co2 on Chesapeake Bay Wetlands. V. Ecosystem and Whole Plant Responses. April-November 1989^ 8U.S. Dept. of Energy, Carbon Dioxide Research Division, Washington, D.C^^^^^^^^^^^^^^^^^^^^^^^^Scirpus olneyi/Spartina patens^^055 in Green Report Series^Response of Vegetation to Carbon Dioxide^^Ȋ2SS^'.<=s[d'.& :191^6^Drake,B G^Curtis,P S^Arp,W J^Leadley,P W^Johnson,J^Whigham,D^1988^5^Effects of Elevated CO2 on Chesapeake Bay Wetlan ;ds. III. Ecosystem and Whole Plant Responses in the First Year of Exposure, April-November 1987^U.S. Dept. of Energy, Carb 192^2^Drake,B G^Leadley,P W^1991^1^Canopy Photosynthesis of Crops and Native Plant Communities Exposed to Long-term Elevated CO2^16^14^^853-860^^^^^^^^^^473^^^^^^^^^^^Scirpus olneyi/Spartina patensns>tit3Rs C^471^Plant Cell Environ.UHϚsu&&¿XP>t t +XPR& AA^471^There have been seven studies of canopy photosynthesis of plants grown in elevated atmospheric CO2: three of seed cr Bops, two of forage crops and two of native plant ecosystems. Growth in elevated CO2 increased canopy photosynthesis in all C cases. The relative effect of CO2 was correlated with increasing temperature: the least stimulation occurred in tundra ve Dgetation grown at an average temperature near 10C and the greatest in rice grown at 43C. In soybean, effects of CO2 were E greater during leaf expansion and pod fill than at other stages of crop maturation. In the longest running experiment wit Fh elevated CO2 treatment to date, monospecific stands of a C3 sedge, _Scirpus olneyi_ (Grey), and a C4 grass, _Spartina pa Gtens_ (Ait.) Muhl., have been exposed to twice normal ambient CO2 concentrations for four growing seasons, in open top cha Hmbers on a Chesapeake Bay salt marsh. Net ecosystem CO2 exchange per unit green biomass (NCEb) increased by an average of I48% throughout the growing season of 1988, the second year of treatment. Elevated CO2 increased net ecosystem carbon assimilation by 88% in the _Scirpus olneyi_ community and 40% in the _Spartina patens_ community.Pfv DlȿD K193^5^Drake,B G^Leadley,P W^Arp,W J^Nassiry,D^Curtis,P S^1989^1^An Open Top Chamber for Field Studies of Elevated Atmosphe Lric CO2 Concentration on Saltmarsh Vegetation^37^3^^363-371^^^^^^^^^^476^^^^^^^^^^^Scirpus olneyi/Spartina patens/Distichlis spicata^^^^stichlis spicata (L.) Greene]XPV >ǿu@sv3FF~:r}]^ON=VN~u ?C^474^Funct. Ecol.u^$FNu-FV^F&EG&FFNN뜋v@s~ud^XPSVUu& OA^474^Small open top chamber (0.8 m x 1.0 m) were developed to maintain elevated CO2 concentrations in three plant communi Pties in a brackish marsh ecosystem. Mean annual CO2 concentrations were 340 +/- 22 uL/L in chambers which received no adde Qd CO2 and 686 +/- 30 uL/L in chambers with elevated CO2 concentrations. Light quality was not effected in the photosynthet Rically active wavelengths but the chamber reduced light quantity by 10%. Night-time air temperatures inside the chamber (_ STi_) averaged 2C above air temperature outside the chamber (_To_) due to heating from the air blowers. Air temperature pr Tofiles through the plant canopy and boundary layer showed that daytime temperature differences (_Ti -To_) were greater tha Un night-time differences and this day/night difference also depended on the plant community. Effects of the chamber on the V micro-environment of the plant communities resulted in a significant growth enhancement in the plant community dominated by the C3 sedge _Scirpus olneyi_ Grey but not in the other two communities.DD^2>! tE]D\ X194^3^Drake,B G^Rogers,H H^Allen,LH,Jr^1985^3^Methods of Exposing Plants to Elevated Carbon Dioxide^Direct Effects of Incr Yeasing Carbon Dioxide on Vegetation^Dept. of Energy, Carbon Dioxide Research Division^Washington, D.C.^11-51^^^^^^^DOE/ER-0238^^^^^^^^^^^^^^^^^^^^^^^^Strain,BR^Cure,JDGG^J @^Y[XPSVt7\DG@uGr [195^4^du Cloux,H C^Andre,M^Daguenet,A^Massimino,J^1987^1^Wheat Response to CO2 Enrichment: Growth and CO2 Exchanges at Two Plant Densities^39^38^^1421-1431^^^^^^^^^^480^^^^^^^^^^^wheat/Triticum aestivumum L.PQR>t9,!u MC^478^J. Exp. Bot.ZYXx778J8-1S,+(}*(JN 9 d+*#pe &3B3u   u) ^A^478^The vegetative growth of wheat (_Triticum aestivum_ L., var. Capitole) was followed for almost 40 d after germinatio _n in controlled conditions. Four different treatments were carried out by combining two air concentrations of CO2, either `normal (330 mm3/dm3) or doubled (660 mm3/dm3) with two plant densities, either 200 plants/m2 or 40 plants/m2. Throughout t ahe experiment the CO2 gas exchanges of each canopy were measured 24 h/d. These provided a continuous growth curve for each b treatment, which were compared with dry weights. After a small stimulation at the start (first 13 d), no further effect o cf CO2 enrichment was observed on relative growth rate (RGR). However, RGR was stimulated throughout the experiment when pl dotted as a function of biomass. The final stimulation of dry weight at 660 mm3/dm3 CO2 was a factor of 1.45 at high densit ey and 1.50 at low density; contrary to other studies, no diminution of this CO2 effect on dry weight was observed over tim fe. Nevertheless, at low density, a transient additional enhancement of biomass (up to 1.70) was obtained at a leaf area in gdex (LAI) below 1. This effect was attributed to a different build up of the gain of carbon in the case of an isolated pla hnt or a closed canopy. In the former, the stimulation of leaf area and the net assimilation rate are both involved; in the i latter the enhancement becomes independent of the effect on leaf area because the canopy photosynthesis per unit ground area as a function of LAI reaches a plateau.:Y[XPN+ٚNĚNXVPSQRUP/uX)t s-AAG k196^4^du Cloux,H^Andre,M^Gerbaud,A^Daguenet,A^1989^1^Wheat Response to CO2 Enrichment: Effect on Photosynthetic and Photorespiratory Characteristics^42^23^^145-153^^^^^^^^^^483^^^^^^^^^^^wheat/Triticum aestivum^^^^.WK> \C^481^Photosynthetica~ <N}>N ~' ~ NN~ <N]_ZY[X1uN1t nA^481^The effects of doubling atmospheric CO2 concentration on photosynthesis and photorespiration were studied on wheat c oultivated for 37 or 72 d in growth chambers at a density of planting of 200 and 40 plants per m2. Net photosynthetic rate p(_Pn_) was measured continuously during the experiments and response curves to CO2 were made at intervals. Differences obs qerved between the CO2 curves of the plants grown in normal and CO2 enriched atmosphere could be explained by the greater l reaf area of the second group of plants. Photorespiration was tested by the Warburg effect or measured directly on isolated s plants by the uptake of 18-O2. Oxygen uptake was reduced by 40% by the high CO2 treatment, but high CO2 plants were ident tical to the control group when returned to the same conditions. The enhancement of dry matter production was due to the ki unetic response of _Pn_ to CO2, as there was no appreciable long-term adaptation of the kinetic characteristics of photosynthesis./DADMDEDMD:D1D0D 3G s !=:Noٚ*DsN[#.T t3P.TXPP.TXX w197^3^Dubois,D^Winzeler,M^Nosberger,J^1990^1^Fructan Accumulation and Sucrose:sucrose fructosyltransferase Activity in Stems of Spring Wheat Genotypes^12^30^^315-319^^^^^^^^^^486^^^^^^^^^^^Triticum aestivum/wheat^^^^^tXVxXVZY lC^484^Crop Sci.=:\1sN1:\1sMThdRIFFWAVECreative Voice FileWVU~FSQv D F=u*rW|T zA^484^Stems of wheat (_Triticum aestivum_ L.) accumulate water-soluble carbohydrates (WSC) during the first 3 wk after ant {hesis. These reserves can later contribute to grain filling. Two spring wheat genotypes ('Kolibri' and breeding line D) we |re tested in growth chambers to determine if they differ in the accumulation of WSC components and in the activation of su }crose:sucrose fructosyltransferase (SST) in stem tissue. Concentration of CO2 was supplied at 1000 or 300 uL CO2/L after a ~nthesis to alter photosynthate production. The WSC accumulation in the penultimate internode during the first 18 d post an thesis (DPA) was substantially higher in Genotype D than in Kolibri. The WSC accumulation up to 7 DPA was due to increases in hexoses and sucrose. Sucrose concentration was initially lower in Kolibri than in Genotype D, but increased to a compa rable level for both genotypes and both CO2 treatments. Fructan synthesis was initiated at 7 DPA. At 18 DPA, fructan was t he dominant component of WSC. Under both CO2 treatments Genotype D accumulated substantially higher fructan concentrations than Kolibri. In a second experiment, induction of SST activity was observed during the first 9 DPA in the penultimate in ternode of plants grown at 1000 and 200 uL CO2/L. There was a positive relationship between sucrose concentration and in v ivo SST activity, suggesting that sucrose induced SST activity; however, Kolibri exhibited a much lower SST activity at gi ven sucrose concentration. Thus, the low fructan synthesis of Kolibri is associated with an initial lower sucrose concentration and with a less effective activation of SST by sucrose.PSQRWV;*2N)t686868688 198^3^Duchein,M-C^Bonicel,A^Betsche,T^1993^1^Photosynthetic Net CO2 Uptake and Leaf Phosphate Concentrations in CO2 Enrich ed Clover (_Trifolium subterraneum_ L.) at Three Levels of Phosphate Nutrition^39^44^^17-22^^^^^^^^^^489^^^^^^^^^^^Trifolium subterraneum/clover^^^^^ȋF3FȋF 3FFCrIF32FFH;FvFF1v76Frys3 xC^487^J. Exp. Bot.vКH${rیFv1&76FrȚ${ЋFNyNAANd${r&&GGF;Fs@FeFry& A^487^Net CO2-uptake of sets of clover plants (_Trifolium subterraneum_ L.) was measured over 3 weeks in ambient air and i n a highly CO2-enriched atmosphere (400 Pa CO2). Phosphate (P) in the nutrient solution was varied between 0.05 mol/m3 P ( reduced P) and 2.0 mol/m3 P (high P). In ambient air, the daily increments of the daily rate of net CO2-uptake (DICU; a pa rameter related to relative growth) were higher at reduced P than at high P. Stimulation by high CO2 of net CO2-uptake in the first day was less at reduced P than at high P. In the following days, high CO2 markedly inhibited DICU at reduced P, and thus growth stimulation by high CO2 ceased after between 4 and 12 d. By contrast, at high P, DICU increased more than 2-fold upon CO2-enrichment, and thus growth stimulation by high CO2 was maintained. Intermediate results were obtained wit h half-strength Hoagland's solution (0.5 mol/m3 P). Leaf pools of inorganic ortho P, soluble esterified P, and total P dec lined markedly in high CO2 when P-nutrition had been reduced. Considerable decline also occurred in high CO2 when P-nutrit ion had been increased suggesting that P-uptake was not well tuned with net CO2-uptake (growth). It is proposed that high CO2 can perturb the P-metabolism of clover, the impairment being less at high levels of P-nutrition. With regard to high C O2 as a growth stimulus, these results demonstrate that increasing P-nutrition to a level supraoptimal in ambient air can considerably improve the growth of a C3-plant in high CO2.$:Ú\GsÚ$:Ú*Ú*Ú*Ú*Ú=:({ y y 199^3^Dugal,A^Yelle,S^Gosselin,A^1990^1^Influence of CO2 Enrichment and its Method of Distribution on the Evolution of Gas Exchanges in Greenhouse Tomatoes^29^70^^345-356^^^^^^^^^^492^^^^^^^^^^^tomato/Lycopersicon esculentumum Mill.>r C^490^Can. J. Plant Sci.Y[RWU$:ru>r&} &Ess]_ZS>r >svrr&_ &GR A^490^Net photosynthesis, stomatal conductance, internal CO2 concentration and transpiration were measured on the fifth we ll-developed and excised leaf of tomato seedlings (_Lycopersicon esculentum_ Mill. 'Vedettos') 48-83 d old. These measurem ents were taken in order to monitor the evolution of the gas exchanges of seedlings exposed to concentrations of 330 or 10 00 ppm, continuously, to 1000 ppm from 06:00 h to 10:00 h or to 1000 and 330 ppm alternately every 2 h. CO2 enrichment sub stantially increased the net photosynthesis rate of the seedlings, particularly at the beginning of the experiment. The lo ng-term effects of CO2 enrichment subsided after a few weeks of treatment. Intermittent CO2 enrichment was partially helpf ul in remedying the loss of effectiveness of the CO2 after a long period of enrichment. High CO2 concentrations reduced th e opening of the stomata. Our work shows that maintaining a high internal CO2 content in the leaves would indirectly reduc e the stomatal conductance of the seedlings. However, our results show that the long-term loss of photosynthetic efficienc y in the enriched seedlings cannot be attributed solely to an increase in the resistance of the stomata, since the interna l CO2 concentration of the leaves remains very high regardless of which method of CO2 enrichment is used. Continuous CO2 enrichment improved the water uptake efficiency of the seedlings. In French.7 u F Ft a,s 200^1^Eamus,D^1992^3^Atmospheric CO2 and Trees, from Cellular to Regional Responses^Encyclopedia of Earth System Science^Academic Press, Inc.^New York^157-169^^^^1^^^^^^^^^^^^^^^^^^^^^^;~u4_;:Y[SQV6rt<u |u4 H^Yq in the cultivated one increased by CO2 enrichment in both soybean varieties, when nitrate was not applied to the plants. 201^1^Eamus,D^1990^3^Carbon Dioxide and Plant Physiological Processes^The Greenhouse Effect and Terrestrial Ecosystems of the UK^Institute of Terrestrial Ecology, Natural Environment Research Council^Edinburgh Research Station, Bush Estate, Penicuik^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^Cannell,M G R^Hooper,M DPV6t  C^507^Bull. Soc. Ecophysiol.W6WWGW&+ߌWWWJ!r[/!.{.}WWWKU.w.&yA^507^In French.dgf.{!WWJ!v svdfDds=trqv@s_^ZY[XþD E E${\ T 208^3^El Kohen,A^Pontailler,J-Y^Mousseau,M^1991^1^Effect of Doubling of Atmospheric CO2 Concentration on Dark Respiration in Aerial Parts of Young Chestnut Trees (_Castanea sativa_ Mill.)^125^t. 312, Serie III^^477-481^^^^^^^^^^512^^^^^^^^^^^Castanea sativa/sweet chestnut^^^^^^^^^^^Castanea sativa/sweet chestnutCDH *sFteW_*P֒uioxylase oxygenase. PGPase in cell extracts shows a transient increase in activity that reaches a maximum 3 to 5 hours afte A^510^Two-year-old sweet chestnut seedlings were grown in constantly ventilated tunnels at ambient (350 vpm) or double (70 0 vpm) CO2 concentration during a full growing season. End-of-night dark respiration of aerial parts was measured in each CO2 concentration throughout the growing season. Dark respiration rate of enriched plants showed a net decrease as compare d to control plants during the first half of the growing season. This difference decreased with time and became negligible in the fall. Atmospheric CO2 concentration acted instantaneously on the respiration rate: when doubled, it decreased cont rol plant respiration and when decreased, it enhanced CO2 enriched plant respiration. The explanation of these findings re mains hypothetical. It is concluded that the rise in carbon dioxide level of the atmosphere will affect the carbon balance of young trees not only through an increase in net photosynthesis during the day, but also at night by reducing respiratory losses. In French.FU*)PSQVWU s*r2o?t @P=rF *- s *]_^Y[XPSQRVWU 209^3^El Kohen,A^Rouhier,H^Mousseau,M^1992^1^Changes in Dry Weight and Nitrogen Partitioning Induced by Elevated CO2 Depen d on Soil Nutrient Availability in Sweet Chestnut (_Castanea sativa_ Mill.)^56^49^^83-90^^^^^^^^^^515^^^^^^^^^^^Castanea sativa/sweet chestnututt 2:2:rrC[XSQtژ*m':Y[PSQRVWU<t<\t|:uV@=!r >Di C^513^Ann. Sci. For.FFF&>DBOSD;[r=\uGasL6D!AF:\2ҴG!6D<u|\t\.s>D@r A^513^The effect of 2 levels of atmospheric carbon dioxide (ambient, i.e. 350 ppm, and double, i.e. 700 ppm) and 2 contras ting levels of mineral nutrition on dry weight, nitrogen accumulation and partitioning were examined in 2-year-old chestnu t seedlings (_Castanea sativa_ Mill.), grown in pots outdoors throughout the vegetative season. Fertilization had a pronou nced effect on dry weight accumulation, tree height, leaf area, and plant nitrogen content. Carbon dioxide enrichment sign ificantly increased total biomass by about 20%, both on fertilized and on unfertilized forest soil, only the root biomass was increased, leading to an increase in the root:shoot ratio. Contrastingly, on fertilized soil only stem biomass and dia meter but not height were increased. Carbon dioxide enrichment significantly reduced the nitrogen concentration in all org ans, irrespective of the nutrient availability. However, the biomass increase made up for this reduction in such a way that the total nitrogen pool per tree remained unchanged.DC6I ;QV0fFɼ6ǼF&D@tF&\ ~]"E$ 210^3^El Kohen,A^Venet,L^Mousseau,M^1993^1^Growth and Photosynthesis of Two Deciduous Forest Species at Elevated Carbon Dioxide^37^7^^480-486^^^^^^^^^^518^^^^^^^^^^^sweet chestnut/Castanea sativa/Fagus sylvatica/beechchInpress^^517^^^^^^^^518^^^^^^^^^^^sweet chestnut/Castanea sativa/Fagus sylvatica/beechn& u4v~s?j&tv~4sS6Ǽ& t C^516^Funct. Ecol. (Cv6C>CC ;@I ;^YPQVDfZ,sv+FA+6Ǽɼ;Z A^516^Two-year-old sweet chestnut (_Castanea sativa_ Mill) and beech (_Fagus sylvatica_ L.) seedlings were grown in large pots on the same forest soil, at ambient (+/- 350 uL/L) and double (700 uL/L) atmospheric CO2 concentration in constantly ventilated minigreenhouses during the entire growing season. CO2 enrichment caused very different changes in these two tem perate deciduous species. A 20% dry weight enhancement was obtained for sweet chestnut, while this increase amounted to 60 % in beech. This greater effect of an elevated CO2 in beech was the result of a significant increase of net photosynthesis of the seedlings occurring during the whole season. On the contrary, this increase in photosynthesis lasted only a few we eks in sweet chestnut and then an acclimation process took place. No effect of an increased CO2 could be found on sweet ch estnut leaf area or leaf number, while a significant effect was found with beech, in which total leaf area per plant incre ased, owing to a greater number of growth flushes, each with larger leaves. The partitioning of the biomass increase due t o elevated CO2 was very different in the two species. All additional dry matter was allocated to the roots in sweet chestn ut, while it was partitioned equally amongst all organs of the beech seedling. The reactions to elevated CO2 of different tree species is discussed in relation to their specific growth strategy.^^^^^^^^^^205^^^^^^^^^^^^^^^^^^^^^Geyer,R A A^519^Supplementary high pressure sodium (HPS) lighting (140 umol/m2/s) and CO2 enrichment (1375 uL/L) improved the vegeta tive growth of _Chrysanthemum morifolium_ cv Dramatic by increases in stem length, stem diameter, root weight ratio, dry w eight, relative growth and net assimilation rates. Three-week-old chrysanthemums grown under CO2 enrichment and HPS lighti ng had lower leaf weight and stem weight ratios as well as lower foliar nutrient content than those grown under ambient CO 2 and natural light. Plants grown on to maturity under CO2 enrichment and supplementary HPS lighting had the longest stem lengths, the most flowers and greatest increase in dry weight. The combination of both additional light and CO2 was superi or to either factor used alone. With 24 h HPS supplementary lighting CO2 enrichment was most effective in improving vegeta tive growth and flower quality when applied during the daytime. Night CO2 enrichment was not commercially beneficial at the light levels employed in this study.8@-:88@/:3):+:K83Ps)O88@-:88@/:3):+:212^1^Enoch,H Z^1990^1^Crop Responses to Aerial Carbon Dioxide^15^268^^17-32^^^^^^^^^^52424U8V8W8X8T8H8I8=%NC^522^Act. Hort.R8U83V8W8T8X8H8I8=%NaPQ58u%8YXôO8u$S3ێۻt'<u  A^522^Crops are subjected to a global bulk atmosphere that contains a supra-optimal oxygen concentration and a sub-optimal  carbon dioxide concentration. It is expected that the present increase in atmospheric CO2 concentration will continue, th at a doubling will occur during the next century and that eventually values of over 2500 ppm will be reached. Until then g reenhouse crops should be CO2 enriched. The potential of intermittent CO2 enrichment (pulse CO2 enrichment) for yields enh ancement and pollution avoidance will be described. The main changes in crops due to elevated CO2 seem to be secondary eff ects of enhanced photosynthesis but some morphogenetic changes, for instance increased branching, are interpreted as parti al suppression of apical dominance and appear to show that CO2 concentration has additional hormone-like effects. Though o ver 1000 papers on CO2 enrichment have been published there is only an incomplete understanding of whether other organs th an leaves are sensitive to CO2 concentration and whether elevated CO2 has a trigger effect or a threshold effect on morpho genesis of crops. Some of the research questions that should be asked in order to improve our understanding of how CO2 enrichment influences plant productivity will be discussed.D2>7.6D^PSQRVWFg7Fg7S5&}SHt+5 213^2^Enoch,H Z^Zieslin,N^1988^1^Growth and Development of Plants in Response to Carbon Dioxide Concentrations^57^3^^248-256^^^^^^^^^^52727>Du4>t*7 jN< tF_rFNdpRr#6D8D:D6..<uD<t<uGrJ.<tD>ʾ@D A^525^Quality of protected crops can be improved by controlling the aerial carbon dioxide (CO2) in the greenhouse. The inf luence of atmosphere CO2 concentration on partitioning of dry matter, leaf growth and development, stem growth, root forma tion, branching and tillering, growth of the whole plant and on flowering is described in this review. At elevated CO2 con centrations apical dominance in C3 and C4 plants is weakened resulting in higher root-to-shoot ratios and increased side s hoot development (branching, tillering, etc.). Most effects of elevated CO2 concentration appear to be secondary effects o f photosynthesis enhancement leading to higher leaf weight per unit area, greater stem weight per unit length, and an incr !ease in absolute growth rate--but not always an increase in relative growth rate. The influence of elevated CO2 concentrat "ion on flowering is discussed in detail. Examples of organ development that can be explained as secondary effects of enhanced photosynthesis, as well as exceptions, are presented.! uE2ģ=D>=D sD!! t?D $214^2^Evans,L S^Hendrey,G R^1992^1^Responses of Cotton Foliage to Short-term Fluctuations in CO2 Partial Pressures^8^11^^203-212^^^^^^^^^^^^^^^^^^^^^cotton/Gossypium hirsutumum L. C^528^Crit. Rev. Plant Sci.@ '215^2^Fajer,E D^Bazzaz,F A^1992^1^Is Carbon Dioxide a 'Good' Greenhouse Gas? Effects of Increasing Carbon Dioxide on Ecolo )gical Systems^58^^^Inpress^^531^^^^^^^^532>~D0*]^MINDSLGLC^530^Global Environ. Change=?!rKظ@?!.?.;@.?.=@.??.??.;@V?D <:u2 *A^530^Carbon dioxide (CO2) in the atmosphere, a Greenhouse gas, may also provide benefits for mankind: many plants grow be +tter under increasing CO2 concentrations. Individuals have speculated that agricultural yields will increase up to 30% und ,er future CO2 concentrations, and natural ecosystems will become more lush and resilient. However, infertile conditions an -d complex ecological interactions often limit improved plant growth under increasing CO2 atmospheres. Future policies to a .dapt to a CO2-rich world must not overstate benefits from these conditions, nor ignore their usefulness for increasing fut (ure agricultural yields or restoring degraded habitats.GGGGGGGGGCGEGGGGGGGGGGGGIGGGGGGGGG 0216^3^Fajer,E D^Bowers,M D^Bazzaz,F A^1992^1^The Effect of Nutrients and Enriched CO2 Environments on Production of Carbon 1-based Allelochemicals in _Plantago:_ A Test of the Carbon/Nutrient Balance Hypothesis^59^140^^707-723^^^^^^^^^^535^^^^^^^^^^^Plantago lanceolatata2\*\rYe2r0D@r%3:|. 4A^533^In a test of the carbon/nutrient (C/N) balance hypothesis, we grew the perennial herb _Plantago lanceolata_ in diffe 5rent CO2 and nutrient environments and then (1) measured the total allocation to shoots, roots, and reproductive parts and 6 (2) quantified aucobin, catalpol, and verbascoside contents of replicate plants of six genotypes. Plants grown under low- 7nutrient conditions do have higher concentrations of carbon-based allelochemicals than plants grown under high nutrient co 8nditions. However, in contrast to the C/N balance hypothesis, plants grown in elevated (700 uL/L) CO2 conditions had simil 9ar, or lower, concentrations of carbon-based allelochemicals than plants grown in ambient (350 uL/L) CO2 conditions. We su :ggest that augmented substrate concentrations (i.e., excess carbohydrates) are a necessary but insufficient trigger for in ;creased secondary metabolism; instead, hormonal and/or direct physical cues (such as light) may be essential to synthesize < or activate the appropriate enzyme systems. Moreover, although plant genotype significantly affected plant growth, reprod =uction, and chemistry, we never observed significant genotype-by-CO2 interactions for these factors, which suggests that changing CO2 environments may not improve the fitness of certain genotypes over others.yment   p  Iwou ?217^3^Fajer,E D^Bowers,M D^Bazzaz,F A^1989^1^The Effects of Enriched Carbon Dioxide Atmospheres on Plant-Insect Herbivore Interactions^48^243^^1198-1200^^^^^^^^^^538^^^^^^^^^^^Plantago lanceolatatanslation/interpretationandteachingfromone 2C^536^Scienceuniversities.Iamconfidentinterpretingsimultaneouslyinanyscientificfield(nuclearscienceandtech BA^536^Little is known about the effects of enriched CO2 atmospheres, which may exist in the next century, on natural plant C-insect herbivore interactions. Larvae of a specialist insect herbivore, _Junonia coenia_ (Lepidoptera: Nymphalidae), were D reared on one of its host plants, _Plantago lanceolata_ (Plantaginaceae), grown in either current low (350 parts per mill Eion) or high (700 ppm) CO2-environments. Those larvae raised on high-CO2 foliage grew more slowly and experienced greater Fmortality, especially in early instars, than those raised on low-CO2 foliage. Poor larval performance on high-CO2 foliage Gwas probably due to the reduced foliar water and nitrogen concentrations of those plants and not to changes in the concent Hration of the defensive compounds, iridoid glycosides. Adult pupal weight and female fecundity were not affected by the CO I2 environment of the host plant. These results indicate that interactions between plants and herbivorous insects will be modified under the predicted CO2 conditions of the 21st century.X 3P 3!0:0:R 3 35 3 K218^3^Fajer,E D^Bowers,M D^Bazzaz,F A^1991^1^The Effects of Enriched CO2 Atmospheres on the Buckeye Butterfly, _Junonia coenia_^2^72^^751-754^^^^^^^^^^^^^^^^^^^^^Plantago lanceolatata(3(3#(3#(33%*33<:%*3, @C^539^Ecology333 N3 N3 >3 >3 3 3 $3 $3 23 23 @3,~33*3jX&3 N219^3^Fajer,E D^Bowers,M D^Bazzaz,F A^1990^1^Performance and Allocation Patterns of the Perennial Herb, _Plantago lanceola Ota_, in Response to Simulated Herbivory and Elevated CO2 Environments^34^87^^37-42^^^^^^^^^^542^^^^^^^^^^^Plantago lanceolata~&F&EF~7 N+~uFFNvvv~LsGr~3I~)V~F2 QA^541^We tested the prediction that plants grown in elevated CO2 environments are better able to compensate for biomass lo Rst to herbivory than plants grown in ambient CO2 environments. The herbaceous perennial _Plantago lanceolata_ (Plantaginac Seae) was grown in either near ambient (380 ppm) or enriched (700 ppm) CO2 atmospheres, and then after 4 weeks, plants expe Trienced either 1) no defoliation; 2) every fourth leaf removed by cutting; or 3) every other leaf removed by cutting. Plan Uts were harvested at week 13 (9 weeks after simulated herbivory treatments). Vegetative and reproductive weights were comp Vared, and seeds were counted, weighed, and germinated to assess viability. Plants grown in enriched CO2 environments had s Wignificantly greater shoot weights, leaf areas, and root weights, yet had significantly lower reproductive weights (i.e. s Xtalks + spikes + seeds) and produced fewer seeds, than plants grown in ambient CO2 environments. Relative biomass allocati Yon patterns further illustrated differences in plant responses to enriched CO2 atmospheres: enriched CO2-grown plants only Z allocated 10% of their carbon resources to reproduction whereas ambient CO2-grown plants allocated over 20%. Effects of s [imulated herbivory on plant performance were much less dramatic than those induced by enriched CO2 atmospheres. Leaf area \removal did not reduce shoot weights or reproductive weights of plants in either CO2 treatment relative to control plants. ] However, plants from both CO2 treatments experienced reductions in root weights with leaf area removal, indicating that p ^lants compensated for lost above-ground tissues, and maintained comparable levels of reproductive output and seed viability, at the expense of root growth.e~uVL43r=u @sZYX[SS3PQRZ u e*L* `220^2^Farrar,J F^Williams,M L^1991^1^The Effects of Increased Atmospheric Carbon Dioxide and Temperature on Carbon Partitioning, Source-sink Relations and Respiration^16^14^^819-830^^^^^^^^^^54545˸vPSQRVP73/ىF)ىF&/ LC^543^Plant Cell Environ.)^ZY[X˸&jNPSQRV/5uP73-@]ٸ 1ٰ-٣_],/^ZY[XPS cA^543^Herbaceous C3 plants grown in elevated CO2 show increases in carbon assimilation and carbohydrate accumulation (part dicularly starch) within source leaves. Although changes in the partitioning of biomass between root and shoot occur, the p eroportion of this extra assimilate made available for sink growth is not known. Root:shoot ratios tend to increase for CO2 f enriched herbaceous plants and decrease for CO2-enriched trees. Root:shoot ratios for cereals tend to remain constant. In g contrast, elevated temperatures decrease carbohydrate accumulation within source and sink regions of a plant and decrease h root:shoot ratios. Allometric analysis of at least two species showing changes in root:shoot ratios due to elevated CO2 s ihow no alteration in the whole-plant partitioning of biomass. Little information is available for interactions between tem jperature and CO2. Cold-adapted plants show little response to elevated levels of CO2, with some species showing a decline kin biomass accumulation. In general though, increasing temperature will increase sucrose synthesis, transport and utilizat lion for CO2-enriched plants and decrease carbohydrate accumulation within the leaf. Literature reports are discussed in re mlation to the hypothesis that sucrose is a major factor in the control of plant carbon partitioning. A model is presented in support.F+F~ t }~5vڍ~FFEFEE6v:v}Føy o221^4^Ferguson,J J^Avigne,W T^Allen,L H^Koch,K E^1986^1^Growth of CO2-enriched Sour Orange Seedlings Treated with Gibberellins/Cytokinins^60^99^^37-39^^^^^^^^^^548^^^^^^^^^^^sour orange/Citrus aurantiumum:r~^_ZYXU&Ur/ aC^546^Proc. Fla. State Hort. Soc.D*UI&Ur3Iwr+@%+P73]ȚTSW rA^546^Enriched CO2 atmospheres and specific plant growth regulators are known to stimulate plant growth, but their combine sd effects on citrus seedlings have not been studied. Sour orange (_Citrus aurantium_ L.) seedlings were treated with plant t growth regulators (6-benzyladenine [250 ul/l]; 6 benzyladenine and gibberellic acid [250 ul/l]; gibberelli un 3 [450 ul/l] and gibberellin 4+7 [250 ul/l]) and grown at either ambient or elevated CO2 levels (330 or 66 v0 ul/l). Seedlings treated with GA4+7 and grown at elevated CO2 levels were taller and had greater leaf weight than plants w given all other treatments. Leaf number increased under elevated CO2 levels when BA or GA4+7 were applied. Stem weight wa xs unaffected by growth regulators except when GA4+7 was applied to plants grown under high CO2 levels. Stem caliper increased slightly under high CO2 levels, especially when GA4+7 was applied.r.3>~Ut@ 辯   羴 z222^4^Fetcher,N^Jaeger,C H^Strain,B R^Sionit,N^1988^1^Long-term Elevation of Atmospheric CO2 Concentration and the Carbon {Exchange Rates of Saplings of _Pinus taeda_ L. and _Liquidambar styraciflua_ L^43^4^^255-262^^^^^^^^^^551^^^^^^^^^^^sweetgum/Liquidambar styraciflua/loblolly pine/Pinus taedadaPSQRVW/ t} Y uq_^ZY[XPQVD1* pC^549^Tree Physiol..3Ú93ÚJ83ó=:ó @+>"V}D3 3 3s0:j0:p0:m0: ~A^549^The relationship between carbon exchange rate (CER) and internal CO2 concentration was measured in leaves of sapling s of _Liquidambar styraciflua_ L. (sweetgum) and _Pinus taeda_ L. (loblolly pine) grown from seed for more than 14 months at atmospheric CO2 concentrations of either 340 or 500 uL/L. An elevated concentration of CO2 during growth reduced CER at any given internal CO2 concentration in sweetgum, but not in loblolly pine. Stomatal limitation of CER showed little resp onse to concentration of CO2 during measurement, but was higher in both species when grown at 500 than at 350 uL/L CO2. Th e net effect of a long-term increase in CO2 concentration from 350 to 500 uL/L was an increase in CER of loblolly pine, bu t a slight decrease in CER of sweetgum. It is suggested that the depression of CER in sweetgum resulted from a reduction in the activity of ribulose-1,5-bisphosphate carboxylase-oxygenase.  -=:^ZY[XPSQRVF umt_<tZ|u 223^1^French,C J^1989^1^Propagation and Subsequent Growth of Rhododendron Cuttings: Varied Response to CO2 Enrichment and Supplementary Lighting^3^114^^251-259^^^^^^^^^^554^^^^^^^^^^^Rhododendron spp.p.U33҉EU X # _PSQRV |C^552^J. Amer. Soc. Hort. Sci.=w tFF9-s v{ |tP583>g7t33^ZY[XWP73_Úg0: A^552^CO2 mist (1100 uL CO2/L) during fall propagation inhibited rooting of _Rhododendron_ 'Anna Rose Whitney' (_R. griers onianum_ x 'Countess of Derby') and had no effect on _R._ 'Vulcan' ('Mars' x _R. griersonianum_), _R._ 'Unique' (_R. campy locarpum_ hybrid), _R._ 'Anah Krushke' (_R. ponticum_ seedling), or _R._ 'Pink Bountiful' (_R. williamsianum_ x 'Linswegea num'). Supplementary lighting from high-pressure sodium lamps (HPS) for 16 hr/day (0400 to 2000 hr) had no effect on rooti ng of any cultivar. There was an interaction between CO2 mist and HPS exposure on rooting in _R._ 'Floriade' ('Britannia' hybrid). CO2 mist inhibited and HPS stimulated shoot development during propagation. CO2 mist during propagation inhibited subsequent development of 'Anna Rose Whitney' and 'Vulcan'. HPS during propagation inhibited subsequent growth of 'Floria de' and 'Vulcan'. CO2 enrichment of stock plants prior to propagation did not affect rooting of _R._ 'Sonata', whereas CO2 mist during propagation was inhibitory. In 'Anna Rose Whitney', there was an interaction between CO2 enrichment before an d during propagation. Application of supplementary HPS for 16 hr/day following propagation stimulated subsequent growth of both cultivars. CO2 mist during spring propagation stimulated rooting of 'Pink Bountiful' and 'Vulcan' and had no effect on _R._ 'Matador' (_R. griersonianum_ x _strigillosum_), _R._ 'Martha Isaacson' (_R. occidentale_ x Ostbo seedling No. 70) , or _R._ 'Elizabeth' (_R. forestii_ var _repens_ x _griersonianum_). Supplementary HPS had no effect on rooting. A low ir radiance night break treatment from incandescent lamps (2000 to 0400 hr) had no effect on rooting of 'Vulcan'. There was a n interaction between night break lighting and CO2 mist on rooting in 'Unique'. CO2 mist and HPS during spring propagation had minor effects on subsequent growth of 'Matador', 'Martha Isaacson', 'Pink Bountiful', and 'Elizabeth'. CO2 mist and supplementary HPS have little value in production of _Rhododendron_.-Fˡ- ;[v[٣-ٚ7(3ˉ-&˸ jNj 224^1^French,C J^1990^1^Rooting of Rhododendron 'Anna Rose Whitney' Cuttings as Related to Stem Carbohydrate Concentration^28^25^^409-411^^^^^^^^^^557^^^^^^^^^^^Rhododendron spp.p.~ڋv^_˻+&! @ C^555^HortSci.֎ދg[3UuUu pu du X u L@u @u4 A^555^Rooting of _Rhododendron_ 'Anna Rose Whitney' (_R. Griersonianum_ x 'Countess of Derby') was delayed in cuttings fro m stock plants grown in full sun, compared to cuttings from plants grown in 80% shade. In the outer stem (extracambium tis sues), concentrations of glucose, sucrose, soluble carbohydrate, and total nonstructural carbohydrates were higher in cutt ings from shaded stock plants. In the inner stem (intracambium tissues), where rooting originates, fructose, starch and no nstructural carbohydrates were lower in cuttings from the shaded stock plants. Rooting percentage was reduced by CO2 mist during propagation. At 7 days, during rooting with a CO2 enrichment to 1100 uL/L, fructose in the inner stem was 3-fold hi gher than in cuttings rooted under atmospheric CO2 (340 uL/L). Under CO2 mist, total nonstructural carbohydrate concentrat ion was higher in the inner stem throughout the rooting period. For both high stock plant irradiance and CO2 enrichment du ring propagation, there was an inverse relationship between fructose concentration in the inner stem and rooting. A possible mechanism for inhibition by fructose is proposed.1t,31PSQR*PwP.TXXZY[XPSQRV0٢ ٢"٢#٢%٢& 225^2^French,C J^Alsbury,J^1989^1^Supplementary Lighting and CO2 Mist Influence Rooting of _Camellia japonica_^28^24^^452-454^^^^^^^^^^2061^^^^^^^^^^^Camellia japonica^^^^^]ZY[X^PSQVWU^vdU vDdpU u W C^558^HortSci.U+u:>u2@u*u""V uu}@t Du3ۉU"V u<}@u4>u,Du$3ۻ 226^3^Fung,I Y^Tucker,C J^Prentice,K C^1987^1^Application of Advanced Very High Resolution Radiometer Vegetation Index to Study Atmosphere-Biosphere Exchange of CO2^62^92^^2999-3015^^^^^^^^^^56262${Y^[XVWPSQRUPPFd3F~U u C^560^J. Geophys. Res.ؚUAssvD DDޱ:Ut:Uu)G3s !=:Nٚ*,s|~UO3U A^560^Normalized difference vegetation indices derived from radiances measured by the Advanced Very High Resolution Radiom eter aboard the NOAA 7 polar-orbiting satellite were used to prescribe the phasing of terrestrial photosynthesis. The sate llite data were combined with field data on soil respiration and a global map of net primary productivity to obtain the se asonal exchange of CO2 between the atmosphere and the terrestrial biosphere. The monthly fluxes of CO2 thus obtained were employed as source/sink functions in a global three-dimensional atmospheric tracer transport model to simulate the annual oscillations of CO2 in the atmosphere. Reasonable agreement was found between the simulated and observed annual cycles of atmospheric CO2 at the locations of the remote monitoring stations. The results demonstrate that satellite data of high sp atial and temporal resolution can be used to provide quantitative information about seasonal and longer-term variations of photosynthetic activity on a global scale. Atmospheric CO2 observations and a three-dimensional atmospheric model have be en used to validate the translation of the nondimensional satellite data into dimensional carbon fluxes. Direct calibration will require extensive ground truth and field measurements at ecosystem scales.~u*PjP.TXXZY[X_^]^_PSQR 227^2^Furbank,R T^Walker,D A^1986^1^Chlorophyll _A_ Fluorescence as a Quantitative Probe of Photosynthesis: Effects of CO2 Concentration during Gas Transients on Chlorophyll Fluorescence in Spinach Leaves^23^104^^207-213^^^^^^^^^^565^^^^^^^^^^^spinach/Spinacia oleraceaea.TXXUAsvrDID=rV.TYY.T+.T.T t B${3ًv@sU X C^563^New Phytol.1SP.TXX]_ZY[XVPSQRUP fv.TXX/t>v|t5.T9ٹDV6; A^563^The relationship between changes in chlorophyll _a_ fluorescence and changes in CO2 concentration in spinach leaves is analyzed. The height of the fluorescence excursion, when plotted against the CO2 concentration during the transient, re sults in a hyperbola. When these data are replotted on an inverse-reciprocal plot, an apparent Km(CO2) for the fluorescenc e transient can be obtained which closely approximates the Km(CO2) for carbon assimilation under similar conditions. Trans itions in CO2 concentration at 2% O2 result in deviation from this hyperbolic relationship, reducing the apparent Km(CO2) for this process. The relationship between carbon assimilation and chlorophyll fluorescence is discussed with reference to the two components of fluorescence quenching. This technique raises the possibility that chlorophyll fluorescence could be used as a quantitative as well as a qualitative tool in plant screening.{r&&GGF;Fs@FeFry&228^1^Gale,J^1986^1^Carbon Dioxide Enhancement of Tree Growth at High Elevation^48^231^^859-860^^^^^^^^^^567868688A^566^Technical comment.&&3ɾʚX-Nu8888sqF~K)tF&&H${rь 229^3^Garbutt,K^Williams,W E^Bazzaz,F A^1990^1^Analysis of the Differential Response of Five Annuals to Elevated CO2 durin g Growth^2^71^^1185-1194^^^^^^^^^^570^^^^^^^^^^^Abutilon theophrasti/Amaranthus retroflexus/Ambrosia artemisiifolia/Chenopodium album/Setaria faberiiii ; mQ' vZ;&L D hvpqA; C^568^Ecology$G%%&x&&(:(:PQVU= tL=tL%=s<.'ȃe*FE t;Fu3F]^YX A^568^In order to investigate the effects, without competition, of CO2 on germination, growth, physiological response, and reproduction, we focused on co-occurring species that are prominent members of an annual community in Illinois. Five spec ies of old field annual plants -- _Abutilon theophrasti_ (C3), _Amaranthus retroflexus_ (C4), _Ambrosia artemisiifolia_ (C 3), _Chenopodium album_ (C3) and _Setaria faberii_ (C4) -- were grown for their entire life cycle as individuals at CO2 co ncentration of 350 uL/L, 500 uL/L, and 700 uL/L. Emergence time, growth rate, shoot water status, photosynthesis, conducta nce, flowering time, nitrogen content, and biomass and reproductive biomass were measured. There was no detectable effect of enhanced CO2 on timing of emergence in any of the species. _Amaranthus_ relative growth rate (RGR) was always higher at 700 uL/L CO2 than at 350 uL/L. In both _Abutilon_ and _Ambrosia_, RGR was greater at 700 uL/L than at 350 uL/L during the first half of the experimental period, but during the second half of the period the reverse was true. Shoot water potenti al significantly increased (became less negative) with increasing CO2 in _Amaranthus_ and _Setaria_. Similar but statistic ally nonsignificant trends were found in _Chenopodium_ and _Abutilon_. Overall rate of photosynthesis increased with CO2 b ut there were no significant effects, at the species level, of CO2 on photosynthetic rates. Stomatal conductance decreased with increased CO2 at both high and low light levels in C3 species but only at high light levels in C4 species. In all sp ecies, intercellular CO2 increased with external CO2. _Amaranthus_ flowered significantly earlier at 700 uL/L than at 350 uL/L, and _Setaria_ flowered significantly later at 700 uL/L than at either of the other CO2 levels. Both _Abutilon_ and _ Ambrosia_ showed a trend towards earlier flowering but this was not statistically significant. Of the morphological charac ters measured at the final harvest only specific leaf area (SLA) showed a consistent response to CO2, decreasing with incr easing CO2. Significant CO2 x species interactions were also found for leaf area, leaf biomass, biomass of reproductive pa rts, and seed biomass indicating species-specific responses for these characters. The proportion of nitrogen declined with increasing CO2; there was also a significant CO2 x species interaction caused by the different rates of decline in propor tion of nitrogen among the species. The response of most characters had a significant species x CO2 interaction. However, this was not simply caused by the C3/C4 dichotomy. Reproductive biomass (seed, fruits, and flowers) increased with increas ing CO2 in _Amaranthus_ (C4) and in _Chenopodium_ and _Ambrosia_ (both C3) but there was no change in _Setaria_ (C4) and _ Abutilon_ (C3) showed a peak at 500 uL/L. Species of the same community differed in their response to CO2, and these differences may help explain the outcome of competitive interactions among these species above ambient CO2 levels.tFF 230^1^Gardestrom,P^1987^1^Adenylate Ratios in the Cytosol, Chloroplasts and Mitochondria of Barley Leaf Protoplasts during Photosynthesis at Different Carbon Dioxide Concentrations^63^212^^114-118^^^^^^^^^^573^^^^^^^^^^^barley/Hordeum vulgarer C^571^FEBS Lett.~9b6S~6H~>g7t2ɆkN>g7~g7H~fNkH~S~F2):&~_^ZY[XÀN A^571^Barley (_Hordeum vulgare_) protoplasts were incubated in darkness and in the light at saturating and limiting CO2 co ncentrations. The protoplasts were fractioned by a membrane filtration technique which allows quenching of the metabolism by acidification within about 0.1 s and the ATP/ADP ratios in the cytosol, chloroplasts and mitochondria were determined. It is concluded that the cytosolic ATP/ADP ratio is considerably higher during photosynthesis at limiting CO2 (which is the normal situation for a C3 plant in air) compared to photosynthesis at saturating CO2 or darkness.VP3SQRW; e L.~&~vxrcFFD<V&vP&!'2& '~bH~&H~S~TFp 231^2^Gastal,F^Saugier,B^1989^1^Relationships Between Nitrogen Uptake and Carbon Assimilation in Whole Plants of Tall Fescue^16^12^^407-418^^^^^^^^^^^^^^^^^^^^^tall fescueNFt \s_6&!['&O2A&O & ߾ C^574^Plant Cell Environ.t &O&OFFF &: v& S'&*G &G[& +F+F+F-&G߾ &O 232^1^Gates,D M^1985^3^Global Biospheric Response to Increasing Atmospheric Carbon Dioxide Concentration^Direct Effects of Increasing Carbon Dioxide on Vegetation^Dept. of Energy, Carbon Dioxide Research Division^Washington, D.C.^171-184^^^^^^^DOE/ER-0238^^^^^^^^^^^^^^^^^^^^^^^^Strain,B R^Cure,JD~0TY:!Y::T:QV8** 233^2^Gaudillere,J-P^Mousseau,M^1989^1^Short Term Effect of CO2 Enrichment on Leaf Development and Gas Exchange of Young Poplars (_Populus euramericana_ cv I 214)^64^10^^95-105^^^^^^^^^^579^^^^^^^^^^^poplars/Populus euroamericanaa'3& C^577^Acta Oecologica/Oecol. Plant.<^&!'&O2F&O s& Q&*O &O߾"Y&O A^577^Fast growing young poplar trees bearing 25 to 30 leaves were placed in a growth chamber. The air CO2 content was 330 uL/L during the first 15 days and 660 uL/L the following 15 days. The leaves in 660 uL/L CO2 in air developed a greater a rea and specific weight and contained more stomata, epidermal cells and chlorophyll per unit area. Leaf developmental char acteristics (Relative Leaf Expansion, Leaf Plastochron Index, Leaf Expansion Duration) were modified by the treatment. Lea ves developed in normal CO2 atmosphere demonstrated a significant regrowth, with increased cell and stomatal number, when exposed to the elevated CO2 treatment. Whole plant and single leaf gas exchange rates were measured at 330 and 660 uL/L. O n single attached leaves, an increased CO2 level during growth promoted a photosynthetic inhibition, shown by a lower _g_ and Pmax. Due to the greater leaf area, whole tree daily photosynthesis and respiration increased with elevated CO2, enhancing growth efficiency. Doubling the CO2 resulted in a threefold increase in whole plant water use efficiency (WUE). 234^2^Geethakumari,V L^Shivashankar,K^1991^1^Studies on Organic Amendment and CO2 Enrichment in _Ragi_/Soybean Intercropping Systems^65^36^^202-206^^^^^^^^^^2045^^^^^^^^^^^soybean/Glycine max/ragi/Eleusine coracana^^^^^coracana^^^^^>tV C^580^Indian J. Agron.*r#W~*E ~*^[23NB_^Z[YøS~VhI*y':r^RVȤ 235^1^Gifford,R M^1988^3^Direct Effects of Higher Carbon Dioxide Concentrations on Vegetation^Greenhouse: Planning for Climate Change^E.J. Brill^New York^506-519^^^^^^^^^^583^^^^^^^^^^^^^^^^^^^^^Pearman,G I !ȚTu" A^582^Higher atmospheric CO2 concentrations are potentially beneficial to agriculture because they usually stimulate plant  growth. The typical magnitude of the 'CO2 fertilizing effect' is a 30-40% increase in yield for a doubling of CO2 concent ration to 700 ppmv. Variation in responsiveness depends on plant species and environmental conditions such as temperature and rainfall which may be changing as a result of the greenhouse effect. The main mechanisms of the 'CO2-fertilizing effec t' involve several physiological phenomena, some that are certainly primary (stimulation of photosynthesis, suppression of  photorespiration, reduction in stomatal aperture) and others that seem so far to be primary but may turn out not to be (g reater leaf area development and branching, reduced stomatal frequency, reduced dark respiration, changes to reproductive development). It is often assumed that the reduction in stomatal conductance at high CO2 concentration will lead to reduce d evapotranspiration from vegetated regions, all else being equal. There are both physiological and boundary-layer meteoro logical considerations which suggest that this effect might be small though there is some argument about that. For annual crops like cereals, a warmer climate will tend to reduce yield owing to the faster attainment of physiological maturity. H owever, the size of the CO2-fertilizing effect on yield for a currently adapted variety is similar to that of the associat ed temperature-dependent reduction of yield. So the net effect on cereal yield in a region will depend on the success at i ntroducing slower maturing and CO2-responsive varieties to compensate for faster development in warm conditions, and on whether the climate change involves more or less rainfall in the region.22Z Z,s ![Z^jNN%y*: 236^1^Gifford,R M^1989^3^The Effects of the Build-up of Carbon Dioxide in the Atmosphere on Crop Productivity^Proceedings of the 5th Australian Agronomy Conference; 1989 Sept. 24-29; University of Western Australia, Perth, Western Australia^Australian Society of Agronomy^^^^^^^^^^^^^^^^^^^^^^^^^^^^nomysI-C *~t*F*@s]^_ZY[X 237^1^Gifford,R M^1989^3^Exploiting the Fertilizer Effect of Increasing Atmospheric Carbon Dioxide^Climate and Food Securi ty, International Symposium on Climate Variability and Food Security in Developing Countries; 1987 Feb. 5-9; New Delhi, In dia^International Rice Research Institute, Manila, and American Association for the Advancement of Science, Washington, D.C.^^477-487^^^^^^^^^^586^^^^^^^^^^^^^^^^ *_^ZY[XPQVd*Ct%:u QU*Y^YXˀP A^585^High CO2 concentrations fertilize plants by stimulating photosynthesis, suppressing photorespiration, and reducing t ranspiration per unit leaf area. CO2 enhancement of growth occurs at both optimal and nonoptimal levels of other environme ntal variables (light, water, temperature, nitrogen nutrients, salinity). Severely phosphate-deficient plants may not resp ond to higher CO2 concentrations. The globally increasing CO2 concentration, therefore, represents an improving component of the fitness of the environment for secure food production. This will partially counter any deteriorating aspects of agr icultural environments (e.g. adverse climatic change, soil loss and deterioration, acid precipitation). Because yield incr ease percentages in response to high CO2 are larger for drought and salt-stressed plants than for nonstressed plants, some marginal cropping sites (e.g. on arid boundaries) may show less year-to-year variation. This would be an improvement in t !he stability of food production from such sites. Because C3 species will benefit more than C4 species, substitution of C3 "for C4 crops may become more worthwhile. Communities with access to fertilizer may be better able to exploit higher CO2 at #mospheres. Cropping boundaries may move onto more saline and drought-prone soils, although this would probably be bad poli $cy in the long term. Genetic variation in within-species responsiveness to high CO2 may enable the breeding of cultivars to take greater advantage of a high CO2 atmosphere.uEvV6Ǽ&\<^tt8<ur=tW>Ǽe&=u &238^1^Gifford,R M^1988^3^Interactions with Vegetation^Greenhouse: Planning for Climate Change^E.J. Brill^New York^83-89^^^^^^^^^^588^^^^^^^^^^^^^^^^^^^^^Pearman,G IS6Ǽ& tv~s6~M$ (Cv6C>CC χ@I (A^587^Plant photosynthesis has transformed the pre-biotic anaerobic atmosphere that was rich in CO2 to a modern atmosphere ), fit for advanced life, containing 21% O2 and only a trace concentration of CO2. Modern vegetation also plays a significa *nt part in determining climate by affecting the partitioning of incoming solar energy over land. This partitioning may cha +nge as a result of CO2 effects on vegetation. In one way or another vegetation contributes to and/or is affected by the ot ,her major changing components of the global atmosphere -- O3, CH4, CFCs, N2O. Current best estimates of the scale of net d -eforestation of the world indicate that it is releasing about a quarter as much CO2 to atmosphere as fossil fuel burning i .s. However, the increasing CO2 concentration in the atmosphere is probably increasing the growth of vegetation. It is esti /mated that the net annual storage of extra carbon in the form of more standing biomass and soil organic matter than hither 0to, may approximately equal the carbon released by net deforestation. Quantitative appraisal of the global carbon cycle re 1veals that to attempt to permanently remove the fossil fuel-derived CO2 from the atmosphere by massive re-afforestation or 2 by storing felled timber is unrealistic. Refraining from continued net deforestation would, however, produce a probably detectable slowdown in the rate of build-up of atmospheric CO2.X;VW*؋*_^SQVWv~!8r\Iv 4239^1^Gifford,R M^1992^3^Interaction of Carbon Dioxide with Growth-Limiting Environmental Factors in Vegetation Productivi 5ty: Implications for the Global Carbon Cycle^^Springer Verlag^Berlin^24-58^^^^I^^Advances in Bioclimatology^^^^^^^^^^^^^^^^^^^^^^^^^Desjardins,R L^Gifford,R M^Nilson,T^Greenwood,E A N A N t+EFs_^ZY[ 7240^1^Gifford,R M^1990^3^Photosynthesis and the Greenhouse Effect^Chemistry and the Environment, Proceedings of Regional Symposium, 1989, Brisbane^Commonwealth Science Council^London^59-71^^^^^^^^^^591^^^^^^^^^^^^^^^^^^^^^Noller,BN^Chadha,MSu 9A^590^The greenhouse effect, whereby atmospheric CO2 and water vapour prevent the Earth's surface from being totally froze :n is likely to be amplified by the anthropogenic emissions of fossil fuel CO2. The global carbon cycle links photosynthesi ;s to the greenhouse effect on all timescales up to millions of years. Major characteristics of the Earth's atmospheric com ts, especially angiosperms, cause. Calcium released by weathering moves to the oceans where it paces the formation of calc ?ium carbonate rocks which are a massive carbon pool that dwarfs all others combined. On a timescale of millions of years t @he carbon from calcium carbonate is cycled back to the atmosphere via volcanoes. On shorter timescales of sociopolitical c Aoncern photosynthesis is involved with the current global change in atmospheric CO2 increase. From what we know about plan Bt photosynthetic and growth responses to increasing CO2 concentration interacting with other limiting environmental factor Cs, it seems very likely that the biosphere is absorbing, into standing biomass and soil organic matter, some of the CO2 em Ditted from fossil fuel burning and net deforestation thereby contributing to the 'missing carbon' that does not appear as Ean increase in atmospheric CO2 concentration. However, the scope for accelerating this CO2 sequestering process by plantin Fg more trees is rather limited owing to the large scale required relative to the land available and to the fact that net carbon sequestration ceases when a forest matures..³뾳L뺳 붳!벳뮚$=:Ú NÚZ,s!.χ&/χ /χ!N2χ&N2χ / H241^3^Gifford,R M^Lambers,H^Morison,J I L^1985^1^Respiration of Crop Species under CO2 Enrichment^44^63^^351-356^^^^^^^^^^594^^^^^^^^^^^wheat/Triticum aestivum/mung bean/Vigna radiata/sunflower/Helianthus annuuss annuus L.ilχkχ( C^592^Physiol. Plant.QmFFD=tNFvjr/FNȋ?~NrFQW3_Y ZFpF= KA^592^Respiratory characteristics of wheat (_Triticum aestivum_ L. cvs Gabo and WW15), mung bean (_Vigna radiata_ L. Wilcz Lek cv. Celera) and sunflower (_Helianthus annuus_ L. cv. Sunfola) were studied in plants grown under a normal CO2 concentr Mation and in air containing an additional 340 or 250 uL/L CO2. Such an increase in global atmospheric CO2 concentration ha Ns been forecast for about the middle of the next century. The aim was to measure the effect of high CO2 on respiration and O its components. Polarographic and, with wheat, CO2 exchange techniques were used. The capacity of the alternative pathway P of respiration in roots was determined polarographically in the presence of 0.1 mM KCN. The actual rate of alternative pa Qthway respiration was assessed by reduction in oxygen consumption caused by 10 mM salicylhydroxamic acid. Each species res Rponded differently. In wheat, growth in high atmospheric CO2 was associated with up to 45% reduction in respiration by bot Sh roots and whole plants. Use of respiratory inhibitors in polarographic measurements on wheat roots implicated reduction Tin the degree of engagement of the alternative pathway as a major contributor to this reduced respiratory activity of high U-CO2 plants. No change was found in the total sugar content per unit wheat root dry weight as a result of high CO2. In non Ve of the species was there an increase in the absolute, or relative, contribution by the alternative pathway to total resp Wiration of the root system. Thus the improved photosynthetic assimilate supply of plants grown in high CO2 did not lead to X increased diversion of carbon through the non-phosphorylating alternative pathway of respiration in the root. On the cont Yrary, in wheat grown in high CO2, the reduced loss of carbon through that route must have contributed to their larger dry weight.FuRF^FFFQ}v&EF&} u&Ezu FFR &EFLFFt ^v's% [242^2^Gifford,R M^Morison,J I L^1985^1^Photosynthesis, Water Use and Growth of a C4 Grass Stand at High CO2 Concentration^18^7^^77-90^^^^^^^^^^597^^^^^^^^^^^Paspalum plicatulumum Michx.^X fvLDތ،¾L&R;r{P&E IC^595^Photosynth. Res.^XrHD&E P&=t4b &&E@Qr&] &M&URSQY[gX=u۾LFN6D ^A^595^Leaf photosynthesis rate of the C4 species _Paspalum plicatulum_ Michx was virtually CO2-saturated at normal atmosph _eric CO2 concentration but transpiration decreased as CO2 was increased above normal concentrations, thereby increasing tr `anspiration efficiency. To test whether this leaf response led growth to be CO2-sensitive when water supply was restricted a, plants were grown in sealed pots of soil as miniature swards. Water was supplied either daily to maintain a constant wat ber table, or at three growth restricting levels on a 5-day drying cycle. Plants were either in a cabinet with normal air ( c340 umol (CO2)/mol (air)) or with 250 umol/mol enrichment. Harvesting was by several cycles of defoliation. With abundant dwater supply high CO2 concentration did not cause increased growth, but it did not cause an increase in growth over a wide e range of growth-limiting water supplies either. Only when water supply was less than 30-50% of the amount used by the sta fnd with a water-table was there evidence that dry weight growth was enhanced by high CO2. In addition, with successive reg growth, the enhancing effect under a regime of minimal water allocations, became attenuated. Examination of leaf gas exchan hge, growth and water use data showed that in the long term stomatal conductance responses were of little significance in m iatching plant water use to low water allocation; regulation of leaf area was the mechanism through which consumption match jed supply. Since high CO2 effects operate principally via stomatal conductance in C4 species, we postulate that for this species higher CO2 concentrations expected globally in future will not have much effect on long term growth.V FV l243^2^Gislerod,H R^Nelson,P V^1989^1^The Interaction of Relative Air Humidity and Carbon Dioxide Enrichment in the Growth of _Chrysanthemum morifolium_ Ramat^53^38^^305-313^^^^^^^^^^2046^^^^^^^^^^^chrysanthemum/Chrysanthemum morifolium^^^^^mat \C^598^Scientia Hortic. UVvFF\ZFVc6h6fFPFPFPFP<χVFu=u ^FV o244^1^Goudriaan,J^1990^3^Primary Productivity and CO2^The Greenhouse Effect and Primary Productivity in European Agro-ecos pystems; 5-10 April 1990; Wageningen, The Netherlands^Pudoc^Wageningen^23-25^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^Goudriaan,J^van Keulen,H^van Laar,H H&G_^F;s[jjFVLNPR:χVFt=t_^UVWv ~ F r245^1^Goudriaan,J^1986^3^Simulation of Ecosystem Response to Rising CO2, with Special Attention to Interfacing with the At smosphere^Climate Vegetation Interactions, a NASA Workshop; 1986 January 27-29; Greenbelt, Maryland^NASA Goddard Space Flight Center^Greenbelt, Maryland^68-75^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^Rosenzweig,C^Dickinson,Rhf66hR6^tIχ=u u246^2^Goudriaan,J^Bijlsma,R J^1987^1^Effect of CO2 Enrichment on Growth of Faba Beans at Two Levels of Water Supply^66^35^^189-191^^^^^^^^^^604^^^^^^^^^^^Vicia faba/broad beanan^&G3_^ UVW,~ v jGIχP=u C^602^Nether. J. Agric. Sci.RT_^6PFPjIχ=t6PjRT_^33_^U6PfIχ]U xA^602^The occurrence of growth enhancement by increased CO2 levels is well established under optimal conditions. A growth yanalysis study of faba beans, grown under two CO2 levels (350 and 700 cm3/m3) in combination with two levels of water supp zly, showed that the beneficial CO2 effect is maintained when there is shortage of water. The effects of additional CO2 and { water were shown to be multiplicative. (This is a short synopsis of M.S. Thesis (R.J.B.), Dept. of Theoretical Production Ecology, Wageningen Agric. Univ., Wageningen, 1983.)Cχ tju5χ=t^^&t;Fv&FFPFv P }247^3^Goudriaan,J^van Keulen,H^van Laar,H H^1990^2^The Greenhouse Effect and Primary Productivity in European Agro-Ecosyst ~ems, Proceedings of the International Workshop on Primary Productivity of European Agriculture and the Greenhouse Effect, Wageningen, The Netherlands, 5-10 April 1990^Pudoc^Wageningen^^N&\FFPF v PCχ tju5χ=t^F 248^2^Goyal,A^Tolbert,N E^1989^1^Variations in the Alternative Oxidase in _Chlamydomonas_ Grown in Air or High CO2^17^89^^958-962^^^^^^^^^^608^^^^^^^^^^^Chlamydomonas reinhardtii^^^^^^^ju5χ=t^FvFFPv vCχ tju5 vC^606^Plant Physiol.FPFv PCχ tju5χ=t^FvFFPFv PCχ tju5χ=t^ A^606^_Chlamydomonas_ in the resting phase of growth has an equal capacity of about 15 micromole O2 uptake per hour per mi lligram of chlorophyll for both the cytochrome _c_, CN-sensitive respiration, and for the alternative, salicylhydroxamic a cid-sensitive respiration. Alternative respiration capacity was measured as salicylhydroxamic acid inhibited O2 uptake in the presence of CN, and cytochrome _c_ respiration capacity as CN inhibition of O2 uptake in the presence of salicylhydrox amic acid. Measured total respiration was considerably less than the combined capacities for respiration. During the log p hase of growth on high (2-5%) CO2, the alternative respiraiton capacity decreased about 90% but returned as the culture en tered the lag phase. When the alternative oxidase capacity was low, addition of salicylic acid or cyanide induced its reap pearance. When cells were grown on low (air-level) CO2, which induced a CO2 concentrating mechanism, the alternative oxida se capacity did not decrease during the growth phase. Attempts to measure _in vivo_ distribution of respiration between the two pathways with either CN or salicylhydroxamic acid alone were inconclusive.~tFvPvvvIχ249^3^Graham,R L^Turner,M G^Dale,V H^1990^1^How Increasing CO2 and Climate Change Affect Forests^67^40^^575-587^^1033 C^609^BioSci.VRTVF^3ɋVRTVFVUV F=!s^FFUVvFVC!sF 250^4^Grant,W J R^Fan,H M^Downton,W J S^Loveys,B R^1992^1^Effects of CO2 Enrichment on the Physiology and Propagation of T wo Australian Ornamental Plants, _Chamelaucium uncinatum_ (Schauer) x _Chamelaucium floriferum_ (MS) and _Correa schlechteNndalii_ (Behr)^53^52^^337-342^^^^^^^^^^613^^^^^^^^^^^Chamelaucium uncinatum/Chamelaucium floriferum/Correa schlechtendalii rrea schlechtendalii (Behr)           =:óu u "Ru#Z C^611^Scientia Hortic.u+u,1uu(u 9uru Qu u u u uu u u u u A^611^Root formation on both _Chamelaucium_ and _Correa_ cuttings maintained at high humidity in an enclosed fog tunnel wa s significantly enhanced when ambient CO2 was increased from 350 to 800 ubar. CO2 enrichment resulted in decreased transpi ration and increased water potential of cuttings implying an effect of CO2 on stomatal conductance. CO2 enrichment led to increased starch levels in cuttings of both species probably by raising the intercellular partial pressure of CO2. Increas ed starch content with CO2 enrichment was able to account for 70-90% of the dry weight increase in _Correa_, but only for 10-30% of the dry weight increase in _Chamelaucium_. It is suggested that the stimulation of rooting associated with CO2 e nrichment probably derives from the improved water relations of the cuttings rather than from increased carbohydrate levels.u2Ҁ>҆t€t%3: rƾ €t3 _^Z[XPSRVGSu >҆t tu 251^1^Graumlich,L J^1991^1^Subalpine Tree Growth, Climate, and Increasing CO2: An Assessment of Recent Growth Trends^2^72^ ^1-11^^^^^^^^^^616^^^^^^^^^^^Juniperus occidentalis/western juniper/Pinus balfouriana/foxtail pine/Pinus murrayana/lodgepole pinene>et ȚTs^[Xr/' PSVȚT^[Xr'' @PRVƾ*r 7u^ZXgRWR C^614^Ecology:['>SU":D ^e'%][ˊ<w&˸<w&˸=s.>D A^614^LaMarche et al. (Science 225: 1019-1021, 1984) hypothesized that recent trends of increasing ring widths in subalpin e conifers may be due to the fertilizing effects of increased atmospheric CO2. Five tree-ring series from foxtail pine (_P inus balfouriana_), lodgepole pine (_P. murrayana_), and western juniper (_Juniperus occidentalis_) collected in the Sierr a Nevada, California, were analyzed to determine if the temporal and spatial patterns of recent growth were consistent wit h the hypothesized CO2-induced growth enhancement. Specifically, I address the following questions: (1) Can growth trends be explained solely in terms of climatic variation? (2) Are recent growth trends unusual with respect to long-term growth records? For three of the five sites, 20th-century growth variation can be adequately modeled as a function of climatic va riation. For the remaining two sites, trends in the residuals from the growth/climate models indicate systematic underesti mation of growth during the past decade that could be interpreted as either CO2 fertilization or as a response to extreme climatic events during the mid 1970s. At all five sites, current growth levels have been equalled or exceeded during some preindustrial periods. Taken together, these results do not indicate that CO2-induced growth enhancement is occurring amon g subalpine conifers in the Sierra Nevada. While the results presented here offer no support for the hypothesized CO2 fert ilization effect, they do provide insights into the response of subalpine conifers to climatic variation. Response surface s demonstrate that precipitation during previous winter and temperature during the current summer interact in controlling growth and that the response can be nonlinear. Although maximum growth rates occur under conditions of high winter precipi tation and warm summers for all three species, substantial species-to-species variation occurs in the response to these two variables.d*ˀ&w twˀ&w twˀ&w twˀ&w ttww eP G 252^1^Graybill,D A^1987^3^A Network of High Elevation Conifers in the Western U.S. for Detection of Tree-Ring Growth Respo nse to Increasing Atmospheric Carbon Dioxide^Proceedings of the International Symposium on Ecological Aspects of Tree-Ring Analysis. U.S. Dept. of Energy Conference Report; DOE/CONF-8608144^NTIS^Springfield, Virginia^463-474^^^^^^^^^^618^^^^^^^^^^^Pinus aristata/Pinus longaeva^^^^^^^^^^Jacoby,GC^Hornbeck,JWW/ 3 /ȚTr>etȚTr A^617^Tree-ring width growth at high elevation upper treeline sites in the western U.S.A. evidences unparalleled increase during the past century in comparison to growth records of the preceding 500 or more years. Causes for this do not yet app ear to be solely climatic in origin because it remains unclear that crucial variables affecting growth such as temperature or precipitation, have changed correspondingly during their length of record. Given the recent exponential rise of CO2, a nd its potential for affecting tree growth at high elevations, it cannot yet be ruled out as an agent of change. The rates of ring-width growth increase in some cases appear to exceed the levels of known or estimated changes in climatic paramet ers and also in CO2. This may in part be due to changes in the growth potential of the organisms themselves, providing an amplifying effect to environmental inputs. This could include changes such as increasing needle mass that provides increas ed photosynthetic capacity, increased root growth that provides greater nutrient availability and increased water use effi ciency that is critical in the arid sites. The net effect may not only be increasing growth but increasing persistence in growth variation. Ongoing analysis of data from the current study should permit further understanding of these changes.! 253^1^Graybill,D A^1985^5^Western U.S. Tree-Ring Index Chronology Data for Detection of Arboreal Response to Increasing Ca rbon Dioxide^U.S. Dept. of Energy, Carbon Dioxide Research Division, Washington, D.C., and Environmental Sciences Division , Oak Ridge National Laboratory, Oak Ridge, Tennessee^^^^^^^^^^^^^^^^^^^^^^^^Pinus longaeva/Pinus aristata/Pinus flexilis^^026 in Green Report Series^Response of Vegetation to Carbon Dioxide^^ Xe~*em=tLuGANr@eOr9=J*254^1^Grodzinski,B^1992^1^Plant Nutrition and Growth Regulation by CO2 Enrichment^67^42^^517-525^^21ҋþrP& t& C^620^BioSci.r1&t&@uH؋v&E &U &+ET2RVWUNlr t t# >D >UNr 255^5^Grulke,N E^Riechers,G H^Oechel,W C^Hjelm,U^Jaeger,C^1990^1^Carbon Balance in Tussock Tundra under Ambient and Elevated Atmospheric CO2^34^83^^485-494^^^^^^^^^^624^^^^^^^^^^^Eriophorum vaginatumumH|J C^622^Oecologiar!|tvn`>r `>raPr%f s*վf s3 t${ t A^622^Whole ecosystem CO2 flux under ambient (340 uL/L) and elevated (680 uL/L) CO2 was measured in situ in _Eriophorum_ t ussock tundra on the North Slope of Alaska. Elevated CO2 resulted in greater carbon acquisition than control treatments an d there was a net loss of CO2 under ambient conditions at this upland tundra site. These measurements indicate a current l oss of carbon from upland tundra, possibly the result of recent climatic changes. Elevated CO2 for the duration of one gro wing season appeared to delay the onset of dormancy and resulted in approximately 10 additional days of positive ecosystem flux. Homeostatic adjustment of ecosystem CO2 flux (sum of species' response) was apparent by the third week of exposure to elevated CO2. Ecosystem dark respiration rates were not significantly higher at elevated CO2 levels. Rapid homeostatic adjustment to elevated CO2 may limit carbon uptake in upland tundra. Abiotic factors were evaluated as predictors of ecosy stem CO2 flux. For chambers exposed to ambient and elevated CO2 levels for the duration of the growing season, seasonality (Julian day) was the best predictor of ecosystem CO2 flux at both ambient and elevated CO2 levels. Light (PAR), soil temp erature, and air temperature were also predictive of seasonal ecosystem flux, but only at elevated CO2 levels. At any comb ination of physical conditions, flux of the elevated CO2 treatment was greater than that at ambient. In short-term manipul ations of CO2, tundra exposed to elevated CO2 had threefold greater carbon gain, and had one half the ecosystem level, lig ht compensation point when compared to ambient CO2 treatments. Elevated CO2-acclimated tundra had twofold greater carbon g ain compared to ambient treatments, but there was no difference in ecosystem level, light compensation point between eleva ted and ambient CO2 treatments. The predicted future increases in cloudiness could substantially decrease the effect of el evated atmospheric CO2 on net ecosystem carbon budget. These analyses suggest little if any long-term stimulation of ecosystem carbon acquisition by increases in atmospheric CO2.2.1sDO@tLPDI.UEPtE_^ZPRV3E 256^1^Gulyaev,B I^1986^1^Influence of CO2 Concentration on Photosynthesis, Growth and Productivity of Plants^68^18^^574-591^^^^^^^^^^62727FEE EEM 04]] EtwM M EtwM M ^ZXSQRVWE E#osE C^625^Physiol. Biochem. of Cultured Plants (Fiziologi i aibiokhimi i akultumykh Rasteni)~2M ~ A^625^The works aimed at studying the responses of plants to higher (up to 1000 uL/L) CO2 (Ca) concentrations are reviewed . An increase in the productivity of C3-plants under the effect of carbon dioxide enrichment (by 30-40%) of the atmosphere is, mainly, a result of the photosynthesis intensification and leaf area growth. The assimilates' pool level in plants de pends on the determination degree of vegetative growth, ability of the root system to utilize an excess of assimilates and on the environmental conditions, which explains why deep inhibition of photosynthesis under these conditions is not alway s observed. Relative effect of CO2 enrichment on the productivity is higher with lower illuminations, as the assimilates' deficiency is compensated by the photosynthesis intensification. The rate of plant development slightly depends on Ca whil e the total plants' resistance increased with Ca. Efficiency of water utilization grows almost twice with Ca duplication. CO2 enrichment makes efficiency of symbiotic nitrogen-fixation in leguminous plants higher. In Russian.UHϚ 257^3^Guy,M^Granoth,G^Gale,J^1990^1^Cultivation of _Lemna gibba_ under Desert Conditions. II: The Effect of Raised Winter Temperature, CO2 Enrichment and Shading on Productivity^41^23^^1-11^^^^^^^^^^630^^^^^^^^^^^Lemna gibba/duckweeded*Ú* C^628^Biomass1-u-u^2.uQ`2u2ud3ua3u6uIB DGc F+ A^628^The aim of this work was to increase the productivity of _Lemna gibba_ ponds under desert conditions. In the winter season, the ponds were covered with transparent plastic tents which raised water temperature. This also allowed CO2 to be added to the air in the tents to either the ambient, about 340 umol/mol, or to higher concentrations. The plastic covers a ttenuated photosynthetically active light by about 30%. Winter-season yields in the covered ponds, maintained at ambient C O2 concentration, were 39% higher than in the uncovered ponds. This could be ascribed to raised temperatures. Enrichment o f the atmosphere with CO2 further increased yields by as much as 28%. The different treatments did not affect protein cont ent expressed as a percentage of dry weight. Laboratory experiments indicated that the shorter the photoperiod the larger is the growth response of _Lemna gibba_ to CO2 enrichment. Shading of the ponds during the June-August summer season reduc ed pond temperatures at midday by about 5-6C and resulted in a 30-80% increase in growth. It was concluded that under des ert conditions similar to those prevailing in this trial, high yields of _Lemna gibba_ can be achieved throughout a growin g season of 12 months per year by covering the ponds and raising ambient [CO2] during the winter, and by shading in summer . Productivity of 7.4 +/- 1.0 g/m2/day can be maintained throughout the year. Whether or not it is worthwhile to do so is a question of local economics3)`3!áȿͿʿϿǿ̿00dayVff uj d 258^2^Guy,R D^Reid,D M^1986^1^Photosynthesis and the Influence of CO2-Enrichment on Delta-13 C Values in a C3 Halophyte^16^9^^65-72^^^^^^^^^^633^^^^^^^^^^^Puccinellia nuttallianana (Schultes) Hitch.^˾d&Ϳ&EϿ˸ C^631^Plant Cell Environ.3dHWנ̿F̿dV̿_QVWmrgF&=t5¾a A^631^Shifts in [delta]-13C of the graminaceous C3 halophyte _Puccinellia nuttalliana_ (Schultes) Hitch. can be induced by salinization. To investigate this phenomenon, three approaches were taken: assay of carboxylases, CO2-enrichment studies, and gas exchange analysis. Although ribulose-1,5-bisphosphate carboxylase activity decreased with salinity, phosphoenolpy ruvate carboxylase activity did not increase and its levels were not atypical of C3 plants. When plants were grown at four NaCl concentrations under atmospheres of 310 and 1300 cm3/m3 CO2, the CO2-enrichment enhanced the effects of salinity on [delta]-13C. This is consistent with a biophysical explanation for salt-induced shifts in [delta]-13C, whereby there is a steepening of the CO2 diffusion gradient into the leaf. Gas exchange analysis indicated that intercellular CO2 concentrati ons were depressed in the leaves of salt-affected plants. This resulted from a greatly decreased stomatal conductance coupled with only small effects on intrinsic photosynthetic capacity. Water-use efficiency was enhanced.k*9 259^1^Hanan,J J^1986^3^CO2 Enrichment for Greenhouse Rose Production^Physiology, Yield, and Economics^CRC Press, Inc.^Boca  Raton, Florida^142-149^^^^II^^Carbon Dioxide Enrichment of Greenhouse Crops^^^^635^^^^^^^^^^^rose^^^^^^^^^^Enoch,HZ^Kimball,BA AB A:|2ɋ&L 2 Qʚ*YbZY[XVT=:tV29^ٚMNȋY:&D t*&DtI&\ A^634^The literature indicates that CO2 enrichment is a successful and important adjunct to commercial plant production, t he actual practices being a function of climatic location and the particular technological surroundings. For roses, there has been a hiatus since the articles published by the Israelis and English in the 1970s. The North Europeans, particularly Danish and Dutch industry, appear to have taken the lead in instrumentation and computerization on a commercial scale, wi th actual use of CO2 monitors. However, there are some shortcomings in our practical knowledge of CO2 enrichment and rose physiology. First, we need to emphasize rates rather than simply CO2 concentration and irradiance level in the photosynthe tically active spectrum. Photosynthesis is a rate process, dependent upon several other rates. Blackman's contribution was the ability to open scientists' eyes to significant interactions in the photosynthetic process in a manner that allowed n ew investigative approaches. Second, we need to emphasize the importance of plant water potential on rates if CO2 enrichme nt is to achieve maximum, efficient utilization. Any student of practical plant physiology learns that the major portion o f radiation impinging upon a well-watered plant is converted to latent heat. The importance of this major energy redistrib ution supplies the rationale for a large portion of research at agricultural research stations. Parenthetically, more than  90% of total water withdrawals in the Southwestern U.S. is for irrigation. Based upon this review, and some 30 years of o bservation, it seems to me that manipulation of water potential to maximize CO2 uptake offers the greatest opportunity for  significant technological advance in increasing rose yields in greenhouses. This will require computers which can rapidly  process information from a number of instruments and recalculate settings of the implementation systems to control irradiance, vapor pressure deficits, CO2 levels, as well as plant temperature.}cG;k wwnkvenwvltu[w260^1^Hand,D W^1989^1^The 'Greenhouse Effect': Is It Best Studied in Greenhouses?^69^3^^76-82^^37 X m Y Z " C^636^Prof. Hort.. ' %JI'(O((p7 w'W=R^Ru>b>>a>>j>>k>>5>55> A^638^CO2 enrichment of the greenhouse atmosphere greatly improves the output, quality and value of vegetables, cut-flower s and ornamental plants. Raising the greenhouse CO2 concentration enhances photosynthesis and growth by increasing the rat e of CO2 fixation concomitantly with a suppression of photo-respiration. Prolonged exposure of plants to elevated CO2 conc entrations can, however, greatly accelerate the decline in the photosynthetic capacity of individual leaves with age. Comm ercially, CO2 for enrichment is normally obtained in liquid form or produced directly in the greenhouse atmosphere by burn !ing hydrocarbon fuels such as natural gas, LPG propane, and premium kerosene (paraffin) which all contain low and acceptab "le levels of sulphur. Plentiful supplies of natural gas in both Britain and The Netherlands have also encouraged growers i #n these countries to practise CO2 enrichment by ducting flue-gases into their greenhouses from centralized, gas-fired boil $er installations. Generating CO2 from hydrocarbon fuels can give rise to several gaseous air pollutants that are potential %ly damaging for crop production. The pollutants that cause most of the trouble in CO2-enriched greenhouses are nitrogen ox &ides such as nitric oxide and nitrogen dioxide, and unburnt hydrocarbons such as ethylene and propylene. Additionally, imp 'rovements to the insulation of heated greenhouses restrict air exchange and increase the hazard of certain plasticisers su (ch as the alkyl esters of phthalic acid which are used to give flexibility to PVC. The risk of incurring losses in yield d )ue to gaseous air pollutants can be minimized by using low-sulphur fuels, avoiding leaks of fuel gases, servicing burners *regularly, limiting fuel consumption and improving ventilation in near-airtight structures. Longer-term measures to improv +e the productivity of crops grown in polluted greenhouse atmospheres include the design of pollution-free burners, and the development and use of cultivars that are tolerant of gaseous air pollutants.vX'vX-vX3vXvXvXvXvXvXvXvX -262^1^Hand,D W^1986^3^CO2 Sources and Problems in Burning Hydrocarbon Fuels for CO2 Enrichment^Status and CO2 Sources^CRC .Press, Inc.^Boca Raton, Florida^99-121^^^^I^^Carbon Dioxide Enrichment of Greenhouse Crops^^^^642^^^^^^^^^^^^^^^^^^^^^Enoch,HZ^Kimball,BAAB AE?ZY[XvX~VvX vX6^tIV8vvX+]_^XVvXvX^ 0A^641^CO2 enrichment of the greenhouse atmosphere is an invaluable technique for improving the performance of high-value s 1alad and flower crops during the difficult winter period when poor light limits growth and development. According to gover 2nment statistics there are approximately 500 ha of heated glasshouses and film-plastic covered structures (greenhouses) in 3 England and Wales equipped specifically for CO2 enrichment. Additional areas of glasshouses receive incidental enrichment 4 when growers either use direct-fired burners for warm-air heating or grow their crops in raised beds of decomposing straw 5. CO2 for enrichment purposes can be either supplied in liquid form or produced directly by burning hydrocarbon fuels with 6 a low-sulfur content in the atmosphere. Bulk storage of liquid CO2 is difficult to justify economically on small areas of 7 glasshouses (i.e., less than 4000 m2) but handling liquid CO2 in cylinders is laborious, time-consuming and expensive. Na 8tural gas, LPG propane, and low-sulfur grades of kerosene (paraffin) are therefore favored by many growers because the CO2 9 is produced comparatively cheaply and the heat of combustion can provide a significant proportion of the daytime heat req :uirement in winter. Government statistics show that low-sulfur hydrocarbon fuels are used on 7 out of every 9 ha equipped ;for CO2 enrichment. Generating CO2 from hydrocarbon fuels can give rise to several gaseous air pollutants that are potenti nt for most of the injuries to crops growing in greenhouses enriched with CO2 produced from hydrocarbon fuels. These are t ?he nitrogen oxides such as NO and NO2 and unburnt hydrocarbons such as ethylene and propylene. Inefficient fuel combustion @ can also give rise to the formation of harmful aldehydes like formaldehyde and acrolein. Nitrogen oxides are formed in th Ae burner flame of a CO2 producer by the heat-promoted combination of atmospheric nitrogen and oxygen. The rate at which ni Btrogen oxides are generated depends essentially on flame temperature, i.e., the hotter the flame the greater the emission Cof nitrogen oxides. Modern CO2 producers have a high flame temperature to ensure efficient fuel combustion and the formati Don of nitrogen oxides is an inevitable consequence of burner design. When threefold CO2 enrichment is practiced the concen Etration of nitrogen oxides in the greenhouse atmosphere can be as high as 0.5 uL/L. Such a level may cause injury to crops F by reducing photosynthesis, inhibiting leaf expansion, depressing growth, and decreasing yield. Ethylene emissions from C GO2 producers are the result of complex reactions involved in the pyrolysis and oxidation of hydrocarbon fuels. Burner desi Hgn and operating variables such as the air-fuel ratio are crucial in determining the amount of ethylene released into the Igreenhouse atmosphere. In a well sealed greenhouse equipped for three-fold CO2 enrichment the ethylene concentration can e Jasily rise to a level at which the pollutant has discernible effects on crops, (i.e., between 0.01 and 0.1 uL/L). Ethylene K differs from the nitrogen oxides in that it is a naturally occurring plant growth regulator and can affect many growth, d Levelopmental, and aging processes. Escape of unburnt propylene gas (a major constituent of LPG propane) from loose-fitting M connections to fuel-supply lines and faulty switching of gas-solenoid valves can cause injuries to crops similar to those N induced by ethylene. Propylene concentrations of between 5 and 100 uL/L are commonly found in greenhouse atmospheres poll Outed by a leak of fuel gases from propane-fired CO2 producers. The pollutant mimics the action of ethylene, albeit at a concentration 100 times that required for injury by ethylene..BbD(ޏyKOr%" Q263^3^Hand,D W^Wilson,J W^Acock,B^1993^1^Effects of Light and CO2 on Net Photosynthetic Rates of Stands of Aubergine and _Amaranthus_^35^71^^209-216^^^^^^^^^^645^^^^^^^^^^^Solanum melongena/aubergine/eggplant/Amaranthus caudatus/grain amaranth Samaranth_A2xUE3t %M /qxDĊ ɗ ov & C^643^Ann. Bot.$" u/*r|"Qzd @?t;P! UA^643^Net photosynthetic rates per unit ground area for plant stands of _Solanum melongena_ L. var. _esculentum_ (aubergin Ve) and _Amaranthus caudatus_ L. var. _edulis_ (grain amaranth) were measured over 10 min intervals in an airtight, glass, Wcontrolled-environment cabinet for a range of light flux densities provided by the diurnal variation in daylight. Light re Xsponse curves for photosynthesis of stands, grown at ambient CO2 concentration, were defined at 400, 800 and 1200 vpm CO2. Y Light compensation points for these stands were around 20-30 J/m2/s and decreased slightly at higher CO2 concentrations. ZFor aubergine, a C3 species, the short-term effects of CO2 enrichment were to increase the initial slope as well as the as [ymptote of the light response curve, reducing light saturation at moderate to high light flux densities; but for amaranthu \s, a C4 species, saturation was less apparent and CO2 enrichment scarcely increased photosynthesis except at light flux de ]nsities above 150 J/m2/s. The canopies intercepted 93-98% of incident light. The efficiency of utilization of intercepted ^light in photosynthesis (ug CO2/J) increased from zero at the light compensation point to a maximum at an optimum light fl _ux density of about 100 J/m2/s (the optimum rose a little with CO2 enrichment) and decreased slightly with further increas `e in light. Maximum utilization efficiencies at 500 vpom CO2 were 8-9 ug CO2/J. Enrichment to 1200 vpm did not affect the apeak utilization efficiency of the C4 amaranthus, but increased that of aubergine to 12.2 ug CO2/J (equivalent to some 14% b when using the heat of combustion of plant dry matter to convert to the dimensionless form). This is among the highest re ccorded efficiencies of light utilization for stands, and relates to the exceptionally favourable environment, with optimal control of CO2 concentration, humidity, temperature, water supply and mineral nutrition. e264^2^Hari,P^Arovaara,H^1988^1^Detecting CO2 Induced Enhancement in the Radial Increment of Trees. Evidence from Northern Timber Line^70^3^^67-74^^^^^^^^^^648^^^^^^^^^^^Pinus sylvestris/Scots pineney~yy\yyyy[yy}!y!y RC^646^Scand. J. For. Res.96F)6F/6F8:8:Sy6Fw6Fx96F8:8:j6F8:x\X8:7:8:7:j6Fj6Fj6Fj6Fj6Fj6Fj6Fj hA^646^Annual Ring data from northern Finland was analysed in order to reveal possible trends in ring width development due i to changes in environmental factors. The data was analysed using a four component multiplicative model. The components ar je: tree age, climatic conditions, tree position and changes in environmental conditions. Since the effect of tree age and kposition in the stand could be easily eliminated the main problem was thus to eliminate the effect of climatic conditions lon ring width. This was based on the dependence of the daily radial increment and daily maximum temperature. The component m associated with changing environmental factors, especially to CO2 enrichment, was determined using the model. The basal a nrea development of the trees was calculated from measured and estimated ring widths. Depending on the value of the autocor orelation parameter, the effect of changes in environmental factors on the basal area increment of the trees is between 15.5-43.3% during the period from 1950 to 1983.0 2 0S / ,FbRXx`<6X9`+Co q265^2^Harley,P C^Sharkey,T D^1991^1^An Improved Model of C3 Photosynthesis at High CO2: Reversed O2 Sensitivity Explained rby Lack of Glycerate Reentry into the Chloroplast^18^27^^169-178^^^^^^^^^^651^^^^^^^^^^^soybean/Glycine max/cotton/Gossypium hirsutumpium hirsutum L.7:8:y=yVyjyly~yy\yyyy[yy}!y!y fC^649^Photosynth. Res.6F96F)6F/6F8:8:Sy6Fw6Fx96F8:8:j6F8:x\X8:7:8:7:3:3:3:3:JsO${${ uA^649^Current models of C3 photosynthesis incorporate a phosphate limitation to carboxylation which arises when the capaci vty for starch and sucrose synthesis fails to match the capacity for the production of triose phosphates in the Calvin cycl we. As a result, the release of inorganic phosphate in the chloroplast stroma fails to keep pace with its rate of sequestra xtion into triose phosphate, and phosphate becomes limiting to photosynthesis. Such a model predicts that when phosphate is y limiting, assimilation becomes insensitive to both CO2 and O2, and is thus incapable of explaining the experimental obser zvation that assimilation, under phosphate-limited conditions, frequently exhibits reversed sensitivity to both CO2 and O2, { i.e., increasing O2 stimulates assimilation and increasing CO2 inhibits assimilation. We propose a model which explains r |eversed sensitivity to CO2 and O2 by invoking the net release of phosphate in the photorespiratory oxidation cycle. In ord }er for this to occur, some fraction of the glycollate carbon which leaves the stroma and which is recycled to the chloropl ~ast by the photorespiratory pathway as glycerate must remain in the cytosol, perhaps in the form of amino acids. In that c ase, phosphate normally used in the stromal glycerate kinase reaction to generate PGA from glycerate is made available for photophosphorylation, stimulating RuBP regeneration and assimilation. The model is parameterized for data obtained on soybean and cotton, and model behavior in response to CO2, O2, and light is demonstrated.P 266^4^Harley,P C^Thomas,R B^Reynolds,J F^Strain,B R^1992^1^Modelling Photosynthesis of Cotton Grown in Elevated CO2^16^15^^271-282^^^^^^^^^^654^^^^^^^^^^^cotton/Gossypium hirsutumum L.!Dd}7  sC^652^Plant Cell Environ.0C:\WPC60DOS\VMATHSYN.WFW?t꤀D (jd>$"8>F"d@ A^652^Cotton plants were grown in CO2-controlled growth chambers in atmospheres of either 35 or 65 Pa CO2. A widely accept ed model of C3 leaf photosynthesis was parameterized for leaves from both CO2 treatments using non-linear least squares re gression techniques, but in order to achieve reasonable fits, it was necessary to include a phosphate limitation resulting from inadequate triose phosphate utilization. Despite the accumulation of large amounts of starch (>50 g/m2) in the high CO2 plants, the photosynthetic characteristics of leaves in both treatments were similar, although the maximum rate of Rub isco activity (Vcmax), estimated from A versus Ci response curves measured at 29C, was about 10% lower in leaves from pla nts grown in high CO2. The relationship between key model parameters and total leaf N was linear, the only difference betw een CO2 treatments being a slight reduction in the slope of the line relating Vcmax to leaf N in plants grown at high CO2. Stomatal conductance of leaves of plants grown and measured at 65 Pa CO2 was approximately 32% lower than that of plants grown and measured at 35 Pa. Because photosynthetic capacity of leaves grown in high CO2 was only slightly less than that of leaves grown in 35 Pa CO2, net photosynthesis measured at the growth CO2, light and temperature conditions was approxim ately 25% greater in leaves of plants grown in high CO2, despite the reduction in leaf conductance. Greater assimilation rate was one factor allowing plants grown in high CO2 to incorporate 30% more biomass during the first 36 d of growth.( 267^3^Harley,P C^Weber,J A^Gates,D M^1985^1^Interactive Effects of Light, Leaf Temperature, CO2 and O2 on Photosynthesis in Soybean^51^165^^249-263^^^^^^^^^^657^^^^^^^^^^^soybean/Glycine maxax (L.) Merr.q^ C^655^Planta A^655^A biochemical model of C3 photosynthesis has been developed by G.D. Farquhar et al. (1980, Planta 149, 78-90) based on Michaelis--Menten kinetics of ribulose-1,5-bisphosphate (RuBP) carboxylase-oxygenase, with a potential RuBP limitation imposed via the Calvin Cycle and rates of electron transport. The model presented here is slightly modified so that parame ters may be estimated from whole-leaf gas-exchange measurements. Carbon-dioxide response curves of net photosynthesis obta ined using soybean plants (_Glycine max_ (L.) Merr.) at four partial pressures of oxygen and five leaf temperatures are pr esented, and a method for estimating the kinetic parameters of RuBP carboxylase-oxygenase, as manifested in vivo, is discu ssed. The kinetic parameters so obtained compare well with kinetic parameters obtained in vitro, and the model fits to the measured data give _r2_ values ranging from 0.87 to 0.98. In addition, equations developed by J.D. Tenhunen et al. (1976, Oecologia 26, 89-100, 101-109) to describe the light and temperature responses of measured CO2-saturated photosynthetic r ates are applied to data collected on soybean. Combining these equations with those describing the kinetics of RuBP carbox ylase-oxygenase allows one to model successfully the interactive effects of incident irradiance, leaf temperature, CO2 and O2 on whole-leaf photosynthesis. This analytical model may become a useful tool for plant ecologists interested in comparing photosynthetic responses of different C3 plants or of a single species grown in contrasting environments. 268^3^Hartz,T K^Baameur,A^Holt,D B^1991^1^Carbon Dioxide Enrichment of High-value Crops under Tunnel Culture^3^116^^970-97 3^^^^^^^^^^660^^^^^^^^^^^Cucumis sativus/cucumber/Cucurbita pepo/squash/Lycopersicon esculentum/tomato/Fragaria ananassa/strawberrysa Duch./strawberryU[5(5,,}h5 C^658^J. Amer. Soc. Hort. Sci.TV\:(:,,h: A^658^The feasibility of field-scale CO2 enrichment of vegetable crops grown under tunnel culture was studied with cucumbe r (_Cucumis sativus_ L. cv. Dasher II), summer squash (_Cucurbita pepo_ L. cv. Gold Bar), and tomato (_Lycopersicon escule ntum_ Mill. cv. Bingo) grown under polyethylene tunnels. The drip irrigation system was used to uniformly deliver a CO2-en riched air stream independent of irrigation. Carbon dioxide was maintained between 700 and 1000 uL/L during daylight hours . Enrichment began immediately after crop establishment and continued for about 4 weeks. At the end of the treatment phase , enrichment had significantly increased plant dry weight in the 2 years of tests. This growth advantage continued through harvest, with enriched cucumber, squash, and tomato plots yielding 30%, 20%, and 32% more fruit, respectively, in 1989. I n 1990, cucumber and squash yields were increased 20%, and 16%, respectively. As performed, the expense of CO2 enrichment represented less than a 10% increase in total preharvest costs. A similar test was conducted on fall-planted strawberries (_Fragaria_ x _ananassa_ Duch. cvs. Irvine and Chandler). Carbon dioxide enrichment under tunnel culture modestly increased 'Irvine' yields but did not affect 'Chandler'.& 269^2^Hartz,T K^Holt,D B^1991^1^Root-zone Carbon Dioxide Enrichment in Field Does Not Improve Tomato or Cucumber Yield^28^26^^1423^^^^^^^^^^^^^^^^^^^^^tomato/Lycopersicon esculentum/cucumber/Cucumis sativus sativus L. C^661^HortSci.\@\ 270^1^Harvey,L D D^1989^1^Effect of Model Structure on the Response of Terrestrial Biosphere Models to CO2 and Temperature Increase^11^3^^137-153^^^^^^^^^^665^^^^^^^^^^^^^^^^^^x (08@HPX C^663^Global Biogeochem. Cycles A^663^The sensitivity of a number of different globally aggregated models of the terrestrial biosphere to changes of atmos pheric CO2 and temperature is investigated. Net primary production (NPP) or net photosynthesis (NP) is modeled as a logist ic function, with enhancement due to increased CO2 using the beta factor widely used in global carbon cycle models. NPP al so increases with temperature using a Q10 of 1.4, while respiration and coefficients for translocation and for detritus to soil, and soil to soil, carbon transfers increase with a Q10 of 2.0. The pathway of carbon flow to the slowly overturning soil reservoir has a significant effect on equilibrium sensitivity of total carbon mass to temperature increases if the t ransfer coefficient from the rapidly to slowly overturning reservoir is fixed; maximum sensitivity occurs if all the carbo n entering the slowly overturning reservoir first passes through the rapidly overturning reservoir. If the transfer coeffi cient increases in parallel with the increase of soil respiration coefficient, the carbon pathway has no effect on equilib rium sensitivity, although the transient response depends strongly on the subdivision of the soil reservoir. Allowing the detritus to soil transfer coefficient to increase in parallel with the coefficient for detrital respiration reduces the eq uilibrium sensitivity of the total carbon mass to temperature increases by about half. The variation in model response to CO2 and temperature increase using different model structures is generally comparable to the variation resulting from uncertainty in feedback parameters.(0PX`hpx 271^4^Hatton,T J^Walker,J^Dawes,W R^Dunin,F X^1992^1^Simulations of Hydroecological Responses to Elevate CO2 at the Catchment Scale^25^40^^679-696^^^^^^^^^^668^^^^^^^^^^^Eucalyptus maculatata Hook. C^666^Aust. J. Bot. (08@HPX` A^666^A spatially explicit hydroecological landscape model of water, carbon and energy balances (Topog-IRM) is described. The landscape is envisaged as a catchment forested with a single stratum comprising _Eucalyptus maculata_ trees. The model was used to simulate the direct effects of a 2x elevation in atmospheric carbon dioxide at two levels of nitrogen on catc hment water yield, soil moisture status and tree growth. Experimental results used to parameterise the model are detailed. Key features of the model are (1) an ability to scale hydrological processes at the catchment scale in three dimensions, and (2) a means to integrate multiple factors/stresses on plant growth. The effects of CO2 on catchment hydrology (water y ield or soil moisture content) and forest growth (expressed as leaf area index, LAI) were modelled for a 2-year period, an d contrasted with the effects of added nitrogen. Results were expressed as totals for the catchment or spatially distribut ed across the catchment. For the total catchment, water yield increased in the order: high CO2 with low N, high CO2 with h igh N, ambient CO2 with low N, ambient CO2 with high N. LAI increased from 3.3 to 5.76 in the order: ambient CO2 with low N, ambient CO2 with high N, high CO2 with low N, high CO2 with high N. These results agree with previous data. New finding s are: (1) with elevated CO2 a new equilibrium in transpiration is established in which leaf area increases offset decreas es in stomatal conductance; (2) the addition of nitrogen increases transpiration without any indication of a new equilibri um being reached during the simulated period; (3) the spatial distribution of soil moisture changes, presenting a new reso urce base for spatial changes to species composition and growth rates. The major hydroecological responses to elevated CO2 are seen as increased maximum upper canopy leaf area, increased litter inputs, especially at times of drought (hence chan ged fire regimes), changes in the composition of the understory (hence litter composition, soil microfauna, and the spatial expression of biological diversity) and a slight increase in water yield. 272^4^He,H^Kirkham,M B^Lawlor,D J^Kanemasu,E T^1992^1^Photosynthesis and Water Relations of Big Bluestem (C4) and Kentucky Bluegrass (C3) under High Concentration of Carbon Dioxide^71^95^^139-152^^^^^^^^^^671^^^^^^^^^^^Kentucky bluegrass/Poa pratensis/big bluestem/Andropogon gerardiiardii Vitman:ϜϜ̙̙ C^669^Trans. Kansas Acad. Sci.眙ǑÑ̟̜̙ A^669^As the carbon dioxide (CO2) concentration in the atmosphere increases, comparing how C3 and C4 plants will respond i s important. The objective of this study was to determine the photosynthetic rate, intercellular CO2 concentration, transp iration rate, stomatal resistance, leaf temperature, water potential, and water requirement of a C3 grass (Kentucky bluegr ass, _Poa pratensis_ L.) and a C4 grass (big bluestem, _Andropogon gerardii_ Vitman) growing in a fall in a tallgrass prai rie in Kansas under two levels of CO2 (ambient and two-times ambient). Elevated CO2 increased the photosynthetic rate of K entucky bluegrass by 151% but did not affect the photosynthetic rate of big bluestem. Intercellular CO2 concentrations of both grasses were increased by about the same amount, which was about half the increase in the atmospheric CO2 concentrati on. Doubled CO2 reduced the transpiration rates and increased stomatal resistance of both grasses, but big bluestem was af fected more than Kentucky bluegrass. The twice-ambient level of CO2 increased (between 0.2 and 0.3 MPa) the water potentia l of both grasses. Doubled CO2 decreased the water requirements of big bluestem and Kentucky bluegrass by 41.6% and 158%, respectively.UT̙灙273^1^Hendrey,G R^1992^1^The DOE/USDA FACE Program: Goal, Objectives, and Results Through 1989^8^11^^75-83^^^^^^^^^^67474 C^672^Crit. Rev. Plant Sci. A^672^The FACE system is a tool for studying the effects of CO2 enrichment on vegetation and natural ecosystems and the ex change of carbon between the biosphere and the atmosphere. FACE experiments are conducted in a true field setting without any chamber effect. FACE studies were conducted in an agronomic setting using cotton because the plant and field condition s are relatively uniform, thus permitting an evaluation of FACE performance. Cotton is a woody perennial with well-known p hysiological characteristics and a high level of response to CO2 enrichment. It is therefore a convenient subject for expe rimentation. The BNL FACE system was shown to be reliable in field experiments conducted in 1987-1989, providing effective control of CO2 concentrations in an open field setting without any type of confinement of ambient air. The system operate s effectively over plant canopies ranging in stature from bare ground to 200 cm with both open and closed canopies. Contro l of CO2 concentrations over large plots is within the criterion range +/- 20% of set point for 1-min averages at least 80 % of the time in all of these situations over both vertical and horizontal profiles. The area under effective control is d escribed, approximately, by the diameter of the FACE array minus 4 m and is as large as 380 m2 in the largest configuratio n tested to date (Hendrey 1992). In 1989 a 12-m diameter 'sweet spot' in the center of the FACE array had season-long aver age CO2 concentrations throughout the volume from ground level to the top of the canopy that were within the range of 94% to 104% of the target concentration. Operating costs for a four-array FACE system are approximately $450-650/m2 of usable plot area under effective CO2 control. Cotton grown under CO2 enrichment showed significant increases in biomass accumulat ion, both above ground and below ground. Soil respiration also increased in CO2 enriched plots. Enriched plants matured ea rlier and, in general, had greater agronomic yields. Water use efficiency increased with CO2 enrichment. The FACE system a s reported here has had two years of successful biological experimentation. Results from these experiments are intended fo r use in evaluating both the effects of CO2 on plants and ecosystems, and on the feedback processes operating between the biosphere and atmosphere that are the primary, short-term regulators of atmospheric CO2 concentration.. 274^1^Hendrey,G R^1992^2^FACE: Free Air CO2 Enrichment for Plant Research in the Field^CRC Press, Inc.^Boca Raton, Florida^^Y^^^^^^Critical Reviews in Plant Sciences^^^11^^^^^^^^^^^^^^^^^^^^^^Conger,BV^^^^^^^^^^^^ increases the internal inorganic carbon concentration and suppresses oxygenase activity of ribulose-1, 5-bisphosphate carb275^1^Hendrey,G R^1992^1^Global Greenhouse Studies: Need for a New Approach to Ecosystem Manipulation^8^11^^61-74^^78 C^677^Crit. Rev. Plant Sci.! 276^3^Hendrey,G R^Lewin,K F^Nagy,J^1993^1^Free Air Carbon Dioxide Enrichment: Development, Progress, Results^123^104/105^^17-31^^^^^^^^^^681^^^^^^^^^^^Gossypium hirsutum/cotton^^^^^^^wn to decrease after young greenhouse plants were placed in the dark. Seasonal variation in the ARA of excised plant roots A^679^Credible predictions of climate change depend in part on predictions of future CO2 concentrations in the atmosphere. Terrestrial plants are a large sink for atmospheric CO2 and the sink rate is influenced by the atmospheric CO2 concentrat ion. Reliable field experiments are needed to evaluate how terrestrial plants will adjust to increasing CO2 and thereby in fluence the rate of change of atmospheric CO2. Brookhaven National Laboratory (BNL) has developed a unique Free-Air CO2 En richment (FACE) system for a cooperative research program sponsored by the U.S. Department of Energy and U.S. Department o f Agriculture, currently operating as the FACE User Facility at the Maricopa Agricultural Center (MAC) of the University o f Arizona. The BNL FACE system is a tool for studying the effects of CO2 enrichment on vegetation and natural ecosystems, and the exchange of carbon between biosphere and the atmosphere, in open-air settings without any containment. The FACE sy stem provides stable control of CO2 at 550 ppm +/- 10%, based on 1-min averages, over 90% of the time. In 1990, this level  of control was achieved over an area as large as 380 m2, at an annual operating cost of 668/m2. During two field seasons of enrichment with cotton (_Gossypium hirsutum_) as the test plant, enrichment to 550 ppm CO2 resulted in significant incr eases in photosynthesis and biomass of leaves, stems and roots, reduced evapotranspiration, and changes in root morphology., In addition, soil respiration increased and evapotranspiration decreased.-S ~Sort by...,D%2HC~ 277^5^Hendrey,G R^Lewin,K F^Lipfert,F^Kolber,Z^Daum,M^1988^5^Free-Air Carbon Dioxide Enrichment (FACE) Facility Developmen t: I. Concept, Prototype Design and Performance^U.S. Dept. of Energy, Carbon Dioxide Research Division, Washington, D.C^^^^^^^^^^^^^^^^^^^^^^^^^^045 in Green Report Series^Response of Vegetation to Carbon Dioxide^^ Filename @@   278^5^Hendrey,G R^Lipfert,F W^Kimball,B A^Hileman,D R^Bhattacharya,N C^1988^5^Free Air Carbon Dioxide Enrichment (FACE) Fa cility Development: II. Field Tests at Yazoo City, MS, 1987^U.S. Dept. of Energy, Carbon Dioxide Research Division, Washin!$gton, D.C^^^^^^^^^^^^^^^^^^^^^^^^cotton/Gossypium hirsutum^^046 in Green Report Series^Response of Vegetation to Carbon Di 279^1^Hendrix,D L^1992^1^Influence of Elevated CO2 on Leaf Starch of Field-Grown Cotton^8^11^^223-226^^^^^^^^^^^^^^^^^^^^^cotton/Gossypium hirsutumum L.UUÁꪪ C^684^Crit. Rev. Plant Sci.ꪪÁUUꪪǙ 280^4^Higginbotham,K O^Mayo,J M^L'Hirondelle,S^Krystofiak,D K^1985^1^Physiological Ecology of Lodgepole Pine (_Pinus contorta_) in an Enriched CO2 Environment^32^15^^417-421^^^^^^^^^^688^^^^^^^^^^^lodgepole pine/Pinus contortata C^686^Can. J. For. Res.UUÁꪪUU !A^686^Relatively little work has been done to evaluate the effects of chronically high levels of carbon dioxide on growth "and physiology of woody plants. In this study, seedlings of lodgepole pine (_Pinus contorta_ Dougl. var. _latifolia_ Engel #m.) were grown for 5-month periods at 330, 1000, or 2000 uL CO2/L. Height growth; leaf area production; biomass of leaves, $ stems, and roots; and photosynthetic responses to changing light, moisture, and CO2 concentration were measured. Signific %ant differences between treatments were found in mean seedling height on all measurement dates. Seedlings grown at 1000 uL & CO2/L were tallest, with seedlings grown in 2000 uL/L intermediate between the control (330 uL/L) and 1000 uL/L treatment 's. The same relationship was found in production of total leaf surface area. Increased leaf surface area yields a producti (ve advantage to seedlings grown at concentrations of CO2 up to 2000 uL/L even if no increase in net photosynthesis is assu )med. Biomass of stems, roots, and secondary leaves was increased in both elevated CO2 conditions, with root biomass approx *imately 15 times greater in seedlings grown at 1000 uL/L than in those grown at 330 uL CO2/L. Stomatal resistances were es +sentially the same for all treatments, indicating no CO2-induced stomatal closure to at least 2000 uL/L. Photosynthetic Vm ,ax (milligrams per square decimetre per hour) for light response curves varied with CO2 concentration. If results are extr -apolated beyond a 5-month period and into field conditions, it appears that size of trees, interactions with competitors, and ecological role of the species might be altered.!s˜ /281^1^Highsmith,M^1989^3^Two Aspects of Starch Formation in Mature Soybean Leaves^Current Topics in Plant Biochemistry and 0 Physiology: Proceedings of the Plant Biochemistry and Physiology Symposium^The Interdisciplinary Plant Biochemistry and Physiology Program, University of Missouri^Columbia^267^^^^8^^^^^^^^^^^^^^^^^soybean/Glycine max^^^^^8l8vv ``oxide^^^^ `00` f< growth rate, the observed adjustments that plants make to light and carbon dioxide concentration appear to be adaptive. W ?e show that the relationship between photosynthesis and leaf nitrogen concentration is complex and depends on the light an @d CO2 levels at which photosynthesis is measured. The shape of this function is important in determining Nopt and the oppo Asite response of leaf nitrogen to light and carbon dioxide is shown to be the result of the different effects of light and CO2 on the photosynthesis-leaf nitrogen curve.ϙ̙˙ɃꪪÙÑ C283^3^Hilbert,D W^Prudhomme,T I^Oechel,W C^1987^1^Response of Tussock Tundra to Elevated Carbon Dioxide Regimes: Analysis of Ecosystem CO2 Flux through Nonlinear Modeling^34^72^^466-472^^^^^^^^^^69696UU 4C^694^OecologiaUTÙ㌙ᙀဃꪪĜćÌ FA^694^The response of tussock tundra to elevated atmospheric concentrations of CO2 was measured at Toolik Lake, Alaska in Gthe summer of 1983. Computer-controlled greenhouses were used to determine diurnal ecosystem flux of CO2 under four treatm Hents: 340 ppm, 500 ppm, and 680 ppm CO2, as well as 680 ppm CO2 with a four degree centigrade increase in temperature. For I the seven days of data analyzed, net daily CO2 flux was significantly different between treatments. Net uptake was positi Jvely correlated with CO2 concentration in the chamber and negatively correlated with temperature. A nonlinear model was us Ked to analyze this data set and to determine some of the reasons for different net CO2 flux. This model allowed an estimat Lion of light utilization efficiency, total conductance of CO2, and a comparable measure of total respiration. From this an Malysis we conclude that nutrient limitations in the arctic decrease the capacity of tundra plants to make use of elevated NCO2 concentrations. The plants respond by decreasing conductance in the presence of elevated CO2, which results in approxi Omately equal gross uptake rates for the three CO2 treatments. Apparent changes in system respiration result in higher net Puptake under elevated CO2 but this may be due to biases in the data. The treatment with increased temperature exhibited hi Qgher conductances and, consequently, higher gross uptake of CO2 than the other treatments. Higher temperatures, however, a Rlso increase respiration with the result being lower net uptake than would be expected in the absence of temperature increases.UTꪪ T284^7^Hildmann,H^Windisch,K^Heissner,A^Weber,W^Domroese,J^Weber,S^Markert,A^1989^1^Testing a Strategy of Growth and Yield "Control in Greenhouse Cucumbers in a Specialized Vegetable Growing Farm^15^260^^123-136^^^^^^^^^^^^^^^^^^^^^Cucumis sativu V285^6^Hileman,D R^Bhattacharya,N C^Ghosh,P P^Biswas,P K^Lewin,K F^Hendrey,G R^1992^1^Responses of Photosynthesis and Stoma Wtal Conductance to Elevated Carbon Dioxide in Field-Grown Cotton^8^11^^227-231^^^^^^^^^^^^^^^^^^^^^cotton/Gossypium hirsutumum L.癌UU癙甙UT DC^698^Crit. Rev. Plant Sci.ꪪϜć Z286^2^Hocking,P J^Meyer,C P^1991^1^Carbon Dioxide Enrichment Decreases Critical Nitrate and Nitrogen Concentrations in Wheat^72^14^^571-584^^^^^^^^^^702^^^^^^^^^^^wheat/Triticum aestivumum L.UT XC^700^J. Plant Nut.UU ]A^700^Atmospheric carbon dioxide (CO2) levels are increasing, In a glasshouse experiment with wheat grown at 5 levels of n ^itrate (NO3) supply, CO2 enrichment (1500 cm3/m3) substantially decreased critical concentrations of NO3-N and total-N in _stem bases and leaves. For example, critical NO3-N concentrations in stem bases at Feekes Stages 1.5, 5, and 10.3, were 4. `5, 2.0, and 2.0 mg/g dry wt, respectively, for CO2-enriched plants, compared with 7.5, 6.2 and 6.4 mg/g dry wt, respective aly, for control plants grown at the ambient level of CO2. However, concentrations of NO3-N in the rooting medium required bto produce maximum dry matter accumulation by CO2-enriched plants were similar to those of control plants at the three gro cwth stages. Critical concentrations of NO3-N and total-N declined with time in stem bases and leaves of plants grown at bo dth ambient and elevated CO2 levels, but the decline was greater for CO2-enriched plants. It was concluded that diagnostic criteria based on current critical N concentrations may become invalid as the atmospheric level of CO2 increases. f287^2^Hocking,P J^Meyer,C P^1991^1^Effects of CO2 Enrichment and Nitrogen Stress on Growth, and Partitioning of Dry Matter and Nitrogen in Wheat and Maize^52^18^^339-356^^^^^^^^^^705^^^^^^^^^^^wheat/Triticum aestivum/maize/Zea mays mays L. [C^703^Austr. J. Plant Physiol.ꪨ iA^703^Atmospheric CO2 levels are increasing, but little is known about how this will affect tissue concentrations and the jpartitioning of agriculturally important nutrients such as nitrogen (N) within crop plants. To investigate this, a glassho kuse experiment was conducted in which wheat, a C3 species, and maize, a C4 species, were grown for 8 weeks at high CO2 (15 l00 cm3/m3) on N supplies ranging from deficient (0.5 mol/m3) to more than adequate for maximum growth (25 mol/m3). Wheat r mesponded to both CO2 enrichment and N supply; maize responded only to N supply. CO2-enriched wheat produced about twice th ne dry matter of control plants at all levels of N supply. Tiller and ear numbers were increased by CO2 enrichment irrespec otive of N supply. Enriched wheat plants had lower Leaf Area Ratio but higher Net Assimilation Rate and Relative Growth Rat pe than control plants. There was no effect of CO2 enrichment on specific leaf weight. The enriched plants had lower shoot qto root dry matter ratios than the controls at 6 mol/m3 N and higher. Shoot to root dry matter ratios of both wheat and ma rize increased with increasing N supply. CO2-enriched wheat plants accumulated more N than the controls but the proportiona sl increase in N content was not as great as that in dry matter, with the result that concentrations of total-N and nitrate t-N were lower in all organs of enriched plants, including ears. Nitrate reductase activity was lower in enriched than in c uontrol wheat plants. N-use efficiency by wheat was increased by CO2 enrichment. From a practical point of view, the study vindicates that critical total-N and NO3-N concentrations used to diagnose the N status of wheat will need to be reassessed w as global CO2 levels increase. Elevated CO2 may also reduce the protein content of grain and thus the baking quality of hard wheats.UU y288^2^Hoddinott,J^Jolliffe,P^1988^1^The Influence of Elevated Carbon Dioxide Concentrations on the Partitioning of Carbon in Source Leaves of _Phaseolus vulgaris_^54^66^^2396-2401^^^^^^^^^^708^^^^^^^^^^^Phaseolus vulgaris/bean/bean gC^706^Can. J. Bot.Ϝ |A^706^Plants may alter their growth pattern in response to being grown in elevated CO2 concentrations. The nature of the c }hange in carbon partitioning underlying those alterations was investigated in _Phaseolus vulgaris_ cv. Gold Crop grown to ~the third trifoliate leaf stage in CO2 concentrations of 380, 800, and 1400 ppm. There was no effect of the CO2 concentrat ion on plant height, leaf area, or dry weight, but the specific leaf weight increased significantly with the CO2 concentra tion, indicating a denser leaf structure. The starch content of the leaves also increased significantly as the CO2 level i ncreased. A primary leaf was pulse labelled with 14-CO2 and the depletion of label from that source leaf was monitored wit h a GM tube. The depletion of the count rate with time was described by a nonlinear curve fitting procedure that allowed t he derivation of rate constants to describe the partitioning of carbon in a two-compartment model. Rates of carbon storage decreased in the light with increasing CO2 concentrations with no effect on the rates of export or remobilization. Both e xport and storage were reduced in the dark at all CO2 levels, with an increase in the residence time of carbon in the expo rt pool. Reducing the CO2 concentration around the source leaf just after labelling did not change carbon partitioning com pared to controls. Increasing the CO2 concentration around the source leaf just after labelling increased all carbon flux rates and reduced the residence times in the leaf pools.E MATV5 .CLDjE MATVE .CLD|$E 289^3^Hogan,K P^Smith,A P^Ziska,L H^1991^1^Potential Effects of Elevated CO2 and Changes in Temperature on Tropical Plants^16^14^^763-778^^^^^^^^^^71111 MIKUL .CLDdRE MILENKY .CLDlRE MIRVIS .CLDj_ E MORA zC^709^Plant Cell Environ..CLDyPjE NAZIROV .CLDUE NEZVAL .CLD*yE NICKOLAY.CLDX A^709^Very little attention has been directed at the responses of tropical plants to increases in global atmospheric CO2 c oncentrations and the potential climatic changes. The available data, from greenhouse and laboratory studies, indicate tha t the photosynthesis, growth and water use efficiency of tropical plants can increase at higher CO2 concentrations. Howeve r, under field conditions abiotic (light, water or nutrients) or biotic (competition or herbivory) factors might limit the se responses. In general, elevated atmospheric CO2 concentrations seem to increase plant tolerance to stress, including lo w water availability, high or low temperature, and photoinhibition. Thus, some species may be able to extend their ranges into physically less favourable sites, and biological interactions may become relatively more important in determining the distribution and abundance of species. Tropical plants may be more narrowly adapted to prevailing temperature regimes tha n are temperate plants, so expected changes in temperature might be relatively more important in the tropics. Reduced tran spiration due to decreased stomatal conductance could modify the effects of water stress as a cue for vegetative or reprod uctive phenology of plants of seasonal tropical areas. The available information suggests that changes in atmospheric CO2 concentrations could affect processes as varied as plant/herbivore interactions, decomposition and nutrient cycling, local and geographic distributions of species and community types, and ecosystem productivity. However, data on tropical plants are few, and there seem to be no published tropical studies carried out in the field. Immediate steps should be undertaken to reduce our ignorance of this critical area.E WOOLFS .CLDYSE WOOLFSON.CLDzE YEGOROV 290^1^Hollinger,D Y^1987^1^Gas Exchange and Dry Matter Allocation Responses to Elevation of Atmospheric CO2 Concentration in Seedlings of Three Tree Species^43^3^^193-202^^^^^^^^^^714^^^^^^^^^^^Pinus radiata/Nothofagus fusca/Pseudotsuga menziesii/Monterey pine/New Zealand red beech/Douglas-fir pine/New Zealand red beech/Douglas-fir C^712^Tree Physiol. A^712^Photosynthetic rates of 13-month-old _Pinus radiata_ D. Don, _Nothofagus fusca_ (Hook f.) Orst. and _Pseudotsuga men ziesii_ (Mirb.) Franco seedlings grown and measured at elevated atmospheric concentrations of CO2 (about 620 uL/L) were 32 to 55% greater than those of seedlings grown and measured at ambient (about 310 uL/L) concentrations of CO2. Seedlings gr own in ambient and elevated concentrations of CO2 had similar rates of photosynthesis when measured at 620 uL/L CO2, but w hen measured at 310 uL/L CO2 the _P. radiata_ and _N. fusca_ seedlings which were grown at elevated CO2 had lower rates of photosynthesis than the seedlings grown at an ambient concentration of CO2. Stomatal conductances in general were lower when measured at 620 uL/L CO2 than at 310 uL/L CO2. 291^1^Houghton,R A^1987^1^Biotic Changes Consistent with the Increased Seasonal Amplitude of Atmospheric CO2 Concentrations^62^92^^4223-4230^^^^^^^^^^71717 C^715^J. Geophys. Res. A^715^Monthly estimates of gross primary production (gross uptake of CO2 by plants) and ecosystem respiration (gross relea se of CO2 from the ecosystem) in an oak-pine forest in the northeastern United States were used in this study to examine t he types of metabolic changes in terrestrial systems that might yield the increased seasonal amplitude of CO2 concentratio ns observed at several monitoring stations in recent years. In this study, increases in either photosynthesis or respirati on increased the amplitude of the seasonal oscillation of CO2 concentrations if the increases were predominantly in the no rthern hemispheric summer and winter, respectively. The quantitative changes in metabolism required to produce the observe d increase in amplitude, however, were too large to be explained by CO2 fertilization or by a temperature-induced increase in winter respiration. Investigations of the role of the biota in causing seasonal and year-to-year variations in atmospheric CO2 concentrations are limited by the lack of stations monitoring CO2 in continental air.=Vjl~\[292^1^Houghton,R A^1987^1^Terrestrial Metabolism and Atmospheric CO2 Concentrations^67^37^^672-678^^19^zZ:yY9 C^718^BioSci.8BxBXB8BwW7wW74w4W474vV6vV6&v&V&6&uU5rurUr5ruU5tT4dtdTd4d t T 4  293^4^Houpis,J L J^Surano,K A^Cowles,S^Shinn,J H^1988^1^Chlorophyll and Carotenoid Concentrations in Two Varieties of _Pin us ponderosa_ Seedlings Subjected to Long-term Elevated Carbon Dioxide^43^4^^187-193^^^^^^^^^^722^^^^^^^^^^^Pinus ponderosa/ponderosa pine^^^^^b'bgG'fF&TfTFT&TeE%eE%FeFEF%FdD$dD$8d8D8$8cC#cC#*c*C*#* C^720^Tree Physiol.A!hahAh!haA!`@ Z`Z@Z Z`@ A^720^Two varieties of ponderosa pine (_Pinus ponderosa_ Dougl. var. scopulorum (Rocky Mountain variety) and _P. ponderosa _ var. ponderosa (Sierran variety)) seedlings were subjected to elevated atmospheric CO2 for two and a half years. The CO2 concentrations were ambient, ambient + 75 uL/L, ambient + 150 uL/L and ambient + 300 uL/L, or approximately 350, 425, 500 and 650 uL/L CO2. After one and a half years of exposure to elevated CO2 and until the end of the study, seedlings of bot h varieties showed symptoms of stress including mottling, mid-needle abscission and early senescence. In both varieties, e xposure to CO2 concentrations greater than ambient + 75 uL/L resulted in lower chlorophyll _a_, chlorophyll _b_ and carote noid concentrations. At elevated CO2 concentrations, the concentration of pigments in needles of the Sierran variety were lower than those in the Rocky Mountain variety. Also, at elevated CO2 concentrations, the pigment concentrations in the 1-year-old needles of both _P. ponderosa_ varieties were lower than those in current-season needles.fE]_^ZY[X 294^4^Houpis,J L J^Surano,K A^Daley,P F^Shinn,J H^1986^3^Growth and Morphology of _Pinus ponderosa_ Seedlings Exposed to L ong-term Elevated Atmospheric Carbon Dioxide Concentration^Proceedings of the Ninth North American Forest Biology Workshop ; 1986 June 15-18; Stillwater, Oklahoma^Society of American Foresters, and Department of Forestry, Oklahoma State University^^19-26^^^^^^^^^^724^^^^^^^^^^^ponderosa pine/Pinus ponderosa^^^^^^^^^^Tauer,CG^Hennessey,TConderosa.d.+bAQW A^723^The growth and morphology of two varieties of _Pinus ponderosa_ were measured after two years of continuous fumigati on with carbon dioxide. After two years of treatment, the seedlings of the Rocky Mountain variety showed no significant di fference in total stem height or volume, but the basal diameters of those grown at +300 ppm CO2 were significantly greater than those grown at +0 ppm and +75 ppm. The response of the seedlings of the Sierran variety in these parameters was quit e different, with those at +150 ppm and +300 ppm significantly greater in height than those at +75 ppm and those at +150 p pm and +300 ppm significantly greater than those at +0 ppm and +75 ppm in basal diameter and stem volume. However, using a combined analysis based on percent change in height, diameter, or volume, seedlings at +150 ppm responded to a significan tly greater degree than all other levels. Thus, the beneficial effects of elevated carbon dioxide increase up to +150 ppm and begin to decrease between +150 ppm and +300 ppm.& GC.:Lr3ۀt#2"&2 & GC.:Lr3"֊2"" 295^4^Houter,G^Gijzen,H^Nederhoff,E M^Vermeulen,P C M^1989^1^Simulation of CO2 Consumption in Greenhouses^15^248^^315-320^^^^^^^^^^2056...>b.0.^.`*.^..`..B.C<uv<uOu#€t& C^725^Act. Hort.FҊ€t& Gt&G & !€t&0Gt&0G"&0...>b.0.^. 296^3^Hrubec,T C^Robinson,J M^Donaldson,R P^1985^1^Effects of CO2 Enrichment and Carbohydrate Content on the Dark Respiration of Soybeans^17^79^^684-689^^^^^^^^^^729^^^^^^^^^^^Glycine max/soybeanMerr./soybean..T.`..6U.6 C^727^Plant Physiol..R2.B2.CSW<u<uuU.T.6U.Pt32"&GC.:Lr3ۀt2& A^727^During the period of most active leaf expansion, the foliar dark respiration rate of soybeans (_Glycine max_ cv Will iams), grown for 2 weeks in 1000 microliters CO2 per liter air, was 1.45 milligrams CO2 evolved per hour leaf density thic kness, and this was twice the rate displayed by leaves of control plants (350 microliters CO2 per liter air). There was a higher foliar nonstructural carbohydrate level (_e.g._ sucrose and starch) in the CO2 enriched compared with CO2 normal pl ants. For example, leaves of enriched plants displayed levels of nonstructural carbohydrate equivalent to 174 milligrams g lucose per gram dry weight compared to the 84 milligrams glucose per gram dry weight found in control plant leaves. As the leaves of CO2 enriched plants approached full expansion, both the foliar respiration rate and carbohydrate content of the CO2 enriched leaves decreased until they were equivalent with those same parameters in the leaves of control plants. A st rong positive correlation between respiration rate and carbohydrate content was seen in high CO2 adapted plants, but not i n the control plants. Mitochondria, isolated simultaneously from the leaves of CO2 enriched and control plants, showed no difference in NADH or malate-glutamate dependent O2 uptake, and there were no observed differences in the specific activit ies of NAD+ linked isocitrate dehydrogenase and cytochrome _c_ oxidase. Since the mitochondrial O2 uptake and total enzyme activities were not greater in young enriched leaves, the increase in leaf respiration rate was not caused by metabolic a daptations in the leaf mitochondria as a response to long term CO2 enrichment. It was concluded, that the higher respiration rate in the enriched plant's foliage was attributable, in part, to a higher carbohydrate status....6b.0. 297^2^Huerta,A J^Ting,I P^1988^1^Effects of Various Levels of CO2 on the Induction of Crassulacean Acid Metabolism in _Portulacaria afra_ (L.) Jacq^17^88^^183-188^^^^^^^^^^732^^^^^^^^^^^Portulacaria afrafra (L.) Jacq.]_^ZY[Xˋ...6d C^730^Plant Physiol..^%.^%.`.+^@+ŋ.PK..U.d.+bAQRVW3..P. A^730^In response to water stress, _Portulacaria afra_ (L.) Jacq. (Portulacaceae) shifts its photosynthetic carbon metabol ism from the Calvin-Benson cycle for CO2 fixation (C3) photosynthesis or Crassulacean acid metabolism (CAM)-cycling, durin g which organic acids fluctuate with a C3-type of gas exchange, to CAM. During the CAM induction, various attributes of CA M appear, such as stomatal closure during the day, increase in diurnal fluctuation of organic acids, and an increase in ph osphoenolpyruvate carboxylase activity. It was hypothesized that stomatal closure due to water stress may induce changes i n internal CO2 concentration and that these changes in CO2 could be a factor in CAM induction. Experiments were conducted to test this hypothesis. Well-watered plants and plants from which water was withheld starting at the beginning of the exp eriment were subjected to low (40 ppm), normal (_ca._ 330 ppm), and high (950 ppm) CO2 during the day with normal concentr ations of CO2 during the night for 16 days. In water-stressed and in well-watered plants, CAM induction as ascertained by fluctuation of total titratable acidity, fluctuation of malic acid, stomatal conductance, CO2 uptake, and phosphoenolpyruv ate carboxylase activity, remained unaffected by low, normal or high CO2 treatments. In well-watered plants, however, both low and high ambient concentrations of CO2 tended to reduce organic acid concentrations, low concentrations of CO2 reduci ng the organic acids more than high CO2. It was concluded that exposing the plants to the CO2 concentrations mentioned had no effect on inducing or reducing the induction of CAM and that the effect of water stress on CAM induction is probably mediated by its effects on biochemical components of leaf metabolism..]u]_^ZY[XPSVW+@+F_^ 298^4^Hunt,R^Hand,D W^Hannah,M A^Neal,A M^1991^1^Response to CO2 Enrichment in 27 Herbaceous Species^37^5^^410-421^^^^^^^^ ^^735^^^^^^^^^^^Agrostis capillaris/Arrhenatherum elatius/Brachypodium pinnatum/Bromus erectus/Bromus sterilis/Cerastium f ontanum/Chamerion angustifolium/Chenopodium album/Dactylis glomerata/Deschampsia flexuosa/Desmazeria rigida/Digitalis purp urea/Epilobium hirsutum/Festuca ovina/Festuca rubra/Helianthemum nummularium/Holcus lanatus/Koeleria macrantha/Plantago la nceolata/Poa annua/Poa trivialis/Rumex acetosella/Urtica dioica/Zea mays/Plantago lanceolata/Lolium perenne/Helianthus annuus/Eriophorum vaginatumlantago lanceolata L./Poa annua L./Poa trivialis L./Rumex acetosella agg./Urtica dioica L./Zea ma ys L./Plantago lanceolata L./Lolium perenne L./Helianthus annuus L./Eriophorum vaginatum L.ك..`.+^A..d.+ C^733^Funct. Ecol.$F €u"Kt ʀu&G&_ rMu]_^ZY[Xˋ6>\ u(D .BD<t \.C A^733^CO2-enrichment experiments were performed on 25 British native species of widely differing ecology. Two crops, one C 3 (sunflower)and one C4 (maize), were also included. The background regime involved full-light, glasshouse conditions, non -limiting supplies of water and mineral nutrients and a daytime mean temperature of 18C. Four CO2 treatments were maintained at nominal concentrations of 350, 500, 650 or 800 v.p.m. over a 56-day period. Hyperbolic functions were fitted to yield _vs_ CO2 concentration. The functions were then used to generate predictions of Q-540/350 (the quotient of present yiel299^1^Idso,S B^1991^1^The Aerial Fertilization Effect of CO2 and Its Implications for Global Carbon Cycling and Maximum Greenhouse Warming^73^72^^962-965^^^^^^^^^^^^^^^^^^^^^Citrus aurantiumum L..;0%s$<u:;Ouu3YSQRVW.;0 C^736^Bull. Amer. Meteorol. Soc._^ZY[t..%؋>AuڎۋAu ڋ&;]vB&U&300^1^Idso,S B^1989^1^Carbon Dioxide, Soil Moisture, and Future Crop Production^74^147^^305-307^^^^^^^^^^74040;NuVNC^738^Soil Sci.u=&u!NVF;Frw;NsF^NFF؋MFC&]&]&]^NAW3pËK&E&A^738^Model simulations of the effects of increases in atmospheric carbon dioxide on air temperature, precipitation, and soil moisture suggest that the resultant 'greenhouse effect' will be bad for agriculture. Experimental evidence, however, i ndicates otherwise, demonstrating that plants can more than compensate for the predicted adverse climatic changes. Indeed, recent evidence from around the globe suggests that a carbon-dioxide-induced stimulation of the biosphere is already in progress.&Ku譗Ž&Ku**P+s3SRZ[r: [=^v${DD_^ZY[X& þLss 301^1^Idso,S B^1991^1^Comment on 'Modelling the Seasonal Contribution of a CO2 Fertilization Effect of the Terrestrial Vegetation to the Amplitude Increase in Atmospheric CO2 at Mauna Loa Observatory' by G.H. Kohlmaier et al^75^43B^^338-341^^4C^741^Telluss;TvS..G._.G[WS_&EG?[o_G?_S..o._.[PRWs#; 2tV,*0;s t^^+s#_ZXQY˱QY˱QY˱ QY˱PSRWFNvLs302^1^Idso,S B^1991^1^A General Relationship between CO2-induced Increases in Net Photosynthesis and Concomitant Reductions in Stomatal Conductance^76^31^^381-383^^^^^^^^^^745^^^^^^^^^^^Citrus aurantium/sour orangerange_Z[XQV+ˋs#+)sC^743^Environ. Exp. Bot.+t!+ t+FuUNF C^751^Plant Physiol.6F| t{^FE;FtQ t.L8E~rntsM^tF.T8]ZrJPsM}t&+A^751^Several years of research on seven different plants (five terrestrial and two aquatic species) suggest that the bene,ficial effects of atmospheric CO2 enrichment may be divided into three distinct growth response phases. First is a well-wa-tered optimum-growth-rate phase where a 300 parts per million increase in the CO2 content of the air generally increases p.lant productivity by approximately 30%. Next comes a nonlethal water-stressed phase where the same increase in atmospheric/ CO2 is more than half again as effective in increasing plant productivity. Finally, there is a water-stressed phase norma0lly indicative of impending death, where atmospheric CO2 enrichment may actually prevent plants from succumbing to the rig1ors of the environment and enable them to maintain essential life processes, as life ebbs from corresponding ambient-treatment plants.@؉Ft]ZY[PQRVU;vsF]^ZYXPQRVU;vsF]^ZYXPSQRWV+Fv+@@F3307^1^Idso,S B^1989^1^Three Stages of Plant Response to Atmospheric CO2 Enrichment^20^27^^131-134^^^^^^^^^^756^^^^^^^^^^^Eichhornia crassipes/water hyacinth/water lily/Nymphaea marliaccarnea marliac carneavV:Vr2ҋvvVOItc)C^754^Plant Physiol. Biochem.+FvرЉFF.L8ЈFF+@FF.T8ЈFFF6tL&56A^754^Weekly assessments of biomass production in water hyacinths (_Eichhornia crassipes_) and daily assessments of new-le7af production in water lilies (_Nymphaea marliac carnea_) demonstrate that the positive effects of atmospheric CO2 enrichm8ent on the growth rates of these plants are considerably greater both before (I) and after (III) the primary maximum-growt9h-rate stage (II) characteristic of the middle portion of a plants' life cycle. For these two particular aquatic macrophyt:es, the growth enhancement factor for a 300 uL/L increase in the atmospheric CO2 concentration went from a mean of 1.54 in stage I, to 1.33 in stage II, to actually approach infinity in stage III.&;Dr^&;\s&\^&D#+ҏw3;sX@Ⰻ<308^4^Idso,S B^Allen,S G^Anderson,M G^Kimball,B A^1989^1^Atmospheric CO2 Enrichment Enhances Survival of _Azolla_ at High Temperatures^76^29^^337-341^^^^^^^^^^759^^^^^^^^^^^Azolla pinnata/water fernrnE u\ T;z9&EvC\r4C^757^Environ. Exp. Bot.3ۉ\\6tC&]&E 3]^[UW~N m_]UW~N [V_]VUP&5D &EPDP?A^757^In 2 years of experimentation with _Azolla pinnata_ var. _pinnata_ at Phoenix, Arizona, growth rates of this floatin@g aquatic fern first decreased, then stagnated, and finally became negative when the mean air temperature rose above 30C.A When the atmospheric CO2 content above the plants was increased from the mean ambient concentration of 340 umol CO2/mol aBir to 640 umol CO2/mol air, however, the debilitating effects of high temperatures were reduced: in one case to a much lesCs severe negative growth rate, in another case to merely a short period of zero growth rate, and in a third case to no disDcernible ill effects whatsoever -- in spite of the fact that the ambient treatment plants in this instance all died. With Ethe double verification of this phenomenon provided by both weekly biomass and periodic net photosynthesis determinations,F it would appear that atmospheric CO2 enrichment may be capable of preventing the deaths of some plant species in situatioGns where their demise is normally brought about by either the direct effects of unduly high temperatures or by associated debilitating diseases.F^ _]UW~F^ _]UVv3ɀ<-uFњ*v 3^]UWVv~ &% t uI309^3^Idso,S B^Allen,S G^Kimball,B A^1990^1^Growth Response of Water Lily to Atmospheric CO2 Enrichment^78^37^^87-92^^^^^^^^^^762^^^^^^^^^^^water lily/Nymphaeaea&G3^_]dQQSVtw^[YSQRWU u_G=C^760^Aquat. Bot.${YDT WTWDLd*s =uDOLGO ;Nv)Nw;G r 7GWGD TO LA^760^Hardy water lilies (_Nymphaea_ cultivar 'Marliacea carnea') were grown out-of-doors at Phoenix, Arizona in sunken meMtal stock tanks located within open-top, clear plastic-wall, CO2-enrichment chambers; two were maintained at a CO2 concentNration of 650 ppm and two were maintained at the ambient CO2 concentration of about 350 ppm. Over a 5-month period, 25 difOferent plant properties were evaluated, each one of which showed some degree of stimulation or enhancement under CO2-enricPhed conditions. In particular, net photosynthesis was increased by about 49%, leaf size by 18%, and integrated leaf numberQ x life span by 16%, which resulted in a whole-plant biomass enhancement of 270%. After 21 months, differences between treRatments were not quite as dramatic; but at the conclusion of the experiment, the rhizomes in the CO2-enriched treatment were still more than two-and-a-half times greater in total biomass than their ambient-grown counterparts.HtaP>DtT310^3^Idso,S B^Clawson,K L^Anderson,M G^1986^1^Foliage Temperature: Effects of Environmental Factors with Implications forU Plant Water Stress Assessment and the CO2/Climate Connection^79^22^^1702-1706^^^^^^^^^^765^^^^^^^^^^^water hyacinth/Eichhornia crassipes/cotton/Gossypium hirsutum/alfalfa/Medicago sativaa/Medicago sativa L.D\!DtD \ND u srJC^763^Water Resources Res.D u})^spPD\+D \r^u;v^Xrl~t QL.fY+s3L\XA^763^Throughout the summer and fall of 1985, several day-long sets of foliage temperature measurements were obtained for Yhealthy and potentially transpiring water hyacinth, cotton, and alfalfa plants growing in a sealed and unventilated greenhZouse at Phoenix, Arizona, along with concurrent measurements of air temperature, vapor pressure and net radiation, plus in[ the case of water hyacinths, leaf diffusion resistance measurements. Some data for these plants were additionally obtaine\d out of doors under natural conditions, while dead, nontranspiring stands of alfalfa and water hyacinth were also monitor]ed, both out of doors and within the greenhouse. Analyses of the data revealed that plant nonwater-stressed baselines, i.e^., plots of foliage-air temperature differential versus air vapor pressure deficit for potentially transpiring vegetation,_ were (1) curvilinear, as opposed to the straight lines which have so often appeared to be the case with much smaller and `restricted data sets, and (2) that these baselines are accurately described by basic theory, utilizing independently measuared values of plant foliage and aerodynamic resistances to water vapor transport. These findings lead to some slight adjusbtments in the procedure for calculating the Idso-Jackson plant water stress index and they suggest that plants can adequatcely respond to much greater atmospheric demands for evaporation than what has been believed possible in the past. In additdion, they demonstrate that the likely net radiation enhancement due to a doubling of the atmospheric carbon dioxide concenetration will have little direct effect on vegetation temperatures, but that the antitranspirant effect of atmospheric CO2 enrichment on foliage temperature may be substantial.E@E&T t &VDD tD_Z[X3D t|g311^3^Idso,S B^Kimball,B A^Anderson,M G^1985^1^Atmospheric CO2 Enrichment of Water Hyacinths: Effects on Transpiration and Water Use Efficiency^79^21^^1787-1790^^^^^^^^^^768^^^^^^^^^^^water hyacinth/Eichhornia crassipeses (Mart.) Solms+ZXQVVC^766^Water Resources Res.D u]^Y3|tD trAPD @tk/$r-D t$L&Su &&P&&Rd &PtjA^766^Open-top clear plastic wall chambers enclosing pairs of sunken metal stock tanks, one of each pair of which containekd a full cover of water hyacinths, were maintained out-of-doors at Phoenix, Arizona for several weeks during the summer ofl 1984. One of these chambers represented ambient conditions, while the other three were continuously enriched with carbon mdioxide to approximate target concentrations of 500, 650, and 900 ppm. During a 4-week period when plant growth was at itsn maximum, water hyacinth biomass production increased by 36% for a 300-600 ppm doubling of the atmospheric CO2 content, whoile water use efficiency, or the biomass produced per unit of water transpired, actually doubled. These results are similapr to hat has been observed in several terrestrial plants and they indicate the general trend which may be expected to occur as atmospheric CO2 continues to rise in the years ahead.9=r/ t&)}3F&r312^3^Idso,S B^Kimball,B A^Mauney,J R^1987^1^Atmospheric Carbon Dioxide Enrichment Effects on Cotton Midday Foliage Temperature: Implications for Plant Water Use and Crop Yield^4^79^^667-672^^^^^^^^^^771^^^^^^^^^^^cotton/Gossypium hirsutum^^^^hC^769^Agron. J.؋%^. _ZXϋ$0<0u)u" t r>u&Ë<t <u &봀uA^769^In an experiment designed to determine the likely consequences of the steadily rising carbon dioxide (CO2) concentravtion of Earth's atmosphere for the foliage temperature, water use, and yield of cotton (_Gossypium hirsutum_ L. var. Deltawpine-61) plants, cotton was grown out-of-doors at Phoenix, AZ, in open-top, clear-polyethylene-wall, CO2-enrichment chambexrs for three summers under mean daylight CO2 concentrations of 340, 500 and 640 umol CO2/mol air on an Avondale clay loam ysoil [fine-loamy, mixed (calcareous), hyperthermic Anthropic Torrifluvent]. Infrared thermometer measurements of the cottozn foliage temperature (Tf) indicated that a 330 to 660 umol CO2/mol air doubling of the atmospheric CO2 content results in{ a midday Tf increase of 1.1C for well-watered cotton at Phoenix in the summer. This temperature increase was predicted t|o produce a 9% reduction in per-unit-leaf-area plant transpiration rate and an 85% increase in crop biomass production, wh}ich compared favorably with the measured crop biomass increase of 82% for such a doubling of the air's CO2 content. These ~findings, together with similar findings for a second plant species -- water hyacinth [_Eichhornia cassipes_ (Mart.) Solms] -- allowed us to develop a technique for assessing the effects of a 330 umol CO2/mol air CO2 concentration increase on the percentage yield increase (Y) of a crop via infrared thermometry by means of the equation Y = 7.6% x (IJ), where IJ represents the Idso-Jackson plant water stress index. If this equation holds up under further scrutiny, it could provide a rapid and efficient means for assessing the yield response of crops to atmospheric CO2 enrichment.BB. a.s.Pa$.>wte((((( (  (( (. (4 (: (@ (313^3^Idso,S B^Kimball,B A^Allen,S G^1991^1^CO2 Enrichment of Sour Orange Trees: 2.5 Years into a Long-term Experiment^16^14^^351-353^^^^^^^^^^774^^^^^^^^^^^sour orange/Citrus aurantiumum L.(((((((C^772^Plant Cell Environ.((((((l(Q(V(\(a(c(A^772^Eight sour orange trees have been grown from seedling stage in the field at Phoenix, Arizona, U.S.A., in four identically-vented, open-top, clear-plastic-wall chambers for close to 2.5 years. Half of the chambers have been maintained at ambient atmospheric CO2 concentrations over this period, while half of them have been maintained at 300 ppm (300 umol CO2 per mol air) above ambient. Initially, the trees in each treatment were essentially identical; but in less than 2 years, the trunks of the CO2 enriched trees had become twice as large as their ambient-treatment counterparts. After 2 full years of growth, the enriched trees had 79% more leaves, 56% more primary branches with 72% more volume, 70% more secondary branches with 90% more volume, and 250% more tertiary branches with 855% more volume. In addition, the CO2-enriched trees also had fourth-, fifth- and sixth-order branches, while the ambient treatment trees had no branches above third order. Total trunk plus branch volume of the CO2-enriched trees was 2.79 times that of the ambient-treatment trees after 2 full years of growth.KMOUPQZR]SQsTtSu v wXWcdnm P  _  _ *7*-J\+N314^2^Idso,S B^Kimball,B A^1991^1^Downward Regulation of Photosynthesis and Growth at High CO2 Levels^17^96^^990-992^^^^^^^^^^777^^^^^^^^^^^sour orange/Citrus aurantiumum L. J  C^775^Plant Physiol. !"#$%&'()*+,-./0123456789:;<=>zNxxx,,XxU^<A^775^Numerous photosynthesis and growth measurements of sour orange (_Citrus aurantium_ L.) trees maintained in ambient air and air enriched with an extra 300 microliters per liter of CO2 have revealed the CO2-enriched trees to have consistently sequestered approximately 2.8 times more carbon than the control trees over a period of three full years. Under field conditions in the natural environment, plants may not experience the downward regulation of photosynthetic capacity typically observed in long-term CO2 enrichment experiments with plants growing in pots.+-/537"(%$=?AEI>F315^4^Idso,S B^Kimball,B A^Anderson,M G^Mauney,J R^1987^1^Effects of Atmospheric CO2 Enrichment on Plant Growth: the Interactive Role of Air Temperature^13^20^^1-10^^^^^^^^^^780^^^^^^^^^^^carrot/Daucus carota/radish/Raphanus sativus/water hyacinth/Eichhornia crassipes/water fern/Azolla pinnataern/Azolla pinnataeEeIIIINnOoOoOoOoUuUuUC^778^Agric. Ecosystems Environ.AaAaAaCcCcCcCcDdEeEeEeEeGgGgGgGg GgGgHhHhIIIA^778^Comprehensive reviews of the plant science literature indicate that a 300 part per million (ppm) increase in atmospheric carbon dioxide (CO2) concentration generally increases plant growth by approximately 30%. Working with two species of floating aquatic plants and three terrestrial species, we demonstrate that this stimulatory effect of atmospheric CO2 enrichment is strongly temperature dependent. Indeed, our results suggest that for a 3C increase in mean surface air temperature (as is generally predicted to result from the 'greenhouse effect' of such an increase in the CO2 content of the air), the growth enhancement factor for such a CO2 increase rises from 1.30 to 1.56. If the non-CO2 trace gas greenhouse effect is equally as strong, as recent model studies suggest, the growth enhancement factor rises still higher to a value of 1.85. On the other hand, our results also indicate that atmospheric CO2 enrichment tends to _reduce_ plant growth at relatively cold air temperatures, i.e. below a daily mean air temperature of approximately 18.5C. As a result, predicting the ultimate biospheric consequences of a doubling of the Earth's atmospheric CO2 concentration may prove to be much more complex than originally anticipated. @&XSQVPYr& PXsx^Y[PrhXSQH3CY[SQ6ur &316^3^Idso,S B^Kimball,B A^Mauney,J R^1988^1^Effects of Atmospheric CO2 Enrichment on Root:Shoot Ratios of Carrots, Radish, Cotton and Soybean^13^22^^293-299^^^^^^^^^^783^^^^^^^^^^^soybean/Glycine max/cotton/Gossypium hirsutum/radish/Raphanus sativus/carrot/Daucus carotarrot/Daucus carota L. r @_ZY[XPSQRVW&> t eF3ۉ^&>uC^781^Agric. Ecosystems Environ.rF~SRZ[s-^6 E~ r6& EF& &t& &tXÃ~tA^781^Detailed analyses of root:shoot ratios, determined at weekly intervals during a succession of cropping cycles, show that the responses of root crops, such as radish and carrot, differ from those of cotton and soybean. Whereas the root:shoot ratios of the latter crops were not affected by atmospheric CO2 enrichment, increasing the CO2 concentration of the air from 340 (ambient) to 650 umol CO2/mol air significantly increased the proportions of assimilates allocated to the roots of radish and carrot. This effect increased the root:shoot ratios of both root crops by approximately 36% at all stages of plant growth, suggesting a response to atmospheric CO2 enrichment that is independent of plant size and not caused by a progressive reduction in nitrogen availability. H&&&&t 3Ҍ^s^YXPS6D36;Dt[&t317^2^Idso,S B^Kimball,B A^1991^1^Effects of Two and a Half Years of Atmospheric CO2 Enrichment on the Root Density Distribution of Three-year-old Sour Orange Trees^46^55^^345-349^^^^^^^^^^786^^^^^^^^^^^Citrus aurantium/sour orangerangeu3C^784^Agric. For. Meteorol. u42fs+6>EtururDs 6>EuX6>Dut`36D6D36;DsXA^784^Eight sour orange trees planted directly into the ground at Phoenix, Arizona, as small seedlings in July 1987 have been enclosed by four clear-plastic-wall, open-top chambers since November of that year, half of which have been continuously supplied with a CO2 enriched atmosphere consisting of an extra 300 cm3 CO2/m3 of air. Extensive soil coring of the trees' root zones conducted in July 1990 indicated that two and a half years of growth under these conditions produced a fine root biomass enhancement of 175% in the CO2 enriched trees. This growth enhancement is of the same order of magnitude as our previously reported results for net photosynthesis and trunk and branch volumes for these trees._^ZY[XWu1 r,318^2^Idso,S B^Kimball,B A^1993^1^Effects of Atmospheric CO2 Enrichment on Net Photosynthesis and Dark Respiration Rates of Three Australian Tree Species^38^141^^166-171^^^^^^^^^^789^^^^^^^^^^^Australian bottle tree/Brachychiton populneum/sour orange/Citrus aurantium/Eucalyptus microtheca/Eucalyptus polyanthemus. Muell./Eucalyptus polyanthemus Schauer2DDC^787^J. Plant Physiol.U&eF&E_^ZY[XQVW6D6D+t u_^YÀ> uuu tsA^787^Net photosynthesis and dark respiration rates of leaves of three Australian tree species exposed to a range of atmospheric CO2 concentrations were measured throughout the summer of 1991. For all three species - the Australian bottle tree (_Brachychiton populneum_ (Schott.) R. Br.) and two eucalyptus (_Eucalyptus microtheca_ F. Muell. and _E. polyanthemus_ Schauer) - dark respiration dropped by approximately 50% for a 360 to 720 uL/L doubling of the air's CO2 concentration, while net photosynthesis rose by a factor of two. These results were not significantly different from results obtained previously for the common orange tree (_Citrus aurantium_ L.).&u.& t && t &n&6DdW&t319^3^Idso,S B^Kimball,B A^Anderson,M G^1986^1^Foliage Temperature Increases in Water Hyacinth Caused by Atmospheric CO2 Enrichment^126^Ser. B 36^^365-370^^^^^^^^^^792^^^^^^^^^^^water hyacinth/Eichhornia crassipes^^^^^art.) Solms^^^^^inth/EicpJSrnia crassipes (Mart.) Solms& 6D !&&6+wvـPX^VC^790^Ser. B 36 Arch. Met. Geoph. Biocl.Ev^6EV6E^& V& !Cvq_^ZY[XSA^790^Atmospheric CO2 enrichment tends to induce partial stomatal closure in most higher plants. This phenomenon reduces per-unit-leaf-area plant transpirational water loss rates, which in turn leads to higher plant temperatures. Working in the field with water hyacinths maintained in open-top, clear-plastic wall, CO2-enrichment chambers at Phoenix, Arizona, we have quantified this relationship for a plant species which has been shown previously to react like most land plants in this regard. Our results indicate that in some parts of the world this non-greenhouse mechanism for surface temperature change may play an important role in determining future climate. Under sunlit and well-watered conditions conducive to active growth, for instance, we found water hyacinth foliage temperatures to increase by 2.7 K in response to a 300 to 600 ppm doubling of the atmospheric CO2 concentration.Hu6:E6EDD WgaQRQ@+D;rV3ҋD;D t@320^4^Idso,S B^Kimball,B A^Anderson,M G^Szarek,S R^1986^1^Growth Response of a Succulent Plant, _Agave vilmoriniana_, to Elevated CO2^17^80^^796-797^^^^^^^^^^795^^^^^^^^^^^Agave vilmorinianana BergergGY˃>EtV^PQREole-plant net CO2 exchange rate (NCER) of Samantha rose plants. At 22C, the NCER was saturated at 1000 umol/m2/s photosyn?thetically active radiation (PAR). The duration of the light period was also important in determining daily carbon (C) gai@n. When roses were exposed to a constant daily radiant energy dose of 17.6 umol/m2 provided either as a 12-h irradiation iAnterval at 410 umol/m2/s PAR or 24 h of irradiation at 204 umol/m2/s PAR, the plants exposed to 24 h of continuous irradiaBtion at the lower photon flux density retained 80% more C. Under saturating irradiance, the net photosynthetic rate at an Cenriched (1000 uL/L) CO2 level was almost double that at ambient (350 uL/L) CO2. However, plants grown at ambient and enriDched CO2 levels had similar whole-plant NCERs when compared at the same assay CO2 level. Under CO2 enrichment the flower sEtem was longer and thicker but the flower bud size at harvest was not significantly different to that of roses grown at the ambient CO2 level.anovWP( U$  HP LaserJeG330^3^Jiao,J^Tsujita,M J^Grodzinski,B^1991^1^Optimizing Aerial Environments for Greenhouse Rose Production Utilizing Whole-plant Net CO2 Exchange^29^71^^253-261^^^^^^^^^^822^^^^^^^^^^^rose/Rosa hybridadaH9q0)\;C^820^Can. J. Plant Sci.ew RomanHd8R8%8>!8>!8>uZ&e&"8Z2[ t<JA^820^A daily growth model was developed for Samantha roses based on nondestructive measurements of whole-plant net CO2 exKchange rate (NCER) under various aerial environmental conditions. Irradiance, CO2 concentration, and temperature accountedL for 70, 20, and 5%, respectively, of the variance in whole-plant net photosynthesis explainable by a second-order polynomMial model (R2=0.86). The predicted optimal temperatures for whole-plant net photosynthesis increased from 19 to 24C with Nincreasing irradiance from 100 to 1200 umol/m2/s and CO2 concentration from 350 to 1500 uL/L. Dark respiration rate increaOsed exponentially with temperature and could be predicted by the Arrhenius equation. Even though respiratory carbon (C) loPss at night increased linearly with daytime C gain, daily C gain (delta C) was still proportional to daytime net photosyntQhesis. The relative contribution of irradiance (100-1200 umol/m2/s), day length (8-16 h), CO2 concentration (350-1500 uL/LR), day temperature (15-30C), and night temperature (15-25C) to plant daily growth was 64, 31, 4, 0.3, and 0.7%, respectively.*˴J!Kl!L!.40!<swss s4C*C%2}sk2}WWV&,&l&T331^3^Johnson,H B^Polley,H W^Mayeux,H S^1993^1^Increasing CO2 and Plant-plant Interactions: Effects on Natural Vegetation^U123^104/105^^157-170^^^^^^^^^^825^^^^^^^^^^^Prosopis glandulosa/mesquite/Schizachyrium scoparium/little bluestem/Brassica Vkaber/field mustard/Avena sativa/oat/Cenchrus incertus/Paspalum setaceum/Panicum cappillare/Digitaria ciliaris/Eragrostis Wspectabilis/Cyperus globulosus/Mollugo verticillata/Sporobolus neglectus/Euphorbia prostrata/Setaria sp./Echinochloa crus-Xgalli/Amaranthus sp./Croton glandulosa/Verbena hastata/Verbena halei/Oenothera sp./Ratibida columnaris/Ambrosia artemisiifYolia/Lesquerella sp./Gaillardia pulchella/Gaura sp./Solanum sp./Gutierrezia dracunculoides/Rudbeckia hirta/Commelina erecta/Panicum angustifolium/Croton capitatum/Monarda punctata/Croton monanthogynus/Oxalis dillenii^^^^^GrJ.<tD>ʾ@D  27%. Further evidence of the dependence of ARA on plant photosynthate was obtained when activity in excised roots was sho\A^823^Plant species and functional groups of species show marked differences in photosynthesis and growth in relation to r]ising atmospheric CO2 concentrations through the range of the 30% increase of the recent past and the 100% increase since ^the last glaciation. A large shift was found in the compositional mix of 26 species of C3's and 17 species of C4's grown f_rom a native soil seed bank in a competitive mode along a CO2 gradient that approximated the CO2 increase of the past 150 `years and before. The biomass of C3's increased from near zero to 50% of the total while that of the C4's was reduced 25% aas CO2 levels approached current ambient. The proposition that acclimation to rising CO2 will largely negate the fertilizabtion effect of higher CO2 levels on C3's is not supported. No signs of photosynthetic acclimation were evident for _Avena csativa, Prosopis glandulosa_, and _Schizachyrium scoparium_ plants grown in subambient CO2. The effects of changing CO2 ledvels on vegetation since the last glaciation are thought to have been at least as great, if not greater, than those which eshould be expected for a doubling of current CO2 levels. Atmospheric CO2 concentrations below 200 ppm are thought to have fbeen instrumental in the rise of the C4 grasslands of North America and other extensive C4 grasslands and savannas of the gworld. Dramatic invasion of these areas by woody C3 species are accompanying the historical increase in atmospheric CO2 concentration now in progress.>>!<u>~D0*]^MINDSLGLi332^2^Johnson,R H^Lincoln,D E^1990^1^Sagebrush and Grasshopper Responses to Atmospheric Carbon Dioxide Concentration^34^84^^103-110^^^^^^^^^^828^^^^^^^^^^^Artemisia tridentata/sagebrushshs u0<tF^V3Ҵo^&CGHC^826^OecologiaDTD>Dt>6D_t>u D):sD@=!r?!r,Wu$PCuu uulA^826^Seed- and clonally-propagated plants of Big Sagebrush (_Artemisia tridentata_ var. _tridentata_) were grown under atmmospheric carbon dioxide regimes of 270, 350 and 650 uL/L and fed to _Melanoplus differentialis_ and _M. sanguinipes_ grasnshoppers. Total shrub biomass significantly increased as carbon dioxide levels increased, as did the weight and area of inodividual leaves. Plants grown from seed collected in a single population exhibited a 3-5 fold variation in the concentratipon of leaf volatile mono- and sesquiterpenes, guaianolide sesquiterpene lactones, coumarins and flavones within each CO2 tqreatment. The concentration of leaf allelochemicals did not differ significantly among CO2 treatments for these seed-propargated plants. Further, when genotypic variation was controlled by vegetative propagation, allelochemical concentrations alsso did not differ among carbon dioxide treatments. On the other hand, overall leaf nitrogen concentration declined signifitcantly with elevated CO2. Carbon accumulation was seen to dilute leaf nitrogen as the balance of leaf carbon versus nitroguen progressively increased as CO2 growth concentration increased. Grasshopper feeding was highest on sagebrush leaves growvn under 270 and 650 uL/L CO2, but varied widely within treatments. Leaf nitrogen concentration was an important positive fwactor in grasshopper relative growth but had no overall effect on consumption. Potential compensatory consumption by thesex generalist grasshoppers was apparently limited by the sagebrush allelochemicals. Insects with a greater ability to feed oyn chemically defended host plants under carbon dioxide enrichment may ultimately consume leaves with a lower nitrogen conczentration but the same concentration of allelochemicals. Compensatory feeding may potentially increase the amount of dietary allelochemicals ingested for each unit of nitrogen consumed.U!  W X,X|333^2^Johnson,R H^Lincoln,D E^1991^1^Sagebrush Carbon Allocation Patterns and Grasshopper Nutrition: The Influence of CO2 Enrichment and Soil Mineral Limitation^34^87^^127-134^^^^^^^^^^831^^^^^^^^^^^sagebrush/Artemisia tridentatata13AugustjC^829^Oecologia.B.G.Ashdown..E.H.Krieg. PossibleEmployment   p  IwouA^829^_Artemisia tridentata_ seedlings were grown under carbon dioxide concentrations of 350 and 650 uL/L and two levels of soil nutrition. In the high nutrient treatment, increasing CO2 led to a doubling of shoot mass, whereas nutrient limitation completely constrained the response to elevated CO2. Root biomass was unaffected by any treatment. Plant root/shoot ratios declined under carbon dioxide enrichment but increased under low nutrient availability, thus the ratio was apparently controlled by changes in carbon allocation to shoot mass alone. Growth under CO2 enrichment increased the starch concentrations of leaves grown under both nutrient regimes, while increased CO2 and low nutrient availability acted in concert to reduce leaf nitrogen concentration and water content. Carbon dioxide enrichment and soil nutrient limitation both acted to increase the balance of leaf storage carbohydrate versus nitrogen (C/N). The two treatment effects were significantly interactive in that nutrient limitation slightly reduced the C/N balance among the high-CO2 plants. Leaf volatile terpene concentration increased only in the nutrient limited plants and did not follow the overall increase in leaf C/N ratio. Grasshopper consumption was significantly greater on host leaves grown under CO2 enrichment but was reduced on leaves grown under low nutrient availability. An overall negative relationship of consumption versus leaf volatile concentration suggests that terpenes may have been one of several important leaf characteristics limiting consumption of the low nutrient hosts. Digestibility of host leaves grown under the high CO2 treatment was significantly increased and was related to high leaf starch content. Grasshopper growth efficiency (ECI) was significantly reduced by the nutrient limitation treatment but co-varied with leaf water content.T|u%>tK4:鵀^ȚT&^ZXSUGR GSw ]334^2^Jolliffe,P A^Ehret,D L^1985^1^Growth of Bean Plants at Elevated Carbon Dioxide Concentrations^54^63^^2021-2025^^^^^^^^^^834^^^^^^^^^^^bean/Phaseolus vulgaris^^^^^^^^^^XPSQRVW҆r36:u &?%3u<@}C^832^Can. J. Bot.0 rƾ u %? p_^ZY[XPSVu2$w rƾ E^[XPSRVWA^832^Plants of _Phaseolus vulgaris_ L. cv. Pure Gold Wax were grown in controlled environment chambers at six CO2 concentrations ranging from 340 to 3000 uL/L. Data for plant growth analysis were obtained from five harvests from 11 to 55 days after planting. Growth curves were fitted to the data using a cubic spline regression procedure. CO2 enrichment caused large and rapid increases in leaf dry weight, unit leaf rate, and specific leaf weight. Smaller responses included a decrease in leaf area ratio and an increase in leaf weight ratio. Root dry weight and leaf area were not significantly affected by CO2 treatments. Relative growth rate was initially higher in CO2 enriched plants and later declined; it may not be a suitable index for the evaluation of CO2 effects during long periods of growth. The results indicate that leaf formation and expansion were not limited by assimilate supply. Maximum growth and pod yield were obtained in plants grown at 1200 uL/L CO2.SFNFF3rNFNVP5:X;t$w+؉d̎w2: +؉d̚n2:Ř*^H335^4^Jones,J W^Dayan,E^van Keulen,H^Challa,H^1989^1^Modeling Tomato Growth for Optimizing Greenhouse Temperatures and Carbon Dioxide Concentrations^15^248^^285-294^^^^^^^^^^837^^^^^^^^^^^tomato/Lycopersicon esculentum^^^^^)FtXFt C^835^Act. Hort. Ft *]XPQV鵀t*uttS Z,s9=:w^YXSW>Rt*r$rA^835^Predictions of crop yield response to a dynamic environment are essential to the development of optimal control strategies for greenhouses. A dynamic tomato growth and yield model (TOMGRO) was developed specifically for coupling to physical models of the greenhouse environment for optimizing temperature and carbon dioxide concentrations for tomato production. The model is based on development and growth components. Experiments were conducted in outdoor, computer-controlled plant growth chambers to parameterize the development, carbon exchange, and growth submodels under combinations of two CO2 (350 and 950 vpm) and three night temperatures (12, 16, and 20 C). Daytime temperatures were held to 28 for all treatments. The model successfully described development, growth, and yield for all combinations of temperature and CO2 in this experiment.F&DF&D#;FsՁׁa;FvF3Ҿ${rM&D &T F;Vw r;FsFVF;Vr w;FvFV;336^3^Jones,P^Roy,B L^Jones,J W^1989^1^Coupling Expert Systems and Models for the Real-time Control of Plant Environments^15^248^^445-452^^^^^^^^^^84040t@S3wt@x wt wt Y][˾ 9d*ˀ&w C^838^Act. Hort.ˀ&w twˀ&w ttww eP G u ePQR&fQA^838^A control system, to regulate CO2 in a plant growth chamber, based on distributed processing and a multi-tasking operating system is described. CO2 controls are based on a model of plant photosynthetic light response. Parameters in the model that change through time are automatically evaluated and updated on a 'daily' basis. The system demonstrates how separation of the processing tasks facilitates sophisticated programming. Results in terms of the quality of controls achieved are favorable. The importance of distributed processing and multi-tasking to the application of data analysis, simulation models, and expert systems in 'real-time' environmental controls is discussed. Low cost hardware and supporting software is quickly becoming available and the challenge will become practical implementation of straightforward ideas. The general conclusion is that practical application of such systems can be expected in the near term.^Z[XPQVhrAA;r+њ*^Y337^1^Kano,A^1985^6^Growth Model of Greenhouse Tomatoes with Carbon Dioxide Enrichment: Development and Experimental Tests (Simulation, Modelling)^^Texas A&M University^^Doctoral Dissertation^^^Dissertation Abstracts Vol. 46:10-B, p.3272 (147 pp.)^^^^^^^842^^^^^^^^^^^tomato/Lycopersicon esculentumMill.;#:PSQ3t@fr tRY[XPSQRVNft &A^841^A deterministic, compartmental growth model of greenhouse tomato plants, written in Pascal computer language, was developed based on a leaf assimilation model and a model of a theory that the photosynthesis rate is controlled both by the environmental conditions and by the internal carbohydrate level in the leaf. The model was tested with data obtained from two experiments conducted in 1983 through 1984 at College Station, Texas. Three 2m x 2m x 10m chambers were built in a plastic-covered greenhouse, and tomato plants were grown in the chambers at three different CO2 concentrations: 340, 700, and 1000 um3/m3. Inputs to the model were the light and CO2 levels and the air temperature. The outputs included the CO2 assimilation rate, dry-mass accumulation rate, and tomato yield, which were compared with the results from the measurements. The model underestimated the CO2 assimilation rate and dry-mass accumulation rate of tomatoes for all CO2 levels; however, it predicted the fruit growth and yield rather accurately. For a growth model with parameters taken not from the measurements, but from earlier published results, the magnitude and trend of the results of the simulation were reasonably acceptable. A potential use of the model is to predict the effects of environmental factors or to estimate the benefit from CO2 enrichment under different environmental conditions. It also can be a part of an integrated greenhouse model which predicts growth and yield of the crop in the greenhouse using the environmental conditions outside the greenhouse and the greenhouse control mechanisms and strategies.LD Dʾ*s=u D tD5*r D;DtPh:X338^2^Karvonen,T^Peltonen-Sainio,P^1990^3^The Influence of CO2 and Air Temperature on Agricultural Productivity in Northern Latitudes^The Greenhouse Effect and Primary Productivity in European Agro-ecosystems; 5-10 April 1990; Wageningen, The Netherlands^Pudoc^Wageningen^61^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^Goudriaan,J^van Keulen,H^van Laar,HHվfH]r_^[þ339^3^Kats,G^Olszyk,D M^Thompson,C R^1985^1^Open Top Experimental Chambers for Trees^27^35^^1298-1301^^45DϡD%=C^844^JapcaWQds|PY_^QWRz<tzʚ*+ GZ_YRVWB&wtr!:340^3^Kaushal,P^Guehl,J M^Aussenac,G^1989^1^Differential Growth Response to Atmospheric Carbon Dioxide Enrichment in Seedlings of _Cedrus atlantica_ and _Pinus nigra_ ssp. _Laricio_ var. _Corsicana_^32^19^^1351-1358^^^^^^^^^^848^^^^^^^^^^^Cedrus atlantica/Pinus nigrassp. Laricio var. Corsicana var. CorsicanaN&L^r$3tBwuB3u 뱋LZC^846^Can. J. For. Res.wt\;tL;\sSRVW&;*5uuuu.u09uEuGEE-A^846^Nine-month-old seedlings of _Cedrus atlantica_ Manetti and _Pinus nigra_ Arn. ssp. _Laricio_ var. _Corsicana_ were transplanted in parallelepipedal containers permitting root growth observations (minirhizotrons) and in 6 L pots and were then transferred into two polyethylene tunnels in a greenhouse, where they were submitted to atmospheric CO2 concentrations of 350 (normal) and 800 umol/mol (enriched) for their 2nd growth year. At the end of the enrichment period, the biomass of the enriched plants was 66 (_C. atlantica_) and 30% (_P. nigra_) higher than those of the plants grown at normal CO2 concentrations. The root:shoot biomass ratio remained unaffected by enrichment in both species. Height and diameter growth were 20 (_C. atlantica_) and 10% (_P. nigra_) higher in the enriched treatment. At the end of the enrichment period, the CO2 assimilation rate was no longer stimulated in the enriched _C. atlantica_ plants as compared with the normal treatment, but remained slightly stimulated in the _P. nigra_ seedlings. The differential growth response to elevated CO2 appears to be related to the distinct genetic growth pattern of the two species, namely to their different patterns of root growth before bud break and during the early aerial growth.M ~2M ~ƃ.~Eu~} 341^3^Kelly,D W^Hicklenton,P R^Reekie,E G^1991^1^Photosynthetic Response of Geranium to Elevated CO2 as Affected by Leaf Age and Time of CO2 Exposure^54^69^^2482-2488^^^^^^^^^^851^^^^^^^^^^^geranium/Pelargonium hortorumorum BailyR22C^849^Can. J. Bot.s[d'.& u@[j'. u@ZY[XPSQRUF t 2؋F3ۊ2NÉFA^849^Geranium plants were grown from seed in chambers maintained at 350 or 1000 uL/L CO2. Photosynthesis as affected by leaf age and by leaf position was determined. Elevated CO2 enhanced photosynthesis to the greatest extent in middle-aged leaves; very young leaves exhibited little enhancement, and net photosynthesis in the oldest leaves was depressed by elevated CO2. Temporary increases in net photosynthesis (relative to leaves developed at high CO2) resulted when young leaves grown at 350 uL/L CO2 were switched to 1000 uL/L CO2. Leaves switched later in development exhibited permanent enhancement. Middle-aged leaves exhibited a temporary depression followed by permanent enhancement. Leaves developed at high CO2 and switched to low CO2 did not exhibit any photosynthetic depression relative to plants grown continuously at low CO2. Similarly, leaves developed at low CO2, switched to high CO2 for various lengths of time, and returned to low CO2 showed no photosynthetic depression. Leaves developed at low CO2 and switched to high CO2 exhibited increases in specific leaf weight and leaf thickness. The increase in leaf thickness was proportional to length of time spent at high CO2. High CO2 depressed the rate at which stomata developed but did not affect final stomatal density. Results suggest that photosynthesis at low CO2 was limited by CO2 regardless of developmental environment, whereas photosynthesis at high CO2 was limited by the developmental characteristics of the leaf. Further, both biochemical and structural modifications appear to be involved in this response. Because of the very different responses of young versus old leaves, future studies should be careful to consider leaf age in assessing response to elevated CO2.f~rF~F&EI&MK^X_SRVW fV!&GD342^4^Kendall,A C^Turner,J C^Thomas,S M^Keys,A J^1985^1^Effects of CO2 Enrichment at Different Irradiances on Growth and Yield of Wheat. II. Effects on Kleiber Spring Wheat Treated from Anthesis in Controlled Environments in Relation to Effects on Photosynthesis and Photorespiration^39^36^^261-273^^^^^^^^^^854^^^^^^^^^^^wheat/Triticum aestivumum L.ȿDʿDVWC^852^J. Exp. Bot.u !=:^X_PU>u,>ƿu%2+ĿZrVzM3K2Ŀ]XPV >ǿu@sA^852^Spring wheat plants were grown in a cage with a glass roof until three days after anthesis and then subjected to treatments in constant environment rooms with any one of all combinations of four irradiances and two concentrations of carbon dioxide. The photoperiod was 16 h and day/night temperatures 19C/14C. Growth and yield of grain were saturated at the two brightest irradiances. Carbon dioxide enrichment from 350 to 1200 mm3/dm3 increased shoot dry weight and grain yield at final harvest at all irradiances, by averages of 10.5 (not significant) and 23.5 (significant) percent respectively. However, increasing the irradiance from 150 to 613 uE/m2/s caused much larger yield increases (approximately 3-fold). Increased grain production by increased light was caused by both increases in dry weight per grain and by increases in grain number per spikelet. The increase caused by CO2 enrichment was mainly because of increased dry weight per grain. Increase in ear dry weight caused by CO2 enrichment took place between 30 and 60 d after anthesis. The increase in shoot dry weight took place immediately after exposure to increased CO2 from 3 to 15 d after anthesis. Net photosynthesis by flag leaves on the main shoots was almost doubled 16 d after anthesis by the CO2 enrichment even though stomatal resistance was also doubled. However, this increase was not reflected by a proportional increase in yield, probably because increased mutual shading by bigger stems and by late tillers reduced total assimilation and because of increased respiration by the shoots. The increase in photosynthesis was not due to a decrease in photorespiration but to an increase in gross photosynthesis.^r343^3^Kendall,A C^Turner,J C^Thomas,S M^1985^1^Effects of CO2 Enrichment at Different Irradiances on Growth and Yield of Wheat^39^36^^252-260^^^^^^^^^^857^^^^^^^^^^^wheat/Triticum aestivumum L.ZYXx778J8-1S,+(}*(JN 9 d+C^855^J. Exp. Bot.   u) 6m24$2 9`7XWs are much larger so there is a huge economy of scale. The cost per enriched area for plant growth was about $500/m/year f?or FACE compared to about $9,300 and $1,800/m/year for SPAR and OTC, respectively. When the additional costs of making sci@entific measurements was addressed, the cost of scientific labor was seen to be the largest expense of conducting researchA, and the costs of producing treated plants were seen to be only about 26, 18, and 28% of the total costs of SPAR, OTC, and FACE projects, respectively.>rU tIپ GٸX3 XZ)پP+ˁ&//1 u7C349^1^Kimball,B A^1986^3^Influence of Elevated CO2 on Crop Yield^Physiology, Yield, and Economics^CRC Press, Inc.^Boca Raton, Florida^105-115^^^^II^^Carbon Dioxide Enrichment of Greenhouse Crops^^^^871^^^^^^^^^^^^^^^^^^^^^Enoch,H Z^Kimball,B A,B A>t/V$Q*DDds^U0r!>5ى7ٸ/پ 3] UFA^870^The prior literature on the effects of CO2 enrichment on plant growth and yield were examined. More than 770 observaGtions of the yields or biomass production of 38 crops and 8 other species grown at elevated CO2 were extracted from more tHhan 40 reports, published during the last 66 years. The percentage increase in yield of the CO2 enriched plants to their rIespective controls were computed and statistically analyzed. CO2 enrichment increased the economic yield of mature agriculJtural crops by 26% with a 95% confidence interval from 18 to 36%. Excluding flower crops, whose yield was measured by numbKer of blooms, the mean yield increase of C3 crops with CO2 enrichment was 36%. Plotting yield increase against CO2 concentLration revealed that 1000 uL/L is about the optimum concentration with relatively little increase occurring at higher valuMes. Further analysis of 147 experiments which had controlled CO2 concentrations for their duration showed that yields probNably will increase by 32% (with a 95% confidence interval from 27 to 38%) with the future doubling of atmospheric CO2 concOentration. How to use these data to estimate grower's yield responses to CO2 enrichment is also discussed, and an example is presented.ٹ <:<:Y[XPN+ٚNĚNXVPSQRUP/uX)t s-AAGًFK`rQ350^7^Kimball,B A^Akey,D H^Mauney,J R^Idso,S B^Allen,S G^Hendrix,D L^Radin,J W^1988^5^Elevated CO2: Modeling Crop ResponseRs, Interaction with Temperature, Effects on Trees and Insects^U.S. Dept. of Energy, Carbon Dioxide Research Division, and SU.S. Dept. of Agriculture, Agric. Res. Serv., Washington, D.C^^^^^^^^^^^^^^^^^^^^^^^^cotton/Gossypium hirsutum/Agave vilmoTriniana/Citrus aurantium/orange trees/sorghum/Sorghum bicolor^^052 in Green Report Series^Response of Vegetation to Carbon Dioxide^^n to Carbon Dioxide^^» ;r 30#ً0%^ZY[XVPSQRUFP.TXX~tF~t@~t:F2 t&/ PV351^10^Kimball,B A^Mauney,J R^Guinn,G^Nakayama,F S^Idso,S B^Radin,J W^Hendrix,D L^Butler,G D^Zarembinski,T I^Nixon,P E^198W5^5^Effect of Increasing Atmospheric CO2 on the Yield and Water Use of Crops^U.S. Dept. of Energy, Carbon Dioxide ResearchX Division, and U.S. Dept. of Agriculture, Agric. Res. Serv., Washington, D.C^^^^^^^^^^^^^^^^^^^^^^^^cotton/Gossypium hirsutum^^027 in Green Report Series^Response of Vegetation to Carbon Dioxide^^^^PPFd3F~U u#.T uz,Z352^10^Kimball,B A^Mauney,J R^Radin,J W^Nakayama,F S^Idso,S B^Hendrix,D L^Akey,D H^Allen,S G^Anderson,M G^Hartung,W^1986^5[^Effects of Increasing Atmospheric CO2 on the Growth, Water Relations, and Physiology of Plants Grown under Optimal and Li\miting Levels of Water and Nitrogen^U.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture,] Agric. Res. Serv., Washington, D.C^^^^^^^^^^^^^^^^^^^^^^^^cotton/Gossypium hirsutum^^039 in Green Report Series^Response of Vegetation to Carbon Dioxide^^^^T.TC.T t1MVUtPAUtXVxXVZY[Xˠ~U t#.T_353^8^Kimball,B A^Mauney,J R^Akey,D H^Hendrix,D L^Allen,S G^Idso,S B^Radin,J W^Lakatos,E A^1987^5^Effects of Increasing At`mospheric CO2 on the Growth, Water Relations, and Physiology of Plants Grown under Optimal and Limiting Levels of Water anad Nitrogen^U.S. Dept. of Energy, Carbon Dioxide Research Division and U.S. Dept. of Agriculture, Agric. Res. Serv., Washin 1gton, D.C^^^^^^^^^^^^^^^^^^^^^^^^cotton/Gossypium hirsutum^^049 in Green Report Series^Response of Vegetation to Carbon Dic354^4^Kimball,B A^Mauney,J R^Nakayama,F S^Idso,S B^1993^1^Effects of Increasing Atmospheric CO2 on Vegetation^123^104/105^^65-75^^^^^^^^^^878^^^^^^^^^^^^^^^^PQ.TF tk IىGSډU5F tٻ <:.-ٚ5EUZ CO2 concentrations (with the light held constant). In field experiments, CO2 enrichment increased plant-associated ARA byfA^876^The increasing atmospheric CO2 concentration probably will have significant direct effects on vegetation whether pregdicted changes in climate occur or not. Averaging over many prior greenhouse and growth chamber studies, plant growth and hyield have typically increased more than 30% with a doubling of CO2 concentration. Such a doubling also causes stomatal coinductance to decrease about 37%, which typically increases leaf temperatures more than 1C, and which may decrease evapotrjanspiration, although increases in leaf area counteract the latter effect. Interactions between CO2 and climate variables kalso appear important. In one study the growth increase from near-doubled CO2 ranged from minus 60% at 12C to 1% at 19C lto plus 130% at 34C, suggesting that if the climate warms, the average growth response to doubled CO2 could be consistentmly higher than the 30% mentioned above. Even when growing in nutrient-poor soil, the growth response to elevated CO2 has bneen large, in contrast to nutrient solution studies which showed little response. Several studies have suggested that undeor water-stress, the CO2 growth stimulation is as large or larger than under well-watered conditions. Therefore, the directp CO2 effect will compensate somewhat, if not completely, for a hotter drier climate. And if any climate change is small, then plant growth and crop yields will probably be significantly higher in the future high-CO2 world.ب`t"@u6ޚ-Tr&r355^6^Kimball,B A^La Morte,R L^Peresta,G J^Mauney,J R^Lewin,K F^Hendrey,G R^1992^1^Weather, Soils, Cultural Practices, ands Cotton Growth Data from the 1989 FACE Experiment in IBSNAT Format^8^11^^271-308^^^^^^^^^^^^^^^^^^^^^cotton/Gossypium hirsutumum L. ^Z[˃S~PSQRVoNjSI[>uh;}?*2)t'66C^879^Crit. Rev. Plant Sci.~ t&6؋+vذ*6)68&)8Sd&v356^2^King,K M^Greer,D H^1986^1^Effects of Carbon Dioxide Enrichment and Soil Water on Maize^4^78^^515-521^^^^^^^^^^883^^^^^^^^^^^corn/Zea maysys L.ut)=:r"= uN#=&t = tjNNS~T&)]_^ZY[XPVW>t>ظtC^881^Agron. J.PS߲< uª u+&O[XPSQVUW3ɋޚ-Ts_.&&2'3& _F ~t#/TNyA^881^The current global rise in atmospheric CO2 concentration may lead to changes in yield and water use of crops. This sztudy was done to determine the effects of increased CO2 in combination with soil water levels on the growth, yield, transp{iration, and water use efficiency of maize (_Zea mays_ L.). Corn plants (cv. PX74) were grown in Opiki humic silty clay lo|am (fine, illitic, mesic Histic Humaquepts) soil in 22-L pots from emergence to maturity (111 days) in controlled environm}ent rooms at CO2 concentrations of 350/360, 600/650/, and 850/900 uL/L (day/night). Within each room, at a given CO2 conce~ntration, the plants were subjected to one of three soil water treatments: complete replacement of weekly transpiration (control) and 75 and 50% replacement of the control transpiration. The 350 uL/L treated plants produced an average of 401 g dry matter across all water treatments and the 600 and 850 uL/L treated plants produced an average of 431 and 436 g dry matter per plant, respectively. The differences in total dry matter between the 600 and 850 uL/L treated plants remained nonsignificant throughout the experiment. There were significant differences between all soil water treatments in dry matter production with the low soil water level averaging 284 g and the medium and high water level averaging 440 and 544 g/plant, respectively. Transpiration was reduced with increased CO2 concentration and was 80.5 and 70.4% at 600 and 850 uL/L, respectively, of that at 350 uL/L averaged across water treatments. The water use efficiency (WUE) increased markedly with increased CO2 concentration. At 600 and 850 uL/L the WUE was 34 and 55% greater, respectively, than at 350 uL/L. Further work is needed on the applicability of this controlled environment experiment to the real world. &S~&H~ H~&&357^5^Kirkham,M B^He,H^Bolger,T P^Lawlor,D J^Kanemasu,E T^1991^1^Leaf Photosynthesis and Water Use of Big Bluestem under Elevated Carbon Dioxide^12^31^^1589-1594^^^^^^^^^^886^^^^^^^^^^^Andropogon gerardii/big bluestem bluestem98r'zwC^884^Crop Sci.&&6&6~&4vS~؉& &&& t&&$FA^884^With the atmospheric concentration of CO2 increasing, it is important to know how this will affect crop growth. The objective of the study was to determine the effect of elevated CO2 on big bluestem (_Andropogon gerardii_ Vitman) growing in a tallgrass prairie on a Tully silty clay loam (fine, mixed, mesic Pachic Argiustoll) kept at a high water level (field capacity) or a low water level (half field capacity). Sixteen cylindrical plastic chambers were placed on the prairie to maintain the two levels of CO2 (mean +/- SD: 337 +/- 32 and 658 +/- 81 umol/mol) over a full growing season. Soil-water content was measured weekly with a neutron probe. Photosynthesis, transpiration, stomatal resistance, and intercellular CO2 concentration were determined with a portable leaf photosynthetic system. Canopy temperature was monitored with an infrared thermometer. Elevated (doubled) CO2 reduced transpiration rate of big bluestem by 25 and 35 % under the high- and low-water treatments, respectively. Under both watering regimes, stomatal resistance was greater by about 1.6 s/cm with doubled CO2 than with ambient CO2. Plants grown with doubled CO2 at high- and low-water levels had warmer canopy temperatures (average 1.15 and 0.70C warmer, respectively) than plants grown at ambient CO2. Carbon-dioxide concentration did not affect the rate of photosynthesis, even though intercellular CO2 concentration was increased under high CO2. Elevated CO2 did not increase the height of plants grown at the high water level, but it did increase the height at the low water level by an average of 9 cm.+T^[t;tV,;:^ &;t::&6u&3T)uXQ&Dt +Tt#,T&&t 358^12^Kirkham,M B^Kanemasu,E T^Harbers,G W^Reed,D W^He,H^Theisen,R D^Bolger,T P^Goodrum,D E^Ballou,L K^Lawlor,D J^Nie,D^Lu,W P^1990^5^Rangeland-Plant Response to Elevated CO2^U.S. Dept. of Energy, Carbon Dioxide Research Division, Washington, !D.C^^^^^^^^^^^^^^^^^^^^^^^^Andropogon gerardii/big bluestem^^056 in Green Report Series^Response of Vegetation to Carbon D359^2^Kirschbaum,M U F^Farquhar,G D^1987^1^Investigation of the CO2 Dependence of Quantum Yield and Respiration in _Eucalyptus pauciflora_^17^83^^1032-1036^^^^^^^^^^890^^^^^^^^^^^Eucalyptus pauciflora/snowgumum *sZY[X `~>C^888^Plant Physiol.^XPSVW_83ۊ2"N_^[XPQW_82䑃"N_YXPQ&t8d &A^888^In leaves of C3 plants, the rate of nonphotorespiratory respiration appears to be higher in darkness than in the light. This change from a high to a low rate of carbon loss with increasing photon flux density leads to an increase in the apparent quantum yield of photosynthetic CO2 assimilation at low photon flux densities (Kok effect). The mechanism of this suppression of nonphotorespiratory respiration is not understood, but biochemical evidence and the observation that a Kok effect is often not observed under low O2, has led to the suggestion that photorespiration might be involved in some way. This hypothesis was tested with snowgum (_Eucalyptus pauciflora_ Sieb. ex Spreng.) using gas exchange methods. The test was based on the assumption that if photorespiration were involved, then it would also have an influence on the Kok effect. Under normal atmospheric levels of CO2 and O2, a Kok effect was found. Changing the intercellular partial pressure of CO2, however, did not affect the estimate of nonphotorespiratory respiration, and it was concluded that its decrease with increasing photon flux density did not involve photorespiration. Concurrent measurements showed that the quantum yield of net assimilation of CO2 increased with increasing intercellular partial pressure of CO2, and this increase agreed closely with predictions based on recent models of photosynthesis.DLGG uwm*s.=MMEU u MEGG u360^2^Knight,S L^Mitchell,C A^1988^1^Effects of CO2 and Photosynthetic Photon Flux on Yield, Gas Exchange and Growth Rate of _Lactuca sativa_ L. 'Waldmann's Green'^39^39^^317-328^^^^^^^^^^893^^^^^^^^^^^lettuce/Lactuca sativava L.N 2V 2 C^891^J. Exp. Bot.F6 t:;r t43 t,‰FNQNVV؈FJu^s vYߋv8NV^ZYXQRVWP>;A^891^Enrichment of CO2 to 46 mmol/m3 (1000 mm3/dm3) at a moderate photosynthetic photon flux (_PPF_) of 450 umol/m2/s stimulated fresh and dry weight gain of lettuce leaves 39% and 75% relative to plants at 16 mmol/m3 CO2 (350 mm3/dm3). Relative growth rate (_RGR_) was stimulated only during the first several days of exponential growth. Elevating CO2 above 46 mmol/m3 at moderate _PPF_ had no further benefit. However, high _PPF_ of 880-900 umol/m2/s gave further, substantial increases in growth, _RGR_, net assimilation rate (_NAR_) and photosynthetic rate (_Pn_), but a decrease in leaf area ratio (_LAR_), at 46 or 69 mmol/m3 (1000 or 1500 mm3/dm3) CO2, the differences being greater at the higher CO2 level. Enrichment of CO2 to a supraoptimal level of 92 mmol/m3 (2000 mm3/dm3) at high _PPF_ increased leaf area and _LAR_, decreased specific leaf weight, _NAR_ and _Pn_ and had no effect on leaf, stem and root dry weight or _RGR_ relative to plants grown at 69 mmol/m3 CO2 after 8 d of treatment. The results of the study indicate that leaf lettuce growth is most responsive to a combination of high _PPF_ and CO2 enrichment to 69 mmol/m3 for several days at the onset of exponential growth, after which optimizing resources might be conserved.}X6F; uY_^ZY[XPS~[X361^3^Knoppik,D^Selinger,H^Ziegler-Jons,A^1986^1^Differences between the Flag Leaf and the Ear of a Spring Wheat Cultivar (_Triticum aestivum_ cv. Arkas) with Respect to the CO2 Response of Assimilation, Respiration and Stomatal Conductance^44^68^^451-457^^^^^^^^^^896^^^^^^^^^^^wheat/Triticum aestivumum L._8dD'D7868d'dD,Dd,^XÀ>I8t T C^894^Physiol. Plant.Tt'"<:4T&|Eu&Dt ;6tF>I8u xi4TrV~u3Tv3T@>I8A^894^The CO2- and H2O-exchanges in the flag leaf and the ear of a spring wheat cultivar (_Triticum aestivum_ cv. Arkas) were measured at CO2 partial pressures, pi(CO2), between 8 and 400 Pa under high photosynthetic photon flux densities (2000 umol/m2/s). The experiments were carried out on each organ separately while attached to the intact plant, from the time of early emergence through senescence. To study the contribution of the kernels to the gas exchange of ears, experiments were also carried out on sterilized ears (treatment A) and on ears from which the kernels were removed (treatment B). Flag leaves and ears differed considerably with regard to CO2-dependence of assimilation, response of stomata to varying pa(CO2), CO2 compensation point (and its temperature dependence), dark respiration, and dissimilation in the light (i.e. CO2 production which is not due to oxygenation of ribulose 1,5-bisphosphate). The higher dark respiration of the ear originated mainly from the kernels and continued to some extent in the light. Thus, the CO2 compensation point was attained at higher CO2 partial pressures for the ear than for the flag leaf. The CO2 uptake of the ear was not saturated at intercellular CO2 partial pressures below 180 Pa CO2, while that of the flag leaf reached saturation at about 80 Pa CO2. CO2-saturated rates of CO2 uptake were 2.5 and 1.5 times the rates at natural CO2 partial pressure for ear and flag leaf, respectively. The stomatal conductance decreased with rising CO2 partial pressure above 35 Pa, in a more pronounced manner for the flag leaf than for the ear.vA@s OPSQRVW@ss FvƪvZ,sv^GfGd)362^4^Koch,K E^Jones,P^Avigne,W T^Allen,LH,Jr^1986^1^Growth, Dry Matter Partitioning, and Diurnal Activities of RuBP Carboxylase in Citrus Seedlings Maintained at Two Levels of CO2^44^67^^477-484^^^^^^^^^^899^^^^^^^^^^^Carrizo citrange/Citrus sinensis/Poncirus trifoliata/Swingle citrumelo/Citrus paradisi/Poncirus trifoliataatata Dd2rD u&C^897^Physiol. Plant.DD+؁w \3 DdPsr&Dr uЋ E E${D\ TUރ9A^897^The long term response of citrus rootstock seedlings to CO2 enrichment was examined in Carrizo citrange [_Poncirus trifoliata_ (L.) Raf. x _Citrus sinensis_ (L.) Osbeck] and Swingle citrumelo [_P. trifoliata_ x _C. paradisi_ Macf.]. Plantlets 14 weeks old were transferred to outdoor controlled environment chambers and maintained for 5 months from Feb. 14 to July 21. During this period, new growth (cm) of citrange and citrumelo shoots at 660 uL/L was 94 and 69% greater, respectively, than at 330 uL/L. Total dry weight of both rootstock shoots had increased by over 100%. Growth of few species is affected this markedly by elevated CO2 levels. More carbon was partitioned to above-ground organs in CO2-enriched citrus seedlings. Stem dry matter per unit length was also 32 and 44 % greater in citrange and citrumelo, respectively. Total leaf area was increased by 24% in citrange and 85% in citrumelo due to greater leaf number and size. Variations in overall relative growth rate appeared to be related to the rapid, sequential, flush-type growth in citrus, in which an entire shoot segment with its associated leaves remains an active sink until fully expanded. RuBP carboxylase (EC 4.1.1.39) activity in leaves of recently-expanded flushes was higher in citrumelo plants grown at 660 vs. 330 uL/L CO2 and changed diurnally for citrange (but not citrumelo) leaves at both CO2 levels. The results are consistent with the hypothesis that positive long-term effects of CO2 enrichment may be greater in species or during growth periods where sink capacity for carbon utilization is high.*D Q<t <u N[XPS&3۹ Ju0:t 2:2:rrC[XSQt363^2^Kondracka,A^Maleszewski,S^1986^3^Effect of Oxygen on Photosynthesis in Bean (_Phaseolus vulgaris_ L.) Leaves at Elevated Carbon Dioxide Concentration^Biological Control of Photosynthesis^Martinus Nijhoff Publishers^Dordrecht, The Netherlands^127-134^^^^^^^^^^^^^^^^^^^^^Phaseolus vulgaris/bean^^^^^^^^^^Marcelle,R^Clijsters,H^Van Poucke,M,Mt 2u364^1^Korner,C^1992^3^CO2 Fertilization: The Great Uncertainty in Future Vegetation Development^Vegetation Dynamics and Global Change^Chapman and Hall Publishers^New York^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^Shugart,H H^Solomon,A MordPerfect Shell 4365^1^Korner,C^1988^1^Does Global Increase of CO2 Alter Stomatal Density?^80^181^^253-257^^^^^^^^^^90404/-,C^902^Flora9 AB0C.D EF!G"H#IJ$K%L&M2N1OPQRSTUV/WX-YZ,0=:ó=768 !޳ڳ֩lBA^902^The hypothesis is tested that global increases of CO2-concentration reduce stomatal density. Historical and recent data for leaves of over 200 plant species are compared. Statistically significant differences in stomatal density occur neither in lowland, nor in alpine plants over the 7 to 12 decades spanning of this comparison.t@tÚ 狣D366^2^Korner,C^Diemer,M^1987^1^_In situ_ Photosynthetic Responses to Light, Temperature and Carbon Dioxide in Herbaceous Plants from Low and High Altitude^37^1^^179-194^^^^^^^^^^90707Ǽ&\<^tt8<ur=tW>Ǽe&=uC^905^Funct. Ecol.u E v6ǼeuE6Ǽ uE6Ǽ 6ϼ6ǼuE6ǼuE6ǼuE 6Ǽɼ&\A^905^Net CO2 assimilation (_A_) was analysed _in situ_ in 112 pairs of altitudinally separated, herbaceous plant species in the Austrian Alps at 600 and 2600 m. Both groups of species show a similar average response to light, saturating at quantum flux densities (400--700 mm) QFD) of more than 1200 umol/m2/s. Temperature optimum of QFD-saturated _A_ differs little (3 K) and corresponds to the median of air temperature at leaf level for hours with rate-saturating light conditions and not to mean air temperature which differs by 10 K. Species with an exclusive high altitude distribution show steeper initial slopes and higher levels of saturation of the response of _A_ to internal partial pressure of CO2 (CPI) than low elevation species. Mean _A_ at local ambient partial pressure (CPA) does not differ between sites (_c._ 18 umol/m2/s), despite the 21% decrease in atmospheric pressure. Plants at high altitude operate at mean CPI of 177 ubar as compared to 250 ubar at low altitude. The higher ECU (efficiency of carbon dioxide uptake [linear slope of _A_/CPI curve]) as well as the steeper CO2 gradient between mesophyll and ambient air of alpine plants are explained by (1) greater leaf and palisade layer thickness and (2) greater nitrogen (protein) content per unit leaf area. We hypothesize that alpine plants profit more from enhanced CO2 levels than lowland plants (Fig. 7).C&} W &}PF 00&&EATX_^T^_XWF^Nv367^3^Korner,C^Farquhar,G D^Roksandic,Z^1988^1^A Global Survey of Carbon Isotope Discrimination in Plants from High Altitude^34^74^^623-632^^^^^^^^^^91010u~v~Nv3PvX_^Y[WVC2>CCVP@XN;t C^908^Oecologia^+Κ狸s^_PSQRVWf~?Ys~UE A}tXvd IA^908^Carbon 13/12 isotope ratios have been determined from leaves of a hundred C3 plant species (or ecotypes) from all major mountain ranges of the globe, avoiding drought stressed areas. A general increase in 13C content was found with increasing altitude, i.e., overall discrimination against the heavy isotope is reduced at high elevation. The steepest decline of discrimination is observed in taxa typically ranging to highest elevation (e.g. the genus _Ranunculus_). Mean [delta] 13C for all samples collected between 2500 and 5600 m altitude is -26.15 per mil compared to the lowland average of -18.80 per mil (_P_ < 0.001). Forbs from highest elevations reach -24 per mil. According to theory of 13C discrimination this indicates decreasing relative limitation of carbon uptake by carboxylation. In other words, we estimate that the ratio of internal to external partial pressure of CO2 (_pi/pa_) in leaves of high elevation plants is lower than in leaves of low altitude. These results confirm recent gas exchange analyses in high and low elevation plants.t &] P<Ƹ s 368^1^Korner,C^1992^1^Responses to Elevated Carbon Dioxide in Artificial Tropical Ecosystems^48^257^^1672-1675^^^^^^^^^^91C^911^ScienceƸ_fvvDD|~| T D\ üD żHDt4ȚT}tPQVA^911^Carbon, nutrient, and water balance as well as key plant and soil processes were simultaneously monitored for humid tropical plant communities treated with CO2-enriched atmospheres. Despite vigorous growth, no significant differences in stand biomass (of both the understory and overstory), leaf area index, nitrogen or water consumption, or leaf stomatal behavior were detected between ambient and elevated CO2 treatments. Major responses under elevated CO2 included massive starch accumulation in the tops of canopies, increased fine-root production, and a doubling of CO2 evolution from the soil. Stim ulated rhizosphere activity was accompanied by increased loss of soil carbon and increased mineral nutrient leaching. This study points at the inadequacy of scaling-up from physiological baselines to ecosystems without accounting for interactio ns among components, and it emphasizes the urgent need for whole-system experimental approaches in global-change research.J'(狏U'狐Tas _egiVA&ȚT^. *-00 il狚k狸(313^^^^9136QmFFD=tNFvjr/FNȋ?~NrFQW3_Y ZFpF=369^2^Kramer,P J^Sionit,N^1987^3^Effects of Increasing Carbon Dioxide Concentration on the Physiology and Growth of Forest Trees^The Greenhouse Effect, Climate Change, and U.S. Forests^The Conservation Foundation^Washington, D.C.^219-246^^^^^^^9-246}*sc ?&IR&EƢ_^ZY[X0SWVȦfv}*sc ^_[PS370^1^Krizek,D T^1986^3^Photosynthesis, Dry Matter Production and Growth in CO2-Enriched Atmospheres^Number One, Cotton Physiology^The Cotton Foundation^Memphis, Tennessee^193-225^^^^^^The Cotton Foundation Reference Book Series^^^^916^^^^^^^^^^^cotton/Gossypium hirsutum^^^^^^^^^^Mauney,JR^Stewart,JMcD McDE D EDt&DE&DE>U}Ǹ؋^R 6A^915^Most studies on CO2 enrichment under greenhouse and growth chamber conditions have demonstrated the stimulatory effects of elevated CO2 levels on the growth and development of cotton and other economically important plants. Recent tests involving CO2 enrichment of cotton and other crops in the field are encouraging, but further studies are needed to determine whether or not the practice is economically feasible. One of the most pronounced effects of CO2 enrichment in cotton, tomato and other species is a large build-up in sugars and starches stored in the leaves. Increasing the CO2 level from 330 uL/L to 630-1000 uL/L under controlled environments lowered the node number of the first flower, doubled boll production and delayed abscission of squares and bolls. The metabolic consequences of CO2 enrichment of cotton plants need to be examined in greater detail. Since CO2 utilization can be influenced by a myriad of genetic, physiological, biochemical and morphological factors, careful studies are required to determine the interaction of CO2 with these factors. Because of the marked influence of CO2 enrichment on water-use-efficiency through its effect on CO2 assimilation, transpiration and stomatal regulation, special attention should be given to this area of research.vH *=:^[X˃S~˃S~PSWVU371^2^Krupa,S V^Kickert,R N^1989^1^The Greenhouse Effect: Impacts of Ultraviolet-B (UV-B) Radiation, Carbon Dioxide (CO2), and Ozone (O3) on Vegetation^81^61^^263-393^^^^^^^^^^91919Qr&] &M&URSQY[gX=u۾LFN6DC^917^Environ. Pollut.VQ&ZVW6D|&\t&\t&\tYcPWS~ jN_X"A^917^There is a fast growing and an extremely serious international scientific, public and political concern regarding ma#n's influence on the global climate. The decrease in stratospheric ozone (O3) and the consequent possible increase in ultr$aviolet-B (UV-B) is a critical issue. In addition, tropospheric concentrations of 'greenhouse gases' such as carbon dioxid%e (CO2), nitrous oxide (N2O) and methane (CH4) are increasing. These phenomena, coupled with man's use of chlorofluorocarb&ons (CFCs), chlorocarbons (CCs), and organo-bromines (OBs) are considered to result in the modification of the earth's O3 'column and altered interactions between the stratosphere and the troposphere. A result of such interactions could be the g(lobal warming. As opposed to these processes, tropospheric O3 concentrations appear to be increasing in some parts of the )world (e.g. North America). Such tropospheric increases in O3 and particulate matter may offset any predicted increases in* UV-B at those locations. The effects of UV-B, CO2 and O3 on plants have been studied under growth chamber, greenhouse and+ field conditions. Few studies, if any, have examined the joint effects of more than one variable on plant response. There, are methodological problems associated with many of these experiments. Thus, while results obtained from these studies ca-n assist in our understanding, they must be viewed with caution in the context of the real world and predictions into the .future. Historically, plant biologists have studied the effects of CO2 on plants for many decades. Evidence is presented f/or various plant species in the form of relative yield increases due to CO2 enrichment. Sensitivity rankings (biomass resp0onse) are again provided for crops and native plant species. However, most publications on the numerical analysis of cause1-effect relationships do not consider sensitivity analysis of the models used. The joint effects of UV-B, CO2 and O3 are p2oorly understood. Based on the literature of plant response to individual stress factors and chemical and physical climato3logy of North America, we conclude that nine different crops may be sensitive to the joint effects: three grain and six ve4getable crops (sorghum, oat, rice, pea, bean, potato, lettuce, cucumber and tomato). In North America, we consider Pondero5sa and loblolly pine as vulnerable among tree species. This conclusion should be moderated by the fact that there are few, if any, data on hardwood species. Note: This abstract has been abridged.;wbr; sZFV;brNu;`rFb`d7372^2^Krupa,S V^Kickert,R N^1993^1^The Greenhouse Effect: The Impacts of Carbon Dioxide (CO2), Ultraviolet-B (UV-B) Radiation and Ozone (O3) on Vegetation (Crops)^123^104/105^^223-238^^^^^^^^^^922^^^^^^^^^^^^^^^^FF;Fv܋FVb`Ud that a five-to sixfold stimulation occurred within 10 to 60 min after the plant leaves were exposed to light or increased:A^920^Man's influence on the 'greenhouse effect', the heating of the atmosphere due to increasing concentrations of tropos;pheric trace gases, is of much international concern. Among the climatic variables, elevated levels of carbon dioxide (CO2<), ultraviolet-B (UV-B) radiation and ozone (O3) are known to have a direct effect on vegetation. Our current knowledge of= these effects is mainly based on studies involving single stress mode. Thus, the joint effects of CO2, UV-B and O3 on veg>etation are poorly understood. Nevertheless, based on the literature analysis of plant response to individual stress facto?rs, it can be concluded that sorghum, pea, bean, potato, oat, lettuce, cucumber, rice and tomato are among the crop specie@s potentially sensitive to the joint effects of the aforementioned three variables. Similar information for tree species iAs essentially lacking. At least with some climatic variables such as O3, present modeling efforts of cause-effect relationBships have proven to be controversial. While at a regional geographic scale ambient CO2 concentrations appear to be relatiCvely homogeneous, ambient concentrations of O3 exhibit significant temporal and spatial variability. Because of the protecDtive action of O3 against UV-B, similar but inverse temporal and spatial variability is expected in the surface levels of EUV-B. Thus, future experimental designs should consider these exposure dynamics and modeling cause-effect relationships should be directed to stochastic processes.^FvFFPFv PC tju5=t^3^UVv 6PG373^5^Kurooka,H^Fukunaga,S^Yuda,E^Nakagawa,S^Horiuchi,S^1990^1^Effect of Carbon Dioxide Enrichment on Vine Growth and Berry Quality of Kyoho Grapes^82^59^^463-470^^^^^^^^^^925^^^^^^^^^^^grapes/Vitis labruscanana^F&G FV&G&Wn&l C^923^J. Japan. Soc. Hort. Sci.FPF V F;F@F@;Fu~u.F V E~ u^v&&\덃~ u&FJA^923^Although ambient temperature is kept adequate, grape cultivation under covered facilities during winter months in JaKpan gives rise to low yields of poor quality berries because of low light intensities. This investigation was conducted inL leaf chamber, using _Vitis labruscana_ Bailey cv. Kyoho, to determine the influence of leaf age, light intensity, and CO2M concentrations on photosynthesis. The effects of CO2 enrichment on vine growth and fruit quality were also investigated iNn growth chambers. 1. The rate of photosynthesis per unit leaf area (Pn) between May 28 and September 19 rapidly increasedO with leaf growth, reaching a maximum of 18.9 mg CO2/dm2/hr, 37 days after the unfolding of a leaf. Pn then gradually decrPeased with leaf age. In young leaves, higher CO2 concentrations and stronger light intensities resulted in a significant iQncrease in Pn. Older leaves exhibited a similar enhancement of Pn upon exposure to high light intensity. Pn was saturated Rat 828 ppm CO2. 2. Administration of 1,000 to 1,100 ppm CO2 to vines for an 8 hr/day at a late stage of berry development Suntil harvest had no effect on berry size but resulted in an increase in sugar and anthocyanin contents but a decrease in Torganic acid content. Dry weight of newly developed roots doubled as a result of CO2 enrichment. 3. Application of CO2 undUer a long-day photoperiod at an early stage of berry development to a week before veraison markedly promoted shoot elongatVion. Furthermore, CO2 enrichment gave a 36% increase in both berry and cluster weights and also a higher sugar-acid ratio at harvest. In Japanese.#MH@6* /&6} F J ~ f _ X m Y Z " X374^2^Laitat,E^Loosveldt,P^1992^3^Open-top Chambers for Study of the Physiology of Acclimated Trees under Enhanced CO2 in YNatural Pollution Climate^Responses of Forest Ecosystems to Environmental Changes^Elsevier Applied Science^London^653-654^Z^^^^^^^^^^^^^^^^^^^^Norway spruce/Picea abies/sycamore/Acer pseudoplatanus/beech/Fagus sylvatica^^^^^^^^^^Teller,A^Mathy,P^Jeffers,JNRhy,P^Jeffers,J N Rᣘ5&'&5>^Ru>b>>a>>j>>k>>5>55>\375^4^LaMarche,V C,Jr^Graybill,D A^Fritts,H C^Rose,M R^1986^1^Carbon Dioxide Enhancement of Tree Growth at High Elevations^48^231^^860^^^^^^^^^^92929HC^927^ScienceA^927^Technical comment.`376^1^Lambers,H^1993^1^Rising CO2, Secondary Plant Metabolism, Plant-herbivore Interactions and Litter Decomposition. Theoretical Considerations^123^104-105^^263-271^^^^^^^^^^93232]C^930^VegetatiocA^930^A brief account is given of the ecological significance of quantitatively important secondary plant compounds, mainldy those of a phenolic nature, in herbivory and decomposition. Phenolic compounds accumulate to a greater extent in slow-greowing species than in fast-growing ones, particularly when soil conditions (nutrients, water) restrict growth. Two hypothefses to explain the increased concentration of phenolics when soil conditions are unfavorable are presented. The first hypogthesis (the 'carbon supply model of secondary plant metabolism') considers the increased levels of non-structural carbohydhrates as the major trigger. The second hypothesis (the 'amino acid diversion model of secondary plant metabolism') states ithat increased accumulation of phenolics stems from a decreased use of a common precursor (phenylalanine or tyrosine) for jprotein synthesis. Current experimental evidence, though still fairly limited, supports the second hypothesis, but furtherk testing is required before the first model can be rejected. So far, there is very little evidence for a direct effect of latmospheric CO2 on the concentration of secondary compounds in higher plants. However, there are likely to be indirect effmects, due to a stronger limitation by the nitrogen supply in plants whose growth has been promoted by atmospheric CO2. It nis concluded that it is very likely that phenolic compounds accumulate to a greater extent in plants exposed to elevated CO2, due to a greater limitation of nutrients, rather than as a direct effect of elevated CO2.vXvX^p377^2^Landsberg,J^Smith,M S^1992^1^A Functional Scheme for Predicting the Outbreak Potential of Herbivorous Insects under Global Atmospheric Change^25^40^^565-577^^^^^^^^^^93535tZY[XPR %t؃u t vXM  vX vX aC^933^Aust. J. Bot.^ZXˀePSQRVU] xaP yQЋ3%+4|7W }݇SQ sA^933^There are many possible ways in which changes in the global atmosphere could influence the outbreak potential of hertbivorous insects; we clarify these by developing a scheme for analysing insect populations in terms of functional attributues that are both important in population regulation and responsive to global change. This analysis shows that elevated CO2v is not likely to have a major influence on probability of insect outbreak, except possibly in systems in which nitrogen-bwased defensive compounds are produced by plants in response to herbivory. Systems that will have high potential to outbreaxk, if climatic conditions become more favourable for plant growth and responses are not constrained by other resources, inyclude those in which both herbivorous insects and host plants have highly flexible growth patterns and activity cues. Globzal changes that increase environmental stress on host plants are most likely to favour sap-feeding insects. Critical enemy{ (predator or parasitoid) control of the dormant phase of herbivorous insects may be very important in preventing or allowing outbreaks, but is often poorly understood.}378^3^Larigauderie,A^Hilbert,D W^Oechel,W C^1988^1^Effect of CO2 Enrichment and Nitrogen Availability on Resource Acquisition and Resource Allocation in a Grass, _Bromus mollis_^34^77^^544-549^^^^^^^^^^938^^^^^^^^^^^Bromus mollisisqC^936^OecologiaA^936^The effects of CO2 enrichment on the growth, biomass partitioning, photosynthetic rates, and leaf nitrogen concentration of a grass, _Bromus mollis_ (C3), were investigated at a favorable and a low level of nitrogen availability. Despite increases in root:shoot ratios, leaf nitrogen concentrations were decreased under CO2 enrichment at both nitrogen levels. For the low-nitrogen treatment, this resulted in lower photosynthetic rates measured at 675 uL/L for the CO2-enriched plants, compared to photosynthetic rates measured at 350 uL/L for the non-enriched plants. At higher nitrogen availability, photosynthetic rates of plants grown and measured at 675 uL/L were greater than photosynthetic rates of the non-enriched plants measured at 350 uL/L. Water use efficiency, however, was increased in enriched plants at both nitrogen levels. CO2 enrichment stimulated vegetative growth at both high and low nitrogen during most of the vegetative growth phase but, at the end of the experiment, total biomass of the high and low CO2 treatments did not differ for plants grown at low nitrogen availability. While not statistically significant, CO2 tended to stimulate seed production at high nitrogen and decrease it at low nitrogen.go= 6I $J3,D*,q07y7o03o(47f379^3^Larigauderie,A^Roy,J^Berber,A^1986^1^Long Term Effects of High CO2 Concentration on Photosynthesis of Water Hyacinth (_Eichhornia crassipes_ (Mart.) Solms)^39^37^^1303-1312^^^^^^^^^^941^^^^^^^^^^^water hyacinth/Eichhornia crassipeses~C^939^J. Expt. Bot.494^^A$v Uj!Bƙșyle?D"A$_zA^939^The photosynthetic response to CO2 concentration, light intensity and temperature was investigated in water hyacinth plants (_Eichhornia crassipes_ (Mart.) Solms) grown in summer at ambient CO2 or at 10,000 umol (CO2)/mol and in winter at 6,000 umol (CO2)/mol. Plants grown and measured at ambient CO2 had high photosynthetic rate (35 umol (CO2)/m2/s), high saturating photon flux density (1,500-2,000 umol/m2/s) and low sensitivity to temperature in the range 20-40C. Maximum photosynthetic rate (63 umol (CO2)/m2/s) was reached at an internal CO2 concentration of 800 umol/mol. Plants grown at high CO2 in summer had photosynthetic capacities at ambient CO2 which were 15% less than for plants grown at ambient CO2, but maximum photosynthetic rates were similar. Photosynthesis by plants grown at high CO2 and high light intensity had typical response curves to internal CO2 concentration with saturation at high CO2, but for plants grown under high CO2 and low light and plants grown under low CO2 and high light intensity photosynthetic rates decreased sharply at internal CO2 concentrations above 1,000 umol/mol.-@' avOsT >5?(( l5/<380^4^Lasceve,G^Gautier,H^Jappe,J^Vavasseur,A^1993^1^Modulation of the Blue Light Response of Stomata of _Commelina communis_ by CO2^44^88^^453-459^^^^^^^^^^944^^^^^^^^^^^Commelina communisis L.P ppC^942^Physiol. Plantarum! 2x current availabilities, the relationship flattens out very rapidly because the plant becomes limited by carbon uptake. Thus, if nitrogen availabilities more than double in the future, _E. vaginatum_ may shift from being a nutrient-limited to a carbon-limited system and, consequently, increased season length and elevated CO2 concentrations may play an important role in controlling _E. vaginatum_ productivity.7"(%$=?AEI>F387^3^Lekkerkerk,L J A^van de Geijn,S C^van Veen,J A^1990^3^Effects of Elevated Atmospheric CO2-levels on the Carbon Economy of a Soil Planted with Wheat^Soils and the Greenhouse Effect^John Wiley & Sons^New York^423-429^^^^^^^^^^^^^^^^^^^^^wheat/Triticum aestivum^^^^^^^^^^Bouwman,AFAaAaAaCcEeEeEeEeIIIINnOoOoOoOoUuUuU388^3^Lekkerkerk,L J A^van Veen,J A^van de Geijn,S C^1990^3^Influence of Climatic Change on Soil Quality; Consequences of Increased Atmospheric CO2-concentration on Carbon Input and Turnover in Agro-ecosystems^The Greenhouse Effect and Primary Productivity in European Agro-ecosystems; 5-10 April 1990; Wageningen, The Netherlands^Pudoc^Wageningen^46-47^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^Goudriaan,J^van Keulen,H^van Laar,H H[Z[\[][^[_[`[a[WX[bcdY\^`egikZ]_afhjl W Y \  389^4^Lenssen,G M^Lamers,J^Stroetenga,M^Rozema,J^1993^1^Interactive Effects of Atmospheric CO2 Enrichment, Salinity and Fl!ooding on Growth of C3 (_Elymus athericus_) and C4 (_Spartina anglica_) Salt Marsh Species^123^104/105^^379-388^^^^^^^^^^967^^^^^^^^^^^Spartina anglica/Elymus athericus^^^^^us (Link) Kerguelen^^^^^[()89<=>?@A artina alterniflora_. In both field experiments and hydroponic assay chambers, nitrogen fixation associated with the roots$A^965^The growth response of Dutch salt marsh species (C3 and C4) to atmospheric CO2 enrichment was investigated. Tillers %of the C3 species _Elymus athericus_ were grown in combinations of 380 and 720 uL/L CO2 and low (0) and high (300 mM NaCl)& soil salinity. CO2 enrichment increased dry matter production and leaf area development while both parameters were reduce'd at high salinity. The relative growth response to CO2 enrichment was high under saline conditions. Growth increase at el(evated CO2 was higher after 34 than 71 days. A lower response to CO2 enrichment after 71 days was associated with a decrea)sed specific leaf area (SLA). In two other experiments the effect of CO2 (380 and 720 uL/L) on growth of the C4 species _S*partina anglica_ was studied. In the first experiment total plant dry weight was reduced by 20% at elevated CO2. SLA also +decreased at high CO2. The effect of elevated CO2 was also studied in combination with soil salinity (50 and 400 mM NaCl) ,and flooding. Again plant weight was reduced (10%) at elevated CO2, except under the combined treatment high salinity/non--flooded. But these effects were not significant. High salinity reduced total plant weight while flooding had no effect. Ca.uses of the salinity dependent effect of CO2 enrichment on growth and consequences of elevated CO2 for competition between C3 and C4 species are discussed. t& PH؀>!u > t XPrXr&> H؀>!u0390^2^Lenssen,G M^Rozema,J^1990^3^The Effect of Atmospheric CO2-enrichment and Salinity on Growth, Photosynthesis and Wate1r Relations of Salt Marsh Species^The Greenhouse Effect and Primary Productivity in European Agro-ecosystems; 5-10 April 12990; Wageningen, The Netherlands^Pudoc^Wageningen^64-67^^^^^^^^^^^^^^^^^^^^^Aster tripolium/Elymus pycnanthus/Spartina anglica^^^^^^^^^^Goudriaan,J^van Keulen,H^van Laar,HHH HD!&[XS6D33s>t3;v 4391^3^Levanon,D^Motro,B^Marchaim,U^1986^3^Organic Materials Degradation for CO2 Enrichment of Greenhouse Crops^Status and 5CO2 Sources^CRC Press, Inc.^Boca Raton, Florida^123-145^^^^I^^Carbon Dioxide Enrichment of Greenhouse Crops^^^^970^^^^^^^^^^^^^^^^^^^^^Enoch,H Z^Kimball,B AB A&&!6;Ds ٌ 36DaQ ˎ6;Ds> u7A^969^Carbon comprises approximately 50% of the dry matter in all organisms. Photoautotrophs (plants and algae) fix atmosp8heric CO2 into organic materials. These organic materials serve as a source of energy and carbon for the heterotrophs (a l9arge group of organisms, including all animals). This utilization of organic materials in the respiration process causes t:he essential return of CO2 to the atmospheric pool. This natural process could be manipulated for CO2 enrichment of greenh;ouse crops. Organic waste materials of agricultural or urban origin can serve as sources of CO2 enrichment. For practical n of organic materials to greenhouses are: composting, anaerobic digestion, and spreading the organic matter on the greenh?ouse ground or incorporating it in the upper soil layer. The use of each of the above methods must be based on knowledge o@f the ecology of aerobic and anaerobic degradation. The decision as to which one of these methods is the most suitable musAt be based on a feasibility study where local conditions, such as the availability of raw materials, climate, labor, and construction costs, etc. are taken into consideration.Ht #rF6E3^V^V6;>DsKN8 u?9]u8UuEFC392^1^Leverenz,J W^1988^1^The Effects of Illumination Sequence, CO2 Concentration, Temperature and Acclimation on the ConvDexity of the Photosynthetic Light Response Curve^44^74^^332-341^^^^^^^^^^973^^^^^^^^^^^Pinus sylvestris/Scots pine/Picea glauca/white spruce/Picea mariana/Picea abies/Norway spruce/Abies lasiocarpacarpa t &n&6DdW&tC^971^Physiol. Plant.&t& &&&&6D6DZ[XPSQR&& 6D&&&GA^971^It was shown previously that the convexity (curvature or rate of bending) of the photosynthetic light response curveH was strongly correlated with chlorophyll content in shade acclimated conifer needles (Leverenz 1987, Physiol. Plant. 71: I20-29) in agreement with an hypothesis that gradients of light within leaves affect the convexity. In the present study itJ is shown that the convexity at any given chlorophyll content can be altered when leaves of _Pinus sylvestris_ L. Picea glKauca (Muench), Picea mariana (M.II.) BS.P. and _Picea abies_ (L.) Karst pre-treated with less shade. This probably inducedL a differential acclimation of cells on the top and bottom side of the leaves to their local light environment. Leaves werMe illuminated on i) their top surface, ii) their bottom surface, or iii) uniformly in a light integrating sphere during meNasurements of photosynthesis. After shoots had been transferred from the growth environment to a new measuring environmentO, the convexity increased from the first to the second day towards a maximum of 0.97. The rate of increase towards this maPximum was 55 to 62% per day and probably is the result of re-acclimation of cells within the leaves. The data show that thQe act of measuring photosynthesis induces a significant alteration in the experimental material when measurements are madeR for more than one day. The convexity of the light response curve of photosynthesis, was independent of whether the steadyS state measurements were made beginning in the dark and sequentially increasing photon flux density or beginning at high lTight and sequentially lowering photon flux density. Neither variation of CO2 concentration from 35 to 200 Pa, nor of temperature from 5 to 32C affected the convexity.EQBYE3E^ZY[PDtSWD@gG_[ V393^3^Lewin,K F^Hendrey,G R^Kolber,Z^1992^1^Brookhaven National Laboratory Free-Air Carbon Dioxide Enrichment Facility^8^11^^135-141^^75SE t;r ;rC[`EDt+6E;,Ew&˴Cg u4E4Eێ8E&C;,Ev{QEg uEC^974^Crit. Rev. Plant Sci.[Z&t2E&&1SREE2E&&& & &!Z["aˋD`EYY394^3^Lieth,J H^Reynolds,J F^Rogers,H H^1986^1^Estimation of Leaf Area of Soybeans Grown under Elevated Carbon Dioxide Levels^86^13^^193-203^^^^^^^^^^978^^^^^^^^^^^Glycine max/soybeanMerr./soybean_^YQVW>r.r(> OWC^976^Field Crops Res.>dwrQVW6NԒn%rԒ.d_^Y˃>uˁ>dw rQVW6\A^976^Leaf area (LA) data are required for describing numerous canopy processes. However, determining LA for a crop is bot]h time consuming and labor intensive, requiring a substantial investment of resources. The objectives of this study were (^1) to develop statistical models for estimating LA of field-grown soybean (_Glycine max_) plants grown in open-top field c_hambers from measurements of destructive (leaf and top dry weight) and non-destructive (leaf number, plant height, and bra`nch length) variables, (2) to examine the effects of CO2 concentration on these statistical relationships, and (3) to testa the applicability of such models to independent data collected under different experimental conditions. Predictive modelsb of LA based on either branch length (LA = 147.6 BRL (exp 0.635), CV = 11%) or top dry weight (LA = 328.8 x TDW (exp 0.731c), CV = 12%) were found to have the lowest coefficient of variation about the regression line, to be unaffected by increasding CO2, and to be reasonable predictors of LA under different growth conditions. Both leaf area per leaf and specific leaf area ratios changed with increasing CO2 and growth conditions. Plant height was a poor predictor of LA.LW^rf395^1^Lincoln,D E^1993^1^The Influence of Plant Carbon Dioxide and Nutrient Supply on Susceptibility to Insect Herbivores^123^104/105^^273-280^^^^^^^^^^981^^^^^^^^^^^^^^^^r[VFV }s;uBrc~LtQV_Yt "A^1791^The coupling of root-associated nitrogen fixation and plant photosynthesis was examined in the salt marsh grass _SpiA^979^The carbon/nutrient ratio of plants has been hypothesized to be a significant regulator of plant susceptibility of ljeaf-eating insects. As rising atmospheric carbon dioxide stimulates photosynthesis, host plant carbon supply is increased kand the accompanying higher levels of carbohydrates, especially starch, apparently 'dilute' the protein content of the lealf. When host plant nitrogen supply is limited, plant responses include increased carbohydrate accumulation, reduced leaf pmrotein content, but also increased carbon-based defensive chemicals. No change, however, has been observed in the concentrnation of leaf defensive allelochemicals with elevated carbon dioxide during host plant growth. Insect responses to carbon-ofertilized leaves include increased consumption with little change in growth, or alternatively, little change in consumptipon with decreased growth, as well as enhanced leaf digestibility, reduced nitrogen use efficiency, and reduced fecundity. qThe effects of plant carbon and nutrient supply on herbivores appear to result, at least in part, from independent processes affecting secondary metabolism.structureofcloudcoverandonmicrostructureofcloudsincludinggeneralphysicalands396^2^Lincoln,D E^Couvet,D^1989^1^The Effect of Carbon Supply on Allocation to Allelochemicals and Caterpillar Consumption of Peppermint^34^78^^112-114^^^^^^^^^^984^^^^^^^^^^^Mentha piperita/peppermint/peppermintntptical,electricalandradiZC^982^Oecologiaoudsaswellastheirradarcharacteristics.Thebookbrieflysummarizesdataonfogandprecipitation.vA^982^The carbon supply of peppermint plants was manipulated by growing clonal propagules under three carbon dioxide regimwes (350, 500 and 650 uL/L). Feeding by fourth instar caterpillars of _Spodoptera eridania_ increased with elevated CO2 hosxtplant regime, as well as with low leaf nitrogen content and by a high proportion of leaf volatile terpenoids. Leaf weighty increased significantly with the increased carbon supply, but the amount of nitrogen per leaf did not change. The amount zof volatile leaf mono- and sesquiterpenes increased proportionately with total leaf dry weight and hence was not influence{d by CO2 supply. These results are consistent with ecological hypotheses which assume that allocation to defense is closely regulated and not sensitive to carbon supply per se.s,CloudStructureandPhysicsofformation.Leningrad.Gidrometeo}397^3^Lincoln,D E^Couvet,D^Sionit,N^1986^1^Response of an Insect Herbivore to Host Plants Grown in Carbon Dioxide Enriched Atmospheres^34^69^^556-560^^^^^^^^^^987^^^^^^^^^^^soybean/Glycine maxax (L.) Merr.edistributionofdifferentthermodyntC^985^Oecologiaparametersinclouds.AlongwiththedescriptionofmicroandmacrophysicalstructureofcloudsandcloA^985^Rising atmospheric carbon dioxide concentration is expected to increase plant productivity but little evidence is available regarding effects on insect feeding or growth. Larvae of the soybean looper, a noctuid moth, were fed leaves of soybean plants grown under three carbon dioxide regimes (350, 500 and 650 uL/L). Larvae fed at increasingly higher rates on plants from elevated carbon dioxide atmospheres: 30% greater on leaves from the 650 uL/L treatment than on leaves from the 350 uL/L treatment. When variation in larval feeding was related to the leaf content of nitrogen and water, there was no significant remaining effect of carbon dioxide treatment. The principal effect on herbivores of increasing the carbon supply of leaves appeared to be reduction of leaf nutrient concentration. This study suggests that feeding by herbivores on the leaves of C3 plants may increase as the level of atmospheric carbon dioxide rises.esforward,theaveragevaluesofful398^2^Lindhout,P^Pet,G^1990^1^Effects of CO2 Enrichment on Young Plant Growth of 96 Genotypes of Tomato (_Lycopersicon esculentum_)^87^51^^191-196^^^^^^^^^^990^^^^^^^^^^^tomato/Lycopersicon esculentumum Mill.sminimaincrease.Indicatrixext~C^988^Euphyticardssmallerscatteringangles.MilenkyM.N.,V.I.Kozintsev,B.A.Konstantinov,andG.N.BaldeA^988^The early growth of 96 genotypes of tomato was studied at 320 ppm CO2 and at 750 ppm CO2 in separate climate rooms. Plants were harvested at 40 and 55 days after sowing. Fresh and dry weights were determined. Large differences between genotypes were found for average plant fresh weight and dry weights and for relative growth rates. The average overall growth enhancement by CO2 enrichment was 2.3. Two genotypes showed significant genotype x CO2 interaction. The consequences of these results for tomato breeding are discussed.inghighervaluesofthecloudboundarycontrastunderconditionsofsubc399^5^Lipfert,F W^Alexander,Y^Hendrey,G R^Lewin,K F^Nagy,J^1992^1^Performance Analysis of the BNL FACE Gas Injection System^8^11^^143-163^^92ndI.P.Guseva.1986.CloudinessovertheNorthAtlanticfromsatelliteandsurfacebaseddata.Proc.C^991^Crit. Rev. Plant Sci.onthlyaveragesofcloudamountfromtheNorthAtlanticOceanWeatherStationsfornineyears400^1^Long,S P^1991^1^Modification of the Response of Photosynthetic Productivity to Rising Temperature by Atmospheric CO2 Concentrations: Has its Importance Been Underestimated?^16^14^^729-739^^^^^^^^^^99595temporaltrendareestimatedsepaC^993^Plant Cell Environ.atherStationdatafor19531974andsatelliteobservationsfor19661983.ItisshownthattheA^993^Climate change will include correlated increases in temperature and atmospheric CO2 concentration (Ca). Rising temperatures will increase the ratio of photorespiratory loss of carbon to photosynthetic gain, whilst rising Ca will have an opposing effect. The mechanism of these effects at the level of carboxylation in C3 photosynthesis are quantitatively well understood and provide a basis for models of the response of leaf and canopy carbon exchange to climate change. The principles of such a model are referred to here and used to quantitatively examine the implications of concurrent increase in temperature and Ca. Simulations of leaf photosynthesis show the increase, with elevation of Ca from 350 to 650 umol/mol, in light saturated rates of CO2 uptake (Asat) and maximum quantum yields (phi) to rise with temperature. An increase in Ca from 350 to 650 umol/mol can increase Asat by 20% at 10C and by 105% at 35C, and can raise the temperature optimum of Asat by 5C. This pattern of change agrees closely with experimental data. At the canopy level, simulations also suggest a strong interaction of increased temperature and CO2 concentration. Predictions are compared with the findings of long-term field studies. The principles used here suggest that elevated Ca will alter both the magnitude of the response of leaf and canopy carbon gain to rising temperature, and sometimes, the direction of response. Findings question the value of models for predicting plant production in response to climate change which ignore the direct effects of rising Ca and the modifications that rising Ca imposes on the temperature response of net CO2 exchange.forindividualstationsforvariousmonthsw401^3^Long,S P^Baker,N R^Raines,C A^1993^1^Analysing the Responses of Photosynthetic CO2 Assimilation to Long-term Elevation of Atmospheric CO2 Concentration^123^103/104^^33-45^^^^^^^^^^998^^^^^^^^^^^^^^^^for19661983.Itisshownthatthesthe same factor that induces the CCM, although secondary regulation must also be involved.nticandanegativeoneintheA^996^Understanding how photosynthetic capacity acclimatises when plants are grown in an atmosphere of rising CO2 concentrations will be vital to the development of mechanistic models of the response of plant productivity to global environmental change. A limitation to the study of acclimatisation is the small amount of material that may be destructively harvested from long-term studies of the effects of elevation of CO2 concentration. Technological developments in the measurement of gas exchange, fluorescence and absorption spectroscopy, coupled with theoretical developments in the interpretation of measured values now allow detailed analyses of limitations to photosynthesis _in vivo_. The use of leaf chambers with Ulbricht integrating spheres allows separation of change in the maximum efficiency of energy transduction in the assimilation of CO2 from changes in tissue absorptance. Analysis of the response of CO2 assimilation to intercellular CO2 concentration allows quantitative determination of the limitation imposed by stomata, carboxylation efficiency, and the rate of regeneration of ribulose 1:5 bisphosphate. Chlorophyll fluorescence provides a rapid method for detecting photoinhibition in heterogeneously illuminated leaves within canopies in the field. Modulated fluorescence and absorption spectroscopy allow parallel measurements of the efficiency of light utilisation in electron transport through photosystems I and II _in situ_..C402^2^Long,S P^Drake,B G^1991^1^Effect of the Long-Term Elevation of CO2 Concentration in the Field on the Quantum Yield of Photosynthesis of the C3 Sedge, _Scirpus olneyi_^17^96^^221-226^^^^^^^^^^1001^^^^^^^^^^^Scirpus olneyieyirameterdeterC^999^Plant Physiol.rocessesinclouds.Interinst.CollectionofRes.Papers.,LeningradHydromet.Inst.84:156164.A^999^CO2 concentration was elevated throughout 3 years around stands of the C3 sedge _Scirpus olneyi_ on a tidal marsh of the Chesapeake Bay. The hypothesis that tissues developed in an elevated CO2 atmosphere will show an acclimatory decrease in photosynthetic capacity under light-limiting conditions was examined. The absorbed light quantum yield of CO2 uptake (phi-abs) and the efficiency of photosystem II photochemistry were determined for plants which had developed in open top chambers with CO2 concentrations in air of 680 micromoles per mole, and of 351 micromoles per mole as controls. An Ulbricht sphere cuvette incorporated into an open gas exchange system was used to determine phi-abs and a portable chlorophyll fluorimeter was used to estimate the photochemical efficiency of photosystem II. When measured in an atmosphere with 10 millimoles per mole O2 to suppress photorespiration, shoots showed a phi-abs of 0.093 +/- 0.003, with no statistically significant difference between shoots grown in elevated or control CO2 concentrations. Efficiency of photosystem II photochemistry was also unchanged by development in an elevated CO2 atmosphere. Shoots grown and measured in 680 micromoles per mole of CO2 in air showed a phi-abs of 0.078 +/- 0.004 compared with 0.065 +/-0.003 for leaves grown and measured in 351 micromoles per mole CO2 in air; a highly significant increase. In accordance with the change in phi-abs, the light compensation point of photosynthesis decreased from 51 +/- 3 to 31 +/- 3 micromoles per square meter per second for stems grown and measured in 351 and 680 micromoles per mole of CO2 in air, respectively. The results suggest that even after 3 years of growth in elevated CO2, there is no evidence of acclimation in capacity for photosynthesis under light-limited conditions which would counteract the stimulation of photosynthetic CO2 uptake otherwise expected through decreased photorespiration. A403^2^Long,S P^Hutchin,P R^1991^1^Primary Production in Grasslands and Coniferous Forests with Climate Change: An Overview^85^2^^139-156^^^^^^^^^^1004004      HP4.PRSFe:\\C^1002^Ecol. Appl.H9q0)\A^1002^In energy terms primary production is the driving step of the global carbon cycle. To predict the interaction of ecosystems with the 'greenhouse' effect, it is necessary to understand how primary production, consumption, and decomposition will respond to climate change. Most estimates of primary production have been made by extrapolation from measured standing crops. For grasslands we show this approach to be seriously in error. Even where detailed studies of turnover and belowground production have been undertaken, errors are invariably high, severely limiting the value of models based on correlation of climate with measured production. Detailed information is available on the responses of individual plant processes to individual climate variables at the leaf, plant, and stand level, giving potential for a more mechanistic approach in modelling. This approach is limited by lack of information on multivariate interactions and on some key physiological processes, and by uncertainties in scaling up to populations and communities. Despite this, some important insights to possible community responses, particularly those of C3 and C4 types, may be gained from knowledge of responses at the plant level and below. This review outlines the expected character of climate change in grasslands and coniferous forests. Knowledge of the responses of different physiological processes underlying production to individual aspects of climate change is considered, and its implications for higher levels of organization are discussed. Although feasible, mechanistic models of production compound the errors associated with individual process responses with uncertainties surrounding interaction and scaling up, and result in very large errors in any prediction of response to climate change. We conclude that there is insufficient information to predict accurately the response of primary production to climate change. The key processes for which information is inadequate and the parameters that have meaning at different scales need to be identified. Of particular promise is the approach of predicting production from light interception and conversion efficiency.rJ.<tD>ʾ@D404^5^Long,S P^Nie,G Y^Drake,B G^Hendrey,G^Lewin,K^1992^3^The Implications of Concurrent Increases in Temperature and CO2 Concentration for Terrestrial C3 Photosynthesis^Proceedings of the IXth International Congress on Photosynthesis; 30 August-4 September 1992; Nagoya, Japan^Kluwer Academic^Dordrecht^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^Murata,Nr)3΋A D A DA405^1^Longuenesse,J J^1990^1^Influence of CO2 Enrichment Regime on Photosynthesis and Yield of a Tomato Crop^15^268^^63-70^^^^^^^^^^1008^^^^^^^^^^^Lycopersicon esculentum/tomatol./tomatog7^ZYþ6D u _FC^1009^Field Crops Res.u_3 *dGG>!_^ZY[XPW0O< w;w_XPV tutV t *&G uF t3ޚ-Tr7&&2'3& lA^1018^Biomass accumulation and area expansion of newly initiated cladodes of _Opuntia ficus-indica_ were studied to help understand the high productivity of this Crassulacean acid metabolism species. In a glasshouse, both dry weight and area increased more and more rapidly for about 30 days and then increased linearly with time up to 63 days. The relative growth rate averaged 0.12/day, comparable to values for productive C3 and C4 plants. New cladodes initiated on basal cladodes with 2-fold higher initial dry weight grew twice as fast. Drought reduced biomass accumulation and area expansion of new cladodes by 62 and 52%, respectively. A 70% reduction in irradiation decreased biomass accumulation of new cladodes by 17% and their thickness by 11%. In a growth chamber containing 720 umol CO2/mol air, biomass of newly initiated cladodes was 7% higher, area was 8% less, specific mass was 16% higher and less carbohydrate was translocated from basal cladodes than for 360 umol CO2/mol. The large capacity for storage of carbohydrate and water in basal cladodes of _O. ficus-indica_ apparently buffered environmental stresses, thereby reducing their effects on growth of daughter cladodes.XËFf%=u ڸactusuN F%uNPQVFt^YX˳)u ~0TY:!Y::T:QV 410^2^Luo,Y^Strain,B R^1992^1^Leaf Water Status in Velvetleaf under Long-term Interactions of Water Stress, Atmospheric Humidity, and Carbon Dioxide^38^139^^600-604^^^^^^^^^^1023^^^^^^^^^^^Abutilon theophrastisti3ɉ؉ب`t"@u6ޚ-Tr&C^1021^J. Plant Physiol.F#/T^rrV<^&!'&O2F&O s& Q&*O &O߾#A^1021^Well watered and water-stressed _Abutilon theophrasti_, were grown with relative humidity of 45% or 85% at 30C and$ CO2 concentrations of 350 or 650 umol/mol. Elevated leaf water potentials of the water-stressed plants grown in both high% and low humidities were caused by CO2 enrichment. Elevated water content (kg/m2 leaf area) caused by CO2 enrichment, high&er water content at a given water potential, and notably lower rate in desiccation from detached leaves all occurred only 'in the plants grown in low humidity. These results may be related to enhanced dehydration resistance of the plants that experienced long-term low humidity.u+&O[XPSQVUW3ɋޚ-Ts_.&&2'3& _F ~t#/TN)411^3^Luxmoore,R J^Norby,R J^O'Neill,E G^1986^3^Seedling Tree Responses to Nutrient Stress under Atmospheric CO2 Enrichmen*t^Forest Plants and Forest Protection^Yugoslav IUFRO World Congress Organizing Committee^Vienna^178-183^^^^I^^18th IUFRO W+orld Congress, Division 2^^^^1025^^^^^^^^^^^Pinus virginiana/Quercus alba/Liriodendron tulipifera^^^^^^^^^^Edwin Donaubaueruer34 7 8" ; < = P9 >p?R Q S TUV `4PSQRVW>8~W&`~DuF u} uN& Ts-A^1024^Three species of seedling trees were grown in pots containing low-nutrient soil for periods of up to 40 weeks under. a range of atmospheric CO2 concentrations. In all cases, total dry weight increased with CO2 enrichment, with a greater r/elative increase in root weight than shoot weight. In an experiment with _Pinus virginiana_ in open-top field chambers, ph0osphorus and potassium uptake did not increase with an increase in CO2 from 365 to 690 uL/L, even though dry matter gain i1ncreased by 37% during the exposure period. In experiments with _Quercus alba_ and _Liriodendron tulipifera_ under control2led environment conditions there were obvious symptoms of nitrogen deficiency and total nitrogen uptake did not increase w3ith CO2 enrichment. However, dry weight gain was more than 90% higher at 690 uL/L CO2. The three experiments with CO2 enri4chment demonstrate that increases in plant dry weight can occur without increased uptake of some nutrients from the low-nu5trient soil. A mechanism for these responses may involve increased mobilization of nutrients in association with increased sucrose transport under elevated CO2 conditions.؁H~)uPQ&& &>uH2TYX2T=:)Fv^F7412^4^Luxmoore,R J^O'Neill,E G^Ells,J M^Rogers,H H^1986^1^Nutrient Uptake and Growth Responses of Virginia Pine to Elevated Atmospheric CO2^9^15^^244-251^^^^^^^^^^1028^^^^^^^^^^^Pinus virginiana/Virginia pineine98r&!98r!C^1026^J. Environ. Qual.kTET# TH~ t#&uS~uH~u N1:dT2K98r298r'z:A^1026^One-year-old Virginia pine (_Pinus virginiana_ Mill.) seedlings with native or _Pisolithus tinctorius_ mycorrhizal ;associations were grown in pots with soil low in organic matter and in cation exchange capacity and were exposed to one of< five atmospheric CO2 levels in the range of 340 to 940 uL/L in open-top field chambers. The mean dry weight of the seedli=ngs increased from 4.4 to 11.0 g/plant during the 122-d exposure period. Significant increases in dry weight and uptake of> N, Ca, Al, Fe, Zn, and Sr occurred with CO2 enrichment. Greater chemical uptake was associated with greater root weight. ?Specific absorption rates for chemicals (uptake per gram of root per day) were generally not affected by CO2 enrichment. T@he uptake of P and K was not increased with elevated CO2, and these elements showed the greater nutrient-use efficiency (CA gain per element uptake). The nutrient-use efficiency for N and Ca were not influenced by atmospheric CO2 enrichment. LarBge increases in Zn uptake at high CO2 suggested an increase in rhizosphere acidification, which may have resulted from theC release of protons from the roots, since it was estimated that cation uptake increasingly exceeded anion uptake with CO2 Denrichment. Potassium, P, and NO3 concentrations in the pot leachate decreased with higher CO2 levels, and a similar trendE was found for Al and Mg. These results suggest that soil-plant systems may exhibit increased nutrient and chemical retention at elevated atmospheric CO2.&H~?&S~H~&&SVt^ t&L2d($T$TQV&DuG413^3^Luxmoore,R J^Tharp,M L^West,D C^1990^3^Simulating the Physiological Basis of Tree-Ring Responses to Environmental ChHanges^Process Modeling of Forest Growth Responses to Environmental Stress^Timber Press^Portland, Oregon^393-401^^^^^^^^^^1030^^^^^^^^^^^^^^^^^^^^^Dixon,RK^Meldahl,RS^Ruark,GA^Warren,WGW G)tMF&\t&L &. :|2ɋ&JA^1029^The detection of possible forest growth responses to changes in atmospheric CO2 or air pollutants is very difficultK by statistical analysis of tree-ring chronologies, and a complementary modeling approach has been initially tested. In thLis new approach, a linked set of mechanistic unified transport models (UTM) of carbon, water, and chemical dynamics in soiMl-plant-litter systems is used to generate a matrix of simulated annual stemwood increment and winter carbon storage valueNs for a range of degree day, water stress, and atmospheric CO2 concentrations. These values represent potential tree growtOh responses as determined by hourly time-step physiological processes. The matrix is accessed by a forest succession modelP (Forests of East Tennessee, FORET) according to selected degree day and water stress values or by use of actual site dataQ. These potential growth responses are modified to realized annual increments according to the competition algorithms of tRhe succession simulator using yearly time-steps. A 12% increase in stemwood production was predicted for an oak-hickory (_SQuercus-Carya_ sp.) forest in eastern Tennessee by the UTM for a change in atmospheric CO2 both from 260 to 340 and from 3T40 to 600 ppmv (uL/L). A signal of +/- 12% was incorporated into the diameter growth algorithms for the species representeUd in Forests of East Tennessee (FORET), and simulations were conducted for 32 plots with slightly different initial specieVs composition representative of the oak-hickory forest (Shugart and West, 1977). Preliminary results suggest that the spatWial variation in the species complement for the 32 plots masked the detection of the CO2 signal in 200-year simulations. IXn a repeat analysis eliminating spatial variability, 24 replicate simulations were conducted for a single plot, and again Ythere were no simulation responses that could be attributed to CO2 enrichment for the five plots evaluated in this manner.Z Temporal variability due to establishment and mortality algorithms in FORET probably masked the CO2 signal from the Unifi[ed Transport Model (UTM). Spatial and/or temporal variability in forest-stand dynamics may mask the detection of tree resp\onse to atmospheric CO2 enrichment. A backcast simulation procedure that largely eliminates spatial and temporal effects is recommended for further testing of the linked-modeling method of tree-ring chronology analysis. : :^414^1^Madsen,T V^1987^1^The Effect of Different Growth Conditions on Dark and Light Carbon Assimilation in _Littorella uniflora_^44^70^^183-188^^^^^^^^^^1033^^^^^^^^^^^Littorella unifloraora9>Rt 3/B3"֒t^8C^1031^Physiol. Plant.r,U^][PSQRVW>҆uPXrƹJھ!r_^ZY[XPSQaA^1031^The effect of long-term exposure to different inorganic carbon, nutrient and light regimes on CAM activity and photbosynthetic performance in the submerged aquatic plant, _Littorella uniflora_ (L.) Aschers was investigated. The potential cCAM activity of _Littorella_ was highly plastic and was reduced upon exposure to low light intensities (43 umol/m2/s), higdh CO2 concentrations (5.5 mM, pH 6.0) or low levels of inorganic nutrients, which caused a 25-80% decline in the potentiale maximum CAM activity relative to the activity in the control experiments (light: 45 umol/m2/s; free CO2: 1.5 mM). The CAMf activity was regulated more by light than by CO2, while nutrient levels only affected the activity to a minor extent. Theg minor effect of low nutrient regimes may be due to a general adaptation of isoetic species to low nutrient levels. The phhotosynthetic capacity and CO2 affinity was unaffected or increased by exposure to low CO2, irrespective of nutrient levelsi. High CO2, low nutrient and low light, however, reduced the capacity by 22-40% and the CO2 affinity by 35-45%, relative tjo control. The parallel effect of growth conditions on CAM activity and photosynthetic performance of _Littorella_ suggestk that light and dark carbon assimilation are interrelated and constitute an integrated part of the carbon assimilation phylsiology of the plant. The results are consistent with the hypothesis that CAM is a carbon-conserving mechanism in certain maquatic plants. The investment in the CAM enzyme system is beneficial to the plants during growth at high light and low CO2 conditions..,s9=:w^YXSW>Rt*r$rwPUr3X_[RV3ҡ tu V*o415^4^Maevskaya,S N^Andreeva,T F^Voevudskaya,S Y^Cherkanova,N N^1990^1^Effect of Elevated CO2 Concentration on Photosynthesis and Nitrogen Metabolism of Mustard Plants^21^37^^921-927^^^^^^^^^^1036^^^^^^^^^^^Brassica juncea/mustardustard2w_C^1034^Fiz. Rast.tg tX tI9 t: tw t tw t tw t twrA^1034^We investigated the effect of prolonged (8- to 10-day) influence of elevated atmospheric CO2 content (0.14%) on thes photosynthetic rate and nitrogen metabolism in mustard plants (_Brassica juncea_ L.). The photosynthetic rate and intensitty of nitrogen metabolism in leaves of mustard plants in the vegetative phase of growth are higher under conditions of eleuvated atmospheric CO2 concentration than in leaves of plants that developed under conditions of normal CO2 content in the vatmosphere. Intensification of nitrogen metabolism occurred mainly due to increase of NR activity. Activity of GS and GO iwncreased to a lesser extent. Significant changes were detected in the rates of synthesis of separate amino acids. Thus, foxrmation of alanine and aspartic acid increased by 84 and 40%, respectively, but the rates of glycine and serine synthesis ydeclined. The excess of amino acids (alanine and aspartic acid) is evacuated from the metabolic pool into vacuoles, with tzhe result that a normal metabolic pool of amino acids is preserved. A state of homeostasis is preserved, protein and chlor{ophyll synthesis is not disturbed, and growth and biomass accumulation intensify in plants under conditions of elevated CO2 concentration.*2䠗 Qr Hˊ<w˸=vˊ/ȚTr/ 3 /}416^4^Maleszewski,S^Kaminska,Z^Kondracka,A^Mikulska,M^1988^1^Response of Net Photosynthesis in Bean (_Phaseolus vulgaris_)~ Leaves to the Elevation of the Partial Pressures of Oxygen and Carbon Dioxide^44^74^^221-224^^^^^^^^^^1039^^^^^^^^^^^bean/Phaseolus vulgarisris L.Sr6PrFX*_^VW*r r_^˾ȚT@˾5ȚpC^1037^Phsiol. Plant.3>҆t t ArQ@>҆tGt@$t`rC tSt@tA^1037^Bean (_Phaseolus vulgaris_ L. cv. Golden Saxa) plants were grown under low artificial light or under natural daylight. The rate of net photosynthesis (Pn) was measured at: CO2 partial pressure, p(CO2), of 0.03, 0.09 or 0.15 kPa; O2 partial pressure, p(O2), of 2, 21 or 31 kPa and at light intensities of 350 or 1000 umol/m2/s (photosynthetically active radiation). In plants which had been grown under natural light, stimulation of Pn at 2 kPa p(O2) was found only at elevated p(CO2) and high light. It is proposed that this phenomenon is dependent on a high capacity of the photosynthetic apparatus to regenerate ribulose 1,5-bis-phosphate. sȸ3YV&&Ie;:^PRI#:r<&E&U&Eu&M  417^3^Mandl,R H^Laurence,J A^Kohut,R J^1989^1^Development and Testing of Open-Top Chambers for Exposing Large, Perennial Plants to Air Pollutants^9^18^^534-540^^^^^^^^^^1042042XSQ3sBY[QRUt}&t&hPtd&C^1040^J. Environ. Qual.2H   &@XV *\*FJ^#:ZYUu@&&<u A^1040^To study the effects of air pollutants on large perennial plants, two designs of large, open-top chambers were tested in wind tunnel studies and subsequent field trials. Flow visualization of air patterns in the wind tunnel showed that a frustum and inner baffle plate covering 50% of the top surface provided the best exclusion capabilities. This was quantified by measurement of pollutant distribution in scale models. Prototype chambers were erected around grape (_Vitus_ sp.) vines in a commercial vineyard and evaluated over two growing seasons. Exclusion efficiencies of 80 to 95% were found during the test period. The rain shadow caused by the frustum was significant with losses greatest near the walls. The average increase in leaf temperature between ambient and within the chamber was 2.5C. Light intensity was reduced 14 and 22% in the circular and rectangular chamber, respectively. Although there is some modification of the plant environment, the chambers provide a suitable environment during the growing season for air pollution studies with large perennial plants.v418^2^Mann,W^Krug,H^1989^1^Production Planning -- CO2 Enrichment^15^248^^201-206^^^^^^^^^^1045^^^^^^^^^^^kohlrabi/Brassica oleracea/radish/Raphanus sativus/lambs lettuce/lambs lettuces lettuce Xt"ο͹"N4:]_^Y[XQR3>Xt 3C^1043^Act. Hort.]6D&DrվfH]r_^[þf sPSQVC<.uDρe*2DtDD D A^1043^Following the approach of Krug and Liebig the CO2 factor was integrated into the planning model for radiation and temperature. The response surface for autumn plantings of lettuce, graphs for the growth periods (100 g) as a function of temperature set point and CO2 concentration as well as corresponding input factor costs, are presented. CO2 enrichment results in remarkable increases of growth rates, particularly in combination with high irradiances and favourable temperatures. Therewith the growth period will be shortened, especially if due to better growth in favourable environments unfavourable conditions will be avoided. This can be achieved in autumn by enhancing growth to finish the crop before winter, in spring by later plantings and enhancing growth to finish at the time scheduled.<r@ us~rwtDE]$419^2^Marek,L F^Spalding,M H^1991^1^Changes in Photorespiratory Enzyme Activity in Response to Limiting CO2 in _Chlamydomonas reinhardtii_^17^97^^420-425^^^^^^^^^^2049^^^^^^^^^^^Chlamydomonas reinhardtii^^^^^^^^ tFFuȊþO*ƊC^1046^Plant Physiol.c}t}tJE:ErZ} t:E wOE u>E;ErA;Ew<}rE u%.}rE u E tE ;Er;Ew 420^2^Margolis,H A^Vezina,L P^1990^1^Atmospheric CO2 Enrichment and the Development of Frost Hardiness in Containerized Black Spruce Seedlings^32^20^^1392-1398^^^^^^^^^^2052^^^^^^^^^^^Picea mariana/black spruce^^^^^/black spruce^^^^^;E9u5EC^1048^Can. J. For. Res.sslD8@tL9D2UWUJ%EPuE9t2.1sDO@tLPDI.U421^1^Mari Torres,J^1989^6^Influence of Carbon Dioxide Dosing on the Photosynthetic Response and Its Relationship with the Production of Different Light Saturation Plants^^University of Barcelona^^Doctoral Dissertation^^^Dissertation Abstracts Vol. 51:01-C, p.29 (297 pp.)^^^^^^^1051^^^^^^^^^^^Fatsia japonica/Pelargonium hortorumm$@u&d2M ~A^1050^In plants of _Fatsia japonica_ and _Pelargonium x hortorum_ cv. Silipen, grown in controlled environment conditions, three growth treatments with CO2 were carried out: (a) control (constant normal CO2 at 340 vpm), (b) selective enrichment (CO2 constant at 800 vpm during the first two and last two hours of the day, maintaining it at 340 vpm during the rest of the day), and (c) constant CO2 enrichment (800 vpm). After three weeks of growth, experiments were carried out on daily courses (gas exchange, water potential, etc.) in nine different treatments (each growth treatment was measured in its CO2 conditions and in those of the other two), in two populations of leaves of both species; and dry-matter production analysis of different initial LAI plants, as well as other observations (cellular and chloroplastic ultrastructure). The growth treatments with CO2 enrichment gave rise to increases in dry-matter production in both species. The percentage increases in comparison with the control being, 34% and 45% in _Pelargonium x hortorum_ of medium LAI, 49% and 76% in _Pelargonium x hortorum_ of low LAI, and 77% and 77% in _Fatsia japonica_ of medium LAI, in the treatments with selective and constant CO2 enrichment respectively. These increases were due to the effect of CO2 on the physiological determinants of crop growth (Charles-Edwards). The most direct effect is felt on the second determinant (the efficiency of the conversion of light intercepted by vegetal material), on increasing the net photosynthesis in an important way which reverts on the first determinant (the quantity of intercepted radiation by the crop) with the effect of autoacceleration and also additivity due to the better water relations. The most relative efficiency of the treatment with selective enrichment in relation to the continued one was related to the mechanisms implied in the acclimatization (photosynthetic and stomatic), each depending on the type of light saturation of the plant, as well as on a negative effect of autoshading in the continued CO2 enrichment treatment. In Spanish. DkȿDʿD! tPSVWhff~EG~ھVV_^[XWPVf~422^2^Marino,B D^McElroy,M B^1991^1^Isotopic Composition of Atmospheric CO2 Inferred from Carbon in C4 Plant Cellulose^77^349^^127-131^^^^^^^^^^1054^^^^^^^^^^^corn/Zea maysays L.D&GD&_^Z[Pfv DlȿDʿDFDC^1052^Nature DxȿDʿDFD !EFM _XV:u:wuT:Wu:wu T:Wu:w^WPA^1052^The isotopic composition of atmospheric carbon dioxide provides an important constraint for models of the global carbon cycle. It is shown that carbon in C4 plants preserves an isotopic record of the CO2 used in photosynthesis. Data for the maize plant _Zea mays_ yield results for the isotopic composition of atmospheric CO2 consistent with measurements of modern air and air trapped in polar ice. Data from C4 plants may thus be used to extend the isotopic record of atmospheric CO2 into the past, complementing data from other sources.Njv*/FVd^ǚ*vT*rVHL423^2^Marks,S^Clay,K^1990^1^Effects of CO2 Enrichment, Nutrient Addition, and Fungal Endophyte-Infection on the Growth of Two Grasses^34^84^^207-214^^^^^^^^^^1057^^^^^^^^^^^Lolium perenne/perennial ryegrass/Tridens flavus/purpletop grassassC^1055^Oecologia=t5¾aVrJW~3ҋ:̿ua"_r-a"r"F0⽌ڿѿa9u4_^YfA^1055^Increasing atmospheric carbon dioxide (CO2) concentration is expected to increase plant productivity and alter plant/plant interactions, but little is known about its effects on symbiotic interactions with microorganisms. Interactions between perennial ryegrass, _Lolium perenne_ (a C3 plant), and purpletop grass, _Tridens flavus_ (a C4 plant), and their clavicipitaceous fungal endophytes (_Acremonium lolii_ and _Balansia epichloe_, respectively) were investigated by growing the grasses under 350 and 750 uL/L CO2 at two nutrient levels. Infected and uninfected perennial ryegrass responded with increased growth to both CO2 enrichment and nutrient addition. Biomass and leaf area of infected and uninfected plants responded similarly to CO2 enrichment. When growth analysis parameters were calculated, there were significant increases in relative growth rate and net assimilation rate of infected plants compared to uninfected plants, although the differences remained constant across CO2 and nutrient treatments. Growth of purpletop grass did not increase with CO2 enrichment or nutrient addition and there were no significant differences between infected and uninfected plants. CO2 enrichment did not alter the interactions between these two host grasses and their endophytic-fungal symbionts.u(u u 424^2^Marks,S^Strain,B R^1989^1^Effects of Drought and CO2 Enrichment on Competition between Two Old Field Perennials^23^111^^181-186^^^^^^^^^^1060^^^^^^^^^^^Aster pilosus/aster/broomsedge/Andropogon virginicuscusXPP7XPSQR*PjC^1058^New Phytol.ZY[PSQRV.TXXZY[XSQRVWn.TZY[SQRSPW.TZY[SQRSPV.TZY[SQR.TZY[SQA^1058^We studied the effects of drought stress and CO2 enrichment on the competition between _Aster pilosus_ Willd. (aster, C3) and _Andropogon virginicus_ L. (broomsedge, C4) under two CO2 concentrations (350 and 650 uL/L CO2) and two water treatments (well-watered and water-limited). Although broomsedge is the more drought-tolerant species, this did not increase its competitive ability against aster under drought conditions. With CO2 enrichment, aster was a stronger competitor than broomsedge and comprised 75% of above-ground pot biomass in both water treatments. CO2 enrichment also increased aster survival when competing with broomsedge under extreme drought conditions. Although drought stress and CO2 enrichment interacted to affect the two species in different ways, there was no interaction of drought stress and competition; aster was a stronger competitor than broomsedge under CO2 enrichment in both well-watered and water-limited conditions. With future increases in the atmospheric CO2 concentration, aster may delay broomsedge dominance in old-field communities.U+u:425^1^Martin,P^1992^1^EXE: a Climatically Sensitive Model to Study Climate Change and CO2 Enhancement Effects on Forests^25^40^^717-735^^^^^^^^^^1063063${s YP t B${3١ t B${3١ t B${3XPSVQ C^1061^Aust. J. Bot.\${d${Y^[XVWPSQRUPPFd3F~U u#.T uz,&،У3ؚA^1061^Vegetation plays a significant role in determining the local and regional hydrology of ice-free continental surfaces and the dynamics of the atmosphere above it. Vegetation also influences the global climate directly by affecting atmospheric chemistry. In particular, it partially controls the carbon cycle. In turn, vegetation is influenced by climate and changes in the ambient concentration of CO2. This may have important consequences for agriculture and natural resource exploitation. A formal recognition of atmosphere/biosphere interrelationships is crucial but insufficient. Systematic investigations of the interactions between climate, plant physiology and ecology are badly needed. In this spirit, this paper presents the results of numerical simulations performed with the Energy, water and momentum eXchange, and Ecological dynamics (EXE) model at a local scale over periods of 400-800 (simulation) years. EXE constitutes a first attempt to couple a physiologically based water budget and an explicit atmospheric general circulation model (GCM). Within this context, the paper demonstrates through the examples it analyses that both potential stomatal response to CO2 and the possible range of changes in atmospheric relative humidity are likely major factors in determining the ecosystem response to greenhouse warming. Consequently, they should be considered in future studies of this kind. The paper also provides explanations regarding the movements of ecotones, defined as the transition zones between different vegetation assemblages. Taking the North American forest/prairie boundary as a case study, the analysis of the results shows how, in the greenhouse warmed world, St Paul, MN, might look like North Platte, NE. Finally, building on the previous example by using two different models, this study illustrates that results can be strongly model dependent and encourages extreme caution in their interpretation./t426^3^Martin,P^Rosenberg,N J^McKenney,M S^1989^1^Sensitivity of Evapotranspiration in a Wheat Field, a Forest, and a Grassland to Changes in Climate and Direct Effects of Carbon Dioxide^88^14^^117-151^^^^^^^^^^1066^^^^^^^^^^^^^^^^l(7(T(`!t(C^1064^Climatic Change9Nx ]+U / 2 @  (#(Np.(: jjPQRW+BV3rI&+ʸA^1064^Micrometeorological and physiological measurements were used to develop Penman-Monteith models of evapotranspiration for a wheat field in eastern Nebraska, a forest in Tennessee, and a grassland in east-central Kansas. The model fit the measurements well over the periods of observation. Model sensitivities to changes in climatic and physiological parameters were then analyzed. The range of changes considered was established from recent general circulation model output and from review of recent plant physiological research. Finally, climate change scenarios produced by general circulation models for the locations and seasons matching the observed data were applied to the micrometeorological models. Simulation studies show that when all climatic and plant factors are considered, evapotranspiration estimates can differ greatly from those that consider only temperature. Depending on ecosystem and on climate and plant input used, evapotranspiration can differ from the control (no climate or plant change) by about -20 to +40%.>tt6r\ &G\G?=iF<FR427^1^Masle,J^1992^1^Will Plant Performance on Soils Prone to Drought or With High Mechanical Impedance to Root Penetratio n Be Improved under Elevated Atmospheric CO2 Concentration?^25^40^^491-500^^^^^^^^^^1069^^^^^^^^^^^wheat/Triticum aestivumC^1067^Aust. J. Bot.HSQWUr}uDD >r&}&]&M\LD*\Ls=tFD&E|uX=rS٭=A^1067^Plants growing on dry soils or on soils with high mechanical resistance to root penetration grow more slowly and exhibit lower stomatal conductance than those growing on moist and loose soils. In most situations in nature where edaphic stresses develop rather slowly (compared to stresses imposed in most pot experiments conducted under controlled conditions), photosynthesis is mainly reduced via stomatal effects rather than via changes in mesophyll capacity for photosynthesis. Elevated CO2 will induce an increase in the internal partial pressure of CO2, despite stomatal conductance being lowered even further. Photosynthesis will therefore be improved, and leaf turgor will be increased. It is widely thought that growth on dry or hard soils is not carbon limited because levels of soluble carbohydrates in the leaves and root cells are increased. It is shown in this paper than growth on soil with high mechanical resistance does respond to elevated CO2. However, this response is smaller than expected from the increase of carbon assimilation rate because: (a) carbon partitioning is altered so that supplementary carbohydrates are preferentially allocated to the roots; (b) leaf growth sensitivity to internal availability of sugars is lower than in plants growing on loose soils. These alterations of 'sink activity' and carbon partitioning are mediated by unknown signalling factor(s) induced in the roots. It is not known whether the root factors acting in droughted plants are of the same nature. In both droughted and impeded plants the interacting effects of these factors and of ambient CO2 levels are likely to result in improved transpiration efficiency. More experiments are needed  in this area, however, especially to ascertain the relative contribution of changes in growth patterns versus changes in t he patterns of water use. In conclusion, the importance of identifying the nature of the sink limitations induced by root  signals is emphasized. It is a fundamental area of research to be developed not only for assessing growth responses to rising CO2 under edaphic stress, but likely also for reconciling conflicting responses of field-grown and pot-grown plants.vum L.N3 ]^YSQU3SٱC˚${[sNs3]Y[V6u@s6rk>r>t]^_XPQWVU<Ss>%429^4^Masuda,T^Fujita,K^Kogure,K^Ogata,S^1989^1^Effect of CO2 Enrichment and Nitrate Application on Vegetative Growth and ]Dinitrogen Fixation of Wild and Cultivated Soybean Varieties^89^35^^357-366^^^^^^^^^^2051^^^^^^^^^^^soybean/Glycine max/GlC^1073^Soi1 Sci. Plant Nutr.D.~]D0d r|2D4t2 r|D 3]^_YPWVU6r t6|z؋ǃc*x(430^4^Mauney,J R^Lewin,K F^Hendrey,G R^Kimball,B A^1992^1^Growth and Yield of Cotton Exposed to Free-Air CO2 Enrichment^8^11^^213-222^^^^^^^^^^1077^^^^^^^^^^^cotton/Gossypium hirsutumtum L._Z[5>g4doj$&C^1075^Crit. Rev. Plant Sci.7;ZY[XPSQR,7;=SRQ9;[=˚!=:ÚT*ÚZsÚ*Ú5*Ú*Ú=Tó=:ó +A^1075^This experiment successfully grew a cotton crop from germination to maturity with controlled CO2 enrichment to 550 ,umol/mol using a vertical vent pipe array to control the CO2 concentration. Four replications were sufficient to obtain st-atistically significant results. On Day Of Year (DOY) 220, 112 days after planting, the FACE plots had 45% greater dry wei.ght than controls. Thereafter, the FACE plots added weight at a slower rate than the controls, so that at the final harves/t the difference was only 20%. The crop allocated a greater proportion of its dry weight to roots in the FACE plots than i0n the controls. On DOY235 when the total dry weight increase was 39%, the root dry weight increase in the FACE plots was 815%. The uniformity of the crop response within the plots and between replications will allow a greater area to be used in 2future experiments. The area for sampling crop responses can be enlarged from the 12 m used in this experiment. It appears that 18 and perhaps 20 m of the 22-m diameter of the plots can be used for sampling crop response.*N 6WV4431^5^Mbikayi,N T^Hileman,D R^Bhattacharya,N C^Ghosh,P P^Biswas,P K^1988^3^Effects of CO2 Enrichment on the Physiology and5 Biomass Production in Cowpeas (_Vigna unguiculata_ L.) Grown in Open Top Chambers^Proceedings of the International Congre6ss of Plant Physiology, 15-20 February 1988^Society for Plant Physiology and Biochemistry^New Delhi, India^640-645^^^^Vol.II^^^^^^1080^^^^^^^^^^^Vigna unguiculata/cowpea^^^^^^^^^^Sinha,SK^Sane,PV^Bhargava,SC^Agrawal,PK[XþD E E${\ T)C^1078^Vol.IIw \3 Dd2rD u&þD E E${\ TDDD+؁w \3 Dd9A^1078^This study was undertaken to investigate the effects of increased concentrations of carbon dioxide on growth, physi:ology and biomass production in cowpeas subjected to 354, 354 (ambient CO2 in open chamber), 506 and 655 uL/L CO2. The CO2; enriched environment increased plant height, fresh and dry weights of whole plant, nodule numbers and mass, and protein-n432^2^McLaughlin,S B^Norby,R J^1991^3^Atmospheric Pollution and Terrestrial Vegetation: Evidence of Changes, Linkages, and? Significance to Selection Processes^Ecological Genetics and Air Pollution^Springer Verlag, Inc.^New York^61-101^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^Taylor,GE,Jr^Pitelka,LF^Clegg,MTM TG GePSQRWVUsF>rUAssA433^1^McMurtrie,R E^1991^1^Relationship of Forest Productivity to Nutrient and Carbon Supply--a Modeling Analysis^43^9^^87-99^^^^^^^^^^1084084*F*@s]^_ZY[XPSr >sVu ! *؃[Xøu7C^1082^Tree Physiol.ul[Ȃ>rqW~*^sV]F3=tG=tGWS3Ҁ=t G<0r,/DA^1082^A simple model of photosynthetic and nutritional controls over foliar dynamics is analyzed to compare the magnitudeE of the growth response of forest stands to increased rates of photosynthesis and nutrient supply. According to the model,F productivity achieved at canopy closure is sensitive to nutrient supply, except where nutrient availability exceeds the pGlants' uptake capacity. Plants growing under nutrient-limited conditions can only respond positively to enhanced photosyntHhetic rates if they simultaneously increase their nutrient uptake, or reduce nutrient concentrations in stem, branch, rootI or senescing leaf tissue, or shift their carbon allocation in favor of biomass components with low nutrient concentrationJs. In particular, a response is more likely where considerable internal cycling of nitrogen occurs before leaf senescence, or where foliar allocation decreases with decreasing leaf nutrient concentrations.t*^_ZY[X˚@sÚ@sÚH L434^4^McMurtrie,R E^Comins,H N^Kirschbaum,M U F^Wang,Y-P^1992^1^Modifying Existing Forest Growth Models to Take Account of Effects of Elevated CO2^25^40^^657-677^^^^^^^^^^1087^^^^^^^^^^^^^^^678 9 AB0C.D EF!G"H#IJ$K%L&M2N1OPQRSTUV/BC^1085^Aust. J. Bot.8 !޳ڳ֩l;B;?;;;$;O${rH${r PpOA^1085^Most published process models of the growth of forest stands are concerned predominantly with either tree physiologPy or nutrient cycling, concentrating respectively on photosynthetic carbon gain and allocation, or on decomposition and nuQtrient uptake processes. Mechanistic formulations of direct CO2 effects on photosynthesis have been incorporated in some pRhysiology-based models, whereas modifications incorporating direct CO2 effect in nutrient-driven models have usually been Smore empirical. Physiology-based models predict considerable CO2-fertiliser effects, while nutrient driven models tend to Tbe less sensitive to elevated ambient CO2 concentration (_Ca_). This paper describes how effects of elevated _Ca_ can be iUncorporated in these various types of forest growth models. The magnitude of the simulated response to elevated _Ca_ varieVs markedly depending on a particular model's spatial and temporal resolution and on which processes are incorporated. Two Wphysiology-based models of forest canopy processes (MAESTRO and BIOMASS) and a plant-soil model (G'DAY) are considered herXe. MAESTRO and BIOMASS incorporate mechanistic descriptions of the biochemical basis of photosynthesis by C3 plants, whileY G'DAY contains a simplified formulation but includes soil processes. All three models are used to simulate the response tZo an instantaneous doubling of _Ca_. Simulations of MAESTRO and BIOMASS show that on a clear day total canopy photosynthes[is is temperature-dependent with increases of approximately 10, 45 and 70% at 10.25 and 40C respectively. A simulation fo\r a stand of _Pinus radiata_ growing with abundant water and nutrients and mean annual day-time temperature of 14.8C show]s an increase of 25% in annual canopy photosynthesis. On nutrient-limited sites plant responses to elevated _Ca_ are const^rained by feedbacks associated with rates of decomposition and nutrient cycling. According to the G'DAY model, which incor_porates these feedbacks, an instantaneous doubling of _Ca_ leads to a 27% initial productivity increase lasting less than a decade and a more modest increase of 8% sustained in the long term.tҼF~V+vF^_RW&<ta435^2^McMurtrie,R E^Wang,Y-P^1993^1^Mathematical Models of the Photosynthetic Response of Tree Stands to Rising CO2 Concentrations and Temperatures^16^16^^1-13^^^^^^^^^^1090090 <\t<:uFZ'F^+Κ;s^_PSQRVWf~?MC^1088^Plant Cell Environ.}tXvd Ij.5ta~Eu LuEM="d udA^1088^Two published models of canopy photosynthesis, MAESTRO and BIOMASS, are simulated to examine the response of tree setands to increasing ambient concentrations of carbon dioxide (_Ca_) and temperatures. The models employ the same equationsf to described leaf gas exchange, but differ considerably in the level of detail employed to represent canopy structure andg radiation environment. Daily rates of canopy photosynthesis simulated by the two models agree to within 10% across a ranghe of CO2 concentrations and temperatures. A doubling of _Ca_ leads to modest increases of simulated daily canopy photosyntihesis at low temperatures (10% increase at 10C), but larger increases at higher temperatures (60% increase at 30C). The jtemperature and CO2 dependencies of canopy photosynthesis are interpreted in terms of simulated contributions by quantum-skaturated and non-saturated foliage. Simulations are presented for periods ranging from a diurnal cycle to several years. Alnnual canopy photosynthesis simulated by BIOMASS for trees experiencing no water stress is linearly related to simulated amnnual absorbed photosynthetically active radiation, with light utilization coefficients for carbon of epsilon = 1.66 and 2.07 g/MJ derived for _Ca_ of 350 and 700 umol/mol, respectively.u ZǾ@^YXPQW^Vd ^&I;N~o436^3^Miao,S L^Wayne,P M^Bazzaz,F A^1992^1^Elevated CO2 Differentially Alters the Responses of Co-ocurring Birch and Maple} Seedlings to a Moisture Gradient^34^90^^300-304^^^^^^^^^^1093^^^^^^^^^^^Betula populifolia/Acer rubrum/red maple/grey birbC^1091^Oecologia~t &FN~tGIjNFte~t &+N^_[XPWt %_XPQVMtEu&rA^1091^To determine the effects of elevated CO2 and soil moisture status on growth and niche characteristics of birch and smaple seedlings, gray birch (_Betula populifolia_) and red maple (_Acer rubrum_) were experimentally raised along a soil mtoisture gradient ranging from extreme drought to flooded conditions at both ambient and elevated atmospheric CO2 levels. Tuhe magnitude of growth enhancement due to CO2 was largely contingent on soil moisture conditions, but differently so for mvaple than for birch seedlings. Red maple showed greatest CO2 enhancement under moderately moist soil conditions, whereas gwray birch showed greatest enhancements under moderately dry soil conditions. Additionally, CO2 had a relatively greater amxeliorating effect in flooded conditions for red maple than for gray birch, whereas the reverse pattern was true for these yspecies under extreme drought conditions. For both species, elevated CO2 resulted in a reduction in niche breadths on the zmoisture gradient; 5% for gray birch and 23% for red maple. Species niche overlap (proportional overall) was also lower at{ elevated CO2 (0.98 to: 0.88:11%). This study highlights the utility of experiments crossing CO2 levels with gradients of |other resources as effective tools for elucidating the potential consequences of elevated CO2 on species distributions and potential interactions in natural communities.r&\tr_^Z[PSQRVWf~R 6DE HchchEDt&DE&DE>U}Ǹ؋^R 6D_^ZY[XSQWV&Lc~*VN&<\t^&Lc+˃437^2^Miglietta,F^Raschi,A^1993^1^Studying the Effect of Elevated CO2 in the Open in a Naturally Enriched Environment in Central Italy^123^104/105^^391-400^^^^^^^^^^1096^^^^^^^^^^^^^^^^&_^ZY[XPSQRVWQS[r&]_^ZY[XPSQRVWRSo limiting CO2 which are different from WT and cia-5 but which are consistent with changes in activity being initiated by A^1094^A gas vents area was recently localized in Central Italy. The gas emitted from the vents is composed by 92% of carbon dioxide and this produces an anomaly in the composition of the atmosphere over an area of about 2 ha. Atmospheric carbon dioxide concentration was measured by means of an infrared gas analyzer and diffusion tubes in several points and for some days within the area. Measurements revealed that the site can be at least divided into three sub-areas having increasing CO2 concentration in the air. A preliminary analysis of natural vegetation in the area was conducted by counting stomatal and epidermal cells number and measuring guard cell size on leaves of several oak trees growing both near and far away from the vents. This analysis suggested that elevated CO2 may have reduced the size of guard cells leaving stomatal density and stomatal index unaltered.[X˃S~˃S~PSWVUt Lt+s3|]^_[XPVSQR;:Y[r &]^&438^3^Miller,W F^Dougherty,P M^Switzer,G L^1987^3^Effect of Rising Carbon Dioxide and Potential Climate Change on Loblolly Pine Distribution, Growth, Survival, and Productivity^The Greenhouse Effect, Climate Change, and U.S. Forests^The Conservation Foundation^Washington, D.C.^157-187^^^^^^^^^^1098^^^^^^^^^^^Pinus taeda/loblolly pine^^^^^^^^^^Shands,WE^Hoffman,JSA^1097^An appreciable northward and northeastward shift in the range of loblolly pine is forecast by the year 2080. The projected southern boundary of the range may extend from the central Louisiana through central Mississippi and central Alabama, and then through northern Georgia, northern South Carolina, and eastern North Carolina. An increase in the probability of summer drought, with durations of up to three months, is also projected throughout the southern portion of the adjusted range. Yields are expected to be reduced over much of the range because of reduced soil water and changes in the edaphic substrates in the adjusted range. Regeneration practices probably will have to be modified to ameliorate the effects of the anticipated climatic change. Ripping, the use of containerized seedlings, and increased herbaceous weed control probably will be necessary under the expected changed conditions to assure satisfactory regeneration success. Tree-breeding programs should be dynamic, anticipating the possibility of range shift and reduced productive potential. Predictions of reduced productive potentials may be overly pessimistic in view of the possibility of increased water-use efficiency related to elevated carbon dioxide levels.tI;3B:Bt ^ Fr~t ^ ~ t ^ 6vjtI;jjvv439^2^Miszalski,Z^Mydlarz,J^1990^1^SO2 Influence on Photosynthesis of Tomato Plants (_Lycopersicon esculentum_ L.) at Different CO2 Concentrations^42^24^^2-8^^^^^^^^^^1101^^^^^^^^^^^tomato/Lycopersicon esculentum^^^^^ill."FvFV;uC^1099^PhotosyntheticaFVFovjv v:;V FF VFV~ u ~u3^ v v;; u3^ 6A^1099^The net photosynthetic rate (Pn) decrease after SO2 fumigation of tomato plants (_Lycopersicon esculentum_ L. cv. Gem) was strongly dependent on the CO2 level in the plants' atmosphere, especially in the post-fumigation period. Differences in SO2 action mode at different CO2 concentrations did not depend directly on Pn.&9tJ@Pj FVLNPR:;440^2^Miszalski,Z^Ziegler,H^1989^1^Sulfite Sensitivity of Oat (_Avena sativa_ L.) Protoplasts^90^185^^233-243^^^^^^^^^^1104^^^^^^^^^^^oat/Avena sativaiva L.UVWv ~ FF~u~u _^FVVFvv;; u _C^1102^Biochem. Physiol. Pflanzen.u=u _^96J} _^t 96JtF9~txFDFVNLVF_A^1102^Determination of the efflux of K+ and 14C fixation products showed isolated oat protoplasts to be in good condition after 1 h incubation in 10 mM sulfide. Evolution of O2 in light by protoplasts incubated in darkness for up to 90 min at 25C did not change significantly, but after incubation in light the photosynthesis rate slowly decreased. The decrease in the photosynthesis rate after incubation in the presence of 10 mM sulfite when measured with the 14C fixation method is much smaller than when measured by O2 evolution. This suggests strong sulfite oxidation. Using both methods it was found that protoplasts incubated in a medium with sulfite and 1 mM bicarbonate at pH 7.0 were more sensitive than when incubated with 5 mM bicarbonate at pH 7.6. Data presented here show that the lower sensitivity to SO2 of plants at high CO2 concentration is not only due to higher stomatal resistance but also to differences in sensitivity of mesophyll cells.^v PC;441^1^Mitchell,R^1990^3^Uncertainty in Prediction of Effects of Environmental Change on Wheat Yields^The Greenhouse Effect and Primary Productivity in European Agro-ecosystems; 5-10 April 1990; Wageningen, The Netherlands^Pudoc^Wageningen^51-52^^^^^^^^^^^^^^^^^^^^^wheat/Triticum aestivum^^^^^^^^^^Goudriaan,J^van Keulen,H^van Laar,HHH H^&pt;Fv&p442^7^Mo,G^Nie,D^Kirkham,M B^He,H^Ballou,L K^Caldwell,F W^Kanemasu,E T^1992^1^Root and Shoot Weight in a Tallgrass Prairie under Elevated Carbon Dioxide^76^32^^193-201^^^^^^^^^^1108^^^^^^^^^^^Andropogon gerardii/big bluestem/Andropogon scoparius/little bluestem/Sorghastrum nutans/Indiangrass/Sporobolus asper/tall dropseed/Panicum virgatum/switchgrass/Bouteloua curtipendula/sideoats grama/Dichanthelium oligosanthes/Scribner panicum/Poa pratensis/Kentucky bluegrass/Carex spp./Artemisia ludoviciana/Louisiana sagewort/Ambrosia spp./ragweed/Aster spp./aster/Amorpha canescens/lead plant/Asclepias spp./milkwee"d/Kuhnia eupatorioides/false boneset/Salva pitcheri/pitcher's sage/Solidago spp./golden rod/Rosa arkansana/Arkansas rose^^ago spp./golden rod/Rosa arkansana/Arkansas rose F u3_^ ^F V &G&WPR* u3_^ 6h6fFPFPFPFPC^1106^Environ. Exp. Bot;^F&G FV&G&Wn&lv v  um6h6fFPFPFPFPF V F;F@A^1106^The atmospheric concentration of carbon dioxide (CO2) is increasing and knowing how this will affect native vegetation is important. The objective of this study was to determine the effect of elevated CO2 on root growth in a tallgrass prairie kept at a high water level (73 cm of water in a 200 cm soil profile) and a low water level (66 cm of water in 200 cm). Sixteen cylindrical plastic chambers were placed on the prairie to maintain two levels of CO2 (ambient or twice ambient). At the end of two seasons' exposure to the different treatments, dry weight and length of roots in the 0-40 cm depth were determined. Shoot growth also was measured to determine shoot:root ratios. The CO2 and water treatments had no significant effect on root dry weight in the 0-40 cm depth. In the 0-10 cm depth, doubled CO2 reduced dry weight and length of roots of plants grown under the high water level by 47 and 31%, respectively. Warm-season, C4 grasses had the highest shoot dry weight, which was greatest under the high water, ambient CO2 treatment. The shoot:root ratio did not change with treatment.sFFU^ @N^ V!sFFUFB^ V!sVFVFUVWv~ N443^2^Moe,R^Mortensen,L M^1986^3^CO2 Enrichment in Norway^Status and CO2 Sources^CRC Press, Inc.^Boca Raton, Florida^59-73^^^^I^^Carbon Dioxide Enrichment of Greenhouse Crops^^^^1110^^^^^^^^^^^^^^^^^^^^^Enoch,HZ^Kimball,BAAB A4F2˸BA^1109^In the last years it has been a great upsurge in the interest for CO2 enrichment of greenhouse crops in Norway. The sources of CO2 are mainly pure liquid CO2 from containers, followed by kerosene and propane burning. Due to risk of air pollution (CO, C2H4, SO2, NOx) by use of kerosene and propane, pure CO2 is recommended to sensitive crops (for example, tomato, cucumber, and flowering plants). Kerosene burning is mainly used in lettuce crops in Norway. Equipment for control of CO2 supply and measurement of the CO2 concentration in the greenhouse atmosphere is available. The cause of increasing interest in CO2 application in Scandinavia is better knowledge about the effects of CO2 enrichment on different crops, more knowledgeable growers, tighter greenhouses, and reduced CO2 flux from decomposition of organic material. Results from research are presented as well as practical experiences in Norwegian greenhouse operations. In the research some of the most important greenhouse species have been studied. The overall effects of CO2 enrichment are fast growth rate, increased yields, and improved plant quality. An important observation is the beneficial effect of CO2 application at low light levels during the winter months (October to March) in Scandinavia. CO2 enrichment lowers the light compensation point and makes artificial lighting more profitable. On basis of the results, a CO2 level of 800 to 1000 uL/L is recommended for most species. Intermittent CO2 enrichment showed promising results in chrysanthemums and further research is following up the idea that intermittent CO2 application might be as beneficial as continuous CO2 application. CO2 enrichment seems to increase the optimum temperature for photosynthesis and growth. More research on intermittent CO2 enrichment and temperature/CO2 interaction studies is needed before final conclusions can be made.<uоۣ <t DuPD${X$dۣ3 t444^1^Mohapatra,P K^1990^1^CO2 Enrichment and Physiology of Inflorescence Development in Wheat^42^24^^9-15^^^^^^^^^^1113^^^^^^^^^^^wheat/Triticum aestivumvum L.]ZYXz:nh u0]ZY[XSQW3;t<-uGF*F3 C^1111^Photosynthetica~D*s t)V+.<3 ;r@^V t؃_Y[PSQRU;t y ؃A^1111^The effect of CO2 fertilization on growth, development and sucrose concentration of the shoot apex of wheat plants (_Triticum aestivum_ L. cv. Warimba) growing in a controlled environment growth cabinet (photoperiod 16h, irradiance 375 umol/m2/s, and temperature 20 +/- 1C) was observed. CO2 enrichment from germination onwards stimulated shoot growth, but did not affect the growth, morphology and sugar concentration of the inflorescence on the main shoot.aeC445^5^Mooney,H A^Drake,B G^Luxmoore,R J^Oechel,W C^Pitelka,L F^1991^1^Predicting Ecosystem Responses to Elevated CO2 Concentrations^67^41^^96-104^^^^^^^^^^^^^^^^^^^^^^^^^^^^^T +DLT\KZY@6 LIC^1114^BioSci. >Hu 5_^]ˀ>Hu5;|5;|446^3^Morin,F^Andre,M^Betsche,T^1992^1^Growth Kinetics, Carbohydrate, and Leaf Phosphate Content of Clover (_Trifolium subterraneum_ L.) after Transfer to a High CO2 Atmosphere or to High Light and Ambient Air^17^99^^89-95^^^^^^^^^^1118^^^^^^^^^^^clover/Trifolium subterraneum^^^^^.5&&=G>+>5Y硓5;5t+&5 t#>5>5>5G5&&"]UC^1116^Plant Physiol.A^1116^Intact air-grown (photosynthetic photon flux density, 400 microeinsteins per square meter per second) clover plants (_Trifolium subterraneum_ L.) were transferred to high CO2 (4000 microliters CO2 per liter; photosynthetic photon flux density, 400 microeinsteins per square meter per second) or to high light (340 microliters CO2 per liter; photosynthetic photon flux density, 800 microeinsteins per square meter per second) to similarly stimulate photosynthetic net CO2 uptake. The daily increment of net CO2 uptake declined transiently in high CO2, but not in high light, below the values in air/standard light. After about 3 days in high CO2, the daily increment of net CO2 uptake increased but did not reach the high light values. Nightly CO2 release increased immediately in high light, whereas there was a 3-day lag phase in high CO2. During this time, starch accumulated to a high level, and leaf deterioration was observed only in high CO2. After 12 days, starch was two- to threefold higher in high CO2 than in high light, whereas sucrose was similar. Leaf carbohydrates were determined during the first and fourth day in high CO2. Starch increased rapidly throughout the day. Early in the day, sucrose was low and similar in high CO2 and ambient air (same light). Later, sucrose increased considerably in high CO2. The findings that (a) much more photosynthetic carbon was partitioned into the leaf starch pool in high CO2 than in high light, although net CO2 uptake was similar, and that (b) rapid starch formation occurred in high CO2 even when leaf sucrose was only slightly elevated suggest that low sink capacity was not the main constraint in high CO2. It is proposed that carbon partitioning between starch (chloroplast) and sucrose (cytosol) was perturbed by high CO2 because of the lack of photorespiration. Total phosphate pools were determined in leaves. Concentrations based on fresh weight of orthophosphate, soluble esterified phosphate, and total phosphate markedly declined during 13 days of exposure of the plants to high CO2 but changed little in high light/ambient air. During this time, the ratio of orthophosphate to soluble esterified phosphate decreased considerably in high CO2 and increased slightly in high light/ambient air. It appears that phosphate uptake and growth were similarly stimulated by high light, whereas the coordination was weak in high CO2. t vXM  vX vX 447^1^Morison,J I L^1988^1^Effect of Increasing Atmospheric CO2 on Plants and Their Responses to Other Pollutants, Climatic and Soil Factors^91^17^^113-122^^^^^^^^^^1121121A QVW}t_^tيl& m2YQPEus@XPE=C^1119^Aspects Appl. Biol.yH/m x*3˺#ځ#t PS ^]rE]^ZY[XP+XSA^1119^The profound effects of increased atmospheric CO2 on plant growth are described. The interactions of increased CO2 with low light, water supply, low temperature and other pollutants are shown to be substantial. It is suggested that for the quantitative prediction of plant growth in future atmospheres the traditional physiological research needs to be accompanied by more studies at the crop and community level of organisation.wwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwww448^1^Morison,J I L^1987^3^Intercellular CO2 Concentration and Stomatal Response to CO2^Stomatal Function^Stanford University Press^Stanford, California^229-251^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^Zeiger,E^Farquhar,GD^Cowan,IRCa/light/temperature/vaZpor pressure deficit/WUE^^^^^^^^^^Zeiger,E^Farquhar,G D^Cowan,I Rwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwww449^1^Morison,J I L^1990^1^Plant and Ecosystem Responses to Increasing Atmospheric CO2^92^5^^69-70^^124wwwwwwwwwwwwwwwwwC^1123^Treewwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwww450^1^Morison,J I L^1987^1^Plant Growth and CO2 History^77^327^^560^^126wwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwC^1125^Naturewwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwww451^1^Morison,J I L^1989^3^Plant Growth in Increased Atmospheric CO2^Proceedings of the Community of European Communities Symposium, Carbon Dioxide and Other Greenhouse Gases: Climatic and Associated Impacts; 3-5 November 1986; Brussels, Belgium^Kluwer Academic Publishers^Dordrecht, The Netherlands^228-244^^^^^^^^^^1128^^^^^^^^^^^^^^^^^^^^^Fantechi,R^Ghazi,AwwwwwA^1127^The major direct and indirect effects of increasing atmospheric CO2 concentration on plant growth are discussed. The physiological processes likely to be affected include net photosynthesis, partitioning and development and stomatal conductance. Attention is drawn to problems in extrapolating from short term experiments and measurements at low scales of organisation to likely effects of CO2 in the field. In particular, it is argued that the likely magnitudes of the negative feedbacks between canopy evaporation, canopy temperature, soil evaporation and local and regional vapour pressure deficit are such that many predictions have overestimated the decrease of evaporation from crops. The increasing contributions that  mechanistic crop-weather models formulated at the level of whole canopies will make to exploring the sensitivity of plant growth to increased CO2 is highlighted.DI $J3,D*q07y7o03o(47f452^1^Morison,J I L^1993^1^Response of Plants to CO2 under Water Limited Conditions^123^104/105^^193-209^^^^^^^^^^1131^^^^glycolate DH activities. Other known mutants of the CCM show patterns of PGPase and glycolate DH activity after transfer t A^1129^The influence of increased atmospheric CO2 on the interaction between plant growth and water use is proving to be one of the most profound impacts of the anthropogenic 'Greenhouse Effect'. This paper illustrates the interaction between CO2 and water in plant growth at a range of scales. Most published work has concentrated on water use efficiency, especially at shorter time scales, and has shown large increases of leaf water use efficiency with increased CO2. However, the magnitude of the effect is variable, and does not consistently agree with predictions from simple leaf gas exchange considerations. The longer the time scales considered, the less the information and the more the uncertainty in the response to CO2, because of the additional factors that have to be considered, such as changes in leaf area, respiration of non-photosynthetic tissues and soil evaporation. The need for more detailed studies of the interactions between plant evaporation, water supply, water status and growth is stressed, as increased CO2 can affect all of these either directly, or indirectly through feedbacks with leaf gas exchange, carbon partitioning, leaf growth, canopy development and root growth.#J@J^^^^^^^^^^^^"=AQ H_sE$=(V@"Z%Mɗɗ!'R2453^4^Moroney,J V^Togasaki,R K^Husic,H D^Tolbert,N E^1987^1^Evidence That an Internal Carbonic Anhydrase Is Present in 5% CO2-Grown and Air-Grown _Chlamydomonas_^17^84^^757-761^^^^^^^^^^1134^^^^^^^^^^^Chlamydomonas reinhardtii^^^^pC^1132^Plant Physiol.!nd longer stem and more lateral breaks in _Chrysanthemum_. Time to flowering was significantly reduced by CO2 enrichment i?n _Saintpaulia_, but was generally not affected in _Chrysanthemum_. Number of flowers and flowerbuds was increased by CO2 @application in both species. Constant high CO2 concentration generally had effects superior to that of the intermittent treatments.~Undo |Ctrl+Z-D$NUPB456^1^Mortensen,L M^1991^1^Effects of Temperature, Light and CO2 Level on Growth and Flowering of Miniature Roses^93^5^^295-300^^^^^^^^^^1143^^^^^^^^^^^rose/Rosa!Dd}7 5C^1141^Norw. J. Agric. Sci.:\WPC60DOS\VMATHSYN.WFW?t꤀D (jd>$"8>F"d@EA^1141^The effect of different temperatures (18, 21, 24, 27 and 30C), supplementary photosynthetic photon flux densities F(2, 60 and 120 umol/m2/s PPFD) and CO2 concentrations (345 and 900 uL/L) on growth and flowering of the miniature rose culGtivar Orange Meillandina were studied at 60N latitude during winter. Growth rate was very low and few flowers developed aHt the lowest PPFD level irrespective of temperature. When the PPFD level was increased to 60 umol/m2/s plant dry weight anId number of flowers increased significantly. A further increase in PPFD level to 190 umol/m2/s gave a significant, but smaJller effect. Increasing the temperature from 18 to 30C at the two highest PPFD caused an almost linear decrease in days uKntil sale (five open flowers), plant dry weight and plant height. The effect of CO2 concentration (345 and 900 uL/L) was sLtudied at 24C. CO2 enrichment increased plant dry weight (15-25%) while there was only a small effect or no effect at all on the other growth parameters.?*N457^1^Mortensen,L M^1992^1^Effects of Ozone Concentration on Growth of Tomato at Various Light, Air Humidity and Carbon Dioxide Levels^53^49^^17-24^^^^^^^^^^1146^^^^^^^^^^^tomato/Lycopersicon esculentumtum Mill.%[;JYc:4CC^1144^Scientia Hortic. $j" dm[=8s]he#M>WwQA^1144^The effect of ozone (O3) concentration on the growth of _Lycopersicon esculentum_ was studied at different photosynRthetic photon flux densities (PPFD), relative air humidities (RH) and carbon dioxide (CO2) concentrations. Increasing the SO3 concentration from <10 to 85 nL/L for 6 h per day reduced the shoot dry weight 35% at 70% RH and 62% at 90% RH. IncreasTing the PPFD from 100 to 350 umol/m2/s significantly reduced the effect of O3 in one of two experiments. The most pronouncUed interaction between RH, PPFD and O3 was found on plant height. High O3 levels generally decreased plant height at low PVPFD and had no, or a stimulating, effect on high PPFD. Raising the RH from 70 to 90% significantly increased the negative Weffect of O3 on height. Increasing the O3 concentration from <10 to 65 nL/L significantly decreased plant height at low CO2 concentration (300-340 uL/L), but small effects were found at high CO2 concentration (700-800 uL/L). >*Y458^1^Mortensen,L M^1985^1^Nitrogen Oxides Produced during CO2 Enrichment. I. Effects on Different Greenhouse Plants^23^10Z1^^103-108^^^^^^^^^^1149^^^^^^^^^^^Lactuca sativa/lettuce/Cucumis sativus/cucumber/Lycopersicon esculentum/tomato/Saintpau[lia ionantha/Rosa/Kalanchoe blossfeldiana/Chrysanthemum morifolium/Helxine soleirolii/Hedera helix/English ivy/Nephrolepis exaltataltataM?xxx,OC^1147^New Phytol.N;SCS,,^A^1147^Plants were grown in chambers with CO2 enrichment (1000 uL/L) and with or without the addition of 0.85 uL/L nitroge_n oxides (NOx). The following species were tested: _Lactuca sativa_ (lettuce), _Cucumis sativus_ (cucumber), _Lycopersicon` esculentum_ (tomato), _Saintpaulia ionantha, Rosa, Kalanchoe blossfeldiana, Chrysanthemum x morifolium, Helxine soleiroliai, Hedera helix,_ and _Nephrolepis exaltata_. All species responded positively to an increase in CO2 level from 330 to 100b0 uL/L. The dry weights of tomato, roses and _Saintpaulia_ responded negatively to the addition of NOx. In tomato, the redcuced dry weight was due to reduction in shoot length and leaf area. In roses the stem was shorter and in _Saintpaulia_ thed leaves smaller when NOx was added. Furthermore, the time to flowering increased and number of flowers/flower buds decreased in _Saintpaulia_.TV\:(:,,h:f459^1^Mortensen,L M^1985^1^Nitrogen Oxides Produced during CO2 Enrichment. II. Effects on Different Tomato and Lettuce Cultivars^23^101^^411-415^^^^^^^^^^1152^^^^^^^^^^^Lycopersicon esculentum/tomato/Lactuca sativa/lettucea/lettuce\C^1150^New Phytol.iA^1150^Eight cultivars of _Lycopersicon esculentum_ (tomato) and six cultivars of _Lactuca sativa_ (lettuce) were subjectejd to CO2-enriched air (1000 uL/L) containing 0.7 or 0.9 uL/L nitrogen oxides (NOx). CO2 enrichment without NOx significantkly increased the dry weight of all tomato (35-81%) and lettuce cultivars (25-101%). In six of the eight tomato cultivars tlhe dry weight was reduced by the addition of NOx. The mean relative growth rate (RGR) decreased by 4-19% depending on the mcultivar. This meant that the benefit of CO2 enrichment was almost completely eliminated in most of the cultivars. Marginanl leaf necrosis appeared in some of the cultivars, while in others no visible injury developed. None of the lettuce cultivars was significantly affected by the addition of NOx.`<@0||q?Ljp460^1^Mortensen,L M^1986^1^Nitrogen Oxides Produced during CO2 Enrichment. III. Effects on Tomato at Different Photon Flux Densities^23^104^^653-660^^^^^^^^^^1155^^^^^^^^^^^Lycopersicon esculentum/tomatol./tomatollgC^1153^New Phytol.\tllsA^1153^Seedlings of _Lycopersicon esculentum_ (tomato) were subjected to CO2-enriched air (1000 uL/L) containing 1.5 uL/L tnitrogen oxides (NOx) for 25 d at four photon flux densities (30, 95, 175, and 250 umol/m2/s PAR). CO2 enrichment without uNOx significantly increased the dry weights (47 to 93%) at all light levels. Addition of NOx strongly reduced the mean dryv weight at the lowest light level even below that of the unenriched control. At the two highest light levels, NOx reduced wthe dry weight, but much less than at the lowest level. NOx caused severe leaf injury at the lowest light level, but this xeffect disappeared with increased photon flux density. A system was constructed for measurement of the net CO2 exchange rayte (CER) for single plants. Short-term measurements showed significant reductions of CER when the NO concentration was inczreased from 0 to 9 uL/L at 550 umol/m2/s but almost no effect at 150 to 200 umol/m2/s. NO caused similar percentage reduct{ions of CER at 335 and 1000 uL/L CO2. The absorption of NO was not significantly affected by increasing the photon flux density from 150 to 550 umol/m2/s.x461^1^Mortensen,L M^1987^1^Review: CO2 Enrichment in Greenhouses. Crop Responses^53^33^^1-25^^^^^^^^^^1158^^^^^^^^^^^^^^^qC^1156^Scientia Hortic.X`PX`hpxA^1156^The interest in CO2 enrichment has risen and declined several times throughout this century. During the last few years the interest of CO2 enrichment has strongly increased, mainly due to a better scientific understanding of how CO2 affects plants and due to the introduction of non-polluting CO2 sources. CO2 enrichment decreases the oxygen inhibition of photosynthesis and increases the net photosynthesis in plants. This is the basis for increased growth rates caused by CO2 at low as well as at high light levels. Elevated CO2 concentrations also increase the optimal temperature for growth. Pot plants, cut flowers, vegetables and forest plants show very positive effects from CO2 enrichment by increased dry weight, plant height, number of leaves and lateral branching. Plant quality expressed by growth habit and number of flowers is often enhanced by CO2 enrichment. The rooting of cuttings is often stimulated by high CO2 levels. The optimal CO2 concentration for growth and yield seems to lie between 700 and 900 uL/L and this CO2 level is generally recommended in greenhouses. CO2 concentrations higher than 1000 uL/L might cause growth reductions and leaf injuries, and certainly do increase the loss of CO2 due to leakage from the greenhouse. Continuous CO2 enrichment during the light period seems to be superior to intermittent CO2 application. CO2 enrichment during periods of ventilation of the greenhouse increase the yield of cucumber, while some other species seem to be less affected. Air pollution in connection with the burning of hydrocarbons for CO2 enrichment might cause visible or invisible injuries to plants. The safest source of CO2 is pure liquid CO2 from containers, which is recommended for general use for greenhouse crops. Further research with the CO2 factor should mainly be concentrated on how CO2 enrichment affects the optimal levels of temperature and air humidity for plant growth and quality.462^2^Mortensen,L M^Gislerod,H R^1989^1^Effect of CO2, Air Humidity, and Nutrient Solution Concentration on Growth and Transpiration of Begonia x hiemalis Fotsch^94^54^^184-189^^^^^^^^^^1161^^^^^^^^^^^Begonia hiemalismalisə}C^1159^Gartenbauwiss.ÙǃÃUU癙A^1159^The effects of CO2 concentration, relative air humidity (RH), and concentration of the nutrient solution (NC) were studied on _Begonia x hiemalis_ plants in growth rooms. The plants were grown from rooted cuttings until flowering at a photon flux density of 110 umol/m2/s. Plant dry weight was significantly increased by increasing the CO2 concentrations from 340 to 900 uL/L at normal (2.0 mS/cm) and high NC (4.0 mS/cm), but not at the low level (1.0 mS/cm). Number of leaves and flowers were enhanced by CO2 enrichment at normal and high NC, but no effects were found at low NC. The effect of CO2 enrichmewnt on dry weight was larger at 60 than at 85% RH. Increasing the RH-level from 60 to 85% particularly increased the dry weight at 340 uL/L CO2 at normal and high NC. A normal NC generally gave the best growth of the plants. A high NC, however, counteracted the negative effects of high RH on plant quality (large leaves and voluminous plants). Transpiration or water consumption of the plants was strongly decreased by either increasing the CO2 or RH level.ꪪ463^2^Mortensen,L M^Moe,R^1992^1^Effects of CO2 Enrichment and Different Day/Night Temperature Combinations on Growth and Flowering of _Rosa_ L. and _Kalanchoe blossfeldiana_ v. Poelln^53^5^^145-153^^^^^^^^^^1164^^^^^^^^^^^Rosa/rose/Kalanchoe blossfeldianadianaUTဃÁꪪÌC^1162^Scientia Hortic.UUUTA^1162^The effects of increasing the CO2 concentration from 350 to 700 uL/L on growth and flowering of _Rosa_ L. and _Kalanchoe blossfeldiana_ at four different day/night temperature combinations (20/20C, 23/14C and 17/26C day/night, and 20/20C with 2 h at 14C in the morning) were studied in 6 growth chambers. An increase in the CO2 concentration resulted in enhanced total dry weight, stem:leaf fresh weight ratio, flower fresh weight, length and diameter of the rose shoot, while the number of days until flowering was not affected. With the 17/26C treatment, rose shoots were 3-4 cm shorter, and with the 23/14C treatment flowering occurred about 2 days earlier than with the other temperature treatments. The results were the same for _Rosa_ cultivars 'Frisco' and 'Kiss'. No significant interactions between CO2 and temperature were found. Plant dry weight and fresh weight of flowers in _Kalanchoe_ were generally enhanced by CO2 enrichment. The effects of CO2 on dry weight, plant height and flower stem length were greater with the 23/14C treatment compared with the effects of the other temperature treatments. A constant temperature (20/20C) and the 23/14C treatments gave the shortest and tallest plants, respectively.UU464^2^Mortensen,L M^Sandvik,M^1987^1^Effects of CO2 Enrichment at Varying Photon Flux Density on the Growth of _Picea abies_ (L.) Karst. Seedlings^70^2^^335-342^^^^^^^^^^1167^^^^^^^^^^^Picea abies/Norway spruceuceꪪC^1165^Scand. J. For. Res.UUUT灙A^1165^Seedlings of Norway spruce (_Picea abies_ (L.)) were grown at 335 and 1000 uL CO2/L for 118 days in growth rooms at different irradiance levels. Photon flux density ranging from 8.6 to 34.6 mol/m2/day (PAR) was given either as constant light or as alternating levels in intervals of two or six hours. CO2 enrichment increased the plant dry weight from 36% to 105% by increasing photon flux density from 8.6 to 25.9 mol/m2/day. At constant light the dry weight apparently reached its maximum at a photon flux density of 25.9 mol/m2/day. At the lower radiation levels alternating in CO2 enriched air gave slightly higher dry weights compared to constant light levels. At the highest radiations the effect on dry weight was the opposite. High CO2 concentration and 300 umol/m2/s constant light (25.9 mol/m2/day) gave the best growth and quality of plants. Top, root, stem and foliage weight were proportionally affected. Shoot length was enhanced by CO2 enrichment. Shoot weight per cm was substantially increased both by CO2 enrichment and increasing photon flux density.465^2^Mortensen,L M^Ulsaker,R^1985^1^Effect of CO2 Concentration and Light Levels on Growth, Flowering and Photosynthesis of _Begonia x hiemalis_ Fotsch^53^27^^133-141^^^^^^^^^^1170^^^^^^^^^^^Begonia hiemalislisUUC^1168^Scientia Hortic.ꪪA^1168^Increasing the CO2 concentration from 330 to 900 uL/L significantly increased the dry weight, number of leaves and flowers and reduced the time until flowering at a range of light levels (45, 130, 270 and 390 umol/m2/s). The mean relative growth rate was enhanced 16% by CO2 enrichment. The plants flowered 7 days earlier in CO2-enriched air at the lowest light level, but not earlier at the highest level. Generally the effect of increasing the CO2 concentration from 900 to 1500 uL/L was negligible. Increasing the irradiance from 45 to 270 umol/m2/s significantly increased plant growth and number of flowers, and reduced the time until flowering. Net photosynthetic rate measured by net CO2 uptake of the plants was increased by increasing the CO2 concentration from 330 to 1500-2000 uL/L at 45, 120 and 195 umol/m2/s photon flux density. The effect of CO2 enrichment was similar at different air temperatures (16, 20, 24 and 28C). Oxygen inhibition of photosynthesis increased with temperature, but was substantially reduced by elevated CO2 concentration.UT466^1^Mott,K A^1988^1^Do Stomata Respond to CO2 Concentrations Other than Intercellular?^17^86^^0200-0203^^^^^^^^^^1173^^^^^^^^^^^Xanthium strumarium/Helianthus annuusannuus L.πꪪC^1171^Plant Physiol.癙猌UUUTဃÁA^1171^Most studies on stomatal responses to CO2 assume that guard cells respond only to intercellular CO2 concentration and are insensitive to the CO2 concentrations in the pore and outside the leaf. If stomata are sensitive to the CO2 concentration at the surface of the leaf or in the stomatal pore, the stomatal response to intercellular CO2 concentration will be incorrect for a 'normally' operating leaf (where ambient CO2 concentration is a constant). In this study asymmetric CO2 concentrations for the two surfaces of amphistomatous leaves were used to vary intercellular and leaf surface CO2 concentrations independently in _Xanthium strumarium_ L. and _Helianthus annuus_ L. The response of stomata to intercellular CO2 concentration when the concentration at the leaf surface was held constant was found to be the same as the response when the surface concentration was varied. In addition, stomata did not respond to changes in leaf surface CO2 concentration when the intercellular concentration for that surface was held constant. It is concluded that stomata respond to intercellular CO2 concentration and are insensitive to the CO2 concentration at the surface of the leaf and in the stomatal pore.467^1^Mott,K A^1990^1^Sensing of Atmospheric CO2 by Plants^16^13^^731-737^^^^^^^^^^1176176C^1174^Plant Cell Environ.A^1174^Despite recent interest in the effects of high CO2 on plant growth and physiology, very little is known about the mechanisms by which plants sense changes in the concentration of this gas. Because atmospheric CO2 concentration is relatively constant and because the conductance of the cuticle to CO2 is low, sensory mechanisms are likely to exist only for intercellular CO2 concentration. Therefore, responses of plants to changes in atmospheric CO2 will depend on the effect of these changes on intercellular CO2 concentration. Although a variety of plant responses to atmospheric CO2 concentration have been reported, most of these can be attributed to the effects of intercellular CO2 on photosynthesis or stomatal conductance. Short-term and long-term effects of CO2 on photosynthesis and stomatal conductance are discussed as sensory mechanisms for responses of plants to atmospheric CO2. Available data suggest that plants do not fully realize the potential increases in productivity associated with increased atmospheric CO2. This may be because of genetic and environmental limitations to productivity or because plant responses to CO2 have evolved to cope with variations in intercellular CO2 caused by factors other than changes in atmospheric CO2.x468^1^Mousseau,M^1993^1^Effects of Elevated CO2 on Growth, Photosynthesis and Respiration of Sweet Chestnut (_Castanea sativa_ Mill.)^123^104/105^^413-419^^^^^^^^^^1179^^^^^^^^^^^sweet chestnut/Castanea sativa^^^^^^^^^^ nd to limiting CO2 conditions: it does not induce any known aspects of the CCM and it does not show changes in PGPase or A^1177^Two year old sweet chestnut seedlings (_Castanea sativa_ Mill.) were grown in pots at ambient (350 umol/mol) and double (700 umol/mol) atmospheric CO2 concentration in constantly ventilated greenhouses during entire growing seasons. CO2 enrichment caused either no significant change or a decrease in shoot growth response, depending on yearly weather conditions. Similarly, leaf area was either reduced or unchanged under elevated CO2. However, when grown under controlled conditions in a growth chamber, leaf area was enlarged with elevated CO2. The CO2 exchanges of whole plants were measured during the growing season. In elevated CO2, net photosynthetic rate was maximum in May and then decreased, reaching the level of the control at the end of the season. End of night dark respiration of enriched plants was significantly lower than that of control plants; this difference decreased with time and became negligible in the fall. The original CO2 level acted instantaneously on the respiration rate: a double concentration in CO2 decreased the respiration of control plants and a reduced concentration enhanced the respiration of enriched plants. The carbon balance of a chestnut seedling may then be modified in elevated CO2 by increased carbon inputs and decreased carbon outputs.469^3^Mousseau,M^El Kohen,A^Saugier,B^1992^3^The Shoot Carbon Balance of Young Chestnut Trees (Castanea sativa Mill.) in Double CO2^Responses of Forest Ecosystems to Environmental Changes^Elsevier Applied Science^London^699-700^^^^^^^^^^^^^^^^^^^^^Castanea sativa/sweet chestnut^^^^^^^^^^Teller,A^Mathy,P^Jeffers,JNRs,J N R470^2^Mousseau,M^Enoch,H Z^1989^1^Carbon Dioxide Enrichment Reduces Shoot Growth in Sweet Chestnut Seedlings (Castanea sativa Mill.)^16^12^^927-934^^^^^^^^^^1183^^^^^^^^^^^Castanea sativa/sweet chestnut chestnutC^1181^Plant Cell Environ.xA^1181^Two-year-old potted sweet chestnut seedlings were grown at 350 ppm CO2 and 700 ppm, day and night in constantly ventilated tunnels during two full growing seasons, near Paris, France (48 N, 2 E). Enrichment with CO2 caused an unusual shoot growth response. After the end of July, stem elongation ceased in 62% of the CO2 enriched plants as compared with 37% in the control. The leaves of CO2-enriched seedlings showed early senescence, indicated by premature yellowing and a decrease in chlorophyll content. This was associated with nutrient dilution brought about by the rapid growth of these trees. The increase in total dry weight of the CO2-enriched seedlings was essentially the result of increase in the root dry weight (69%). Shoot weight decreased by 22% relative to the control. Total leaf area per enriched plant was 25% smaller than the control. This unusual pattern of growth and carbon allocation of the CO2 treated Chestnut trees emphasizes the concept of a response specificity within trees to an increase of atmospheric CO2.UU471^2^Mousseau,M^Enoch,H Z^1989^1^Effect of Doubling Atmospheric CO2 Concentration on Growth, Dry Matter Distribution and CO2 Exchange of 2-Yr Old Sweet Chestnut Trees (Castanea sativa Mill.)^56^46 suppl^^506-508^^^^^^^^^^^^^^^^^^^^^Castanea sativa/sweet chestnutUUUTC^1184^Ann. Sci. For.ꪪ?!| |472^2^Mousseau,M^Saugier,B^1992^1^The Direct Effect of Increased CO2 on Gas Exchange and Growth of Forest Tree Species^39^43^^1121-1130^^^^^^^^^^1188188open-top chambers/leaf area development" ayer are desirable objectives. Similarly, moC^1186^J. Exp. Bot.water vapor and carbon dioxide exchange will extend the usefulness of open top chambers to include nonA^1186^CO2 enrichment of the atmosphere is now well documented and its effect on the growth of world forests is being questioned by the scientific community. The direct effects of increased CO2 on tree species are reviewed: the different experiA^1189^The availability of water imposes one of the major limits on rainfed maize (_Zea mays_ L.) productivity. This analysis was undertaken in an attempt to quantify the effects of limited water on maize growth and yield by extending a simple, mechanistic model in which temperature regulates crop biomass accumulation. A soil water budget was incorporated into the model by accounting for inputs from rainfall and irrigation, and water use by soil evaporation and crop transpiration. The response functions of leaf area development and crop gas exchange to the soil water budget were developed from experimental studies. The model was used to interpret a range of field experiments using observed daily values of temperature, solar radiation, and rainfall or irrigation, where water deficits of varying durations developed at different stages of growth . The relative simplicity of the model and its robustness in simulating maize yields under a range of water-availability c onditions allows the model to be readily used for studies of crop performance under alternate conditions. One such study,  presented here, was a yield assessment for rainfed maize under possible 'greenhouse' climates where temperature and atmosp heric CO2 concentration were increased. An increase in temperature combined with decreased rainfall lowered grain yield, a lthough the increase in crop water use efficiency associated with elevated CO2 concentration, ameliorated the response to the greenhouse climate. Grain yields for the greenhouse climates as compared to current conditions increased, or decreased only slightly, except when the greenhouse climate was assumed to result in severely decreased rainfall.؃t 474^1^Musgrave,M E^1986^6^Studies on the Physiological Significance of Cyanide-Resistant Respiration^^Duke University^^Doctoral Dissertation^^^Dissertation Abstracts Vol.47:09-B, p.3626 (169 pp.)^^^^^^^1193^^^^^^^^^^^pea/Pisum sativumL.A^1192^Studies of the relationship between cyanide-resistant (alternative) respiration and plant responses to relatively low (20-40 uM) concentrations of cytokinins showed a disengagement of the alternative pathway to occur prior to evidence of a cytokinin response in six different bioassays. Treatment of bioassay material with specific inhibitors of the alternative pathway produced results expected from cytokinins. These results suggest that disengagement of the alternative pathway is an early step in some plant responses to cytokinins. Two pea cultivars differing in the presence of absence of the alternative pathway were used to investigate the above relationship further. The cultivar lacking the alternative pathway failed to respond to exogenous application of cytokinins. Hybridization of the cultivars showed the alternative pathway to be a maternally inherited character and, in reciprocal F-1's, only the cross having the alternative pathway was responsive to cytokinins in the ethylene bioassay. A comparison of the growth of pea hybrids differing in the presence of absence of the alternative pathway was undertaken. Plants were grown in Phytotron greenhouses at 350 or 650 ppm carbon dioxide to test the hypothesis that the alternative pathway operates under conditions of excess carbon assimilates. The results showed the hybrid lacking the pathway to outperform the reciprocal cross in terms of total dry matter, seed weight and height. The hybrid lacking the alternative pathway responded markedly to carbon dioxide enrichment with increases in a number of growth parameters while the reciprocal cross showed little response to elevated carbon dioxide levels. The results suggest that  the alternative pathway does consume luxury carbohydrates and may be an important component of whole plant carbon budgets.! Respiration by seven male-sterile lines of four unrelated species was compared with that of fertile lines. Alternative re"spiration was generally not expressed in tissues from male-sterile plants. Male-sterile lines have been reported to have h#igher vigor than corresponding fertile lines, and it is suggested that the absence of the energetically wasteful alternative pathway may account for these observed differences in vigor.666&&&?&ZY[XPSQR&>t!<u&%475^3^Musgrave,M E^Strain,B R^Siedow,J N^1986^1^Response of Two Pea Hybrids to CO2 Enrichment: A Test of the Energy Overflow Hypothesis for Alternative Respiration^95^83^^8157-8161^^^^^^^^^^1196^^^^^^^^^^^pea/Pisum sativumvum L.66S׋1C^1194^Proc. Natl. Acad. Sci. USA658tPSQW8˓Us]_Y[Xs2O66,N6>I8u ptp2&$:&62v,N[(A^1194^Two pea (_Pisum sativum_ L.) hybrids differing in the presence or absence of the cyanide-resistant (alternative) pa)thway of respiration were constructed by reciprocally crossing cv. Alaska and cv. Progress No. 9. The F1 hybrids were grow*n in greenhouses maintained at either 350 or 650 ppm CO2, and the growth, flowering, and dry matter accumulation were comp+ared. The objective was to assess the significance of the alternative respiratory pathway to whole-plant carbon budgets an,d further to test the hypothesis that the alternative pathway is important in oxidizing excess carbohydrates such as might- accumulate under conditions of CO2 enrichment. More carbohydrates were available in the F1 hybrid lacking the pathway, as. evidenced by greater plant height, leaf area, specific leaf weight, and total dry matter compared with the reciprocal hyb/rid, especially at 650 ppm CO2. Specific leaf weight increased markedly under CO2 enrichment in the hybrid lacking the pat0hway, while it was the same at 350 and 650 ppm in the reciprocal cross. The hybrid lacking the alternative pathway also ou1tperformed the reciprocal cross in terms of total dry matter and seed production. Increased branching with CO2 enrichment 2was observed in the hybrid lacking the pathway, while branching in the reciprocal cross was only slightly stimulated. Thes3e results suggest that alternative respiration consumes luxury carbohydrate and that respiration via this pathway may be considered energetically wasteful in terms of whole-plant carbon budgets.)t:& 7u03+VrF&))t 5476^2^Musgrave,M E^Strain,B R^1988^1^Response of Two Wheat Cultivars to CO2 Enrichment under Subambient Oxygen Conditions^17^87^^346-350^^^^^^^^^^1199^^^^^^^^^^^wheat/Triticum aestivumvum L.`5!v x %!a`.v t%!aP&C^1197^Plant Physiol. E D F G M.w.svutn$r(o,pFyXwYxZx_:]$^_qk8A^1197^Two cultivars of wheat (_Triticum aestivum_ L. cvs Sonoita and Yecora Rojo) were grown to maturity in a growth cham9ber within four sub-chambers under two CO2 levels (350 or 1000 microliters per liter) at either ambient (21%) or low O2 (5:%). Growth analysis was used to characterize changes in plant carbon budgets imposed by the gas regimes. Large increases i;n leaf areas were seen in the low O2 treatments, due primarily to a stimulation of tillering. Roots developed normally at <5% O2. Seed development was inhibited by the subambient O2 treatment, but this effect was overcome by CO2 enrichment at 10=00 microliters per liter. Dry matter accumulation and seed number responded differently to the gas treatments. The greates>t dry matter production occurred in the low O2, high CO2 treatment, while the greatest seed production occurred in the amb?ient O2, high CO2 treatment. Growth and assimilation were stimulated more by either CO2 enrichment or low O2 in cv Yecora @Rojo than in Sonoita. These experiments are the first to explore the effect of whole plant low O2 treatments on growth andA reproduction. The finding that CO2 enrichment overcomes low O2-induced sterility may help elucidate the nature of this effect.TD~[QW<-0Pl,s~XvĚ/):rL>f7t`7uPvĚ(:XY7#r'3*A@srF6Z73C477^4^Musselman,R C^McCool,P M^Oshima,R J^Teso,R R^1986^1^Field Chambers for Assessing Crop Loss from Air Pollutants^9^15^^152-157^^^^^^^^^^12022027}Wb7 tPou * N~u5>^7u 6\7F6^76^7 t6^76Z7u ^76C^1200^J. Environ. Qual.U7XP>g7tXP>g7tXSQRWUٻdۋٹ֚@ss6S7΋I׋FA^1200^A new field fumigation facility has been developed for determining effects of air pollutants on cops. The permanentG facility consists of closed-top, octagonal chambers 2.1 m tall by 2.5 m across. Each chamber is supplied with air via undHerground ducting from two centralized blowers, one charcoal-filtered and the other nonfiltered. Individual chambers can beI adjusted to 100% filtered air for fumigation with specific levels of pollutants, or a pollutant gradient can be generatedJ by combining filtered and ambient air. Air exchange rates through the chambers are also adjustable. Each chamber is constKructed of several flat aluminum-frame panels covered with Teflon film which has remained clear and durable after three yeaLrs of continuous service. Panels are easily removed for repair if necessary. Teflon film walls minimize environmental diffMerences between chamber and ambient air. Chamber temperatures closely track ambient, but are higher than ambient at middayN. Temperatures remain uniform at different locations within each chamber. Light intensity within chambers averages 11% lesOs than ambient. Pollutant levels set within each chamber remain relatively stable in both time and space. Native soil undePr each chamber has been replaced with a standard greenhouse soil mix which is irrigated with a drip system. The fumigationQ facility is comparable in construction costs to open-top fumigation chamber systems, and is especially useful for experiments requiring precise control of pollutant levels.:uk:)u  s) XPSQVURW:tY:>[:*68*S478^5^Nagy,J^Lewin,K F^Hendrey,G R^Lipfert,F W^Daum,M L^1992^1^FACE Facility Engineering Performance in 1989^8^11^^165-185^^^^^^^^^^1205205-)tY8>[8 8R 8 sZ 268 :8wi_Z]^Y[X::u N: DC^1203^Crit. Rev. Plant Sci.Y8[8[8Y8qt8>8t Nu낃>'8t& &78)8>H8t&J8VA^1203^Following prototype development of the first BNL FACE system on Long Island in 1986, the first full-scale (22-m diaWmeter) FACE array was built at Yazoo City, MS, in 1987. Three additional arrays were built (with some modification of the Xconfiguration of all four arrays) in 1988 in Yazoo City. In 1989 the four arrays were moved to Maricopa, AZ. The FACE systYem has proven to be very reliable with 3 to 7% of available experimental time lost to system failures in 1989 in the varioZus arrays. Analysis of modes of failure and component failures are presented. Wind speed, direction and stability are the [most important variables governing CO2 distribution within the FACE arrays. For this reason detailed analyses of system co\ntrol deviations as a function of these variables are presented. A statistical model relating CO2 use to wind speed and so]lar altitude (a surrogate for stability) is derived that may be helpful in evaluating CO2 use for FACE experiments planned^ for other locations. System reliability and control improved with changes in engineering features between 1987 and 1989. _Over the entire 1989 growing season, omitting times when the FACE systems were not functioning properly, average CO2 conce`ntrations measured at the center of the arrays were within 1 umol/mol of the 550 umol/mol target concentration. Averaging aover all four arrays and all periods of operation, the 1-s observations measured at the center of the FACE arrays remainedb within +/- 20% of 550 umol/mol for 88% of the time. The corresponding 1-min average was within +/- 10% for 88% of the timce and within +/- 20% for 98% of the time. Studies of spatial control within one of the arrays demonstrated the general accdeptability of control of CO2 concentrations in a central plot of 12-m diameter. Experiments using tracers and multi-port meonitoring of the spatial distribution of CO2 showed that this area constituted a 'sweet spot' within which CO2 concentratifons were +/- 20% of the target CO2 concentration at least 80% of the time. A 63-port selectable sequencing sampler was setg up as a three-dimensional sampling system. Over 16,000 observations of 1-s grab samples were taken with this multiport sahmpler. Average values at each sampling node showed that spatial variability of CO2 concentrations throughout the volume ofi the 'sweet spot' in 1989 varied by less that +/- 5%. Of these 1-s grab samples 0.44% exceeded twice the target concentratjion of 550 umol/mol but 110 umol at the top of the canopy. Grab-samples taken in 'bucket tests' averaging over 5-min foundk a wind-dependent gradient across the 'sweet spot' that was as high as 160 umol. However, those ranges are still within the design criteria.iD!s"𝜚B${a33ҹ`58t U s]rZ]8 ym479^2^Nakayama,F S^Kimball,B A^1988^1^Soil Carbon Dioxide Distribution and Flux within the Open-top Chamber^4^80^^394-398^^^^^^^^^^1208208BB@BB>H8u&B3hR&iRjR>kRlR.mR2@JP>R8pTC^1206^Agron. J.W8X8@ I8s uoR3aR3ҎڢeZ`:DDDDD *D s >N8uU"pA^1206^Open-top chamber use for exposing plants to various levels of CO2 and pollutant gases is increasing in field studieqs. In making a C balance of cotton [_Gossypium hirsutum_ (L.) 'Deltapine-61'] for such a system, soil CO2 fluxes were obserrved to be significantly greater outside than inside the chamber. To find the cause, CO2 concentration was measured in thes soil profile from 50 to 60-cm depths of an Avondale clay loam [fine-loamy, mixed (calcareous), hyperthermic Typic Trifluvtent]. The soil CO2 contents at the various depths sampled outside the chamber were higher than those inside the chamber. Tuhe differences in concentration were observable within 2 wk after the blower used to pass ambient or CO2-enriched air throvugh the chamber was turned on. The largest differences were present approximately 16 wk after the system had been in operawtion. Approximately 30 d was required for the soil CO2 levels inside and outside the chamber to become similar after the bxlower was turned off. Soil water content was not a factor causing this difference because it was nearly equal at both siteys. Pressure differentials inside the growth chamber resulting from the blower operation could lead to a decrease in soil CO2 concentration and fluxes measured using the closed chamber technique.:t:_ZYXP8@ 8A t Ȋ8480^1^Nederhoff,E M^1990^1^Technical Aspects, Management and Control of CO2 Enrichment in Greenhouses^15^268^^127-138^^21nC^1209^Act. Hort.CXPSQRVW:&::H${r3>:7s*:${&:&::: t N&:_^ZY[XPSQ{0ى^33ɋ:^:^:u&&;u&D&;Eu &D&;EtV!s ys;r fv~~481^2^Nederhoff,E M^Buitelaar,K^1992^1^Effects of CO2 on Glasshouse Grown Eggplant (_Solanum melongena_ L.) II. Leaf Chlorosis and Fruit Production^19^67^^805-812^^^^^^^^^^2057^^^^^^^^^^^Solanum melongena/eggplant^^^^^u^+^^*°FC^1211^In Press:؋~|NI:)8~tNs*v~Nu3NW_~Nu*Ú*ÀODT'482^2^Nederhoff,E M^Buitelaar,K^1992^1^Effects of CO2 on glasshouse&GGÀgGW+D Txu uO@RWww3483^3^Nederhoff,E M^de Koning,A N M^Rijsdijk,A A^1992^1^Leaf Deformation and Fruit Production of Glasshouse Grown Tomato (_Lycopersicon esculentum_ Mill.) as Affected by CO2, Plant Density and Pruning^19^67^^411-420^^^^^^^^^^1216^^^^^^^^^^^tomato/Lycopersicon esculentumtum Mill.;tu ${ BZX3r!GwG@GH;rUPVw3G|C^1214^J. Hort. Sci.E EEDOGDGtPB tV^G tXgQRVwOG3.62+A^1214^During summer, glasshouse grown tomato plants (_Lycopersicon esculentum_ Mill.) often demonstrate leaf deformation, reduced leaf area (short leaves) and low Specific Leaf Area (SLA), sometimes accompanied by higher dry matter content of leaves and stems and higher leaf starch content. This so-called 'Short Leaves Syndrome' (SLS), which decreases the production capacity, was investigated with emphasis on the effects of CO2 concentration. As a working hypothesis it was postulated that SLS is indirectly caused by an oversupply of assimilates relative to the sink capacity. An experiment was conducted between 10 May and 31 July 1990 in 12 glasshouse compartments. The sink/source ratio was varied by maintaining two levels of CO2, multifactorially combined with two plant densities and three pruning treatments. CO2 enrichment and wider planting enhanced SLS and decreased leaf area and SLA of upper leaves. Leaf pruning and fruit pruning, however, did not give clear effects on vegetative characteristics, although the impact on the sink/source ratio was of the same order of magnitude. As a mechanism for these effects, we suggest that SLS is caused by calcium deficiency in the apex, a condition more severe when much phloem sap (with low calcium content) is available, i.e. when the sink/source ratio is lower. Stronger effects of CO2 and plant density than of pruning on the incidence of SLS, may be due to local effects of sink/source relationships or to involvement of other processes, like transpiration. In crops with little SLS-symptoms, CO2 enrichment increased the weight of fruits grown during the treatment period by 31%, whereas in crops with severe SLS, CO2 enrichment aggravated SLS and had no significant effect on fruit production. CO2 enrichment in summer is beneficial if SLS is prevented, which can be achieved by maintaining a higher plant density or, in an early crop, an extra shoot on the plants in spring and summer.?tIrO&Mu &}u_^XPVW*rO&Mu &}u_^XPVWr &M&EO_^XPVWr &M&EO_^484^2^Nederhoff,E M^Rijsdijk,A A^1990^1^CO2 kan verdamping teveel beinvloeden^96^45^^28-29^^^^^^^^^^2044qD_^ZYQRVW485^3^Nederhoff,E M^Rijsdijk,A A^de Graaf,R^1992^1^Leaf Conductance and Rate of Crop Transpiration of Glasshouse Grown Swe#et Pepper (_Capsicum annuum_ L.) as Affected by Carbon Dioxide^53^52^^283-301^^^^^^^^^^2060^^^^^^^^^^^Capsicum annuum/swee,DW^Schulze,E-D^Walker,BHEUQFYrWU3ґ.62GF@HrAOQW3_YF+Gv%.&2S u t;sr+ك486^2^Nederhoff,E M^van Uffelen,J A M^1988^1^Effects of Continuous and Intermittent Carbon Dioxide Enrichment on Fruit Set and Yield of Sweet Pepper (_Capsicum annuum_ L.)^66^36^^209-217^^^^^^^^^^1222^^^^^^^^^^^Capsicum annuum/sweet pepperpeppC^1220^Nether. J. Agric. Sci. u t8} MrE P uX_Z[PSSr[X˚=NÚNÚ${Úؘ*ÚA^1220^The effects of carbon dioxide (CO2) enrichment on vegetative growth, fruit set and yield of an autumn crop of sweet pepper (_Capsicum annuum_ L., cv. Bolero) were studied. In 12 greenhouse compartments of 9.6 m x 6 m each, 6 CO2 treatments were tested: 3 continuous CO2 levels, setpoints 200, 340 and 500 ppm (uL/L), 2 intermittent dosings (8 minutes per 40 and per 104 minutes, respectively) and a control (without dosing or filtering). It was not possible to maintain the set points of the continuous CO2 levels throughout the experiment, therefore the measured CO2 concentrations were used to explain the effects. The results show a positive effect of elevated CO2 concentrations on fruit set and yield. The number of fruits harvested per m2 was 60% higher at the 500 ppm treatment than at the 200 ppm treatment, whereas the average fruit weight was not significantly affected. The dry matter content of the leaves increased, the SLA and LAR were smaller at higher CO2 concentrations. The vegetative growth tended to decrease at higher CO2 levels, which was ascribed to competition between vegetative and generative organs. The results with respect to the setting and yield were less favourable at intermittent CO2 enrichment than at continuous CO2 levels, if plotted versus the measured, average CO2 concentration.w uwerR^ZVPG 2ZC*Xr^SWؚYt*u_[PQVW&+x*&._^YXÉ uL=N8PSQءBr!487^5^Nie,D^He,H^Mo,G^Kirkham,M B^Kanemasu,E T^1992^1^Canopy Photosynthesis and Evapotranspiration of Rangeland Plants under Doubled Carbon Dioxide in Closed-top Chambers^46^61^^205-217^^^^^^^^^^1225^^^^^^^^^^^big bluestem/Andropogon gerardii/little bluestem/Andropogon scoparius/Indiangrass/Sorghastrum nutans^^^^^strum nutans^^^^^ass/Sorghastrum nutansSQR C^1223^??; Agric. For. Meteorol.?Nor4rr ZY[PSV>}tL':O':R':6I':XVh^rA^1223^It is important to know how the increasing atmospheric concentration of carbon dioxide (CO2) will affect growth of agricultural plants. The objective of this study was to determine the effect of elevated CO2 on canopy photosynthetic rate of prairie (rangeland) plants growing under natural field conditions. The dominant plants were warm-season grasses with the C4 type of photosynthesis. Sixteen closed-top, cylindrical, plastic chambers (1.5 m in diameter; 1.8 m tall) were placed on the prairie to maintain two levels of CO2 (ambient and twice ambient) over a full growing season in 1990. The soil (silty clay loam) was kept at a high water (field capacity) or a low water level (no water added). Carbon dioxide concentration, air temperature, net radiation, canopy photosynthetic rate, and canopy evapotranspiration rate were measured in the 16 chambers on 49 sunny days during the season. The target value for high-CO2 chambers was 720 cm3 CO2/m3; the measured mean concentrations varied from 710.8 to 720.1 cm3 CO2/m3. For chambers with ambient CO2, the chamber-to-chamber variation was minor, with mean values ranging from 350.8 to 356.0 cm3 CO2/m3. Daytime air temperatures at 100 cm aboveground in the chambered plots averaged 2.7C warmer than outside. Early in the season, net radiation was usually similar among chambers with the different CO2 and water treatments, but late in the season, differences occurred among chambers, possibly because of the amount of tall grasses that shaded the radiometers. Under the high-water treatment, canopy photosynthesis of plants grown with doubled and ambient CO2 averaged 41.8 umol/m2/s and 44.5 umol/m2/s, respectively. These results are consistent with previous findings, which showed that the photosynthetic rate of C4 plants on rangeland was not augmented when the CO2 concentration was increased. Under the low-water treatment, photosynthesis of plants grown with doubled CO2 was slightly more (36.9 umol/m2/s) than that of plants grown with ambient CO2 (31.7 umol/m2/s). This observation is in agreement with other results, which have shown that high CO2 alleviates water-stress effects on plants. Elevated CO2 reduced canopy evapotranspiration rate by 18 and 8%, under the high- and low-water levels, respectively. The results suggested that, as the CO2 concentration in the atmosphere increases, water lost from rangelands will be reduced.L!rLFII t =+u488^4^Nie,D^He,H^Kirkham,M B^Kanemasu,E T^1992^1^Photosynthesis of a C3 Grass and a C4 Grass under Elevated CO2^42^26^^189-198^^^^^^^^^^1228^^^^^^^^^^^Kentucky bluegrass/Poa pratensis/big bluestem/Andropogon gerardiirardii Vitman6Z7P&CFC^1226^PhotosyntheticaC.&T}tJu_Z[PSVWC6>KXMX00T.&T_^[X.T.&T.TA^1226^The net photosynthetic rate (_P_n), intercellular CO2 concentration (_C_i), transpiration rate (_E_), stomatal resistance (_r_s), and water potential (Psi-w) of a C3 grass (Kentucky bluegrass, _Poa pratensis_ L.) and a C4 grass (big bluestem, _Andropogon gerardii_ Vitman) growing in the spring in a tallgrass prairie under two levels of CO2 (ambient and twice ambient) were compared. Elevated CO2 (HC) increased _P_n of Kentucky bluegrass (C3) by 47.0% but did not affect _P_n of big bluestem (C4). HC increased _C_i of both grasses by about the same amount (about 270 cm3/m3), but reduced _E_ (and parallelly increased _r_s) of big bluestem more than those of Kentucky bluegrass. HC increased (Psi-w) of both grasses by about 30%. Kentucky bluegrass had a lower (Psi-w) than big bluestem, but HC increased Psi-w of Kentucky bluegrass to values more similar to those of big bluestem under ambient CO2 (LC). Hence a high Psi-w resulting from HC, was necessary for high _P_n.ـ ˀ3Vt^YQ3YQYQYQUVWF V ^N u ti teu y ؃489^5^Nie,D^Kirkham,M B^Ballou,L K^Lawlor,D J^Kanemasu,E T^1992^1^Changes in Prairie Vegetation under Elevated Carbon Dioxide Levels and Two Soil Moisture Regimes^127^3^^673-678^^^^^^^^^^1231^^^^^^^^^^^Poa pratensis/Kentucky bluegrass/Andropogon gerardii/big bluestem/Andropogon scoparius/little bluestem/Sorghastrum nutans/Indiangrass^^^^^^^ nutans/Indian grassesponse of Vegetation to Carbon Dioxide^^Ds2Њӊ%[&&W“&WS& } +sA^1229^It is important to know how increasing levels of atmospheric CO2 will affect native vegetation. The objective of this study was to determine the effect of elevated CO2 concentrations on species composition in a tallgrass prairie kept at a high water level (730 mm of water in a 2000 mm soil profile) and a low water level (660 mm of water in 2000 mm). 16 cylindrical plastic chambers were placed on the prairie to maintain two levels of CO2 (ambient or twice ambient) during two growing seasons in 1989 and 1990. Frequency of species was determined on 25 July 1989 and on 5 and 10 October 1990. At the beginning of the study, _Poa pratensis_ (Kentucky bluegrass), the dominant C3 species, had the highest frequency of 43.3%, but decreased with time. However, at the end of the experiment and under the high soil-water level, there were more _P. pratensis_ plants in the elevated CO2 treatment (frequency: 13.5%) than in the ambient CO2 treatment (1.0 %). Under the low soil water regime, the reverse occurred (frequencies: 3.6% and 11.0% for high and low CO2, respectively). The frequency of major C4 plants, _Andropogon gerardii_ (big bluestem), _A. scoparius_ (little bluestem) and _Sorghastrum nutans_ (Indian grass) was not affected by CO2. However, water did affect their frequency. Under low water, the frequency of _A. gerardii_ decreased between 1989 and 1990. Under both soil moisture levels, the frequencies of _S. nutans_ and _A. scoparius_ increased. At the end of the study, Indian grass grown with high water had the highest frequency of all species on the prairie (frequency at the end of the study in October, 1990, of 44.4% and 47.4% for the high and low CO2 levels, respectively). Unlike Indian grass, little bluestem grew better under low water conditions than under high water conditions. These results suggest that, if the climate becomes drier, _A. scoparius_ will flourish more than _S. nutans_ or _A. gerardii_ and _P. pratensis_ may die out. Elevated CO2 might not increase survival of C3 plants under dry conditions, if temperatures are too high for them.$]^ZY[XPSQRVW68~؃u $rB68~&Sw |t$[#Euut&u S~490^3^Nijs,I^Impens,I^Van Hecke,P^1992^1^Diurnal Changes in the Response of Canopy Photosynthetic Rate to Elevated CO2 in a Coupled Temperature-Light Environment^18^32^^121-130^^^^^^^^^^1234^^^^^^^^^^^Lolium perenne/perennial ryegrassegrass~C^1232^Photosynth. Res.&tH~ua_X^[H~uHPS6S~8~ t4;:~t.Gu'6H~3:rO S~&S~A^1232^The relative increase with elevated CO2 of canopy CO2 uptake rate (A), derived from continuous measurements during the day, was examined in full-cover vegetative _Lolium perenne_ canopies after 17 days of regrowth. The stands were grown at ambient 358 +/- 50 umol/mol) and increased (626 +/- 50 umol/mol) CO2 concentration in sunlit growth chambers. Over the entire range of temperature and light conditions (which were strongly coupled and increased simultaneously), A was on average twice as large in high compared to ambient CO2. This response (called M = A in high CO2/A in ambient CO2) could not be explained by changes in canopy conductance for CO2 diffusion (GC). In spite of interaction and strong coupling between temperature and light intensity, there was evidence that temperature rather than light determined M. Further, high CO2 treatment was found to alleviate the afternoon depression in A observed in ambient CO2. A temperature optimum shift or/and a larger carbohydrate sink capacity through altered root/shoot ratio are proposed in explanation..Dt &D@uB&tv491^3^Nijs,I^Impens,I^Behaeghe,T^1988^1^Effects of Rising Atmospheric Carbon Dioxide Concentration on Gas Exchange and Growth of Perennial Ryegrass^42^22^^44-50^^^^^^^^^^1237^^^^^^^^^^^Lolium perenne/perennial ryegrassegrass&Gu =:&6C^1235^Photosynthetica~ ^Y[X&D@t&|Dt&|@t&|  QVU&L20&D@u&Dt&u&Duv&tA^1235^Long-term effects of rising atmospheric CO2 concentrations on gas exchange, growth and productivity were investigated on _Lolium perenne_ L. cv. Vigor. Pure stands of this species in vernalized condition were cultivated in small acrylic greenhouses in an artificial atmosphere of mean 367 or 620 cm3/m3 CO2 (C350 or C600), respectively. Canopies grown at C600 showed an average higher dry matter of almost 43% than those of C350. Functional growth analysis indicated that an important fraction of the yield increase under C600 originated from CO2 fixed in the first few days of the regrowth period after cutting the stand. Gas exchange measurements in spring showed a higher maximum canopy photosynthetic rate of 77% and a higher transpiration rate of around 20% at C600 than C350 if expressed on a ground area basis. Development of a larger canopy leaf area was the primary cause for both increases. Water-use efficiency calculations on the summer data indicated a slight decrease under C600.=:[s2I^Y[XZPQRVWF3 t&u&Gu&Dt &;t&D@tY&;6u492^3^Nijs,I^Impens,I^Behaeghe,T^1988^1^Effects of Elevated Atmospheric Carbon Dioxide on Gas Exchange and Growth of White Clover^18^15^^163-176^^^^^^^^^^1240^^^^^^^^^^^Trifolium repens/white clovercloverRVWU&\S^ [&L u(&DuC^1238^Photosynth. Res. ut23T u &L 2^ 6)u&)Z)uj 4T^ 3T)A^1238^Effects of rising atmospheric CO2 concentrations on gas exchange, growth and productivity were investigated on an important grassland species, _Trifolium repens L. cv. Blanca_. Pure stands of this species were cultivated over an entire growing season in small acrylic greenhouses with an artificial atmosphere of +/- 367 or +/- 620 ppm CO2, respectively. Effects on growth and development were examined in a functional growth analysis, while consequences for gas exchange were determined by photosynthesis and transpiration measurements on canopy level. The stands were regularly clipped for production assessment. Canopies grown at high CO2 levels showed an average increase in productivity of almost 75%. Growth analysis indicated development of a larger foliage area as the major cause, particularly in the first days of regrowth after cutting. The growth advantage that began in this stage was maintained or bettered during the following weeks. The difference between gas exchange measurements expressed per unit leaf area and per unit ground area suggested that changes in net photosynthesis and respiration did not contribute to the increase in total yield. Transpiration declined under high CO2 if expresse d on a leaf area basis but total canopy transpiration was at least as large as in ambient CO2 due to the larger leaf area. Water-use efficiency calculations on the summer data indicated a 35% improvement with a doubling of CO2 concentration.= 493^3^Nijs,I^Impens,I^Behaeghe,T^1989^1^Effects of Long-term Elevated Atmospheric CO2 Concentration on _Lolium perenne_ an d _Trifolium repens_ Canopies in the Course of a Terminal Drought Stress Period^54^67^^2720-2725^^^^^^^^^^1243^^^^^^^^^^^Lolium perenne/perennial ryegrass/Trifolium repens/white cloverte clovert8v&!l +_Z[XPS&tC^1241^Can. J. Bot.PS&t8& 2+s3&[XP8&8&u&&t &&X&T SQRVQA^1241^A terminal drought stress regime was imposed on vegetatively fully developed _Lolium perenne_ L. cv. Vigor and _Trifolium repens_ L. cv. Blanca canopies in semicontrolled growth chambers that provided a high (626 +/- 50 uL/L) and an ambient (358 +/- 35 uL/L) CO2 growth environment. The chambers served as measurement units in an open system for continuous CO2 and water vapour exchange assessment. When stress was building up, high CO2 increased the ratio of real to potential canopy evapotranspiration in both species, thus reducing the higher potential rates that are generally observed in high CO2 under unstressed conditions towards the level of the ambient CO2 stands, without immediately affecting the net higher CO2 exchange rates that characterize the high CO2 treatment. _Lolium perenne_ is more sensitive to drought stress in its initial response and divides the available amount of water more proportionally over the stress period than _Trifolium repens_. Water-use efficiency is roughly doubled and is affected later by drought stress in high CO2 for both species. It is concluded that long-term high CO2 treatment favours the survival of the species examined when exposed to severe, rapidly developing drought stress.t &M+h݇ro]&&F&> t+މ^& ^& & tDW&su494^3^Nijs,I^Impens,I^Behaeghe,T^1989^1^Effects of Different CO2 Environments on the Photosynthesis-Yield Relationship and the Carbon and Water Balance of a White Clover (_Trifolium repens_ L. cv. Blanca) Sward^39^40^^353-359^^^^^^^^^^1246^^^^^^^^^^^Trifolium repens/white clovercloverQӋ&L2Ys &t_ZÚjNsR**rF&>uN&6& C^1244^J. Exp. Bot.&6v&LS~@PSRVW&6&u&D@t&Dt&\ &|u &Dt&6 uA^1244^Effects of atmospheric CO2 enrichment to a level above 600 ppm on leaf and canopy gas exchange characteristics were investigated in _Trifolium repens_, using an open system for gas exchange measurement. The cuvette of the system served a s growth chambers, allowing continuous measurement in a semi-controlled environment of +/- 350 and +/- 600 ppm, respective!ly. Carbon balance data were compared with crop yield and effects on the canopy level were compared with measured leaf res"ponses of photosynthesis and stomatal behavior. Photosynthetic stimulation by high CO2 was stronger at the canopy level (1#03% on average) than for leaves (90% in full light), as a consequence of accelerated foliage area development. The latter $increased absolute water consumption by 16%, despite strong stomatal closure. The overall result was a 63% improvement in %canopy water use efficiency (_WUE_), while leaf _WUE_ increased almost 3-fold in saturating light. The stomatal response w&as such that, while the internal CO2 concentration in the leaf, _Ci_, increased with rising atmospherical CO2 concentratio'n, _Ca_, _Ci/Ca_ was somewhat decreased. Total canopy resistance, _Rc_, was generally lower at high CO2 levels, despite hi(gher leaf resistance. Higher canopy CO2 loss at night and faster light extinction in a larger-sized high CO2 canopy were m)ajor drawbacks which prevented a further increase in dry matter production (the harvest index was increased by a factor 1.83).;u&6&D@u&u&Du&Du&L^Y[XQW)&;6t#&DtQ&L2rYs &t_Y&D+495^2^Nijs,I^Impens,I^1993^1^Effects of Long-term Elevated Atmospheric Carbon Dioxide on _Lolium perenne_ and _Trifolium r,epens_, Using a Simple Photosynthesis Model^123^104/105^^421-431^^^^^^^^^^1249^^^^^^^^^^^Lolium perenne/perennial ryegrass/Trifolium repens/white clover^^^^^^^^^^~uG~us~~ -6Z~\~D ^~D\DD~$s~^RV^^^^Acer pseudoplatanus/Fagus sylvaticaDL T~DD~\r~ ^ZSQRW~t ~~&~~ur,&/A^1247^Changes in gross canopy photosynthetic rate (PGc), produced by long-term exposure to an elevated atmospheric CO2 le0vel (626 +/- 50 umol/mol), were modelled for _Lolium perenne_ L. cv. Vigor and _Trifolium repens_ L. cv. Blanca, using a s1imple photosynthesis model, based on biochemical and physiological information (leaf gross CO2 uptake in saturating light,2 Pmax, and leaf quantum efficiency, alpha) and structural vegetation parameters (leaf area index, LAI, canopy extinction c3oefficient, k, leaf transmission, M). Correction of PGc for leaf respiration allowed comparison with previously measured c4anopy net CO2 exchange rates, with the average divergence from model prediction amounting to about 6%. Sensitivity analysi5s showed that for a three-week old canopy, the PGc increased in high CO2 could be attributed largely to changes in Pmax an6d alpha, while differences in canopy architecture were no longer important for the PGc-stimulation (which they were in the7 early growth stages). As a consequence of this increasing LAI with canopy age, the gain of daytime CO2 uptake is progress8ively eroded by the increasing burden of canopy respiration in high-CO2 grown _Lolium perenne_. Modelling canopy photosynt9hesis in different regrowth stages after cutting (one week, two weeks,. . .), revealed that the difference in a 24-h CO2 b:alance between the ambient and the high CO2 treatment is reduced with regrowth time and completely disappears after 6 weeks."<:&Dt&|Et&|@u0)uPR%$ZX)t&;6u H~u88T)ut}tut&;6ult<496^1^Nobel,P S^1991^1^Environmental Productivity Indices and Productivity for _Opuntia ficus-indica_ under Current and Elevated Atmospheric CO2 Levels^16^14^^637-646^^^^^^^^^^1252^^^^^^^^^^^prickly pear cactus/Opuntia ficus-indicaica6FÚX5C^1250^Plant Cell Environ.Y[XPSQRFF&>&%&t&>!ÃFFF̋:>8|2?A^1250^The productivity of the prickly-pear cactus _Opuntia ficus-indica_, which is cultivated worldwide for its fruits an@d stem segments, was predicted based on the responses of its net CO2 uptake to soil water status, air temperature and photAosynthetic photon flux density (PPFD). Each of these environmental factors was represented by an index with maximum value Bof unity when that factor was not limiting net CO2 uptake over a 24-h period. The water index, the temperature index, and Cthe PPFD index were determined for 87 sites in the contiguous United States using data from 189 weather stations and for 1D48 sites worldwide using data from 1464 weather stations. The product of these three indices, the environmental productiviEty index (EPI), was used to predict the productivity of _O. ficus-indica_ under current climatic conditions and under thosFe accompanying a possible increase in the atmospheric CO2 level to 650 umol/mol. Sites with temperatures always above -10GC and hence suitable for prickly-pear cultivation numbered 37 in the United States and 110 worldwide; such sites increasedH by 43 and 5%, respectively, for the global warming accompanying the elevated CO2. Productivity of _O. ficus-indica_ was aIt least 15 tonnes dry weight/hectare/year, comparable to that of many agronomic crops, for 20 sites with temperatures alwaJys above -10C in the contiguous United States and for 12 such sites worldwide under current climatic conditions; such sitKes increased by 85 and 117%, respectively, under the elevated CO2 condition, mainly because of direct effects of the atmosLpheric CO2 level on net CO2 uptake. In summary, simulations based on EPI indicate that _O. ficus-indica_ may presently be Madvantageously cultivated over a substantial fraction of the earth's surface, such regions increasing markedly with a future doubling in atmospheric CO2 levels.Z=T!Y[X˳=: t˰ ذPSV~F &=uO497^2^Nobel,P S^de Cortazar,V G^1991^1^Growth and Predicted Productivity of _Opuntia ficus-indica_ for Current and Elevated Carbon Dioxide^4^83^^224-230^^^^^^^^^^1255^^^^^^^^^^^Opuntia ficus-indica/prickly pear cactusly pear cactusFt vF=C^1253^Agron. J.[XV@&D^r %FtXFt9vu{NFGoFu frtNFt=@tGFu =u@N:RA^1253^_Opuntia ficus-indica_ (L.) Mill., a prickly pear cactus cultivated worldwide for its fruits and stem segments, canS have an annual dry weight productivity exceeding that of many crops. Using a recently introduced environmental productiviTty index (EPI), the influences of water status, temperature, and photosynthetically active radiation (PAR) on its productiUvity can be predicted. This investigation calculated the water index, the temperature index, and the PAR index, whose prodVuct equals EPI, for 169 sites distributed approximately uniformly across the contiguous USA for present climatic conditionWs as well as for those associated with an elevated CO2 concentration of 650 uL/L. The effect of elevated CO2 on growth of X_O. ficus-indica_ was directly measured, and low temperature limitations on productivity were considered. The dry weight gYain of _O. ficus-indica_ during 6 mo in an environmental growth chamber was 23% greater at 650 compared with 350 uL/L CO2 Zand increased as the duration of the wet period increased, in agreement with predictions of the water index (the fraction [of maximal net CO2 uptake during a 24-h period for the prevailing plant water status). For closely spaced plants that lead\ to a high productivity per unit ground area, EPI averaged about 0.10, except in desert regions where the water index lowe]red EPI, in the far North or South and at high elevations where the temperature index lowered EPI, and in the Northeast an^d Northwest where the PAR index lowered EPI. The predicted annual dry weight productivity for _O. ficus-indica_ was 12.8 M_g/ha/yr under current conditions, and 16.3 Mg/ha/yr under those associated with 650 uL/L CO2. Both productivities are rela`tively high compared with other agronomic plants. The percentage of sites where temperatures fall below -15C at least oncae during the 10 years simulated, which would be lethal to most prickly pear cacti, was reduced from 49 to 18% by the general warming expected to accompany an approximate doubling of the atmospheric CO2 concentration.u։S&&G [P&Gc498^2^Nobel,P S^Hartsock,T L^1986^1^Short-term and Long-term Responses of Crassulacean Acid Metabolism Plants to Elevated CO2^17^82^^604-606^^^^^^^^^^1258^^^^^^^^^^^Agave deserti/Ferocactus acanthodes acanthodes (Lemaire) Britton and Rose4LPC^1256^Plant Physiol.4u E rt+~EsF_^ZY[XPV t3^XfA^1256^For the leaf succulent _Agave deserti_ and the stem succulent _Ferocactus acanthodes_, increasing the ambient CO2 lgevel from 350 microliters per liter to 650 microliters per liter immediately increased daytime net CO2 uptake about 30% whhile leaving nighttime net CO2 uptake of these Crassulacean acid metabolism (CAM) plants approximately unchanged. A similari enhancement of about 30% was found in dry weight gain over 1 year when the plants were grown at 650 microliters CO2 per ljiter compared with 350 microliters per liter. Based on these results plus those at 500 microliters per liter, net CO2 uptakke over 24-hour periods and dry weight productivity of these two CAM succulents is predicted to increase an average of about 1% for each 10 microliters per liter rise in ambient CO2 level up to 650 microliters per liter.O$0^NtsFm499^1^Nonhebel,S^1990^3^The Impact of Changes in Weather and CO2 Concentration on Spring Wheat Yields in Western Europe^Thne Greenhouse Effect and Primary Productivity in European Agro-ecosystems; 5-10 April 1990; Wageningen, The Netherlands^Pudoc^Wageningen^48-50^^^^^^^^^^^^^^^^^^^^^wheat/Triticum aestivum^^^^^^^^^^Goudriaan,J^van Keulen,H^van Laar,HHH H${p500^1^Norby,R J^1989^3^Direct Responses of Forest Trees to Rising Atmospheric Carbon Dioxide^Proceedings of the Second US-qUSSR Symposium, Air Pollution Effects on Vegetation including Forest Ecosystems, 13-25 September 1988, Corvallis, Oregon, rRaleigh, North Carolina, Gatlinburg, Tennessee, and Broomall, Pennsylvania^USDA Forest Service, Northeastern Forest Experiment Station^^243-248^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^Noble,RD^Martin,JL^Jensen,KFPQR=tttZYXt501^1^Norby,R J^1987^1^Nodulation and Nitrogenase Activity in Nitrogen-fixing Woody Plants Stimulated by CO2 Enrichment of the Atmosphere^44^71^^77-82^^^^^^^^^^1263^^^^^^^^^^^Robinia pseudoacacia/Alnus glutinosa/Elaeagnus angustifoliaeagnus anvgustifolia L.`&G!&?(rQ&MtSr@R&62&PXZ&Lt,|tr_r t _ F F dC^1261^Physiol. Plant.9‹\_rNt]&6~*v76:r+^ m^€~ t2tĚ__rFxA^1261^The responses of three species of nitrogen-fixing trees to CO2 enrichment of the atmosphere were investigated undery nutrient-poor conditions. Seedlings of the legume, _Robinia pseudoacacia_ L. and the actinorhizal species, _Alnus glutinozsa_ (L.) Gairtn. and _Elaeagnus angustifolia_ L. were grown in an infertile forest soil in controlled environment chambers{ with atmospheric CO2 concentrations of 340 uL/L (ambient) or 700 uL/L. In _R. pseudoacacia_ and _A. glutinosa_, total nit|rogenase (N2 reduction) activity per plant, assayed by the acetylene reduction method, was significantly higher in elevate}d CO2, because the plants were larger and had more nodule mass than did plants in ambient CO2. The specific nitrogenase ac~tivity of the nodules, however, was not consistently or significantly affected by CO2 enrichment. Substantial increases in plant growth occurred with CO2 enrichment despite probable nitrogen and phosphorus deficiencies. These results support the premises that nutrient limitations will not preclude growth responses of woody plants to elevated CO2 and that stimulation of symbiotic activity by CO2 enrichment of the atmosphere could increase nutrient availability in infertile habitats.V502^5^Norby,R J^Gunderson,C A^Wullschleger,S D^O'Neill,E G^McCracken,M K^1992^1^Productivity and Compensatory Responses of Yellow-poplar Trees in Elevated CO2^77^357^^322-324^^^^^^^^^^1266^^^^^^^^^^^Liriodendron tulipifera/yellow poplarpoplaruC^1264^Natureĸer;u7;s.@t|r+t nr t`rYSQVWU;9u;>tA^1264^Increased forest growth in response to globally rising CO2 concentrations could provide an additional sink for the excess carbon added to the atmosphere from fossil fuels. The response of trees to increased CO2, however, can be expected to be modified by the interactions of other environmental resources and stresses, higher-order ecological interactions and internal feedbacks inherent in the growth of large, perennial organisms. To test whether short-term stimulation of tree growth by elevated CO2 can be sustained without inputs from other environmental resources, we grew yellow-poplar (_Liriodendron tulipifera_ L.) saplings for most of three growing seasons with continuous exposure to ambient or elevated concentrations of atmospheric CO2. Despite a sustained increase in leaf-level photosynthesis and lower rates of foliar respiration in CO2-enriched trees, whole-plant carbon storage did not increase. The absence of a significant growth response is explained by changes in carbon allocation patterns, specifically a relative decrease in leaf production and an increase in fine root production. Although these compensatory responses reduced the potential increase in carbon storage in increased CO2 concentrations, they also favour the efficient use of resources over the longer term.VbrD&=&EF&}~ 503^4^Norby,R J^O'Neill,E G^Hood,W G^Luxmoore,R J^1987^1^Carbon Allocation, Root Exudation and Mycorrhizal Colonization of _Pinus echinata_ Seedlings Grown under CO2 Enrichment^43^3^^203-210^^^^^^^^^^1269^^^^^^^^^^^Pinus echinata/shortleaf pineleaf pineuX0F_ZYXV\rJF`=b?^V &&D/rF^SQRV&\&L2&D&T2o4:r7C^1267^Tree Physiol.]&]`brBE&4&D504^3^Norby,R J^O'Neill,E G^Luxmoore,R J^1986^1^Effects of Atmospheric CO2 Enrichment on the Growth and Mineral Nutrition of _Quercus alba_ Seedlings in Nutrient-poor Soil^17^82^^83-89^^^^^^^^^^1272^^^^^^^^^^^Quercus alba/white oakte oak]C^1270^Plant Physiol.PWU\${sFF]_XPQUǚ${sFF]YXQPbء${XYPSQRVWUtA^1270^One-year-old dormant white oak (_Quercus alba_ L.) seedlings were planted in a nutrient-deficient forest soil and grown for 40 weeks in growth chambers at ambient (362 microliters per liter) or elevated (690 microliters per liter) levels of CO2. Although all of the seedlings became severely N deficient, CO2 enrichment enhanced growth by 85%, with the greatest enhancement in root systems. The growth enhancement did not increase the total water use per plant, so water-use efficiency was significantly greater in elevated CO2. Total uptake of N, S, and B was not affected by CO2, therefore, tissue concentrations of these nutrients were significantly lower in elevated CO2. An increase in nutrient-use efficiency with respect to N was apparent in that a greater proportion of the limited N pool in the CO2-enriched plants was in fine roots and leaves. The uptake of other nutrients increased with CO2 concentration, and P and K uptake increased in proportion to growth. Increased uptake of P by plants in elevated CO2 may have been a result of greater proliferation of fine roots and associated mycorrhizae and rhizosphere bacteria stimulating P mineralization. The results demonstrate that a growth response to CO2 enrichment is possible in nutrient-limited systems, and that the mechanisms of response may include either increased nutrient supply or decreased physiological demand.WV[P=bXtPSQbؠ 6tY[XW*[P=bXtPSQbؠ 505^2^Norby,R J^O'Neill,E G^1989^1^Growth Dynamics and Water Use of Seedlings of _Quercus alba_ L. in CO2-enriched Atmospheres^23^111^^491-500^^^^^^^^^^1275^^^^^^^^^^^Quercus alba/white oakte oak҃ǀt t t tC^1273^New Phytol. ҃&PXr; u40&C^1276^New Phytol.[XSRQU&DžOv&t%&%N.P&%&!Y&Q&!U&tD&!vP&+Uy&!&A^1276^The responses of yellow-poplar (_Liriodendron tulipifera_ L.) seedlings to elevated levels of atmospheric CO2 were investigated to identify attributes governing growth and physiological responses to CO2. Based on the pattern of leaf initiation and nutrient requirements of the species, it was predicted that (1) CO2 enrichment would enhance growth of yellow-poplar seedlings both through accelerated leaf area production and through higher rates of carbon assimilation per unit leaf area; and (2) growth enhancement of yellow-poplar by CO2 enrichment would be reduced by nutrient limitations. The hypotheses were tested in an experiment in which yellow-poplar plants were grown from seed for 24 weeks in controlled environment chambers. The experimental design comprised three atmospheric CO2 concentrations (371, 493, and 787 cm3/m3), two levels of mineral nutrients (unfertilized or weekly additions of complete nutrient solution), and three harvests (6, 12, and 24 weeks). Plant growth rate, water use, foliar gas exchange, component dry weights, and nutrient contents were measured. Both hypotheses were rejected. Whole-plant dry weight increased similarly with CO2 enrichment in plants provided with additional mineral nutrients and in unfertilized plants, although the fertilized plants grew 10-fold larger. The increase in dry weight resulting from elevated CO2 occurred only in root systems. Although leaves were produced continuously during the experiment, leaf area was slightly reduced in elevated CO2, and the whole-plant growth response was wholly attributable to an increase in carbon assimilation per unit leaf area. Although the compensation between photosynthesis and leaf area reduced the potential growth response to CO2, the reduction in leaf area ratio was associated with a significant increase in water-use efficiency. This unexpected result demonstrated the importance of feedbacks and interactions between resources in shaping the response of a plant to CO2.>t W&|E _V&F&D& K&TM^^ f ~t507^3^Norby,R J^Pastor,J^Melillo,J M^1986^1^Carbon-nitrogen Interactions in CO2-enriched White Oak: Physiological and Long-term Perspectives^43^2^^233-241^^^^^^^^^^1281^^^^^^^^^^^Quercus alba/white oakte oak]_^ZY[XPSQRVW2NVC^1279^Tree Physiol.NN׋fN6v FWt= tN *rwu2^2;sOPDŽ&DŽA^1279^The responses of forest trees to atmospheric CO2 enrichment will depend in part on carbon-nutrient linkages. Insights into the possible long-term ecological consequences of CO2 enrichment can be gained from studying physiological responses in short-term experiments. One-year-old white oak (_Quercus alba_ L.) seedlings were grown in unfertilized forest soil for 40 weeks in controlled environment chambers with ambient (362 uL/L) or elevated (690 uL/L) CO2. As previously reported, seedling dry weight was 85% greater in the elevated CO2 environment, despite severe nitrogen deficiency in all seedlings. The increase in growth occurred without a concomitant increase in nitrogen uptake, indicating an increase in nitrogen-use efficiency in elevated CO2. The weight of new buds was greater in elevated CO2, suggesting that shoot growth in the next year would have been enhanced relative to that of seedlings in ambient CO2. However, there was less translocatable nitrogen in perennial woody tissue in elevated CO2; thus, further increases in nitrogen-use efficiency may not be possible. The leaves that abscised from seedlings in elevated CO2 contained higher amounts of soluble sugars and tannin and a lower amount of lignin compared with amounts in abscised leaves in ambient CO2. Based on lignin:N and lignin:P ratios, the rates of litter decomposition might not be greatly affected by CO2 enrichment, but the total amount of nitrogen returned to soil would be lower in elevated CO2.tV܉!QttXtQ1-Xu&t2ҋW%^؀ 508^2^Norby,R J^Sigal,L L^1989^1^Nitrogen Fixation in the Lichen _Lobaria pulmonaria_ in Elevated Atmospheric Carbon Dioxide^34^79^^566-568^^^^^^^^^^1284^^^^^^^^^^^Lobaria pulmonaria/lichen) Hoffm./lichen.DŽXÀNc~uC^1282^OecologiaWPVF6%f^XS ^Հ t  t s  [SWA^1282^Thalli of _Lobaria pulmonaria_ (L.) Hoffm., a nitrogen-fixing epiphyte common in mesic temperate forests, were collected in a Douglas-fir (_Pseudotsuga menziesii_ Franco) forest near Corvallis, Oregon, and maintained for 20 to 40 days in controlled-environment chambers with atmospheric CO2 concentrations of 374 and 700 uL/L. Nitrogenase activity, which was assayed by the acetylene reduction method, was approximately doubled in the lichen maintained in elevated CO2. Increases in nitrogen fixation by lichens may be an important part of the integrated ecosystem response to rising CO2.^6FYN509^3^O'Neill,E G^Luxmoore,R J^Norby,R J^1987^1^Elevated Atmospheric CO2 Effects on Seedling Growth, Nutrient Uptake, and Rhizosphere Bacterial Populations of _Liriodendron tulipifera_ L^98^104^^3-11^^^^^^^^^^1287^^^^^^^^^^^yellow poplar/Liriodendron tulipiferaera L.V̉F3FЉFΉFԉFҋ3Fċ1FvWc6F_F F}{FtC^1285^Plant and Soilufuc6F>3=;A?GIuecc 3 t<3A^1285^Yellow-poplar (_Liriodendron tulipifera_ L.) seedlings were planted in unfertilized forest soil in boxes with a removable side panel and grown in atmospheres containing either ambient (367 uL/L) or elevated (692 uL/L) CO2. Numbers of total bacteria, nitrifiers, and phosphate-dissolving bacteria in the rhizosphere and in nonrhizosphere soil were measured every 6 weeks for 24 weeks. Seedling growth and nutrient content were measured at a final whole-plant harvest. Root, leaf, and total dry weights were significantly greater, and specific leaf area was significantly less, in 692 uL/L than in ambient CO2. Uptake per gram plant dry weight of N, S, and B was lower at elevated CO2 whereas uptake of P, K, Cu, Al, and Fe was proportional to growth in both CO2 treatments. Total uptake and uptake per g plant dry weight of Ca, Mg, Sr, Ba, Zn, and Mn were not affected by CO2 treatment. Bacterial populations differed due to CO2 only at the final harvest, where there were significantly fewer nitrite-oxidizers and phosphate-dissolving bacteria in the rhizosphere of seedlings grown at 692 uL/L CO2.FrXesPi?:5&Dr9s&Dus&Dut F_^ZY[XPRVU510^3^O'Neill,E G^Luxmoore,R J^Norby,R J^1987^1^Increases in Mycorrhizal Colonization and Seedling Growth in _Pinus echinata_ and _Quercus alba_ in an Enriched CO2 Atmosphere^32^17^^878-883^^^^^^^^^^1290^^^^^^^^^^^Quercus alba/white oak/Pinus echinata/shortleaf pineortleaf pineN VV _^ZY[XPSQRVWtSFrR2&V&| ^v7&Lt6F\C^1288^Can. J. For. Res.t _^ZY[XPQW3&&Eu_YXVU&&t5r3&&\ v &Lg6A^1288^Forest tree biomass is hypothesized to increase in a CO2-enriched atmosphere if mechanisms exist to ensure acquisition of limiting nutrients in forest soils. Investment of additional photosynthate produced at elevated CO2 into mycorrhizal proliferation and root growth may provide one such mechanism. To test this hypothesis, mycorrhizal density and seedling biomass were measured in shortleaf pine (_Pinus echinata_ Mill.) and white oak (_Quercus alba_ L.) grown in unfertilized forest soil in controlled-environment chambers at 360 uL/L and 700 uL/L CO2. Mycorrhizal density was greater at elevated CO2 in both species after 6 weeks of exposure; in white oak, the increased density persisted for 24 weeks. Root dry weight was increased 76% in _P. echinata_ and 91% in _Q. alba_ at 700 uL/L CO2; total seedling dry weight was increased by 66 and 56%, respectively. It is hypothesized that increased photosynthesis at elevated CO2 offsets the carbon requirement for mycorrhizal establishment on shortleaf pine. Greater mycorrhizal density and enhanced 1st year root growth in both species may facilitate future nutrient acquisition, supporting further increases in an enriched CO2 atmosphere.RUhrNXA=511^3^Oberbauer,S F^Oechel,W C^Riechers,G H^1986^1^Soil Respiration of Alaskan Tundra at Elevated Atmospheric Carbon Dioxide Concentrations^98^96^^145-148^^^^^^^^^^1293293>u>=t|   ##ډَ>dC^1291^Plant and SoilEu &M&Et#&}s&E&}s2&*]&]t&Mt&Mt&M؁l>A^1291^CO2 efflux from tussock tundra in Alaska that had been exposed to elevated CO2 for 2.5 growing seasons was measured to assess the effect of long- and short-term CO2 enrichment on soil respiration. Long-term treatments were: 348, 514, and 683 uL/L CO2 and 680 uL/L CO2 + 4C above ambient. Measurements were made at 5 CO2 concentrations between 87 and 680 uL/L CO2. Neither long- or short-term CO2 enrichment significantly affected soil CO2 efflux. Tundra developed at elevated temp erature and 680 uL/L CO2 had slightly higher, but not statistically different, mean respiration rates compared to untreated tundra and to tundra under CO2 control alone.|~|s&f&ftq&>&%RZ\v\FDF 512^4^Oberbauer,S F^Sionit,N^Hastings,S J^Oechel,W C^1986^1^Effects of CO2 Enrichment and Nutrition on Growth, Photosynthesis, and Nutrient Concentration of Alaskan Tundra Plant Species^54^64^^2993-2998^^^^^^^^^^1296^^^^^^^^^^^Carex bigelowii/Betula nana/Ledum palustredum palustre!tFvF{_^ZY[PQWNrȁtV.Mt _C^1294^Can. J. Bot.3]ZY[_^F&FF tFF 7X7XÚ${Ú${ÚO${ÚA^1294^Three Alaskan tundra species, _Carex bigelowii_ Torr., _Betula nana_ L., and _Ledum palustre_ L., were grown in controlled-environment chambers at two nutrition levels with two concentrations of atmospheric CO2 to assess the interactive effects of these factors on growth, photosynthesis, and tissue nutrient content. Carbon dioxide concentrations were maintained at 350 and 675 uL/L under photosynthetic photon flux densities of 450 umol/m2/s and temperatures of 20:15C (light:dark). Nutrient treatments were obtained by watering daily with 1/60- or 1/8-strength Hoagland's solution. Leaf, root, and total biomass were strongly enhanced by nutrient enrichment regardless of the CO2 concentration. In contrast, enriched atmospheric CO2 did not significantly affect plant biomass and there was no interaction between nutrition and CO2 concentration during growth. Leaf photosynthesis was increased by better nutrition in two species but was unchanged by CO2 enrichment during growth in all three species. The effects of nutrient addition and CO2 enrichment on tissue nutrient concentrations were complex and differed among the three species. The data suggest that CO2 enrichment with or without nutrient limitations has little effect on the biomass production of these three tundra species.rq3W2&Dt &L?2A513^7^Oechel,W C^Hastings,S^Hilbert,D^Lawrence,W^Prudhomme,T^Riechers,G^Tissue,D^1984^5^The Response of Arctic Ecosystems to Elevated Carbon Dioxide Regimes^U.S. Dept. of Energy, Carbon Dioxide Research Division, Washington, D.C^^^^^^^^^^^^^^^^^^^^^^^^Carex bigelowii/Eriophorum vaginatum/Ledum palustre/Vaccinium vitis-idaea/Vaccinium uliginosum/Betula nana/Salix pulchra^^019 in Green Report Series^Response of Vegetation to Carbon Dioxide^^;5_^Y[ˀ>@ t>@ u 514^6^Oechel,W C^Riechers,G^Lawrence,W T^Prudhomme,T I^Grulke,N^Hastings,S J^1992^1^'CO2LT' an Automated, Null-balance System for Studying the Effects of Elevated CO2 and Global Climate Change on Unmanaged Ecosystems^37^6^^86-100^^^^^^^^^^1300C^1298^Funct. Ecol.t&t̽r:^[ PSQRWVU/r\&2&y tN&y sG&E' u@3&E&0t$r2w&D u)WV#A^1298^An automated, CO2-controlled, long-term greenhouse system ('CO2LT') has been developed to provide replicated _in si$tu_ ecosystem-level manipulation of atmospheric CO2 concentration and temperature for intact plots of tussock tundra, and %to measure the instantaneous ecosystem-level CO2 exchange rates within each of the plots under the treatments imposed. Thi&s is a computer-controlled, closed, null-balance greenhouse system consisting of 12 chambers with individual control of CO'2 concentration and temperature. Carbon dioxide can be maintained in each chamber at concentrations from well below ambien(t (150-200 uL/L) to more than 900 uL/L. Air temperature can be fixed, set to track ambient, or can track ambient temperatu)re with a specified offset allowing studies of the interaction of CO2 and temperature. Despite the complications involved *in tracking a naturally fluctuating environment, the CO2LT system performs very well. Temperatures in individual chambers +averaged within 1C of ambient or target temperatures over a 24-h period and carbon dioxide concentration control rivals t,hat of laboratory-based, control-environment systems. Photon flux density within the chambers is within 93% of ambient val-ues. Comparison to unenclosed tundra indicates minimal chamber effects on depth of thaw, air, leaf or soil temperatures, o.r net ecosystem CO2 flux. Chamber effects are generally small, and the experimental design allows separation and interpret/ation of treatment effects despite any unavoidable chamber effects. Both diurnal and seasonal patterns of net ecosystem CO02 flux can be accurately tracked with this system. Field measurements indicate net ecosystem CO2 loss under current enviro1nmental conditions, a possible response to recent climate change. Field measurements also indicate initial enhancement of 2net ecosystem CO2 uptake with elevated atmospheric CO2. Photosynthetic adjustment to elevated CO2 lowers ecosystem respons3e to that of ambient chambers by mid-season. Also indicated is the possibility of delayed senescence of photosynthetic capacity at elevated CO2.rw tuEr:sF^ZXPSQRWVUb0s&>t+&M&] 2&=re&E (uRrWw!300rG&2&>Cѐr2&;}*&O 軐r&E'(u2 wr rsF]^_ZY[XPSQVU u}rT&E&0t6515^9^Oechel,W C^Riechers,G H^Beyers,J^Cowles,S^Grulke,N^Hastings,S^Oberbauer,S^Prudhomme,T^Sionit,N^1986^5^Response of a 7Tundra Ecosystem to Elevated Atmospheric Carbon Dioxide^U.S. Dept. of Energy, Carbon Dioxide Research Division, Washington8, D.C^^^^^^^^^^^^^^^^^^^^^^^^Vaccinium vitis-idaea/Eriophorum vaginatum/Ledum palustre/Carex bigelowii/Betula nana^^037 in Green Report Series^Response of Vegetation to Carbon Dioxide^^rbon Dioxide^^ *3>et:6bt)F:516^2^Oechel,W C^Strain,B R^1985^3^Native Species Responses to Increased Atmospheric Carbon Dioxide Concentration^Direct E;ffects of Increasing Carbon Dioxide on Vegetation^Dept. of Energy, Carbon Dioxide Research Division^Washington, D.c.^117-154^^^^^^^DOE/ER-0238^^^^^^^^^^^^^^^^^^^^^^^^Strain,BR^Cure,JDsuFu^~[XPSRUbۀt.0.=517^1^Olesen,J E^1990^3^Evaluating the Effect of Climatic Change on Productivity of Agricultural Crops in Denmark^The Gree>nhouse Effect and Primary Productivity in European Agro-ecosystems; 5-10 April 1990; Wageningen, The Netherlands^Pudoc^Wageningen^53-56^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^Goudriaan,J^van Keulen,H^van Laar,H H F& -& $&" $¿ r@518^3^Osbrink,W L A^Trumble,J T^Wagner,R E^1987^1^Host Suitability of _Phaseolus lunata_ for _Trichoplusia ni_ (Lepidoptera: Noctuidae) in Controlled Carbon Dioxide Atmospheres^6^16^^639-644^^^^^^^^^^1306^^^^^^^^^^^Phaseolus lunata/lima beana 4C^1304^Environ. Entomol.!ZXPR&>t &!ZXVQP&& & & & & &&&>uCA^1304^Elevated atmospheric carbon dioxide (CO2) levels of 1,000 parts per million (ppm) significantly increased consumptiDon of foliage by _Trichoplusia ni_ (Hubner) and significantly enhanced growth of _Phaseolus lunata_ L. when compared with Eambient levels of 340 ppm. Mean pupal weight was less under treatments with elevated atmospheric CO2 under a high fertilizFation regime, but larval survival and percent nitrogen content of pupae were not affected by level of CO2 treatments at hiGgh, medium or low fertilizer rates. Regardless of CO2 concentration, larval survival and pupal weight were reduced in abseHnce of fertilizer. Nitrogen and protein consumption increased with fertilization rate. Because percent leaf area of plantsI consumed by _T. ni_ larvae was not affected by CO2 concentration, this study suggests that increased plant growth resulting from elevated atmospheric CO2 may benefit the plant proportionately more than the insect.v<Lsv Abean&E'@ti&u^ W~_uS?t?t~t W~_u'^ &E'u&u;uuv(u: @@L519^1^Overdieck,D^1990^3^Direct Effects of Elevated CO2 Concentration Levels on Grass and Clover in 'Model-ecosystems'^ExpMected Effects of Climatic Change on Marine Coastal Ecosystems^Kluwer Academic Publishers^Dordrecht, The Netherlands^41-47^N^^^^^^^^^1308^^^^^^^^^^^Trifolium repens/white clover/Lolium perenne/perennial ryegrass/Trifolium pratense/red clover/Festuca pratensis/meadow grass^^^^^^^^^^Beukema,JJ^Wolff,WJ^Brouns,JJWMJ^Brouns,J J W MGXv3ҋF&;uGG t uB:PA^1307^In long-term experiments (up to 2.5 vegetation periods) grass/clover-mixtures (1:1) were exposed to 4 CO2 concentraQtion levels (340, 450, 600, and 800 mm3/dm3) in acrylic-miniglasshouses which were climatized according to the microclimatRe outside. At 600 mm3/dm3, plant growth and production were enhanced by 20-40% compared to cultures at 340 mm3/dm3. Only tShe seed weight of the clover species increased by max. 28% with elevated CO2 concentration levels. Without clippings, the Tclover species tended to be more enhanced by additional CO2. With clippings, the grass was more successful in competition.U The C/N-, C/P-, C/Ca- and C/K-relationships were higher at elevated CO2 concentration level. The CO2 net fixation of the Vwhole canopy increased by 40% when the CO2 concentration was raised from 340 to 600 mm3/dm3. This enhancement decreased until the end of the third vegetation period to about 10%. The ecological consequences of these findings are discussed.X520^1^Overdieck,D^1989^1^The effects of Preindustrial and Predicted Future Atmospheric CO2 Concentration on _Lyonia mariana_ L.D. Don^37^3^^569-576^^^^^^^^^^1311^^^^^^^^^^^Lyonia marianaana L.D. Don t&D$ t:ug t &D t:u2JC^1309^Funct. Ecol.Gt3PSQV_2 t&ul3&D3 t;u _^Y[XPSVW&u8&D_=[A^1309^CO2 net assimilation and transpiration rates were measured on the entire above-ground parts of 7-8-month-old seedli\ngs of _Lyonia mariana_ L.D. Don (Ericaceae) grown for 2-3 months at 270 (preindustrial concentration), 350 and 650 uL CO2]/L at constant climatic conditions in growth chambers. Slight CO2-enrichment from 270 to 350 uL CO2/L elevated the level o^f the light response curve by about 25% at light saturation and enrichment from 350 to 650 uL CO2/L elevated this level by_ about 27%. The light compensation points decreased with increasing CO2 (270: about 108; 350: about 94; 650 uL CO2/L: abou`t 83 umol photons/m2/s. At each CO2 treatment the response to the increase of internal CO2 could be described by polynomiaals (maxima at 600-800 uL CO2/L). The curves differed in CO2 compensation points (270: about 55; 350: about 58; 650 uL CO2/bL: about 70 uL CO2/L (_Ci_). The initial CO2 yield per uL CO2/L concentration increase amounted to about 10.5 (270), aboutc 9.5 (350) and 7.1 ug CO2/dm2/h (650 uL CO2/L). The mean transpiration rate during the investigation of light and CO2-response was 16% lower at 350 than at 270 and 15.5% lower at 650 than at 350 uL CO2/L.&MN&M0&&O&G{re521^1^Overdieck,D^1990^3^Effects of Elevated CO2-concentration Levels on Nutrient Contents of Herbaceous and Woody Plants^fThe Greenhouse Effect and Primary Productivity in European Agro-ecosystems; 5-10 April 1990; Wageningen, The Netherlands^Pgudoc^Wageningen^31-37^^^^^^^^^^^^^^^^^^^^^Trifolium pratense/red clover/Festuca pratensis/meadow fescue/Acer pseudoplatanus/mountain maple/sycamore maple/Fagus sylvatica/beech^^^^^^^^^^Goudriaan,J^van Keulen,H^van Laar,HH,H^van Laar,H HG &i522^1^Overdieck,D^1993^1^Elevated CO2 and the Mineral Content of Herbaceous and Woody Plants^123^104/105^^403-411^^^^^^^^^j^1315^^^^^^^^^^^Trifolium repens/white clover/Trifolium pratense/red clover/Lolium perenne/perennial ryegrass/Festuca pratensis/meadow fescue/Acer pseudoplatanus/sycamore maple/Fagus sylvatica/beech^^^^^lvatica L./beech^^^^^PS2P$X$$es^^^^104/105; VegetatiorM~\t ~ltur,0>r!&2&3ҁ~|u &L&L&;Lt&mA^1313^The CO2 enrichment effects (300-650 umol/mol) on mineral concentration (N, P, K, Ca, Mg, Mn, Fe, Zn), absolute totanl mineral contents per individual and of whole stands of four herbaceous (_Trifolium repens_ L., _Trifolium pratense_ L., o_Lolium perenne_ L., _Festuca pratensis_ HUDS.) and two woody species (_Acer pseudoplatanus_ L., _Fagus sylvatica_ L.) werpe investigated. In general, the mineral concentration of the plant tissues decreased (all six species: N>Ca>K>Mg) with theq exception of P. Mn and Fe were only determined for the tree species. Both decreased in concentration (Mn>Fe). Zn was onlyr analysed for _Trifolium pratense_ and _Festuca pratensis_ and decreased significantly in the grass. Despite of decreases sin concentrations of as much as 20% in some cases there were increases in absolute amounts per individual and, therefore, in the whole vegetation up to 25% because of the enhanced dry matter accumulation at elevated CO2 supply.V6^u523^1^Overdieck,D^1986^1^Long-term Effects of an Increased CO2 Concentration on Terrestrial Plants in Model Ecosystems. Movrphology and Reproduction of _Trifolium repens_ L. and _Lolium perenne_ L^100^30^^323-332^^^^^^^^^^1318^^^^^^^^^^^Trifolium repens/white clover/Lolium perenne/perennial ryegrassryegrassgsF]^_Z[XPSQRVWUٹ_&524^1^Overdieck,D^1987^5^Untersuchungen uber die voraussichtlichen Langzeiteffekte einer CO2-bedingten Klimaveranderung auf die einheimische Vegetation^Universitat Osnabruck, Fachbereich Biologie/Chemie, Arbeitsgruppe Okologie, Osnabruck^^^^^^^^^^^^^1320^^^^^^^^^^^Vigna unguiculata/cowpea/Abelmoschus esculentus/okra/Raphanus sativus/radish/Lolium perenne/perennial ryegrass/Trifolium repens/white clover/Festuca pratensis/meadow fescue/Trifolium pratense/red clover^^ifolium pratense wL./red clover^^p([(B(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p( /.,,,,, , , , , ,,,A^1319^Long-term experiments were conducted on herbaceous species at constant microclimatic conditions and at natural conditions on simplified stands of Middle-European grassland-vegetation units using atmospheric CO2 concentrations from 270 to 650 uL/L CO2. At elevated CO2 supply stems grow longer and more voluminously, leaf areas increase, and in most cases more material is translocated to storage organs. A minor CO2 impoverishment (270 uL/L CO2) leads to overproportionate losses in production. Increasing CO2 concentrations have more effect at lower than at higher CO2 levels. The CO2 enrichment effect is enhanced by increasing light intensities. Increasing temperatures support the positive CO2 effect up to 35C beyond that their effect is negative. Grassland ecosystems can only be an effective sink for additionally emitted CO2 during their juvenile phases and after mowing. This CO2 effect on the systems decreases in the second year considerably. CO2 enrichment influences the performance of grassland species in competition (changes in the spectrum of species). At the beginning of growth the absolute nutrient uptake increases with CO2 enrichment which can lead to nutrient deficiencies on poorer soils. Two mathematical methods were developed for modelling the CO2 effect on grassland-ecosystems in dependance of many ecological factors including all microclimatic factors of the experiments (1st approach: 4 factors, 2nd: 7 factors). One of the methods is based on pseudocubical splines. In German.gdkmnol,,525^2^Overdieck,D^Bossemeyer,D^1985^1^Langzeit-Effekte eines erhohten CO2-Angebotes auf den CO2-Gaswechsel eines Modell-Okosystems^101^59^^179-198^^^^^^^^^^1323^^^^^^^^^^^Trifolium repens/white clover/Lolium perenne/perennial ryegrass ryegrassC^1321^Angew. Bot.=dQHKpA^1321^A model ecosystem composed of 30 cm deep homogenized garden soil and a mixture of clover and grass (_Trifolium repens_ L. and _Lolium perenne_ L., 1:1, 45 seeds/dm2) was supplied with about 600 ppm CO2 in the air in an acrylic glasshouse from the beginning of germination for a total period of one year (03. Sept.-31. Aug.). With slight deviations (+/- 0.5C) the air temperature in the glasshouse was adjusted to the air outside. The values of relative air humidity corresponded approximately with the outside values. Besides, the photon flux density (photosynthetically active radiation) inside the glasshouse and the CO2 gas exchange rates of the system were continuously registered together with the climatic parameters (measuring interval: 48 s). A parallel control experiment was run in the same way; there the CO2 concentration was held at about 330 ppm. The better CO2 supply caused higher CO2 net fixation rates during the whole experiment with the exception of days with low photon flux densities (mostly <100 umol/m2/s). This positive CO2 effect grew with increasing photon flux density and increasing air temperature. An influence of the relative air humidity on the CO2 effect could not be identified. In most cases the relationship between photon flux density and CO2 gas exchange rates within different temperature classes and different stages of development could easily be approximated by saturation curves. With growing age the 600 ppm CO2 system reached increasingly higher compensation points compared to the 330 ppm CO2 system and the level of irradiation saturation was relatively more elevated than at 330 ppm CO2. In the total balance at about 600 ppm CO2 approximately 1.7 kg/m2/a more CO2 were net fixed than at about 330 ppm (50% more). At the peak of growth the difference of the total phytomass between the systems was 0.6 g/m2 (dry matter increase of 43%). In German. # {qw4_ZbZ526^2^Overdieck,D^Forstreuter,M^1991^3^Carbon Dioxide Effects on Vegetation^Modern Ecology: Basic and Applied Aspects^Elsevier^New York^623-657^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^Esser,G^Overdieck,D;"m4xx527^2^Overdieck,D^Lieth,H^1986^5^Long-term Effects of an Increased Atmospheric CO2 Concentration Level on Terrestrial Plants in Model-ecosystems^Universitat Osnabruck, Fachbereich Biologie/Chemie, Arbeitsgruppe Okologie, Osnabruck^^^^^^^^^^^^^1326^^^^^^^^^^^Lolium perenne/perennial ryegrass/Trifolium repens/white clover/Fagus sylvatica/Picea abies/Pinus sylvestris/Lyonia mariana/Lyonia lucida/Acer pseudoplatanus/Quercus robur/Beta vulgaris/sugar beet/beet/Chenopodium album/white chenopod/Plantago major/broadleaf plantain/Urtica dioica/stinging nettle/Rumex obtusifolia/bluntleaved sorrel/Taraxacum officinale/dandelion/Polygonum aviculare/bird's knotweed/Capsella bursa-pastoris/shepherd's purse/Festuca rubra/red fescue/Festu!ca pratensis/meadow fescue/Trifolium pratense/red clover/Secale cereale/rye/Triticum aestivum/wheat/Hordeum vulgare/barleym/wheat/Hordeum vulgare/barleyy-F/ A^1325^The following results are most important for European landscape management, agriculture, and forestry (30 plants were tested): 1. A number of plants increase their productivity with increasing atmospheric CO2 concentrations only during the juvenile phase of development. 2. Different plants growing together in semi-natural or managed plant communities vary in their response to increasing CO2 concentrations. 3. Increasing atmospheric CO2 will cause changes in competition of plants. 4. The additional growth at elevated CO2 is not nutrient-limited on medium fertile soils. 5. The absolute nutrient uptake increases at CO2-enrichment. Grassland communities are a sink for additional CO2 only in the first vegetation period after sowing. 6. The CO2-effect on growth and productivity is enhanced by increasing light intensity. 7. Increasing temperatures support the positive CO2 effect up to 35C. 8. The vegetation period starts earlier for several plants under higher CO2 concentrations. The results of the experiments were used to construct models for better data analysis and to improve our regional and global models. From the results we can conclude that no immediate major threats to plant growth may be expected from slightly elevated CO2 concentrations. Most probable are changes in species composition in several ecosystems due to different responses of growth and seed production, there may be a higher susceptibility to late frosts in certain species, and there may be higher nutrient-uptake rates. These aspects require further studies because they are important for the management of grasslands, orchards, and fields. In German.528^2^Overdieck,D^Reining,F^1986^1^Effect of Atmospheric CO2 Enrichment on Perennial Ryegrass (_Lolium perenne_ L.) and White Clover (_Trifolium repens_ L.) Competing in Managed Model-ecosystems. I. Phytomass Production^64^7^^357-366^^^^^^^^^^1329^^^^^^^^^^^Trifolium repens/white clover/Lolium perenne/perennial ryegrass ryegrassC^1327^Acta Oecologica/Oecol. Plant.A^1327^A model ecosystem composed of 0.14 m3 homogenized garden soil and a mixture of _Trifolium repens_ L. and _Lolium perenne_ L. (1:1, 45 seeds/dm2) was supplied with about 620 ppm CO2 in an acrylic glasshouse (0.26 m3) for 90 days, started 10 days after germination (9 July-5 October, 1983). A control experiment was run at about 300 ppm CO2. Aerial phytomass was removed by mowing four times in both systems. Air temperatures in the glasshouses were adjusted to that of the air outside (+/- 0.5C) and the wind velocity to 0.5 m/s. The relative air humidities corresponded approximately with those from the outside (+15%). Leaf area and above and below ground phytomass accumulation of both species, net primary production and net primary productivity were enhanced by the CO2 enrichment. Before mowing _Trifolium repens_ was more enhanced but after mowing _Lolium perenne_ became the most enhanced species.529^2^Overdieck,D^Reining,E^1986^1^Effect of Atmospheric CO2 Enrichment on Perennial Ryegrass (_Lolium perenne_ L.) and White Clover (_Trifolium repens_ L.) Competing in Managed Model-ecosystems. II. Nutrient Uptake^64^7^^367-378^^^^^^^^^^1332^^^^^^^^^^^Trifolium repens/white clover/Lolium perenne/perennial ryegrass ryegrassC^1330^Acta Oecologica/Oecol. Plant.DP >Frd>$"8>FA^1330^A model ecosystem composed of 0.14 m3 homogenized garden soil and a mixture of _Trifolium repens_ L. and _Lolium perenne_ L. (1:1, 45 seeds/dm2) was supplied with about 620 ppm CO2 in an acrylic glasshouse (0.26 m3) for 90 days, started 10 days after germination (9 July-5 October, 1983). A control experiment was run at about 300 ppm CO2. Aerial phytomass was removed by mowing four times in both systems. Air temperatures and relative humidities in the glasshouse corresponded approximately with those from the outside, the wind velocity was at 0.5 m/s. The soil was medium fertile and was loosing more Ca (total and Na-formate extractable), P (total and Na-formate extractable), and K (Na-formate extractable) at about 620 ppm CO2 until the end of the experiment. This was not the case of Kjeldahl-N. Due to the lower N contents of the plant tissues the C/N relationships were higher at the elevated CO2 concentration. These differences were greater with the grass than with the clover. P was not significantly influenced, but at about 620 ppm CO2 lower K percentages were found in the petioles and leaves of clover and lower Ca percentages in the grass (total). Expressed on the ground area unit (m2) 49.6% C, 10.9% N, 39.1% P, 32.8% K and 36.4% more Ca was totally exported from the system with the elevated CO2 concentration via the mowed above ground plant parts.* xZ'3*p*@@530^3^Overdieck,D^Reid,C^Strain,B R^1988^1^The Effects of Preindustrial and Future CO2 Concentrations on Growth, Dry Matter Production and the C/N Relationship in Plants at Low Nutrient Supply: _Vigna unguiculata_ (Cowpea), _Abelmoschus esculentus_ (Okra) and _Raphanus sativus_ (Radish)^101^62^^119-134^^^^^^^^^^1335^^^^^^^^^^^cowpea/Vigna unguiculata/okra/Abelmoschus esculentus/radish/Raphanus sativush/Raphanus sativus L. Ŀ C^1333^Angew. Bot.   WordPerfect  A^1333^The effects of preindustrial atmospheric CO2 concentration (270 uL/L), of current ambient CO2 concentration (350 uL/L) and the CO2 concentration predicted for the next century (650 uL/L) on growth, dry matter production and the carbon/nitrogen relationship in dry matter was studied with herbaceous annual plants grown from seed for 32-34 days in environmentally controlled chambers. The plants were cowpea (_Vigna unguiculata_ L.), okra (_Abelmoschus esculentus_ (L.) Moench) and radish (_Raphanus sativus_ L.). Total soil nutrients were lowered to 1/8 of a normal Hoagland's solution. Stem length, petiole length, and leaf area were not significantly affected by the different CO2 levels. Stem diameter increased with increasing CO2 in all three species. Lowering the CO2 concentration from ambient to 270 uL/L decreased the mean total dry matter accumulation by+/-8% and increasing the CO2 concentration to 650 uL/L enhanced it by +/- 40%. The CO2 response was the least in okra where only the dry weight of the roots differed noticeably between the CO2 treatments. With the 'root crop' radish, the hypocotyl provided a sink for assimilates. Specific leaf areas (SLA) of the three species increased under low CO2 and decreased under CO2 enrichment. Net Assimilation rates (NAR) increased with increasing CO2 supply (270 < 340 < 650 uL/L). The highest nitrogen contents on total dry weight basis were found at 270 uL/L, medium contents at 350 uL/L, and lowest at 650 uL/L. The differences were the greatest in leaves. The roots of the legume cowpea contained the greatest N-amounts with 650 uL CO2/L at the end of the experiment. C/N ratios increased with increasing atmospheric CO2 concentrations (except for cowpea roots). Total absolute carbon accumulated per plant increased 20-63% from 270 to 650 uL/L CO2 by the end of the study.SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS531^3^Owensby,C E^Coyne,P I^Auen,L M^1989^5^Rangeland-Plant Responses to Elevated CO2. Part II: Large-Chamber Systems^U.S. Dept. of Energy, Atmospheric and Climate Research Division, Washington, D.C^^^^^^^^^^^^^^^^^^^^^^^^Andropogon gerardii/big bluestem/Indiangrass/Sorghastrum nutans/Kentucky bluegrass/Poa pratensis/sideoats grama/Bouteloua curtipendula/tall dropseed/Sporobolus asper/western ragweed/Ambrosia psilostachya/Louisiana sagewort/Artemisia ludoviciana/manyflower scurfpea/Psoralea tenuiflora^^059 in Green Report Series^Response of Vegetation to Carbon Dioxide^^db.^^059 in Green Report Series^Response of Vegetation to Carbon Dioxide^^SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS532^4^Owensby,C E^Coyne,P I^Auen,L M^Sionit,N^1990^5^Rangeland-Plant Response to Elevated CO2: Large-Chamber System; Washington, D.C^U.S. Dept. of Energy, Atmospheric and Climate Research Division, Washington, D.C^^^^^^^^^^^^^^^^^^^^^^^^Andropogon gerardii/big bluestem/Sorghastrum nutans/Indiangrass/Poa pratensis/Kentucky bluegrass/Bouteloua curtipendula/sideoats grama/Sporobolus asper/tall dropseed/Ambrosia psilostachya/western ragweed/Artemisia ludoviciana/Louisiana sagewort/Psoralea tenuiflora/manyflower scurfpea^^054 in Green Report Series^Response of Vegetation to Carbon Dioxide^^pea^^054 in Green Report Series^Response of Vegetation to Carbon Dioxide^^SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS533^1^Pallas,J E^1986^3^CO2 Measurement and Control^Status and CO2 Sources^CRC Press, Inc.^Boca Raton, Florida^77-98^^^^I^^Carbon Dioxide Enrichment of Greenhouse Crops^^^^1339^^^^^^^^^^^^^^^^^^^^^Enoch,HZ^Kimball,BA,BA^^^^^^^Enoch,H Z^Kimball,B ASSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSA^1338^The needs for CO2 measurement and control are many. We know (see other chapters of these two volumes) that plants are very responsive to the atmospheric CO2 concentration in which they are growing. In some instances greater economic return can even be obtained by elevating ambient CO2 concentration. In controlled environmental experimentation the researcher should always measure CO2 concentration for it may be his greatest variable. If it is highly variable then it obviously needs control. Generally infrared gas analyzers are the workhorses behind such CO2 measurement and control. This chapter is primarily intended to not only provide information but inspiration to those attempting control and measurement.CF@534^4^Palmqvist,K^Ramazanov,Z M^Gardestrom,P^Samuelsson,G^1990^1^Mechanisms of Adaptation of Microalgae to Conditions of Carbon Dioxide Limitation of Photosynthesis. Possible Role of Carbonic Anhydrase^21^37^^912-920^^341!oF>C^1340^Fiziol. Rast.d>$"8>F"dZz+!p'd#C@dd#CC$dCC+a *FS 535^1^Parker,M L^1985^3^Recent Abnormal Increase in Tree-ring Widths: A Possible Effect of Elevated Atmospheric Carbon Dio xide^Proceedings of the International Symposium on Ecological Aspects of Tree Ring Analysis^NTIS^Springfield, Virginia^511-521^^^^^^^^^^1343^^^^^^^^^^^^^^^^^^^^^Jacoby,GC^Hornbeck,JW^^^^^^^^^^Jacoby,G C^Hornbeck,J WWP}WPC{G.001  A^1342^Atmospheric CO2 has increased from a preindustrial level of from 250 to 290 parts per million to a current level of about 345 ppm. It is expected to double at some time in the 21st century. Increased levels of CO2 have been shown to increase tree growth under controlled conditions. Some forest trees may respond to increased CO2 with increases in ring width, but this effect may be obscured by other environmental influences at some sites. Ring width values of Douglas-fir trees from a moist British Columbia site show a marked increase during the past few decades. Environmental influences other than increased CO2 have not been found that would explain this. Pronounced growth increase during the last few decades is not present for Douglas-fir from the dry British Columbia interior. Raw ring width values were examined for individual radii of trees from 17 sites in Canada and the northwest United States. For the period after 1920, 7 sites show greater ring-width growth than would be expected if age were the only factor influencing growth. There is enough evidence to conclude that increased atmospheric CO2, as well as other environmental factors, can affect forest growth. We should now determine the extent of that effect...()J i"c]7m]7pwhvuse defective component in each was sufficient to prevent any increase in the affinity for inorganic carbon. It was conclude"d that the genes corresponding to the_ca-1_ and _pmp-1_ loci exhibit at least partially constitutive expression and that a A^1046^The activity of two photorespiratory enzymes, phosphoglycolate phosphatase (PGPase) and glycolate dehydrogenase (gl537^6^Parker,M L^Taylor,F G^Doyle,T W^Foster,B E^Cooper,C^West,D C^1985^5^Radiation Densitometry in Tree-Ring Analysis: A Review and Procedure Manual^U.S. Dept. of Energy, Carbon Dioxide Research Division, Washington, D.C., and Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee^^^^^^^^^^^^^^^^^^^^^^^^^^020 in Green Report Series^R538^6^Parry,M A J^Delgado,E^Vadell,J^Keys,A J^Lawlor,D W^Medrano,H^1993^1^Water Stress and the Diurnal Activity of Ribulose-1,5 Bisphosphate Carboxylase in Field Grown _Nicotiana tabacum_ Genotypes Selected for Survival at Low CO2 Concentrations^20^31^^113-120^^^^^^^^^^1348^^^^^^^^^^^tobacco/Nicotiana tabacumcumXvXvXvX!vXUvXvXvXvX'vX1vXevXvXC^1346^Plant Physiol. Biochem.X)vX*vX*vX*vX+vX+vX+vX+vX+vX+vX+vX+vX+vX+vX,vX,vX,vX ,vX&,vX2,vXe,vX"A^1346^Despite large differences in total dry matter at final harvest, no significant differences (p frequency of weather extremes, may have greater impact than direct effects of CO2 on physiological processes. Carbon dioxi?de enrichment up to twice ambient levels or more generally increases plant growth, although the magnitude of growth stimul@ation varies greatly with species, photosynthetic pathway, growth stage, and water and nutrient status. In both natural anAd managed ecosystems, differential growth responses to both CO2 concentration and climatic change will affect future compeBtitive ability and fitness of plants. The relative importance of various weed species in agroecosystems may change, but seClection of adapted crop varieties and management methods may minimize negative impacts. In natural ecosystems, species extDinctions probably will increase, because migration and adaptation through natural selection may be too slow to accommodateE the rapid climatic changes involved. Weedy species with broad ecological amplitudes are likely to prosper at the expense of endemic species or those already in marginal habitats.G541^3^Patterson,D T^Highsmith,M T^Flint,E P^1988^1^Effects of Temperature and CO2 Concentration on the Growth of Cotton (_HGossypium hirsutum_), Spurred Anoda (_Anoda cristata_), and Velvetleaf (_Abutilon theophrasti_)^102^36^^751-757^^^^^^^^^^1356^^^^^^^^^^^velvetleaf/Abutilon theophrasti/cotton/Gossypium hirsutum/spurred anoda/Anoda cristatanoda cristata (L.) Sc,C^1354^Weed Sci.  4?TT@;KsKA^1354^Cotton, spurred anoda, and velvetleaf were grown in controlled-environment chambers at day/night temperatures of 32L/23 or 26/17 C and CO2 concentrations of 350 or 700 ppm. After 5 weeks, CO2 enrichment to 700 ppm increased dry matter accMumulation by 38, 26, and 29% in cotton , spurred anoda, and velvetleaf, respectively, at 26/17 C and by 61, 41, and 29% atN 32/23 C. Increases in leaf weight accounted for over 80% of the increase in total plant weight in cotton and spurred anodOa in both temperature regimes. Leaf area was not increased by CO2 enrichment. The observed increases in dry matter productPion with CO2 enrichment were caused by increased net assimilation rate. In a second experiment, plants were grown at 350 pQpm CO2 and 29/23 C day/night for 17 days before exposure to 700 ppm CO2 at 26/17 C for 1 week. Short-term exposure to highR CO2 significantly increased net assimilation rate, dry matter production, total dry weight, leaf dry weight, and specificS leaf weight in comparison with plants maintained at 350 ppm CO2 at 26/17 C. Increases in leaf weight in response to shortT-term CO2 enrichment accounted for 100, 87, and 68% of the observed increase in total plant dry weight of cotton, spurred Uanoda, and velvetleaf, respectively. Comparisons among the species showed that CO2 enrichment decreased the weed/crop ratiVo for total dry weight, possibly indicating a potential competitive advantage for cotton under elevated CO2, even at suboptimum temperatures.@    P@@ @ @ WPC4Ihlecht.U.d %U8 0Y542^2^Pavel,E W^DeJong,T M^1993^1^Seasonal CO2 Exchange Patterns of Developing Peach (_Prunus persica_) Fruits in Response to Temperature, Light and CO2 Concentration^44^88^^322-330^^^^^^^^^^1359^^^^^^^^^^^peach/Prunus persicaica (L.) BatschWC^1357^Physiol. Plant.\A^1357^CO2 exchange rates per unit dry weight, measured in the field on attached fruits of the late-maturing Cal Red peach] cultivar, at 1200 umol photons/m2/s and in dark, and photosynthetic rates, calculated by the difference between the rates^ of CO2 evolution in light and dark, declined over the growing season. Calculated photosynthetic rates per fruit increased_ over the season with increasing fruit dry matter, but declined in maturing fruits apparently coinciding with the loss of `chlorophyll. Slight net fruit photosynthetic rates ranging from 0.087 +/- 0.06 to 0.003 +/- 0.05 nmol CO2/g dry weight/s waere measured in midseason under optimal temperature (15 and 20C) and light (1200 umol photons/m2/s) conditions. Calculatebd fruit photosynthetic rates per unit dry weight increased with increasing temperatures and photon flux densities during fcruit development. Dark respiration rates per unit dry weight doubled within a temperature interval of 10C; the mean seasodnal Q10 value was 2.03 between 20 and 30C. The highest photosynthetic rates were measured at 35C throughout the growing eseason. Since dark respiration rates increased at high temperatures to a greater extent than CO2 exchange rates in light, ffruit photosynthesis was apparently stimulated by high internal CO2 concentrations via CO2 refixation. At 15C, fruit photgosynthetic rates tended to be saturated at about 600 umol photons/m2/s. Young peach fruits responded to increasing ambienth CO2 concentrations with decreasing net CO2 exchange rates in light, but more mature fruits did not respond to increases iin ambient CO2. Fruit CO2 exchange rates in the dark remained fairly constant, apparently uninfluenced by ambient CO2 concejntrations during the entire growing season. Calculated fruit photosynthetic rates clearly revealed the difference in CO2 rkesponse of young and mature peach fruits. Photosynthetic rates of younger peach fruits apparently approached saturation atl 370 uL CO2/L. In CO2-free air, fruit photosynthesis was dependent on CO2 refixation since CO2 uptake by the fruits from tmhe external atmosphere was not possible. The difference in photosynthetic rates between fruits in CO2-free air and 370 uL nCO2/L indicated that young peach fruits were apparently able to take up CO2 from the external atmosphere. CO2 uptake by peoach fruits contributed between 28 and 16% to the fruit photosynthetic rate early in the season, whereas photosynthesis in maturing fruits was supplied entirely by CO2 fixation..LRSCP!!!#.MRGWP}WPC{E.MRG*.WPPWP}WPC{.WAVMT32.MIDWP{WPC}.LCNq543^1^Peet,M M^1986^1^Acclimation to High CO2 in Monoecious Cucumbers. I. Vegetative and Reproductive Growth^17^80^^59-62^^^^^^^^^^1362^^^^^^^^^^^Cucumis sativus/cucumbercumber.QFIWP}WPC{.FIWP0TSG.BLTH %?ZC^1360^Plant Phsyiol.҆HHtA^1360^CO2 concentrations of 1000 compared to 350 microliters per liter in controlled environment chambers did not increasue total fruit weight or number in a monoecious cucumber (_Cucumis sativus_ L. cv Chipper) nor did it increase biomass, leavf area, or relative growth rates beyond the first 16 days after seeding. Average fruit weight was slightly but not signifiwcantly greater in the 1000 microliters per liter CO2 treatment because fruit numbers were changed more than total weight. xPlants grown at 1000 and 350 microliters per liter CO2 were similar in distribution of dry matter and leaf area between mayinstem, axillary, and subaxillary branches. Early flower production was greater in 1000 microliters per liter plants. Subszequent flower numbers were either lower in enriched plants or similar in the two treatments, except for the harvest at fruiting when enriched plants produced many more male flowers than the 350 microliters per liter treatments.|544^3^Peet,M M^Huber,S C^Patterson,D T^1986^1^Acclimation to High CO2 in Monoecious Cucumbers. II. Carbon Exchange Rates, Enzyme Activities, and Starch and Nutrient Concentrations^17^80^^63-67^^^^^^^^^^1365^^^^^^^^^^^Cucumis sativus/cucumberumrC^1363^Plant Physiol.C:\WP60\A^1363^Carbon exchange capacity of cucumber (_Cucumis sativus_ L.) germinated and grown in controlled environment chambers at 1000 microliters per liter CO2 decreased from the vegetative growth stage to the fruiting stage, during which time capacity of plants grown at 350 microliters per liter increased. Carbon exchange rates (CERs) measured under growth conditions during the fruiting period were, in fact, lower in plants grown at 1000 microliters per liter CO2 than those grown at 350. Progressive decreases in CERs in 1000 microliters per liter plants were associated with decreasing stomatal conductances and activities of ribulose bisphosphate carboxylase and carbonic anhydrase. Leaf starch concentrations were higher in 1000 microliters per liter CO2 grown-plants than in 350 microliters per liter grown plants but calcium and nitrogen concentrations were lower, the greatest difference occurring at flowering. Sucrose synthase and sucrose-P-synthase activities were similar in 1000 microliters per liter compared to 350 microliters per liter plants during vegetative growth and flowering but higher in 350 microliters per liter plants at fruiting. The decreased carbon exchange rates observed in this cultivar at 1000 microliters per liter CO2 could explain the lack of any yield increase (MM Peet 1986 Plant Physiol 80:59-62) when compared with plants grown at 350 microliters per liter.0VWPMAIN.WPBWPGEDIT.WPB}berPBWPPREV.WPB ,545^7^Peet,M M^Willits,D H^Tripp,K E^Pharr,D M^Depa,M A^Kuehny,J S^Nelson,P V^1990^3^Case Studies of CO2 Enrichment Responses: Chrysanthemum, Cucumbers and Tomatoes^Proceedings, Global Climate Change Symposium, 9 April 1990; McKimmon Center, North Carolina State University^North Carolina Agricultural Research Service^Raleigh^52-61^^^^^^^^^^1367^^^^^^^^^^^tomato/Lycopersicon esculentum/cucumber/Cucumis sativus/chrysanthemum/Chrysanthemum morifolium^^^^^ium Ramat.^^^^^olium Ramat.^^^A^1366^In experiments conducted in our greenhouses from 1981-1988, yield, photosynthetic and carbohydrate responses to CO2 enrichment were compared in chrysanthemum, cucumbers and tomatoes. Cucumbers were the most responsive, showing a 54% increase in yield with daylong enrichment. Tomatoes were the least responsive, showing only a 20% yield response when enriched for most of the day. Tomatoes also exhibited foliar deformation, purpling and chlorosis at high CO2 concentrations. We had hypothesized that this deformation was caused by high starch levels in leaves of enriched plants. We found more leaf deformation in CO2-enriched tomatoes and higher starch, but based on developmental patterns and differential responses to source/sink manipulations, starch did not appear to cause leaf deformation. In tomatoes, in situ lower leaf canopy photosynthetic rates were not much different in enriched and ambient plants. In chrysanthemum, dry weight increases with enrichment averaged 37% across 5 experiments, ranging from 24% to 52%. Photosynthesis models showed that CO2-enriched chrysanthemum leaves were more efficient at irradiances below 400 umol/m2/s, but above this irradiance, ambient-grown leaves were more efficient because of greater CO2 conductance. Thus, measured at the same CO2 concentration, ambient leaves had higher photosyunthetic rates than enriched leaves. _In situ_ photosynthetic rates were still higher in enriched plants, however, accounting for the higher dry weights observed.: : :, :2 :5 :) :( :# :& : : : :Z__nic carbon only in wild type. Although other components of the CO2-concentrating system were induced in these mutants, th546^7^Peet,M M^Willits,D H^Tripp,K E^Kroen,W K^Pharr,D M^Depa,M A^Nelson,P V^1991^3^CO2 Enrichment Responses of Chrysanthemum, Cucumber and Tomato: Photosynthesis, Growth, Nutrient Concentrations and Yield^Proceedings of the Indo-US Workshop, Global Climatic Changes on Photosynthesis and Plant Productivity; 8-12 January 1991; New Delhi, India^Oxford and IBH Publishing Co. Pvt. Ltd.^New Delhi^193-212^^^^^^^^^^1369^^^^^^^^^^^chrysanthemum/Chrysanthemum morifolium/cucumber/Cucumis sativus/tomato/Lycopersicon esculentum^^^^^New Delhi, India; New Delhi; Oxford and IBH Publishing Co. Pvt. Ltd.; 193-212^^^^^^A^1368^Yield increases from CO2 enrichment varied from 54% in cucumber fruit weight, to 37% in chrysanthemum dry weight and 20% in tomato fruit weight. To determine the basis for response differences, photosynthesis was modeled in chrysanthemum and photosynthesis, growth and leaf concentrations of starch, nutrients and carbon were measured in tomato. CO2-enriched chrysanthemum leaves were more efficient than ambient-CO2 grown leaves at irradiances below 400 umol (photons)/m2/s because of greater photosynthetic efficiencies. At higher irradiances, ambient CO2-grown leaves were more efficient because of greater CO2 conductance, but dry weights and _in situ_ photosynthetic rates were still higher in enriched plants. Cucumber yield data appeared to fit this model, but CO2-enriched tomatoes were much less responsive to CO2 increases. In tomatoes, response to CO2 enrichment did not increase with increasing irradiance and short daily periods of enrichment did not increase yield, suggesting that the CO2 conductances declined significantly. Lower leaves of CO2-enriched tomato plants were inrolled, chlorotic and purpled. We thought this was because of carbohydrate accumulation, possibly associated with feedback inhibition of photosynthesis. We concluded, however, after a 3-year study, that deformation severity was not directly related to foliar starch concentrations. We found more starch in CO2-enriched leaves, but the pattern of accumulation did not appear to account for changes in deformation through development and with source-sink treatments. Severity of leaf deformity was also not correlated with low leaf photosynthetic rates. _In situ_ photosynthetic rates were only slightly higher in enriched plants and did not differ with genotype. Severity of deformation was correlated with high fruit yields and high C/N ratios, but low root weights and low foliar concentrations of K and N. We suggest that in tomatoes CO2-enrichment increases sink strength more than source strength in tomatoes. During fruit development, carbohydrates may be partitioned to fruit at the expense of roots, leading to higher yields, but late-season nutrient stress. 3547^2^Peet,M M^Willits,D H^1987^1^Greenhouse CO2 Enrichment Alternatives: Effects of Increasing Concentration or Duration of Enrichment on Cucumber Yields^3^112^^236-241^^^^^^^^^^1372^^^^^^^^^^^Cucumis sativus/cucumbercumber #"%$C^1370^J. Amer. Soc. Hort. Sci.>GFCI@ ?mKmWmlmmmmmmmA^1370^Extended duration (delayed venting) and greater intensity were investigated as alternatives for CO2 enrichment of fall and spring greenhouse cucumber (_Cucumis sativus_ L.) crops in North Carolina. The use of rockstorages allowed greenhouses to be enriched an average of 83% longer than was possible in conventionally ventilated greenhouses. Differences in daily enrichment times between rockstorage and conventionally ventilated houses were greatest during periods of high temperatures and high solar radiation levels in the early fall and late spring. In the rockstorage houses, enrichment increased fruit weights from 31-57%. Plants enriched to 600 uL/L yield as well or better than those enriched to 1000 or 1200 uL/L CO2. In the conventional houses, enrichment to 1000, 3000, and 5000 uL/L raised yields 18.5-34.5% in Fall 1983, Spring 1984, and Fall 1984. Cucumbers enriched to 1000 uL/L produced slightly less than the control plants in Spring 1983, however. In the conventionally vented houses, spring crops yielded best at the highest CO2 enrichment level, whereas for the fall crops the reverse was true.548^2^Penuelas,J^Azcon-Bieto,J^1992^1^Changes in Leaf Delta 13C of Herbarium Plant Species during the Last 3 Centuries of CO2 Increase^16^15^^485-489^^^^^^^^^^1375^^^^^^^^^^^Pinus uncinata/Pinus pinea/Alnus glutinosa/Betula pendula/Juniperus communis/Ceratonia siliqua/Buxus sempervirens/Pistacia lentiscus/Helleborus foetidus/Rhododendron ferrugineum/Amaranthus caudatus/Papaver alpinum/Cynodon dactylon/Gentiana alpina/Amaranthus caudatus L./Papaver alpinum L./Cynodon dactylon Pers./Gentiana alpina Vill.C^1373^Plant Cell Environ.A^1373^Delta 13C were determined for herbarium specimens of 12 C3 plants (trees, shrubs and herbs) collected during the last 240 years in Catalonia, an area with a Mediterranean climate. Values were 19.91 (S.E. = 0.32, _n_ = 21) for 1750--1760, 19.86 (S.E. = 0.21, _n_ = 49) for 1850-1890 and 19.95 (S.E. = 0.29, _n_ = 25) for 1925-1950, and decreased significantly to 18.87 (S.E. = 0.31, _n_ = 29) for 1982-1988. More irregular temporal changes were found in delta 13 C of two C4 species, but they also suggest a decrease in discrimination in recent decades. These results suggest that either carbon assimilation rates have increased or stomatal conductance has decreased, and therefore, that there has been an increase in water use efficiency over the last few decades.549^2^Penuelas,J^Matamala,R^1990^1^Changes in N and S Leaf Content, Stomatal Density and Specific Leaf Area of 14 Plant Species during the Last Three Centuries of CO2 Increase^39^41^^1119-1124^^^^^^^^^^1378^^^^^^^^^^^Pinus pinea/Alnus glutinosa/Betula pendula/small birch/Juniperus communis/Ceratonia siliqua/Buxus sempervirens/Pistacia lentiscus/Helleborus foetidus/Rhododendron ferrugineum/Amaranthus caudatus/Papaver alpinum/Cynodon dactylon/Gentiana alpinapaver alpinum L./Cynodon dactylon Pers./Gentiana alpina Vill.C^1376^J. Exp. Bot.A^1376^Parallel to the increase in atmospheric CO2 from 278 umol/mol in AD 1750 to the current ambient level of 348 umol/mol there have been overall decreases in leaf nitrogen content and stomatal density from 144% and 121%, respectively, in AD 1750 to 100% today of herbarium specimens of 14 trees, shrubs, and herbs collected over the last 240 years in Catalonia, a Mediterranean climate area. These decreases were steeper during the initial slower increases in CO2 atmospheric levels as compared with the relatively faster CO2 increases in recent years. The declines in leaf N content and stomatal density have also been reported in experimental studies on leaves of plants grown under enriched CO2 environments. Meanwhile, the stomatal index and overall carbon and sulphur leaf contents have not changed significantly. Leaf S content was higher in the 1940s samples coinciding with the burning of increased quantities of sulphur-rich coal. Consequently, the epidermal cell density has decreased parallel to the stomatal density and the C/N ratio of leaves has increased, implying possible important consequences on herbivores, decomposers and ecosystems. An overall decrease in the specific leaf area (_SLA_) from 184% in the 18th century to 100% today has also been found, as would be expected under CO2 enrichment, but which might also be an artifact of prolonged storage.ddU<k d f e h g j i < @)y550^2^Pettersson,R^McDonald,A J S^1992^1^Effects of Elevated Carbon Dioxide Concentration on Photosynthesis and Growth of Small Birch Plants (_Betula pendula_ Roth.) at Optimal Nutrition^16^15^^911-919^^^^^^^^^^1381^^^^^^^^^^^small birch/Betula pendulaula9 NUOUMUONvO UMO q Y!/ ? C^1379^Plant Cell Environ.(WordPerfectA^1379^Small birch plants (_Betula pendula_ Roth.) were grown from seed for periods of up to 70 d in a climate chamber at optimum nutrition and at present (350 umol/mol) or elevated (700 umol/mol) concentrations of atmospheric CO2. Nutrients were sprayed over the roots in Ingestad-type units. Relative growth rate and net assimilation rate were slightly higher at elevated CO2, whereas leaf area ratio was slightly lower. Smaller leaf area ratio was associated with lower values of specific leaf area. Leaves grown at elevated CO2 had higher starch concentrations (dry weight basis) than leaves grown at present levels of CO2. Biomass allocation showed no change with CO2, and no large effects on stem height, number of side shoots and number of leaves were found. However, the specific root length of fine roots was higher at elevated CO2. No large difference in the response of carbon assimilation to intercellular CO2 concentration (A/Ci curves) were found between CO2 treatments. When measured at the growth environments, the rates of photosynthesis were higher in plants grown at elevated CO2 than in plants grown at present CO2. Water use efficiency of single leaves was higher in the elevated treatment. This was mainly attributable to higher carbon assimilation rate at elevated CO2. The difference in water use efficiency diminished with leaf age. The small treatment difference in relative growth rate was maintained throughout the experiment, which meant that the difference in plant size became progressively greater. Thus, where plant nutrition is sufficient to maintain maximum growth, small birch plants may potentially increase in size more rapidly at elevated CO2. Tn551^3^Pinter,P J,Jr^Anderson,R J^Kimball,B A^1992^1^Evaluating Cotton Response to Free-Air Carbon Dioxide Enrichment with Canopy Reflectance Observations^8^11^^241-249^^^^^^^^^^^^^^^^^^^^^cotton/Gossypium hirsutumtum L.dXC^1382^Crit. Rev. Plant Sci.E?552^4^Pinter,P J^Anderson,R J^Kimball,B A^Mauney,J R^1990^3^_In situ_ Measurements of Canopy Reflectance for Evaluating Cotton Responses to Free Air Carbon Dioxide Enrichment^Proceedings, Beltwide Cotton Production Research Conferences; 9-14 January 1990; La Vegas, Nevada^National Cotton Council of America^Memphis, Tennessee^717-719^^^^^^^^^^1385^^^^^^^^^^^cotton/Gossypium hirsutum^^^^^^^^^^Brown,JM^Richter,DA,D AH'@@5A^1384^Remotely-sensed observations of visible and near-infrared canopy reflectance were used to monitor the response of cotton to elevated CO2 concentrations during the 1989 FACE Experiment. Data were collected several times each week using a portable, handheld radiometer along permanent transects in four enriched arrays (550 ppm CO2 and paired controls (ambient CO2). A spectral vegetation index (VI) was computed as the ratio of NIR and Red reflectances. The VI was sensitive to the amount and condition of green plant material viewed by the radiometer. Differences in growth, leaf area and biomass between enriched and control cotton plants were evident in the temporal VI values. The non-destructive spectral measurements were useful for quantifying plant response to experimental treatment variables between biweekly, destructive samples of plant material. These techniques can be used in a near-realtime fashion to supervise conduct of the experiment.aN F69A^1386^During one growing period, 5-year-old spruce trees (_Picea abies_ L. Karst.) were exposed in environmental chambers to elevated concentrations of carbon dioxide (750 cm3/m3) and ozone (0.08 cm3/m3) as single variables or in combination. Control concentrations of the gases were 350 cm3/m3 CO2 and 0.02 cm3/m3 ozone. To investigate whether an elevated CO2 concentration can prevent adverse ozone effects by reducing oxidative stress, the activities of the protective enzymes superoxide dismutase, catalase and peroxidase were determined. Furthermore, shoot biomass, pigment and protein contents of two needle age classes were investigated. Ozone caused pigment reduction and visible injury in the previous year's needles and growth reduction in the current year's shoots. In the presence of elevated concentrations of ozone and CO2, growth reductio n in the current year's shoots was prevented, but emergence of visible damage in the previous year's needles was only dela yed and pigment reduction was still found. Elevated concentrations of ozone or CO2 as single variables caused a significan t reduction in the activities of superoxide dismutase and catalase in the current year's needles. Minimum activities of su peroxide dismutase and catalase and decreased peroxidase activities were found in both needle age classes from spruce tree s grown at enhanced concentrations of both CO2 and ozone. These results suggest a reduced tolerance to oxidative stress in spruce trees under conditions of elevated concentrations of both CO2 and ozone.Y>)FMraB3G\)c=H\CkFId~QJAj554^4^Polley,H W^Johnson,H B^Mayeux,H S^Malone,S R^1993^1^Physiology and Growth of Wheat Across a Subambient Carbon Dioxide Gradient^35^71^^347-356^^^^^^^^^^1391^^^^^^^^^^^wheat/Triticum aestivumvum L.h<=]KEZc$>>*?UUUUC^1389^Ann. Bot. )VD Jb0@P;f?&{?9B.?XoR>op|?? 8o?@?QBqq?A^1389^Two cultivars of wheat (_Triticum aestivum_ L.), 'Yaqui 54' and 'Seri M82', were grown along a gradient of daytime carbon dioxide concentrations ([CO2]) from near 350-200 umol CO2/mol air in a 38 m long controlled environment chamber. Carbon dioxide fluxes and evapotranspiration were measured for stands (plants and soil) in five consecutive 7.6-m lengths of the chamber to determine potential effects of the glacial/interglacial increase in atmospheric [CO2] on C3 plants. Growth rates and leaf areas of individual plants and net assimilation per unit leaf area and daily (24-h) net CO2 accumulation of wheat stands rose with increasing [CO2]. Daytime net assimilation (_P_D, mmol CO2/m2 soil surface area) and water use efficiency of wheat stands increased and the daily total of photosynthetic photon flux density required by stands for positive CO2 accumulation (light compensation point) declined at higher [CO2]. Nighttime respiration (_R_N, mmol CO2/m2 soil surface) of wheat, measured at 369-397 umol/mol CO2, apparently was not altered by growth at different daytime [CO2], but _R_N/_P_D of stands declined linearly as daytime [CO2] and _P_D increased. The responses of wheat to [CO2] if representative of other C3 species, suggest that the 75-100% increase in [CO2] since glaciation and the 30% increase since 1800 reduced the minimum light and water requirements for growth and increased the productivity of C3 plants. 7*<555^1^Poorter,H^1989^3^Interspecific Variation in Relative Growth Rate: On Ecological Causes and Physiological Consequences^Causes and Consequences of Variation in Growth Rate and Productivity of Higher Plants^SPB Academic Publishing^The Hague^45-68^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^Lambers,H^Cambridge,M L^Konings,H^Pons,T L!556^1^Poorter,H^1993^1^Interspecific Variation in the Growth Response of Plants to an Elevated Ambient CO2 Concentration^1"23^104/105^^77-97^^^^^^^^^^1395^^^^^^^^^^^Carex diandra/Deschampsia flexuosa/Festuca ovina/Alnus glutinosa/Lolium perenne/#perennial ryegrass/Trifolium repens/white clover/Plantago major/broadleaf plantain/Silene dioica/Taraxacum officinale/dandelion/Urtica dioica/stinging nettle^^^^^tica dioica L./stinging nettle^^^^^    [ eon Dioxide^^5; Vegetatiowxyz{|}~&A^1393^The effect of a doubling in the atmospheric CO2 concentration on the growth of vegetative whole plants was investig'ated. In a compilation of literature sources, the growth stimulation of 156 plant species was found to be on average 37%. (This enhancement is small compared to what could be expected on the basis of CO2-response curves of photosynthesis. The ca)uses for this stimulation being so modest were investigated, partly on the basis of an experiment with 10 wild plant speci*es. Both the source-sink relationship and size constraints on growth can cause the growth-stimulating effect to be transie+nt. Data on the 156 plant species were used to explore interspecific variation in the response of plants to high CO2. The ,growth stimulation was larger for C3 species than for C4 plants. However the difference in growth stimulation is not as la-rge as expected as C4 plants also significantly increased in weight (41% for C3 _vs._ 22% for C4). The few investigated CA.M species were stimulated less in growth (15%) than the average C4 species. Within the group of C3 species, herbaceous cro/p plants responded more strongly than herbaceous wild species (58% _vs._ 35%) and potentially fast-growing wild species in0creased more in weight than slow-growing species (54% _vs._ 23%). C3 species capable of symbiosis with N2-fixing organisms1 had higher growth stimulations compared to other C3 species. A common denominator in these 3 groups of more responsive C32 plants might be their large sink strength. Finally, there was some tendency for herbaceous dicots to show a larger respon3se than monocots. Thus, on the basis of this literature compilation, it is concluded that also within the group of C3 species differences exist in the growth response to high CO2.KLL2LL8P4PL5557^4^Poorter,H^Gifford,R M^Kriedemann,P E^Wong,S C^1992^1^A Quantitative Analysis of Dark Respiration and Carbon Content as Factors in the Growth Response of Plants to Elevated CO2^25^40^^501-513^^^^^^^^^^1398398̀΀π C^1396^Aust. J. Bot.:OC2} :ALTX)) C:\WP60\WP}WPC{J.168A^1396^An analysis of elevated CO2 effects (2-4 times ambient) on dark respiration rate and carbon content was undertaken 9for a wide range of plant species, using both published reports and new data. On average, leaf respiration per unit leaf a:rea was slightly higher for plants grown at high CO2 (16%), whereas a small decrease was found when respiration was expres;sed on a leaf weight basis (14%). For the few data on root respiration, no significant change due to high CO2 could be detgets under elevated CO2 identified changes in respiration rate, and to a lesser extent carbon content, as important factor?s affecting the growth response to elevated CO2 in quite a number of cases. Any comprehensive analysis of growth responses to increased CO2 should therefore include measurements of these two variables.A558^3^Poorter,H^Pot,S^Lambers,H^1988^1^The Effect of an Elevated Atmospheric CO2 Concentration on Growth, Photosynthesis and Respiration of _Plantago major_^44^73^^553-559^^^^^^^^^^1401^^^^^^^^^^^Plantago major/broadleaf plantainainLONG PH6C^1399^Physiol. Plant.HORT ROUTING=SHORT BILLING=DA^1399^The effect of an elevated atmospheric CO2 concentration on growth, photosynthesis and respiration of _Plantago majoEr_ L. ssp. _major_ L. was investigated. Plants were grown in a nutrient solution in growth chambers at 350 and 700 uL/L COF2 during 7 weeks. The total dry weight of the CO2-enriched plants at the end of this period was 50% higher than that of coGntrol plants. However, the relative growth rate (RGR) was stimulated only during the first half of the growing period. TheH transient nature of the stimulation of the RGR was not likely to be due to end-product inhibition of photosynthesis. It iIs suggested that in _P. major_, a rosette plant, self-shading causes a decline in photosynthesis and results in an increasJe in the shoot:root ratio and a decrease in RGR. CO2-enriched plants grow faster and consequently suffer more from self-shKading. Corrected for this ontogenetic drift, high CO2 concentrations stimulated the RGR of _P. major_ throughout the entire experiment.to/Lycopersicon esculentum^^^^^,H^1990^1^Carbon and Nitrogen Economy of 24 Wild Species Differing in Relative Growth Ratehlamydomonas reinhardtii/Euglena gracilis/Porphyridium cruentum* -[]      '6Ӗ'0(60^2^Poorter,H^Remkes,C^1990^1^Leaf Area Ratio and Net Assimilation Rate of 24 Wild Species Differing in Relative Growth ^^^^^^^^^^^lettuce/Lactuca sativa^^^^^>:z>:z>:z>:>:>:>:>:\>:T>:[>:S>:>:F}>: z>:&z>:&z>561^2^Porter,MA^Grodzinski,B^1985^1^CO2 Enrichment of Protected Crops^103^7^^345-398^^4055h~HBC^1404^Hort. Rev.S562^1^Porter,J R^1990^3^Modeling the Effects of Climate Change on Cereal Production^The Greenhouse Effect and Primary ProdTuctivity in European Agro-ecosystems; 5-10 April 1990; Wageningen, The Netherlands^Pudoc^Wageningen^57-59^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^Goudriaan,J^van Keulen,H^van Laar,H HV563^1^Potvin,C^1985^1^Amelioration of Chilling Effects by CO2 Enrichment^104^23^^345-352^^^^^^^^^^1409^^^^^^^^^^^Echinochloa crus-galli/barnyardgrass/Eleusine indica/goosegrassdica (L.) Gaertn./goosegrassQC^1407^Phsiol. Veg.*A)$Fn\RI ^jL8Wm=`p  ^YA^1407^To analyse the effect of CO2 enrichment on the chilling-sensitivity of C4 plants from contrasting habitats, plants Zof _Echinochloa crus-galli_ from Quebec, North Carolina and Mississippi and of _Eleusine indica_ from Mississippi were gro[wn for 4 weeks under three thermoperiods (28/22, 24/18 and 21/15C and two atmospheric CO2 concentrations (350 and 675 uL/\L). They were then submitted to 1 night chilling at 7C. Photosynthetic carbon uptake, stomatal conductances, and internal] CO2 concentration were measured using an infra-red gas analyser in an open system before and after chilling and during th^e recovery. Chilling induces a decrease in photosynthesis and conductance and, at 350 uL/L, in internal CO2. The decrease _in photosynthesis is less important for high CO2 grown plants at 28/22C. Chilling generates chlorotic bands on leaf blades but less chlorosis is observed in enriched CO2.TX; *,.0246:<@BDHJLMNOPQRSTUa564^1^Potvin,C J^1985^6^Responses of Two Carbon(4) Grasses to Carbon Dioxide Enrichment and Low Temperature: Implications bfor Biogeographical Distribution of Carbon (4) Plants (Mississippi, North Carolina, Quebec)^^Duke University^^Doctoral Discsertation^^^Dissertation Abstracts Vol. 46:11-B, p. 3690 (171 pp.)^^^^^^^1411^^^^^^^^^^^Echinochloa crus-galli/barnyardgrass/Eleusine indica/goosegrass (L.) Gaertn./goosegrass  #'*+/013   eA^1410^This study was carried out to examine the responses of C4 plants to low temperature and to CO2 enrichment. Such infformation should help to understand the distributional limits of C4 plants in cool environments and to predict how a globalg increase in atmospheric CO2 concentration would affect C4 distribution. Two C4 grasses were analyzed, Echinochloa crus-gahlli and Eleusine indica. Echinochloa crus-galli was represented by 3 populations originating from contrasting thermal enviironments (Quebec, North Carolina, Mississippi) while a single population of Eleusine indica, from Mississippi, was includejd in the study. The results indicate clear physiological differences among northern and southern plants. Plants from Quebekc have higher photosynthetic rates and more efficient translocation of 11C regardless of the temperature at which they arel grown. Plants from the north have a better potential to adjust to chilling with or without light. The growth pattern of pmlants from Quebec is characterized by a shorter life cycle; the northern plants flower consistently before the other populnations. Plants from all three populations were grown in field plots in North Carolina and in Quebec. While plants from Queobec do not survive through the summer in North Carolina, those from Mississippi fail to reproduce in Quebec. Thus, it appepars that the various populations are ecotypically differentiated. The effects of CO2 enrichment on the physiology and growqth of the two C4 grasses under study were minor. Plants respond to high CO2 concentration by a slight increase in photosynrthesis, in export pool size and in net assimilation rates during the first 20 days of growth. There was a consistent tempesrature by CO2 interaction in both chilling experiments. CO2 enrichment partially ameliorates the deleterious effects of chilling. @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ u565^3^Potvin,C^Simon,J-P^Strain,B R^1986^1^Effect of Low Temperature on the Photosynthetic Metabolism of the C4 Grass _Echinochloa crus-galli_^34^69^^499-506^^^^^^^^^^1414^^^^^^^^^^^Echinochloa crus-galli/barnyardgrass./barnyardgrassSQRWC^1412^Oecologia@=D uBt"t!sH r)<t"<tDt3ɺ!xA^1412^CO2 curves of photosynthesis and activities of the four C4 enzymes and Ribulose bisphosphate carboxylase (RUBPc) weyre compared in two populations of the C4 grass _Echinochloa crus-galli_ from contrasting thermal environments (Quebec and zMississippi). Analyses were conducted both before and after 14 h of chilling at 7C under high light conditions. This comp{arison provides the opportunity to assess which steps of the C4 pathway are more susceptible to become limiting at low tem|peratures. Both populations maintained, after chilling, a pattern of CO2 fixation typical of C4 plants with photosynthesis} saturating at low external CO2 concentrations. However, the chilling treatment led to reductions in carbon uptake and in ~the activities of the C4 enzymes. RUBPc activity was not significantly affected by chilling. Reductions in photosynthesis were significantly larger for plants of the Mississippi population. The enzyme data suggest that two steps of the C4 pathway, NADP+ -malate dehydrogenase and pyruvate Pi dikinase, are likely to be associated with the reduction of CO2 uptake in C4 plants under cool conditions. When the experiment was replicated under enriched atmospheric CO2 (675 uL/L CO2), similar differences were observed between the two populations. CO2 enrichment resulted in an increase of activity of phospho-enol-pyruvate carboxylase and NADP+ -malate dehydrogenase while activities of phospho-enol-pyruvate carboxylase and NADP+ -malic enzyme were less reduced following chilling. Such an interaction was not observed for gas exchange parameters but net photosynthesis was lower when plants were grown under enriched CO2.VNVD t PQRr|#t ;T#u ;L%ud ZYXÚ566^4^Prior,S A^Rogers,H H^Sionit,N^Patterson,R P^1991^1^Effects of Elevated Atmospheric CO2 on Water Relations of Soya Bean^13^35^^13-25^^^^^^^^^^1417^^^^^^^^^^^Glycine max/soybean Merr./soybeanX_^˷RVWV32۬ tB<\t<:t<.t#CvC^1415^Agric. Ecosystems Environ.:t u^32ɬ tMt >>r>>-r >s8t|t4*:߁&A^1418^The rise in atmospheric CO2 is predicted to have a positive impact on agro-ecosystem productivity. However, an area which requires further investigation centers on responses of crop root systems to elevated atmospheric CO2 under field conditions. The advent of free-air CO2 enrichment (FACE) technology provides a new method of CO2 exposure with minimal alteration of microclimate. In 1990 and 1991, cotton [_Gossypium hirsutum_ (L.) 'Delta Pine 77'] was grown on a Trix clay loam [fine, loamy, mixed (calcareous), hyperthermic Typic Torrifluvents] under two atmospheric CO2 concentrations (360 and 550 umol/mol) and two water regimes [wet, 100% of evapotranspiration (ET) replaced and dry, 67% of ET replaced]. Plant root samples were collected at early vegetative nad mid-reproductive growth for both years. At all sampling periods for both years, taproots of CO2-enriched plants displayed increases in volume and dry weight (P=0.001 to 0.053). Taproot lengths were either significant (P-0.001 to 0.028) or tended to be higher (P=0.183). Taproot tissue density was significant at each sampling date (P=0.003 to 0.067) except at the first period in 1990 (P=0.209). Significant water treatment effects were noted for length, volume, and dry weight of roots at the reproductive sampling in 1991. Whole soil profile root length densities at the initial sampling for both years were either significant or showed a strong tendency to be increased at each of three positions from row center (0.00 m) to the middle of the interrow space (0.50 m) under CO2 enrichment. In all cases, corresponding measurements of whole profile root dry weight densities were significantly higher under CO2-enriched conditions (P=0.009 to 0.070). Root weight per unit length of root was generally greater under the high CO2 conditions at these initial sampling dates. At the second sampling, length density and root dry weight density were generally unaffected by water stress. Root weight per unit length was either significant or tended to be higher under water stress conditions. In both years, CO2 enrichment significantly increased whole profile root length density only at the 0.50 m interrow position (P=0.030 and 0.099). Corresponding measurements of whole profile root dry weight density were generally higher under elevated CO2 at all three psoitions from row center to the middle interrow space (P=0.015 to 0.109). Root weight per unit length was either significant or showed a strong tendency toward increasing under CO2 enrichment at this sampling. The results from this field experiment strongly indicate that additional atmospheric CO2 enhances plant root growth.TUTD3*+t* ) gi_ and soybean. Availability of P and K were also favourably influenced. Uptake of nutrients by soybean was promoted by CO2 enrichment. Available P status was higher in intercropped _ragi_ and soybean as compared to pure crops but nutrient upt%the shoots. Between 16% and 21% of total net fixed carbon (defined as 14C retained in the plant plus 14C lost from the roake was higher by pure crops.tton (_Gossypium hirsutum_ L.) differs between controlled environments and the field. Two imA^598^Plants of _Chrysanthemum_ x _morifolium_ cultivar 'Fiesta' were grown hydroponically for 6 weeks in growth chambers at relative humidity (RH) levels of 50 and 95% and CO2 levels of 340 and 940 uL/L in a Latin square combination. High RH as well as high CO2 resulted in increased relative growth rate (RGR), increased dry weight of leaves, stems and roots, and increased leaf area on main and lateral stems during the first 2 weeks of growth. During this period, high CO2 levels interacted to stimulate the RH effects. During the third to sixth weeks of growth, the interaction of RH and CO2 was either lost or, as in the case of RGR and root dry weight, reversed in such a way that a negative effect of high CO2 at high RG was found. At 6 weeks there were positive main effects of RH and CO2, but no interaction on plant height, number of leaves on lateral shoots, number of lateral shoots, and length of lateral shoots. The shoot to root dry weight ratio increased at high RH. Water consumption of plants decreased sharply at high RH and moderately at the high CO2 level. Stomatal aperture was larger at high RH, but smaller at the high CO2 level. It is concluded that increased plant growth resulting from increased RH might be caused by an increase in stomatal aperture which in turn facilitates CO2 absorption and utilization.or in the field may be related to heat tolerance of the crop, with the very high conductances at high temperatures per m.^^^^^ substantial evaporative cooling of the foliage. Both plant physiology and agronomy need controlled environments, bA^1789^The effects of three ranges of CO2 concentration on growth, carbon distribution and loss of carbon from the roots of maize grown for 14 d and 28 d with shoots in constant specific activity 14-CO2 are described. Increasing concentrations of CO2 led to enhancement of plant growth with the relative growth rate (RGR) of the roots affected more than the RGR of 569^4^Radin,J W^Hartung,W^Kimball,B A^Mauney,J R^1988^1^Correlation of Stomatal Conductance with Photosynthetic Capacity of Cotton Only in a CO2-enriched Atmosphere: Mediation by Abscisic Acid?^17^88^^1058-1062^^^^^^^^^^1426^^^^^^^^^^^cotton/Gossypium hirsutumtum L.u!NVF;Frw;NsF^NFF؋MFC&]&]&]^NAW3pËK&E&C^1424^Plant Physiol.A&;ErXPW؋>t(_XÎ&MI+t+ىG&MA>4+tA^1424^Some evidence indicates that photosynthetic rate (_A_) and stomatal conductance (_g_) of leaves are correlated across diverse environments. The correlation between _A_ and _g_ has led to the postulation of a 'messenger' from the mesophyll that directs stomatal behavior. Because _A_ is a function of intercellular CO2 concentration (_Ci_), which is in turn a function of _g_, such a correlation may be partially mediated by _Ci_ if _g_ is to some degree an independent variable. Among individual sunlit leaves in a cotton (_Gossypium hirsutum_ L.) canopy in the field, _A_ was significantly correlated with _g_ (_r_2 = 0.41, _n_ = 63). The relative photosynthetic capacity of each leaf was calculated as a measure of mesophyll properties independent of _Ci_. This approach revealed that, in the absence of _Ci_ effects, mesophyll photosynthetic capacity was unrelated to _g_ (_r_2 = 0.06). When plants were grown in an atmosphere enriched to about 650 microliters per liter of CO2, however, photosynthetic capacity remained strongly correlated with _g_ even though the procedure discounted any effect of variable _Ci_. This 'residual' correlation implies the existence of a messenger in CO2-enriched plants. Enriched CO2 also greatly increased stomatal response to abscisic acid (ABA) injected into intact leaves. The data provide no evidence for a messenger to coordinate _g_ with _A_ at ambient levels of CO2. In a CO2-enriched atmosphere, though, ABA may function as such a messenger because the sensitivity of the system to ABA is enhanced.s%s#\\L*r[Xþs#570^4^Radin,J W^Kimball,B A^Hendrix,D L^Mauney,J R^1987^1^Photosynthesis of Cotton Plants Exposed to Elevated Levels of Carbon Dioxide in the Field^18^12^^191-203^^^^^^^^^^1429^^^^^^^^^^^cotton/Gossypium hirsutumtum L.rF$FÚH${C^1427^Photosynth. Res.,Q*=uF]GF\D D D*s3D*FF]Gs~tKsCFA^1427^The cotton (_Gossypium hirsutum_ L.) plant responds to a doubling of atmospheric CO2 with almost doubled yield. Gas exchange of leaves was monitored to discover the photosynthetic basis of this large response. Plants were grown in the field in open-top chambers with ambient (nominally 350 uL/L) or enriched (nominally either 500 or 650 uL/L) concentrations of atmospheric CO2. During most of the season, in fully-irrigated plants the relationship between assimilation (A) and intercellular CO2 concentration (Ci) was almost linear over an extremely wide range of Ci. CO2 enrichment did not alter this relationship or diminish photosynthetic capcity (despite accumulation of starch to very high levels) until very late in the season, when temperature was somewhat lower than at midseason. Stomatal conductance at midseason was very high and insensitive to CO2, leading to estimates of Ci above 85% of atmospheric CO2 concentration in both ambient and enriched chambers. Water stress caused A to show a saturation response with respect to Ci, and it increased stomatal closure in response to CO2 enrichment. In fully-irrigated plants CO2 enrichment to 650 uL/L increased A more than 70%, but in water-stressed plants enrichment increased A only about 52%. The non-saturating response of A to Ci, the failure of CO2 enrichment to decrease photosynthetic capcity for most of the season, and the ability of the leaves to maintain very high Ci, form in part the basis for the very large response to CO2 enrichment.Cˋٚ${r&&&&&&&571^3^Radoglou,K M^Aphalo,P^Jarvis,P G^1992^1^Response of Photosynthesis, Stomatal Conductance and Water Use Efficiency to Elevated CO2 and Nutrient Supply in Acclimated Seedlings of _Phaseolus vulgaris L._^35^70^^257-264^^^^^^^^^^1432^^^^^^^^^^^Phaseolus vulgaris/bean./bean ƌҳA=:^ZY[X]?@ PSQRWVUd&cvr<6t\DC^1430^Ann. Bot.*C>c ]^_ZY[XS& 2F&&T&\Q[PdccXPVU6|uJSQRWA^1430^Plants of _Phaseolus vulgaris_ L. were grown from seed in open-top growth chambers at present day (350 umol/mol) and double the present day (700 umol/mol) atmospheric CO2 concentration with either low (L, without additional nutrient solution) or relatively high (H, with additional nutrient solution) nutrient supply. Measurements of assimilation rate, stomatal conductance and water use efficiency were started 17 d after sowing on each fully expanded, primary leaf of three plants per treatment. Measurements were made in external CO2 concentrations (_Ca_) of 200, 350, 450, 550 and 700 umol/mol and related to both _Ca_ and to _Ci_, the mean intercellular space CO2 concentration. Fully adjusted, steady state measurements were made after approximately 2 h equilibration at each CO2 concentration. The rate of CO2 assimilation by leaves increased and stomatal conductance decreased similarly over the range of _Ca_ or _Ci_ in all four CO2 and nutrient supply treatments but both assimilation rate and stomatal conductance were higher in the high nutrient supply treatment than in the low nutrient treatment. The relation between assimilation rate or stomatal conductance and _Ci_ was not significantly different amongst plants grown in present-day or elevated CO2 concentration in either nutrient supply treatment, i.e., there was no evidence of down regulation of photosynthesis or stomatal response. Increase in CO2 concentration from 350 to 700 umol/mol doubled water use efficiency of individual leaves in the high nutrient supply treatment and tripled water use efficiency in the low nutrient supply treatment. The results support the hypothesis that acclimation phenomena result from unbalanced growth that occurs after the seed reserves are exhausted, when the supply of resources becomes growth limiting.FO]^Z572^2^Radoglou,K M^Jarvis,P G^1990^1^Effects of CO2 Enrichment on Four Poplar Clones. II. Leaf Surface Properties^35^65^^627-632^^^^^^^^^^1435^^^^^^^^^^^Populus deltoides/Populus trichocarpa/Populus euroamericanaana${QRVWF33ɡ C^1433^Ann. Bot. r ~t&<t&;|s&|&;L s&L n^~uă~uߋ_^ZYQRVWF P tNA^1433^The poplar clones Columbia River, Beaupre, Robusta and Raspalje have been investigated in the present (350 umol/mol) and double (700 umol/mol) atmospheric CO2 concentration. Cuttings were planted in pots and were grown in open-top chambers inside a glasshouse. Stomatal density, stomatal index, length of stomatal pore and epidermal cell density were not affected by CO2 enrichment in any of the clones. Lack of differences in stomatal density or index indicate that there were no direct effects of CO2 enrichment on the initiation of the number of stomata during ontogenesis or on epidermal cell expansion at a later stage. Stomatal conductance decreased because of the effect of CO2 on stomatal opening. The average reduction in both adaxial and abaxial surface has been estimated at 41%. Beaupre showed the largest response of stomatal conductance and Columbia River the smallest.K\6t^&]^UW~h~ & _]UWV~&5&E u'\F &Mr ;Lw &573^2^Radoglou,K M^Jarvis,P G^1992^1^The Effects of CO2 Enrichment and Nutrient Supply on Growth Morphology and Anatomy of _Phaseolus vulgaris_ L. Seedlings^35^70^^245-256^^^^^^^^^^1438^^^^^^^^^^^Phaseolus vulgaris/bean./bean]UW3N ~C^1436^Ann. Bot.=t)6zt9vtD Du+ ^]RWVSQ6>rtu&u &u&u3ۃA^1436^Plants of _Phaseolus vulgaris_ were grown from seed in open-top growth chambers at the present (P, 350 umol/mol) atmospheric CO2 concentration and at an elevated (E, 700 umol/mol) CO2 concentration, and at low (L, without additional nutrient solution) and high (H, with additional nutrient solution) nutrient supply for 28 d. The effects of CO2 and nutrient a vailability were examined on growth, morphological and biochemical characteristics. Leaf area and dry mass were significan tly increased by CO2 enrichment and by high nutrient supply. Stomatal density, stomatal index and epidermal cell density w ere not affected by elevated CO2 concentration or by nutrient supply. Leaf thickness responded positively to CO2 increasin g particularly in mesophyll area as a result of cell enlargement. Intercellular air spaces in the mesophyll decreased slig htly in plants grown in elevated CO2. Leaf chlorophyll content per unit leaf area or dry mass was significantly lower in elevated CO2 grown plants and increased significantly with increasing nutrient availability. The content of reducing carbohydrates of leaves, stem, and roots was not affected by CO2 but was significantly increased by nutrient addition in all plant parts. Starch content in leaves and stem was significantly increased by elevated CO2 concentration and by high nutrient supply.FI <u FC*XY^PV>Du4FDIDCDDD dD*r 5**^X6DtC^1439^Adv. Hort. Sci.H>Dt & && XDuSQR3HDd ߉TTTT!T TTD @tL D t575^1^Raschke,K^1986^3^The Influence of the CO2 Content of the Ambient Air on Stomatal Conductance and the CO2 Concentration in Leaves^Physiology, Yield, and Economics^CRC Press, Inc.^Boca Raton, Florida^88-102^^^^II^^Carbon Dioxide Enrichment of Greenhouse Crops^^^^^^^^^^^^^^^^^^^^^^^^^Enoch,H Z^Kimball,B AB Au;v^Xrl~t QL.fY+s3L\576^7^Rastetter,E B^Ryan,M G^Shaver,G R^Melillo,J M^Nadelhoffer,K J^Hobbie,J E^Aber,J D^1991^1^A General Biogeochemical Model Describing the Responses of the C and N Cycles in Terrestrial Ecosystems to Changes in CO2, Climate, and N Deposition^43^9^^101-126^^^^^^^^^^2053^^^^^^^^^^^^^^^^^^^L |PRr L TZXr9;Twr;D w܉D Tr"juA cu:r:3C^1442^Tree Physiol.YriD uQLiY+;w+ً||)LLL TD Tr,&;Zrw&;XvDTDT!&X&577^1^Raven,J A^1991^1^Physiology of Inorganic C Acquisition and Implications for Resource Use Efficiency by Marine Phytoplankton: Relation to Increased CO2 and Temperature^16^14^^779-794^^^^^^^^^^14464464rTFW33_FF~t&C^1444^Plant Cell Environ.3&bhk^YXSQVW=t*r"&dr۾f3_^Y[SQVWr"A^1444^Photosynthesis by many marine phytoplankton algae is saturated by the inorganic C concentration in air-equilibrated sea water. These organisms appear to use an active inorganic C transport process (CO2-concentrating mechanism) which incr!eases the CO2 concentration around rubisco and saturates this enzyme with CO2 and suppresses its oxygenase activity. A min"ority of marine phytoplankton algae have photosynthetic characteristics more suggestive of diffusive CO2 entry; the inorga#nic C concentration present in sea water does not saturate photosynthesis by these organisms. Theoretical considerations, $tested when possible against observation, suggest that the organisms with a CO2-concentrating mechanism could have a lower% cost of photons, nitrogen, iron, manganese and molybdenum to achieve a given rate of carbon accumulation by the cells tha&n is the case for the organisms with diffusive CO2 entry. Zinc and selenium costs may show the reverse effect. The increas'ed sea-surface inorganic C, and CO2 concentrations which will result from anthropogenic increases in atmospheric CO2 conte(nt are predicted to increase the rate of photosynthesis, and of growth when other resources are abundant, and to reduce, o)r reverse, the higher resource (photons, nitrogen, iron, manganese and molybdenum) cost of a given rate of CO2 assimilatio*n in organisms with CO2 diffusion relative to those which have CO2 concentrating mechanisms and do not repress them at hig+her inorganic C concentrations. These effects may well alter species composition, and overall resource cost of growth, of ,phytoplankton; any influence that these effects may have on CO2 removal from the atmosphere are severely constrained by ot-her trophic levels and, especially, oceanic circulation patterns. Changed sea-surface temperatures are unlikely to qualitatively alter these conclusions.QR u&E u&E 3[&E3O&E&]d$X+ t+W&M&Uc UEE578^1^Rawson,H M^1992^1^Plant Response to Temperature under Conditions of Elevated CO2^25^40^^473-490^^^^^^^^^^1449449C^1447^Aust. J. Bot.r> t>&C>_[SW u>&Kt >_[G;>r3PSQ1A^1447^A literature survey of the interactive effects of CO2 enrichment and temperature on plant development and growth, i2ndicated that the responses cannot be interpreted within a simple framework. For example, although plant development is ge3nerally accelerated by increased temperature, CO2 enrichment can accelerate it even further in some instances, or CO2 enri4chment may have neutral or even retarding effects in other cases. Where the temperature and CO2 effects are additive, it i5s argued that CO2 is operating in the same way as radiation to reduce a carbon limitation. If this were true, CO2 enrichme6nt would be most likely to accelerate development in tropical regions during the low-radiation monsoon season. Similarly, 7while it would be expected that CO2-enrichment would have increasingly enhancing effects with increasing temperature on ph8ytomass growth, this is not invariably the case. In extreme examples which followed the expected trend, plants grown in tw9ice-normal CO2-enriched atmospheres performed progressively better than those grown at current levels of CO2 by 8.7% for e:very 1C rise in temperature. However, the difference between the two CO2 treatments more commonly increased by only aroun;d 2% for every 1C rise in temperature. Of examples examined, both sunflower and nodulated cowpea showed the reverse respotion strongly modify the responses to temperature. It is also clear that plant factors such as stage of development can al?ter the response to CO2. Long-term studies with several species are required which will take into account many environment@al variables within a realistic envelope. One methodology for doing this is presented. There was no evidence among speciesA that responses to CO2 arise through any consistent change in morphology such as via increased branching or increased leafB number. Plant plasticity is such that responses can be expressed in a variety of ways determined by other environmental variables..>wt666666666666D580^3^Reardon,J C^Lambert,J R^Acock,B^1990^5^The Influence of Carbon Dioxide Enrichment on the Seasonal Patterns of NitrogEen Fixation in Soybeans^U.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture, Agric. Res.F Serv., Washington, D.C^^^^^^^^^^^^^^^^^^^^^^^^soybean/Glycine max^^016 in Green Report Series^Response of Vegetation to Carbon Dioxide^^ Dioxide^^ hjH581^3^Reddy,V R^Acock,B^Acock,M C^1989^1^Seasonal Carbon and Nitrogen Accumulation in Relation to Net Carbon Dioxide Exchange in a Carbon Dioxide-Enriched Soybean Canopy^4^81^^78-83^^^^^^^^^^1454^^^^^^^^^^^soybean/Glycine maxmax (L.) Merr.9"/C^1452^Agron. J.: T4:4:s:_:h:(:b:P::>:|:):Y:F$:O$:t:k:7*:=*::*:":%:(::zKA^1452^Crop modelers routinely equate net CO2 exchange (CE) in crop canopies with biomass to simulate crop growth and prodLuctivity. This study was initiated to validate this relationship experimentally by monitoring CE during a whole-season CO2M-enrichment study on soybean [_Glycine max_ (L.) Merr. cv. Forrest]. Dry weights of soybean grown in sunlit plant growth cNhambers in CO2 concentrations ([CO2]) of 330, 450, 600, or 800 uL/L were sampled at 25 d after emergence (DAE) and after pOhysiological maturity. Photosynthetic rates (P) and respiration rates were calculated from CE rates measured at 0.25-h intPervals, day and night, throughout an entire season. The accuracy of CE measurement was tested by plotting gross P against Q[CO2] at 28, 54, and 80 DAE (days when light flux density was at least 1300 umol photons/m2/s). Gross P had the expected hRyperbolic dependence on [CO2] with all estimated coefficients of determination > 0.93. The net CO2 required for producing Svarious plant parts was calculated from measurements of dry weight and N content and from assumptions about carbohydrate, Toil, mineral, and lignin content. The amount of C required to fix 1.0 g of N symbiotically has been reported to be anywherUe from 2.5 to 19.4 g. In this study the relationship between CO2 fixation and biomass was closest when calculations were bVased on the theoretical value of 2.0 g of C for each gram of N reduced for all [CO2] treatments except 800 uL/L, where a value of 4.0 g of C per gram of N fitted the data better.X582^2^Reekie,E G^Bazzaz,F A^1989^1^Competition and Patterns of Resource Use among Seedlings of Five Tropical Trees Grown aYt Ambient and Elevated CO2^34^79^^212-222^^^^^^^^^^1457^^^^^^^^^^^Cecropia obtusifolia/Myriocarpa longipes/Piper auritum/Senna multijuga/Trichospermum mexicanumnum $  UDIC^1455^OecologiaAaAaAaAaAaCcEeEeEeEeIIIINnOoOoOoOoUuUuU\A^1455^Seedlings of five tropical trees, _Cecropia obtusifolia, Myriocarpa longipes, Piper auritum, Senna multijuga_ and _]Trichospermum mexicanum_, were grown both as individuals, and in competition with each other at ambient (350) and two leve^ls of elevated CO2 (525 and 700 uL/L) for a period of 111 days. Growth, allocation, canopy architecture, mid-day leaf wate_r potential and soil moisture content were assessed three times over this period for individually grown plants, and at the` end of the experiment for competitively grown plants. In addition, leaf photosynthesis and conductance were assessed for athe individually grown plants midway through the experiment, and light profile curves were determined for the competitive barrays at three stages of development. Elevated CO2 did not affect photosynthesis or overall growth of the individually-grcown plants but did affect canopy architecture; mean canopy height increased with CO2 in _Piper_ and _Trichospermum_ and dedcreased in _Senna_. Stomatal conductance decreased slightly as CO2 increased from 350 to 525 uL/L but this had no significeant effect upon whole plant water use or leaf water potential. Soil moisture content for the individuals increased marginaflly as CO2 increased, but this did not occur in the competitive arrays. There was a marked effect of CO2 upon species compgosition of the competitive arrays; _Senna_ decreased in importance as CO2 increased while _Cecropia, Trichospermum_ and _Phiper_ increased in importance. Stepwise regression analysis using competitive performance as the dependent variable, and tihe various morphological and physiological parameters measured on the individually grown plants as independent variables, jsuggested that canopy height was the single most important variable determining competitive ability. Also significant werek photosynthetic rate (particularly at low light levels) and allocation to roots early in the experiment. Light profiles inl the canopy revealed that less than 15% of incident light penetrated to the level of mean canopy height. Results suggest tmhat competition for light was the major factor determining community composition and that CO2 affected competitive outcome through its effect upon canopy architecture.& &E&e&M& a`I `r5PS$ &o583^2^Reekie,E G^Bazzaz,F A^1991^1^Phenology and Growth in Four Annual Species Grown in Ambient and Elevated CO2^54^69^^2475-2481^^^^^^^^^^1460^^^^^^^^^^^Guara brachycarpa/Gailardia pulchella/Oenothera laciniata/Lupinus texensissisEZC^1458^Can. J. Bot.rTD&tD^ _^ZY[PQV v^Au7tPQr uYXks'brA^1458^The objectives of this study were _(i)_ to test the hypothesis that changes in phenology with CO2 are a function ofs the effect of CO2 upon growth and _(ii)_ to determine if CO2-induced changes in phenology can influence competitive outcotme. We examined the effect of 350, 525, and 700 uL/L CO2 on _Guara brachycarpa, Gailardia pulchella, Oenothera laciniata,_u and _Lupinus texensis_. Plants were grown as individuals in 150-, 500-, or 1000-ml pots and in competition in 1000-ml potvs. Growth and development were monitored at twice-weekly intervals by recording the number of leaves and noting the presenwce or absence of stem elongation, branching, flower buds, and open flowers. Elevated CO2 affected both growth and phenologxy, but the direction and magnitude of effects varied with species and soil volume. Elevated CO2 did not appear to affect dyevelopment through its effect on growth. Those treatments in which there were significant effects of CO2 on growth were geznerally different from those treatments in which CO2 affected phenology. Rather than affecting phenology by changing plant{ size, CO2 appeared to affect phenology by modifying the size at which plants switched from one stage to the next. The lev|el of CO2 changed competitive outcome; the importance of _Lupinus_ increased whereas that of _Oenothera_ decreased with increased CO2. These changes were more closely related to the effect of CO2 on growth than its effect on phenology.&]&U~584^1^Reining,E^1991^6^Langzeiteffekte von erhohtem CO2-Angebot auf den Mineralstoffhaushalt von _Acer pseudoplatanus_ und _Fagus sylvatica_^^Universitat Osnabruck, Fachbereich Biologie/Chemie, Osnabruck, Germany^^Doctoral Dissertation^^^^^^^^^^1462^^^^^^^^^^^Acer pseudoplatanus/Fagus sylvaticaoplatanus/Fagus sylvaticaH rGEFN6 EuVI6 A^1461^In German.r^E u[;Ft F^r$&؎F&&U^VFuF6 EuUu585^1^Reining,F^1990^6^Langzeiteffekte von erhohtem CO2-Angebot auf das Wachstum von _Acer pseudoplatanus_ und _Fagus sylv-atica_^^Universitat Osnabruck, Fachbereich Biologie/Chemie, Osnabruck, Germany^^Doctoral Dissertation^^^^^^^^^^1464^^^^^^^apted WT cells is double that seen in CO2-enriched cells. Unlike WT, the high-CO2-requiring mutant, cia-5, does not respoA^1463^In GermanXNþD\T| D DPSR&&&u.& t && t &n&6DdW&t586^1^Retzlaff,W A^1987^6^Effect of Carbon-dioxide Enrichment on Container-grown _Pinus taeda_ L. Seedlings and Their Field Survival Potential^^Clemson University^^Doctoral Dissertation^^^Dissertation Abstracts Vol. 48:06-B, p.563 (113 pp.)^^^^^^^1466^^^^^^^^^^^Pinus taeda/loblolly pinene !&&6+wvـPX^VA^1465^The effects of increased atmospheric CO2 levels on growth of container-grown loblolly pine (_Pinus taeda_ L.) seedlings were examined. Seedlings were grown in CO2 concentrations of 363, 430, 780, and 1263 ppm in near airtight chambers. A 4 x 4 Latin Square experimental design was employed with four 90-day replications among four treatment-chambers. At 10-day intervals during each replication, nine seedlings from each treatment were harvested to measure growth. Foliar and rooting medium nutrient analyses, diffusive resistance and photosynthetic rates of foliar types, tissue starch content, seedling root growth potential, and stomate physiology were also examined. Following each replication, pretreated seedlings were outplanted to determine field survival and growth. Seedling morphology was significantly different (alpha=0.05) with increasing CO2 concentration. Carbon dioxide enrichment increased total seedling height, root collar diameter, number and projected surface area of primary needles, and root, stem, primary needle, shoot and total dry weights of the seedlings. Growth analysis at 90-days shows that optimum CO2 concentration for growth occurs at 1000 ppm. Balanced root and shoot growth suggests there was some mechanism for response to CO2 enrichment other than changes in biomass partitioning. Carbon dioxide transfer resistance measurements showed that both diffusive resistance and internal (intercellular) CO2 concentration were unaffected by the CO2 level in the atmosphere. However, net photosynthesis increased tenfold in the 1009 ppm atmospheric CO2 concentration when compared to the 350 ppm CO2 concentration. Because photosynthetic rates of primary and secondary needle tissue were greater in high atmospheric CO2 concentrations and less in the low atmospheric CO2 concentrations, and diffusive resistance and internal CO2 concentration were unaffected by atmospheric CO2 concentration, it was concluded that biochemical resistance was the rate limiting process in the flux relationship for primary and secondary needle tissue at ambient CO2 levels. No differences in field survival were found. Also, first-year height and diameter growth was not significantly affected by CO2 pretreatment. Initially larger seedlings from the higher CO2 pretreatments lost their significant size advantage following 1 year in the field.QO~ȃ&Ғ+[9؃} 3ҋۋ0+;ԒvԒ6~H587^2^Reuveni,J^Gale,J^1985^1^The Effect of High Levels of Carbon Dioxide on Dark Respiration and Growth of Plants^16^8^^623-628^^^^^^^^^^1469^^^^^^^^^^^Medicago sativa/alfalfa/Xanthium strumariummariumP P && tX3XrpC^1467^Plant Cell Environ.Xt+33;sPFQYF+wN+^[PW>rҒ_X˃>ҒuWҒ>wA^1467^Raising ambient levels of CO2 during the night, between 350 and 950 cm3/m3, reduced the dark respiration rate of _Medicago sativum_ seedlings. The percentage effect was greater for maintenance respiration then for dark respiration as a whole, and when the plants were in a low photosynthate status. Twenty-four h carbon balance studies confirmed a reduction in night time respiration and an increase of net carbon gain when night time [CO2] was high. Growth experiments showed a small but significant increase of dry weight in _Medicago sativum_ seedlings exposed to high [CO2] (about 1200 cm3/m3) at night. This effect was greater for plants grown with _Rhizobium_ nodules than for plants grown with nitrate in the absence of _Rhizobium_. A similar, but smaller and statistically non-significant effect of high night time [CO2] on growth was found for _Xanthium strumarium_ seedlings. The significance of these findings is discussed in relation to the rising CO2 content of the atmosphere.|rFV W|tw_^ZY[X;Tu;D rt PDXftheglobalclo588^2^Reynolds,J F^Acock,B^1985^3^Modeling Approaches for Evaluating Vegetation Responses to Carbon Dioxide Concentration^Direct Effects of Increasing Carbon Dioxide on Vegetation^Dept. of Energy, Carbon Dioxide Research Division^Washington, D.c.^33-51^^^^^^^DOE/ER-0238^^^^^^^^^^^^^^^^^^^^^^^^Strain,BR^Cure,JDarmeasurementsofcloudvelocity,AtmosphericOptics589^2^Reynolds,J F^Acock,B^1985^1^Predicting the Response of Plants to Increasing Carbon Dioxide: A Critique of Plant Growth Models^106^29^^107-129^^^^^^^^^^1473473fcloudfieldvelocityiscomparedonthebasisoftheoreticalanalysisofcorC^1471^Ecol. Model.sollidarsignals.AsaresultoffieldlidarmeasurementsusingdifferentgeometricalschemesitisA^1471^It is widely recognized that increasing global carbon dioxide concentration in the atmosphere may alter the growth of plants. This has led to speculation about the long-term impact of rising CO2 on agricultural productivity and on natural ecosystems, e.g., shifts in native species distributions and sequestering of carbon in forests. In this paper we critique some existing plant growth models with regard to their potential for predicting and evaluating possible scenarios of vegetation response to elevated CO2 levels. To facilitate this, we present various criteria for model evaluation, specify a minimum set of plant processes that should be considered for inclusion in a generic model capable of predicting plant response to CO2, survey numerous published plant growth models with respect to these criteria, and propose a scheme for identifying the various options available for modeling the response of vegetation to CO2.lclouds.ProblemsofCloudPhysics:We590^4^Reynolds,J F^Bachelet,D^Leadley,P^Moorhead,D^1986^5^Assessing the Effects of Elevated Carbon Dioxide on Plants: Towards the Development of a Generic Plant Growth Model^U.S. Dept. of Energy, Carbon Dioxide Research Division, Washington, D.C^^^^^^^^^^^^^^^^^^^^^^^^^^028 in Green Report Series^Response of Vegetation to Carbon Dioxide^^geandthathighdispers591^6^Reynolds,J F^Chen,J^Harley,P C^Hilbert,D W^Dougherty,R L^Tenhunen,J D^1992^1^Modeling the Effects of Elevated CO2 on Plants: Extrapolating Leaf Response to a Canopy^46^61^^69-94^^^^^^^^^^1477^^^^^^^^^^^Quercus cocciferaeraaelow40$C^1475^Agric. For. Meteorol.S.M.Shmeter.1983.Clouds,CloudStructureandPhysicsofformation.Leningrad.GidrometeoA^1475^The response of canopies to short-duration exposure to elevated CO2 was examined by using a detailed submodel of single-leaf gas exchange combined with a model of canopy structure and light penetration. The leaf model included a mechanistic gas exchange model and leaf energy balance equations, and the canopy model included a detailed description of spatial variability in environmental conditions within the canopy. The structure of the canopy model was designed to facilitate implementation of different leaf aggregation schemes. To compare six aggregation methods of increasing simplicity, daily carbon gain, and water use were simulated for _Quercus coccifera_ under current ambient and future doubled CO2. Analyses of simulated canopy responses confirmed the importance of including (1) leaf energy balance and (2) distinguishing between sunlit and shaded leaves. A multi-layer canopy model with Gaussian integration for sunlit leaves and a single leaf class for shaded leaves in each layer gave excellent results. A multi-layer model with one shaded and one sunlit leaf class gave a reasonable approximation, and the single-layer model with one sunlit and one shaded leaf class resulted in errors of up to 15%. Vertical gradients in leaf nitrogen content and leaf and stem area index had greater effects on canopy assimilation and transpiration than did gradients of stem or leaf inclination or leaf width. However, predictions of the relative response of CO2 assimilation and transpiration to doubled CO2 are rather robust and were not greatly affected by simplifications of the canopy model.llerscatteringangles.MilenkyM.N.,V.I.Kozintsev,B.A.Konstantinov,andG.N.Balde592^4^Reynolds,J F^Dougherty,R L^Tenhunen,J D^Harley,P C^1988^5^A Model for the Simulation of Plant Response to Elevated CO2^U.S. Dept. of Energy, Carbon Dioxide Research Division, Washington, D.C^^^^^^^^^^^^^^^^^^^^^^^^^^042 in Green Report Se593^3^Reynolds,J F^Skiles,J W^Moorhead,D L^1987^5^SERECO: A Model for the Simulation of Ecosystem Response to Elevated CO2)^U.S. Dept. of Energy, Carbon Dioxide Research Division, Washington, D.C^^^^^^^^^^^^^^^^^^^^^^^^^^041 in Green Report Seri594^2^Riechers,G H^Strain,B R^1988^1^Growth of Blue Grama (_Bouteloua gracilis_) in Response to Atmospheric CO2 Enrichment^54^66^^1570-1573^^^^^^^^^^1482^^^^^^^^^^^Bouteloua gracilislis (HBK.) Griffithsionsofseriesequipmentisshown.C^1480^Can. J. Bot.andI.P.Guseva.1986.CloudinessovertheNorthAtlanticfromsatelliteandsurfacebaseddata.Proc.A^1480^Blue grama (_Bouteloua gracilis_ (HBK.) Griffiths), an important C4 species in the Great Plains grasslands of the north central United States, was grown under three concentrations of CO2: 350, 675, and 1000 uL/L. Growth of the blue grama was significantly enhanced by enrichment to 675 but not to 1000 uL/L. At the end of the experiment, 7 weeks after planting, plants grown at 675 uL/L had 35% more total biomass and nearly 90% greater leaf area than controls grown at 350 uL/L. This growth enhancement is large for a C4 species, but is modest compared with the response typical of C3 species. It is concluded that blue grama may experience increasing competition from its C3 associates if atmospheric CO2 continues to increase in the future.rameterdeterminingthedevelopmentofprocessesinclouds.Interinst.CollectionofRes.Papers.,Len595^3^Robinson,S P^Grant,W J R^Loveys,B R^1988^1^Stomatal Limitation of Photosynthesis in Abscisic Acid-treated and in Water-stressed Leaves Measured at Elevated CO2^52^15^^495-503^^^^^^^^^^1485^^^^^^^^^^^Prunus armeniaca/apricot/Helianthus annuus/sunflower/Spinacia oleracea/spinachachcomputationsandexperimentssupporttheimportanceoftakingthepropertiesiC^1483^Aust. J. Plant Physiol.aL.I.,Characterandnatureofcloudanomaliesoverbrokenlithospherediscontinuities.A^1483^Feeding 10(-5)M (+/-)-abscisic acid (ABA) via the petioles of detached leaves of apricot (_Prunus armeniaca_) or sunflower (_Helianthus annuus_) decreased stomatal conductance and assimilation rate but not the calculated intercellular CO2 concentration (_Ci_) suggesting non-stomatal as well as stomatal inhibition of photosynthesis. Evidence for non-stomatal inhibition was not observed in spinach (_Spincia oleracea_). There was no significant decrease in rates of electron transport nor ribulose bisphosphate carboxylase (Rubisco) activity in intact chloroplasts isolated from ABA-treated sunflower leaves. Oxygen evolution by leaf discs with 3% CO2 in the gas phase was inhibited in ABA-treated sunflower and apricot leaves but not in spinach; the inhibition was only half as great as the inhibition of assimilation rate at ambient CO2. The quantum yield of oxygen evolution decreased in ABA-treated sunflower leaves in proportion to the decrease in the light-saturated rate. There was no significant difference in room temperature chlorophyll fluorescence of ABA-treated leaves compared to controls. Stomatal conductance of sunflower leaves decreased by more than 90% when the CO2 concentration was increased from 340 ppm to 1000 ppm but at much higher CO2 concentrations the stomata appeared to reopen. Stomatal conductance at 2-3% CO2 (20,000-30,000 ppm) was 50% that at ambient CO2. This reopening of stomata at high CO2 was inhibited in previously water-stressed or ABA-treated plants. In unstressed leaves, the maximum rate of oxygen evolution occurred at 0.5-2% CO2 but in ABA-treated leaves 10-15% CO2 was required for maximum rates. It is suggested that stomatal closure may limit photosynthesis in ABA-treated or previously water-stressed leaves even at the relatively high CO2 concentrations normally used in the leaf disc oxygen electrode. The inhibition of photosynthesis by ABA is largely overcome at saturating CO2. The apparent non-stomatal inhibition suggested by gas exchange measurements and the decreased quantum yield could be explained by patchy stomatal closure in response to ABA.A.,,XR-596^2^Rochefort,L^Bazzaz,F A^1992^1^Growth Response to Elevated CO2 in Seedlings of Four Co-occurring Birch Species^32^22^^1583-1587^^^^^^^^^^1488^^^^^^^^^^^Betula lenta/black birch/Betula papyrifera/white birch/Betula alleghaniensis/yellow birch/Betula populifolia/grey birch^^^^^yellow birch P-(4 cirruscloudparticles.RadiationPropertiesofCirruimiting CO2 characteristic of the induction of the CO2-concentrating system, resulting in an increased affinity for inorgaA^1486^Seedlings of four birch species were examined to evaluate the presence and extent of phylogenetic constraints on the response of species to global CO2 change. The species differ in their habitat preferences and their successional status. Seedlings were grown for 3 months at near ambient (380 uL/L) and double (690 uL/L) CO2 concentrations in glasshouses. We found the following: (i) yellow birch (_Betula alleghaniensis_ Britton) was the only species whose survival differed among CO2 treatments. Survival was slightly increased by elevated CO2. (ii) All growth parameters considered in all four species were significantly stimulated by enriched CO2 conditions, but the magnitude of response was different among species. The most shade-intolerant, fast-growing species (grey birch; _Betula populifolia_ Marsh.) took greater advantage of the elevated CO2 resource than the more shade-tolerant, later successional species (e.g., yellow birch). (iii) Patterns of allocation, shoot architecture, and leaf nitrogen content were affected differently by CO2 concentrations for the different species. (iv) The presence and identity of a neighbor did not influence the magnitude or pattern of response to CO2 in birches of a given community. Our results suggest that congeneric species might be more similar in their response to global CO2 in comparison to unrelated species of the same ecosystem that had been studied by others, despite the fact that these closely related birch species differ in their habitat preferences and successional status.ishedRussiantoEnglishtranslations.597^2^Rochefort,L^Woodward,F I^1992^1^Effects of Climate Change and a Doubling of CO2 on Vegetation Diversity^39^43^^1169-1180^^^^^^^^^^1491491rpretingsimultaneouslyatsomeORNLmeetingsonvarioussubjects.IparticipateinOakRidgecivC^1489^J. Exp. Bot.oftheSisterCitySupportGroupandIreadRecordingsfortheBlind.Ihave35daysofunusedconsulA^1489^A model is presented for predicting the response of global family diversity to global environmental change. The model assumes that three primary mechanisms determine diversity: the capacity to survive the absolute minimum temperature of a site, the ability to complete the life cycle in a given length and warmth of the growing season, and the capacity to expand leaves in a defined regime of precipitation and vegetation transpiration. The direct effects of CO2 on vegetation transpiration are also included. About one-third of the floristic regions of the world exhibit increased diversity with a 3C increase in temperature, a 10% increase in precipitation, and a doubling of the CO2 concentration. The addition of CO2 off sets the increased rates of transpiration, caused by global warming through its capacity to reduce transpiration. As a consequence, the diversity of dry regions displayed the greatest increase in diversity due to increased CO2.8@/:3):+: 598^11^Rogers,H H^Beck,R D^Bingham,G E^Cure,J D^Davis,J M^Heck,W W^Rawlings,J O^Riordan,A J^Sionit,N^Smith,J M^Thomas,J F^ 1981^5^Field Studies of Plant Responses to Elevated Carbon Dioxide Levels^U.S. Dept. of Energy, Carbon Dioxide Research Di vision, and U.S. Dept. of Agriculture, Agric. Res. Serv., Washington, D.C^^^^^^^^^^^^^^^^^^^^^^^^soybean/Glycine max^^005 in Green Report Series^Response of Vegetation to Carbon Dioxide^^ Dioxide^^>N@N_^ZY[XSQV3/* u@^Y[P599^9^Rogers,H H^Bingham,G E^Cure,J D^Heck,W W^Heagle,A S^Israel,D W^Smith,J M^Surano,K A^Thomas,J F^1980^5^Field Studies of Plant Responses to Elevated Carbon Dioxide Levels^U.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture, Agric. Res. Serv., Washington, D.C^^^^^^^^^^^^^^^^^^^^^^^^soybean/Glycine max/loblolly pine/Pinus taeda/sweetgum/Liquidambar styraciflua/corn/Zea mays^^001 in Green Report Series^Response of Vegetation to Carbon Dioxide^^Carb600^8^Rogers,H H^Bingham,G E^Brownie,C^Cure,J D^Drake,B G^Heck,W W^Huber,S C^Israel,D W^1982^5^Field Studies of Plant Responses to Elevated Carbon Dioxide Levels^U.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture, Agric. Res. Serv, Washington, D.C^^^^^^^^^^^^^^^^^^^^^^^^soybean/Glycine max^^009 in Green Report Series^Response of Vegetation to Carbon Dioxide^^o Carbon DioxideHHK϶HHHHHH IIHQIIEIIiIJIIH*H-I9I!I]IIJlJ.=1==.==.==601^9^Rogers,H H^Brownie,C^Cure,J D^Heck,W W^Huber,S C^Israel,D W^Mowry,F L^Reynolds,J F^Thomas,J F^1983^5^Field Studies of Plant Responses to Elevated Carbon Dioxide Levels^U.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture, Agric. Res. Serv., Washington, D.C^^^^^^^^^^^^^^^^^^^^^^^^soybean/Glycine max/sweet potato/Ipomoea batatas^^012 in Green Report Series^Response of Vegetation to Carbon Dioxide^^on to Carbon Dioxide^^GrJ.<tD>ʾ@D602^3^Rogers,H H^Cure,J D^Smith,J M^1986^1^Soybean Growth and Yield Response to Elevated Carbon Dioxide^13^16^^113-128^^^^^^^^^^1499^^^^^^^^^^^Glycine max/soybean Merr./soybeanDs~3D D\|Ls=Wt}PCt}tkC^1497^Agric. Ecosystems Environ.DDkr_3ۋIyt,sDFÉFD 3DD5r)3΋A D A DAA^1497^Soybeans (_Glycine max_ L. Merr. 'Bragg') were grown in seeded rows in open-top field chambers and exposed continuously to a range of elevated CO2 concentrations throughout the 1982 and 1983 growing seasons. During 1983, a water stress t reatment was also imposed. Comparison of vegetative growth with a similarly conducted pot experiment showed an increased r!atio of leaf area to total top dry weight in the seeded row plants, but generally similar qualitative effects of elevated "CO2. Careful recording of mainstem leaf emergence rates and reproduction stages showed no consistent effect of CO2 under w#ell watered conditions, but in 1983 there was a distinct modification by high CO2 of the water stress-induced hastening of$ the time to physiological maturity. In 1982, and for the well watered plants in 1983, standing biomass at maturity was in%creased significantly by elevated CO2, but harvest index decreased and yield was (statistically) unaffected by the treatme&nt. The yield responses calculated for a doubling of the current CO2 concentration for these well watered treatments were '1.07 and 0.93, respectively. In the water stress treatment in 1983, however, harvest index did not decrease in the presence of elevated CO2, and a highly significant yield response occurred (1.41 at 700 uL/L).603^2^Rogers,H H^Dahlman,R C^1992^1^Crop Responses to CO2 Enrichment^123^104/105^^117-131^^^^^^^^^^1502^^^^^^^^^^^^^^^^ es^Response of Vegetation to Carbon Dioxide^^^Vָ~Ms u0<tF^V3Ҵo^&CG+A^1500^Carbon dioxide is rising in the global atmosphere, and this increase can be expected to continue into the foreseeab,le future. This compound is an essential input to plant life. Crop function is affected across all scales from biochemical- to agro-ecosystems. An array of methods (leaf cuvettes, field chambers, free-air release systems) are available for exper.imental studies of CO2 effects. Carbon dioxide enrichment of the air in which crops grow usually stimulates their growth a/nd yield. Plant structure and physiology are markedly altered. Interactions between CO2 and environmental factors that inf0luence plants are known to occur. Implications for crop growth and yield are enormous. Strategies designed to assure futur1e global food security must include a consideration of crop responses to elevated atmospheric CO2. Future research should 2include these targets: search for new insights, development of new techniques, construction of better simulation models, i3nvestigation of belowground processes, study of interactions, and the elimination of major discrepancies in the scientific knowledge base.^_ZY[  PSVW^NvvfsDZ[sD\3:sE2.Db3:!&P\&5604^4^Rogers,H H^Peterson,C M^McCrimmon,J N^Cure,J D^1992^1^Response of Plant Roots to Elevated Atmospheric Carbon Dioxide^16^15^^749-752^^^^^^^^^^1505^^^^^^^^^^^soybean/Glycine maxmax (L.) Merr.tZXsF _^[XPSR6FDZP&*+ЉTNC^1503^Plant Cell Environ.DPDT&&D^&(D`Z[X4:rFFr7DNDVr,DXr$DRrDPDTrD^r D`8A^1503^Plant root response to atmospheric CO2 enrichment can be great. Results from this controlled environment investigat9ion demonstrate substantial effects on root system architecture, micromorphology and physiology. The most pronounced effec:ts were an increase in root length (110%) and root dry weight (143%). Root diameter, stele diameter, cortex width, root/sh;oot and root weight ratios all increased; root numbers did not increase. The long-term implications for belowground processes could be enormous.X{XX, U!  W  =605^3^Rogers,H H^Prior,S A^O'Neill,E G^1992^1^Cotton Root and Rhizosphere Responses to Free-Air CO2 Enrichment^8^11^^251-263^^^^^^^^^^1508^^^^^^^^^^^cotton/Gossypium hirsutumtum L.ieg. PossibleEmployment   p  Iwou6C^1506^Crit. Rev. Plant Sci.ighlyqualifiedtranslator/interpreterfromRussianintoEnglish.MynativetongueisRussia@A^1506^The increase in atmospheric CO2 concentration is known to enhance the growth and yield of many crops. However, therAe is a paucity of data on belowground responses to CO2 enrichment. New information is needed in the related areas of: rootB systems, rhizosphere populations and dynamics, and the edaphic factors with which they interact. Free-air CO2 enrichment C(FACE) studies initiated at Yazoo City, MS (1988), and Maricopa, AZ (1989) provided the first opportunity to examine belowDground processes of an agro-ecosystem at elevated levels of CO2 under realistic environmental conditions. Cotton (_GossypiEum hirsutum_ L.) was grown under ambient CO2 conditions (360 ppm) and CO2 enriched conditions (550 ppm). Carbon dioxide exFposure times were just over 6 weeks, ending August 31, in 1988 and 14 weeks, ending September 22, in 1989. In 1988, the nuGmber of lateral roots was 20% higher for the elevated CO2 treatment. Strong increasing trends were observed for taproot leHngth, top diameter, dry weight, and volume. Root length and dry weight densities were either significant or showed a tendeIncy to increase at depth increments between 0-45 cm and 15-30 cm soil depth, respectively, due to CO2 enrichment. Whole prJofile root length density appeared to be higher at the 550 ppm level; root dry weight density went up by 33%. Consistent iKndications of increased bacterial populations and microbial activity were observed. Although mycorrhizal infection was notL enhanced, the greater root length densities suggested greater total plant mycorrhization. In 1989, CO2 enrichment increasMed taproot volume and dry weight by 73 and 83%, respectively. Lateral root length, dry weight, and total number were up 10N0, 157, and 35%. At the 550 ppm treatment level root length density was increased by 21-32% in the upper layers of the soiOl profile (0-45 cm), with an average increase of 18% for the whole profile. Root dry weight density showed a 100% increaseP due to added CO2. Elevated CO2 increased dry weight densities by 71-147% at the top three depths (0-45 cm) and clear pattQerns of increase were observed from 45-75 cm. Field data presented here indicate that elevated CO2 stimulates cotton root Rproliferation. These new data provide a valuable first time insight into belowground responses of an agro-ecosystem exposed to elevated atmospheric CO2.€t3 _^Z[XPSRVGSu >҆t tu K3ҁ' pKrƾ 7T_kaber_ exposed to mean [CO2] below 200 umol/mol, while _Rn/_Pd differed little among five stands of _P_. _glandulosa/S._ V_scoparium_ that were grown at mean [CO2] from 219 to 331 umol/mol. 3. Evapotranspiration was reduced and water-use effici C^1509^?; Environ. Pollut.Xr'' @PRVƾ*r 73^ZXgRWRgRWRSK4:['>SUWency (WUE) was increased in _A_. _sativa/B._ _kaber_ stands by higher [CO2]. 4. _P_d and WUE of _P_. _glandulosa/S._ _scopXarium_ were not related to [CO2] across either of two growing seasons. Both _P_d and WUE, however, were greater at higherY [CO2] in three of four stands when [CO2] was varied in consecutive days. 5. We conclude that past increases in atmospheric [CO2] have promoted higher WUE and increased carbon uptake in C3-dominated ecosystems.ms. [ 5. We conclude that past increases in atmospheric [CO2] have promoted higher WUE and increased carbon_ uptake in C3-dominated ecosystems.e, salinity, and air pollution have been shown to be ameliorated when CO2 levels are endulosa/mesquite/Schizachyrium scoparium/little bluestem^^^^^^^ shortened for some crops with the application of more COycine soja^^^^^cine soja Sieb. and Zucc.^^^^^, been observed and is under further study; experimental studies have shownganic carbon. yield for most crops increases by about 33% for a doubling of ambient CO2 concentration. However, there are` some reports of negligible or negative effects. Plant species respond differently to CO2 enrichment, therefore, clearly caompetitive shifts within natural communities could occur. Though of less importance in managed agro-ecosystems, competitiobn bewtween crops and weeds could also be altered. Tissue composition can vary as CO2 increases (e.g., higher C:N ratios) lceading to changes in herbivory, but tests of crop products (consumed by man) from elevated CO2 experiments have generally dnot revealed significant differences in their quality. However, any CO2-induced change in plant chemical or structural makee-up could lead to alterations in the plant's interaction with any number of environmental factors--physicochemical or bioflogical. Host-pathogen relationships, defense against physical stressors, and the capacity to overcome resource shortages gcould be impacted by rises in CO2. Root biomass is known to increase but, with few exceptions, detailed studies of root grhowth and function are lacking. Potential enhancement of root growth could translate into greater rhizodeposition, which, iin turn, could lead to shifts in the rhizosphere itself. Some of the direct effects of CO2 on vegetation have been reasonabjly well-studied, but for others work has been inadequate. Among these neglected areas are plant roots and the rhizosphere.k Therefore, experiments on root and rhizosphere response in plants grown in CO2-enriched atmospheres will be reviewed and,l where possible, collectively integrated. To this will be added data which has recently been collected by us. Having lookemd at the available data base, we will offer a series of hypotheses which we consider as priority targets for future researUch.*Ug+TDT2Z:Xc^Y[XVW`rSr6PrFX*o607^3^Rose,D W^Ek,A R^Belli,K L^1987^3^A Conceptual Framework for Assessing Impacts of Carbon Dioxide Change on Forest Indpustries^The Greenhouse Effect, Climate Change, and U.S. Forests^The Conservation Foundation^Washington, D.C.^259-279^^^^^^^^^^1513^^^^^^^^^^^^^^^^^^^^^Shands,WE^Hoffman,JSSwF Jݵ҆r7ݵ|v'~&>&=&> V/#rA^1512^An analytical framework was developed for assessing possible impacts on forest industries of global warming caused sby rising atmospheric carbon dioxide (CO2) levels. Impacts on the aspen-based forest industry of the Great Lakes states antd the loblolly pine-based forest industry of the southeastern United States were analyzed with available, limited informatuion. In the unchanged-CO2 scenario, long-term supply shortages are predicted for the Great Lakes aspen-based and the southveastern United States Loblolly pine-based industries. These shortages can be reduced through technological changes and subwstitution with underutilized hardwood species. Because an increase of the aspen and loblolly pine range is expected under xthe doubled-CO2 scenario, industrial decisions to deal with pending supply shortages will be influenced more by less specuylative factors than future climate. Changes in species ranges will, however, have important implications for state forestry programs.XVu=:^˚${Ú҆ucbۊ u8u8>}>{608^4^Rosenberg,N J^Kimball,B A^Martin,P^Cooper,C F^1990^3^From Climate and CO2 Enrichment to Evapotranspiration^Climate Change and U.S. Water Resources^John Wiley & Sons^New York^151-175^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^Waggoner,P Er1&t&@}609^5^Rouhier,H^Billes,G^Bottner,P^Mousseau,M^Couteaux,M M^1992^3^The Effect of Increased Atmospheric CO2 Concentration on~ the Growth and Nitrogen Allocation of a Woody Plant (_Castanea sativa_ Mill.)^Responses of Forest Ecosystems to Environmental Changes^Elsevier Applied Science^London^701-702^^^^^^^^^^1516^^^^^^^^^^^Castanea sativa/sweet chestnut^^^^^^^^^^Teller,A^Mathy,P^Jeffers,JNRs,J N R%f s*վf s3 t${ tB${V<u::XA^1515^The N uptake by the plants was not significantly modified by CO2 enrichment and the N distribution, expressed as N in the organs % whole plant, was only slowly modified by the CO2 treatment. The storage organs tended to act as source of N and the leaves and fine roots as sink. The fundamental question is to know to what extent the change of the quality of the plant material will modify the decomposition rates, the residence time of carbon in the soil, and the nitrogen availability.C<.uDρe*2DtDD D D>FtD?*s3=u|t D&=uDϡD%=610^1^Rozema,J^1993^1^Plant Responses to Atmospheric Carbon Dioxide Enrichment: Interactions with Some Soil and Atmospheric Conditions^123^104/105^^173-190^^^^^^^^^^1519^^^^^^^^^^^Zea mays/corn/Triticum aestivum/wheat^^^^^t^^^^^,wt ries^Response of Vegetation to Carbon Dioxide^^XSQRV|t03;s*r"& t&u@&|vn`>^ZY[ËA^1517^In general, C3 plant species are more responsive to atmospheric carbon dioxide (CO2) enrichment than C4 plants. Increased relative growth rate at elevated CO2 primarily relates to increased Net Assimilation Rate (NAR), and enhancement of net photosynthesis and reduced photorespiration. Transpiration and stomatal conductance decrease with elevated CO2, water use efficiency and shoot water potential increase, particularly in plants grown at high soil salinity. Leaf area per plant and leaf area per leaf may increase in an early growth stage with increased CO2, after a period of time Leaf Area Ratio (LAR) and Specific Leaf Area (SLA) generally decrease. Starch may accumulate with time in leaves grown at elevated CO2. Plants grown under salt stress with increased (dark) respiration as a sink for photosynthates, may not show such acclimation to increased atmospheric CO2 levels. Plant growth may be stimulated by atmospheric carbon dioxide enrichment and reduced by enhanced UV-B radiation but the limited data available on the effect of combined elevated CO2 and ultraviolet B (280-320 nm) (UV-B) radiation allow no general conclusion. CO2-induced increase of growth rate can be markedly modified at elevated UV-B radiation. Plant responses to elevated atmospheric CO2 and other environmental factors such as soil salinity and UV-B tend to be species-specific, because plant species differ in sensitivity to salinity and UV-B radiation, as well as to other environmental stress factors (drought, nutrient deficiency). Therefore, the effects of joint elevated atmospheric CO2 and increased soil salinity or elevated CO2 and enhanced UV-B to plants are physiologically complex.S8Uu] t;tM611^7^Rozema,J^Dorel,F^Janissen,R^Lenssen,G^Broekman,R^Arp,W^Drake,B G^1991^1^Effect of Elevated Atmospheric CO2 on Growth, Photosynthesis and Water Relations of Salt Marsh Grass Species^78^39^^45-55^^^^^^^^^^1522^^^^^^^^^^^Scirpus maritimus/Puccinellia maritima/Spartina anglica/Spartina patenslica C.E. Hubbard/Spartina patens (Ait.) Muhl.u2& td>C^1520^Aquat. Bot.5!%sں]6>t]!BB&!"!]^ZY[XPSR&! !A^1520^The C3 grass species _Scirpus maritimus_ L. and _Puccinellia maritima_ (Huds.) Parl., and the C4 grass species _Spartina anglica_ C.E. Hubbard and _Spartina patens_ (Ait.) Muhl. were grown at ambient (340 p.p.m. CO2) and elevated (580 p.p.m. CO2) atmospheric CO2 concentration, at low (10 mM NaCl) and high salinity (250 mM NaCl) under aerated and anaerobic conditions in the culture solution. The relative growth rate of both the C3 grass species was enhanced with atmospheric CO2 enrichment, no such increase was found in the C4 grass species. High salinity reduced growth of the C3 species tested, but this relative growth reduction was not prevented by elevated CO2 concentration. The growth increase at elevated CO2 of _Scirpus maritimus_ and _Puccinellia maritima_ is greater under aerated than under anaerobic solution conditions. Water-use efficiency of all species was increased by elevated CO2. In the case of _Scirpus_ (C3), this increase was caused by increased net photosynthesis, for _Spartina patens_ (C4) photosynthesis was not increased, but transpiration was reduced. The water potential of the shoot was less negative under conditions of CO2 enrichment, in particular at increased salinity (250 mM NaCl).&EG^CVƿ^ƿ ,ȚTƿPQVUa,sr2~oQa,sr `WV8&]G_r e612^3^Rozema,J^Lenssen,G M^van de Staaij,J W M^1990^3^The Combined Effect of Increased Atmospheric CO2 and UV-B Radiation on Some Agricultural and Salt Marsh Species^The Greenhouse Effect and Primary Productivity in European Agro-ecosystems; 5-10 April 1990; Wageningen, The Netherlands^Pudoc^Wageningen^68-71^^^^^^^^^^^^^^^^^^^^^Aster tripolium/Lycopersicon esculentum/tomato/pea/Pisum sativum^^^^^^^^^^Goudriaan,J^van Keulen,H^van Laar,HHvan Laar,H HDxȿDʿDFD 613^4^Rozema,J^Lenssen,G M^Broekman,R A^Arp,W P^1990^3^Effects of Atmospheric Carbon Dioxide Enrichment on Salt-marsh Plants^Expected Effects of Climatic Change on Marine Coastal Ecosystems^Kluwer Academic Publishers^Dordrecht, The Netherlands^49-54^^^^^^^^^^1525^^^^^^^^^^^Aster tripolium/Spergularia maritima^^^^^^^^^^Beukema,JJ^Wolff,WJ^Brouns,JJWMff,W J^Brouns,J J W Mv@s~ud^XPSVUu&=t3&EG&F_ FPvT*&EI&MK/:]^[XW`=4A^1524^_Aster tripolium_ and _Spergularia maritima_ were cultivated at 340 ppm CO2 (Ambient) and 580 ppm CO2 (Elevated); salinity of the culture medium was varied at 10 mM NaCl and 250 mM NaCl. Culture solutions were flushed either with oxygen or nitrogen gas. In both species the mean relative growth rate was increased at elevated CO2, but in the present paper there was no significant interaction with the salinity treatment. Flushing of the nutrient solution with nitrogen reduced the mean relative growth rate of both species under all conditions tested. Increased salinity reduced the mean relative growth rate of both species under all conditions tested. The rate of photosynthesis was increased with enriched CO2 in _Spergularia maritima_ and to a lesser extent in _Aster tripolium_. Transpiration rates of both species decreased with CO2 enrichment. The total water potential of the shoot was less negative at elevated CO2. As a result of an increased photosynthetical rate and decreased stomatal conductance the water use efficiency was significantly increased in _Spergularia maritima_ and less pronounced so in _Aster tripolium_.!=:$}K4:XtDg*PRV614^4^Rozema,J^Lenssen,G M^Arp,W J^van de Staaij,J W M^1991^3^Global Change, the Impact of the Greenhouse Effect (Atmospheric CO2 Enrichment) and the Increased UV-B Radiation on Terrestrial Plants^Ecological Responses to Environmental Stresses^Kluwer Academic Publishers^The Netherlands^220-231^^^^^^^^^^1527^^^^^^^^^^^^^^^^^^^^^Rozema,J^Verkleij,JACCB4:&&A^1526^Atmospheric enrichment of CO2 will favour growth of C3 plant species and as a result the competitive balance between C3 and C4 plant species may markedly change. The greenhouse effect consists, however, of both an increase of atmospheric CO2 and global warming, with an expected increase of the global temperature of 1.5-4.5C with a doubling of the atmospheric concentration of carbon dioxide. Such a rise of temperature will prove advantageous to C4 plants. It is also indicated that below a mean air temperature of 18.5C no positive growth response to CO2 enrichment will occur. Increased UV-B radiation will negatively affect the growth of many plant species, monocots possibly being less sensitive than dicot plants. Both the causes of physiological damage by increased UV-B and adaptations to increased UV-B are incompletely understood. There is special need for assessment of UV-B effects on plants in long term field studies. The combined effect of CO2 enrichment, global warming, UV-B increase, and soil and air pollution (ozone, SO2, acid rain, etc.) on terrestric and aquatic ecosystems is unknown. The combined effects of climatic change factors and the soil and air pollution factors need to be studied in the near future.3dˊP֎ދXPP7fXPSQR*PjP.TXXZY[XSQR#.TZY[PSQRV.TXXZY[X615^1^rufty:secondary metabolites^9UNKNOWN YEAR^5^ZY[SQR.TZY[SQ1.TY[ó=:óP3-ٰ0٢ ٢"٢#٢%٢&f soil organic matter turnover and N mineralization, and ultimately a redistribution of C and N between vegetation and soils. The model is a highly aggregated, process-based, biogeochemical model designed to examine changes in the fluxes and aSCO2] gradient. 2. The ratio of night respiration (_Rn_) to daytime net assimilation (_Pd) was greatest in _A. _sativa/B._ temperature, soil water, irradiance, and inorganic nitrogen inputs. We use the model to explore how changes in CO2 concentration, temperature, and N inputs affect carbon storage in two ecosystems: arctic tundra and temperate hardwood forest.  The qualitative responses of the two ecosystems were similar. Quantitative differences are attributed to the initial distribution of C and N between vegetation and soils, to the amounts of woody tissue in the two ecosystems, and to their relative degree of N limitation. We conclude with a critical analysis of the model's strengths and weaknesses, and discuss possible future direction.ssed. Root-zone soil was analyzed for populations of nematodes, microarthropods and _Rhizoctonia_increasing allocation of the gains to growth in height? (b) Are allocation patterns of vines from different types of tropical forests similar or different? 2. We chose congeneric tuberous vines from two types of tropical forest (_Psiguria_ _ racemosa_) from tropical premontane moist forest and _Psiguria_ _umbrosa_ from tropical dry forest) and grew seedlings at three concentrations of ambient CO2 in controlled environment chambers. 3. Both species increased markedly in height: average height of _Psiguria_ _racemosa_ increased 5.5 times at 1000 umol/mol CO2, and average height of _Psiguria_ _umbrosa_ increased 7.1 times, compared to plants at 350 umol/mol CO2. In _Psiguria_ _racemosa_, biomass allocation to shoot growth relative to root growth increased from 55% at 350 umol/mol CO2 to 78% at 1000 umol/mol CO2, whereas allocation ratios remained constant in _Psiguria_ _umbrosa_. 4. Differences in allocation patterns may reflect adaptive responses to environmental constraints imposed by different habitats. For _Psiguria_ _umbrosa_, which is deciduous and often dies back during the dry season, allocation to root biomass may be important for the development of storage root tissue that may affect future growth and height.portant for the development of storage root tissue that may affect future growth and height. were iSchizachyrium_ _scoparium_, respectively, were grown in a 38-m long chamber along a continuous gradient of daytime CO2 concentrations ([CO2]) from near the current 350 umol/mol to 150 (annuals) or 200 umol/mol (perennials). Diurnal CO2 and water fluxes were calculated for plant stands in five consecutive, 7.6-m lengths of the chamber arranged linearly along the [llocation of C and N among foliage, fine roots, stems, and soils in response to changes in atmospheric CO2 concentration, 617^1^Ryan,M G^1991^1^Effects of Climate Change on Plant Respiration^85^1^^157-167^^^^^^^^]Uv7f-]3:}618^3^Ryle,G J A^Powell,C E^Tewson,V^1992^1^Effect of Elevated CO2 on Photosynthesis, Respiration and Growth of Perennial Ryegrass^39^43^^811-818^^^^^^^^^^1535^^^^^^^^^^^perennial ryegrass/Lolium perennenne L.VPSQRUP fv.TXC^1533^J. Exp. Bot.DV6;ٚdsPQ.T.T/tv|t+.T+f.T]ZY[X^VPSQRUFA^1533^Single, seed-grown plants of ryegrass (_Lolium perenne_ L. cv. Melle) were grown for 49 d from the early seedling stage in growth cabinets at a day/night temperature of 20/15C, with a 12 h photoperiod, and a CO2 concentration of either 340 or 680 uL/L CO2. Following complete acclimation to the environmental regimes, leaf and whole plant CO2 effluxes and influxes were measured using infra-red gas analysis techniques. Elevated CO2 increased rates of photosynthesis of young, fully expanded leaves by 35-46% and of whole plants by more than 50%. For both leaves and whole plants acclimation to 680 uL/L CO2 reduced rates of photosynthesis in both CO2 regimes, compared with plants acclimated to 340 uL/L. There was no significant effect of CO2 regime on respiration rates of either leaves or whole plants, although leaves developed in elevated CO2 exhibited generally lower rates than those developed in 340 uL/L CO2. Initially the seedling plants in elevated CO2 grew faster than their counterparts in 340 uL/L CO2, but this effect quickly petered out and final plant weights differed by only _c._ 10%. Since the total area of expanded and unexpanded laminae was unaffected by CO2 regime, specific leaf area was persistently 13-40% lower in elevated CO2 while, similarly, root/shoot ratio was also reduced throughout the experiment. Elevated CO2 reduced tissue nitrogen contents of expanded leaves, but had no effect on the nitrogen contents of unexpanded leaves, sheaths or roots. The lack of a pronounced effect of elevated CO2 on plant growth was primarily due to the fact that CO2 concentration did not influence tiller (branch) numbers. In the absence of an effect on tiller numbers, any possible weight increment was restricted to the _c._ 2-5 leaves of each tiller. The reason for the lack of an effect on tillering is not known.&&.!:+!:ɚ\${${Y[XPSQR)F~tJFF(!:r<4Rd${r+&%619^2^Ryle,G J A^Powell,C E^1992^1^The Influence of Elevated CO2 and Temperature on Biomass Production of Continuously Defoliated White Clover^16^15^^593-599^^^^^^^^^^1538^^^^^^^^^^^Trifolium repens/white cloverclovert &>u&C^1536^Plant Cell Environ.@t &>Zu&ɿ|ZY[XSu][VuAY^PSWVUƋu}3ۃ9t9utA^1536^Clonal plants of white clover (_Trifolium repens_ L.), grown singly in pots of Perlite and solely dependent for nitrogen on root nodule N2 fixation, were maintained in controlled environments which provided four environments: 18/13C day/night temperature at 340 and 680 umol/mol CO2 and 20.5/15.5C day/night temperature at 340 and 680 umol/mol CO2. The daylength was 12 h and the photon flux density 500 +/- 25 umol/m2/s (PFD). All plants were defoliated for about 80 d, nominally every alternate day, to leave the youngest expanded leaf intact on 50% of stolons, plus expanding leaves (simulated grazing). Elevated CO2 increased the yield of biomass removed at defoliation by a constant 45% during the second 40 d of the experiment and by a varying amount in the first half of the experiment. Elevated temperature had little effect on biomass yield. Nitrogen, as a proportion of the harvested biomass, was only fractionally affected by elevated CO2 or temperature. In contrast, N2 fixation increased in concert with the promoting effect of elevated CO2 on biomass production. The increased yield of biomass harvested in 680 umol/mol CO2 was primarily due to the early development and continued maintenance of more stolons. However, the stolons of plants grown in elevated CO2 also developed leaves which were heavier and slightly larger in area than their counterparts in ambient CO2. The conclusion is that, when white clover plants are maintained at constant mass by simulated grazing, they continue to respond to elevated CO2 in terms of a sustained increase in biomass production.*Ú*Ú=:({ ̇ ̇: ̇̇8̇:HSQWUr}uDD >r&}&]&M\LDA^1048^The hypothesis that a relatively brief exposure to elevated atmospheric CO2 could increase the frost resistance of shoots was tested on containerized black spruce seedlings (_Picea_ _mariana_ (Mill.) B.S.P.). Seedlings were exposed to 10ss enzymatic responses, shifts in tissue stoichiometry, changes in biomass allocation among plant tissues, altered rates o00 ppm CO2 toward the end of their second growing season in an unheated production tunnel and in a heated greenhouse. In 1987, continuous 10-week CO2 exposures were applied in conjunction with mineral nutrient fertilization, and freezing tests were conducted each week. In 1988, a series of shorter 2-week CO2 exposures was applied to different groups of seedlings and no mineral nutrients were added. Controlled freezing tests were conducted at -10xC and were followed by electrolytic conductivity measurements to assess frost injury. Under all experimental conditions, freezing tests on seedlings from bo th the production tunnel and the greenhouse indicated significantly greater frost damage for the CO2-enriched seedlings th an for the controls. Late-growing season CO2 enrichment negatively affected the bud initiation - bud development stage of frost-hardiness development..quivalent between the treatments. These results indicate that little modulation of enzyme A^1442^A model that simulates carbon (C) and nitrogen (N) cycles in terrestrial ecosystems is developed. The model is based on the principle that the responses of terrestrial ecosystems to changes in CO2, climate, and N deposition will encompaA^580^Organic amendment comprising of _ragi_ husk and FYM mixed in 1:1 ratio by weight promoted organic carbon content and available P status of the soil. A level of 4 t/ha of organic amendment promoted the uptake of N significantly by both _ra622^3^Sage,R F^Sharkey,T D^Seemann,J R^1989^1^Acclimation of Photosynthesis to Elevated CO2 in Five C3 Species^17^89^^590-596^^^^^^^^^^1545^^^^^^^^^^^Chenopodium album/lambsquarters/Phaseolus vulgaris/bean/Solanum tuberosum/potato/Solanum melongena/eggplant/Brassica oleracea/cabbage^^^^cea L./cabbagelXP t UXP t >XC^1543^Plant Physiol.t|u*sr 3N3 ]^YSQU3SٱC˚${[sNs3A^1543^The effect of long-term (weeks to months) CO2 enhancement on (a) the gas-exchange characteristics, (b) the content and activation state of ribulose-1,5-bisphosphate carboxylase (rubisco), and (c) leaf nitrogen, chlorophyll, and dry weight per area were studied in five C3 species (_Chenopodium album, Phaseolus vulgaris, Solanum tuberosum, Solanum melongena_, and _Brassica oleracea_) grown at CO2 partial pressures of 300 or 900 to 1000 microbars. Long-term exposure to elevated CO2 affected the CO2 response of photosynthesis in one of three ways: (a) the initial slope of the CO2 response was unaffected, but the photosynthetic rate at high CO2 increased (_S. tuberosum_); (b) the initial slope decreased but the CO2-saturated rate of photosynthesis was little affected (_C. album, P. vulgaris_); (c) both the initial slope and the CO2-saturated rate of photosynthesis decreased (_B. oleracea, S. melongena_). In all five species, growth at high CO2 increased the extent to which photosynthesis was stimulated following a decrease in the partial pressure of O2 or an increase in measureme nt CO2 above 600 microbars. This stimulation indicates that a limitation on photosynthesis by the capacity to regenerate o!rthophosphate was reduced or absent after acclimation to high CO2. Leaf nitrogen per area either increased (_S. tuberosum," S. melongena_) or was little changed by CO2 enhancement. The content of rubisco was lower in only two of the five species#, yet its activation state was 19% to 48% lower in all five species following long-term exposure to high CO2. These result$s indicate that during growth in CO2-enriched air, leaf rubisco content remains in excess of that required to support the observed photosynthetic rates.@@&623^2^Sage,R F^Sharkey,T D^1987^1^The Effect of Temperature on the Occurrence of O2 and CO2 Insensitive Photosynthesis in 'Field Grown Plants^17^84^^658-664^^^^^^^^^^1548^^^^^^^^^^^Phaseolus vulgaris/bean/Capsicum annuum/bell pepper/Lycopersicon esculentum/tomato/Scrophularia desertorum/Cardaria draba/hoary cress/Populus fremontii/cottonwood^^^^^s/Populus fremonti)i Wats./cottonwood!Fu&o&OF2y&O Ft& Ft&VFFt&P;XC^1546^Plant Physiol.FtF&: vF& &*G Ft&GFt@߾xB & *FN*,&G&O PX(+A^1546^The sensitivity of photosynthesis to O2 and CO2 was measured in leaves from field grown plants of six species (_Pha,seolus vulgaris, Capsicum annuum, Lycopersicon esculentum, Scrophularia desertorum, Cardaria draba_, and _Populus fremonti-i_) from 5C to 35C using gas-exchange techniques. In all species but _Phaseolus_, photosynthesis was insensitive to O2 i.n normal air below a species dependent temperature. CO2 insensitivity occurred under the same conditions that resulted in /O2 insensitivity. A complete loss of O2 sensitivity occurred up to 22C in _Lycopersicon_ but only up to 6C in _Scrophula0ria_. In _Lycopersicon_ and _Populus_, O2 and CO2 insensitivity occurred under conditions regularly encountered during the1 cooler portions of the day. Because O2 insensitivity is an indicator of feedback limited photosynthesis, these results in2dicate that feedback limitations can play a role in determining the diurnal carbon gain in the field. At higher partial pr3essures of CO2 the temperature at which O2 insensitivity occurred was higher, indicating that feedback limitations in the field will become more important as the CO2 concentration in the atmosphere increases.Ft \s_6&!['5624^3^Sage,R F^Sharkey,T D^Pearcy,R W^1990^1^The Effect of Leaf Nitrogen and Temperature on the CO2 Response of Photosynthesis in the C3 Dicot _Chenopodium album_ L^52^17^^135-148^^^^^^^^^^1551^^^^^^^^^^^Chenopodium album/lambsquartersarters(C^1549^Aust. J. Plant Physiol.t&&8&*& :sĊ&8*&&&creased to a greater extent than the capacity of starch and sucrose synthesis to regenerate orthophosphate. As a result, i?n high nitrogen leaves, photosynthesis appeared to be limited by the capacity to regenerate phosphate at lower CO2 partial@ pressures than in low nitrogen leaves. In high nitrogen leaves, increasing temperature appeared to enhance the phosphate Aregeneration capacity to a greater extent than the capacity of RuP2 carboxylase. Consequently, while under cool conditionsB (<20C), CO2 assimilation in normal atmospheric air appeared to be limited by the phosphate regeneration capacity, under warm conditions (34C), RuP2 carboxylase capacity appears to limit CO2 assimilation.VSQVSQR6 Y[=ttPD625^3^Sage,R F^Sharkey,T D^Seemann,J R^1988^1^The In-vivo Response of the Ribulose-1,5-bisphosphate Carboxylase ActivationE State and the Pool Sizes of Photosynthetic Metabolites to Elevated CO2^51^174^^407-416^^^^^^^^^^1554^^^^^^^^^^^Phaseolus vulgaris/bean./bean s  n   jiknge_ Q36C^1552^Planta>tV>rf~3Қ]*r#W~*E ~*^[23NB_^Z[YøHA^1552^The short-term, in-vivo response to elevated CO2 of ribulose-1,5-bisphosphate carboxylase (RuBPCase, EC 4.1.1.39) aIctivity, and the pool sizes of ribulose 1,5-bisphosphate, 3-phosphoglyceric acid, triose phosphates, fructose 1,6-bisphospJhate, glucose 6-phosphate and fructose 6-phosphate in bean were studied, Increasing CO2 from an ambient partial pressure oKf 360-1600 ubar induced a substantial deactivation of RuBPCase at both saturating and subsaturating photon flux densities.L Activation of RuBPCase declined for 30 min following the CO2 increase. However, the rate of photosynthesis re-equilibrateMd within 6 min of the switch to high CO2, indicating that RuBP-Case activity did not limit photosynthesis at high CO. FollNowing a return to low CO2, RuBPCase activation increased to control levels within 10 min. The photosynthetic rate fell immOediately after the return to low CO2, and then increased in parallel with the increase in RuBPCase activation to the initiPal rate observed prior to the CO2 increase. This indicated that RuBPCase activity limited photosynthesis while RuBPCase acQtivation increased. Metabolite pools were temporarily affected during the first 10 min after either a CO2 increase or decrRease. However, they returned to their original level as the change in the activation state of RuBPCase neared completion. SThis result indicates that one role for changes in the activation state of RuBPCase is to regulate the pool sizes of photosynthetic intermediates.s I`CDH *sFteW_*P֒u*H: *\Ƙ*KD DU626^3^Sage,R F^Sharkey,T D^Seemann,J R^1990^1^Regulation of Ribulose-1,5-bisphosphate Carboxylase Activity in Response to VLight Intensity and CO2 in the C3 Annuals _Chenopodium album_ L. and _Phaseolus vulgaris_ L^17^94^^1735-1742^^^^^^^^^^1557^^^^^^^^^^^Chenopodium album/lambsquarters/Phaseolus vulgaris/beans L./beanuUs]:B${&58#N>yNFC^1555^Plant Physiol.%!_ZXYQQPSRsغ/#%!l NN${2sNt-VRS3&22Z Z,YA^1555^The light and CO2 response of (a) photosynthesis, (b) the activation state and total catalytic efficiency (_Kcat_) Zof ribulose-1,5-bisphosphate carboxylase (rubisco), and (c) the pool sizes of ribulose 1,5-bisphosphate (RuBP), ATP, and A[DP were studied in the C3 annuals _Chenopodium album_ and _Phaseolus vulgaris_ at 25C. The initial slope of the photosynt\hetic CO2 response curve was dependent on light intensity at reduced light levels only (less than 450 micromoles per squar]e meter per second in _C. album_ and below 200 micromoles per square meter per second in _P. vulgaris_). Modeled simulatio^ns indicated that the initial slope of the CO2 response of photosynthesis exhibited light dependency when the rate of RuBP_ regeneration limited photosynthesis, but not when rubisco capacity limited photosynthesis. Measured observations closely `matched modeled simulations. The activation state of rubisco was measured at three light intensities in _C. album_ (1750, a550, and 150 micromoles per square meter per second) and at intercellular CO2 partial pressures (_Ci_) between the CO2 combpensation point and 500 microbars. Above a _Ci_ of 120 microbars, the activation state of rubisco was light dependent. At clight intensities of 550 and 1750 micromoles per square meter per second, it was also dependent on _Ci_, decreasing as thed _Ci_ was elevated above 120 microbars at 550 micromoles per square meter per second and above 300 microbars at 1750 microemoles per square meter per second. The pool size of RuBP was independent of _Ci_ only under conditions when the activationf state of rubisco was dependent on _Ci_. Otherwise, RuBP pool sizes increased as _Ci_ was reduced. ATP pools in _C. album_g tended to increase as _Ci_ was reduced. In _P. vulgaris_, decreasing _Ci_ at a subsaturating light intensity of 190 microhmoles per square meter per second increased the activation state of rubisco but had little effect on the _Kcat_. These resiults support modelled simulations of the rubisco response to light and CO2, where rubisco is assumed to be down-regulated when photosynthesis is limited by the rate of RuBP regeneration.PV=tHx>t.^X3ۀ>Ѽutk627^1^Sage,RF^1990^1^A Model Describing the Regulation of Ribulose-1,5-Bisphosphate Carboxylase, Electron Transport, and Triose Phosphate Use in Response to Light Intensity and CO2 in C3 Plants^17^94^^1728-1734^^^^^^^^^^15605601560t8<uWC^1558^Plant Physiol._s!=:6Ǽ]u E v6ǼeuE6Ǽ uE6Ǽ 6ϼ6ǼuE6ǼnA^1558^A model of the regulation of the activity of ribulose-1,5-bisphosphate carboxylase, electron transport, and the ratoe of orthophosphate regeneration by starch and sucrose synthesis in response to changes in light intensity and partial prepssures of CO2 and O2 is presented. The key assumption behind the model is that nonlimiting processes of photosynthesis areq regulated to balance the capacity of limiting processes. Thus, at CO2 partial pressures below ambient, when a limitation ron photosynthesis by the capacity of rubisco is postulated, the activities of electron transport and phosphate regeneratiosn are down-regulated in order that the rate of RuBP regeneration matches the rate of RuBP consumption by rubisco. Similarlty, at subsaturating light intensity or elevated CO2, when electron transport of Pi regeneration may limit photosynthesis, uthe activity of rubisco is downregulated to balance the limitation in the rate of RuBP regeneration. Comparisons with published data demonstrate a general consistency between modelled predictions and measured results.t ~AJF^w628^1^Sasek,T W^1985^6^Implications of Atmospheric Carbon Dioxide Enrichment for the Physiological Ecology and Distributioxn of Two Introduced Woody Vines, _Pueraria lobata_ Ohwi (Kudzu) and _Lonicera japonica_ Thunb. (Japanese Honeysuckle)^^Dukye University^^Doctoral Dissertation^^^Dissertation Abstracts Vol. 47:02-B, p.479 (218 pp.)^^^^^^^1562^^^^^^^^^^^Lonicera japonica/Japanese honeysuckle/Pueraria lobata/kudzuWilld.) Ohwi/Kudzu^_RW&<tGFX;VW*؋*{A^1561^The vine growth habit increases competitive potential for light capture. More biomass is allocated to height and le|af area because support structures are minimized. This study considered the effects of the continuing increase in atmosphe}ric carbon dioxide concentration on the growth and morphology of vines. Vines were hypothesized to allocate CO2-induced in~creases in production to height and leaf area more efficiently than erect growth forms. Kudzu (_Pueraria lobata_ Ohwi) and Japanese honeysuckle (_Lonicera japonica_ Thunb.) are perennial woody vines, introduced into the United States from Japan. Both have become naturalized in the eastern US and are pernicious weeds in the Southeast capable of suppressing the native flora. Kudzu and honeysuckle were grown in controlled environment chambers in the Duke University phytotron at 350, 675 and 1000 uL/L CO2, simulating double and triple current ambient CO2 concentration. Long-term growth at elevated CO2 concentrations resulted in less enhancement of photosynthesis than predicted by short-term exposure. The reduction of photosynthetic capacity was not due to stomatal limitations. Rather, starch accumulation in the leaves at high CO2 probably reduces photosynthesis by biochemical feedback inhibition. Dry weight and leaf area were increased by CO2 enrichment especially in the young seedlings. Kudzu stems were 40% and 60% longer at double and triple CO2, respectively, than at current ambient CO2. Branching was enhanced by 50% with CO2 enrichment. Honeysuckle stem height was unaffected but branching was enhanced three-fold by CO2 enrichment. Height increase with CO2 enrichment was much greater than stem diameter increase, which is in contrast to erect growth forms. Vines maintain their favorable allocation patterns while still incorporating CO2-induced increases in productivity. Kudzu seedling establishment, currently rare, may be enhanced by CO2 enrichment due to improved growth at low irradiance and by increased water use efficiency. The geographic range of both species may be increased due to direct effects of CO2 enrichment and indirect climatic effects due to the Greenhouse Effect. Westward spread may occur due to enhanced water use efficiency. Northward spread may occur due to improved growth at low temperatures with CO2 enrichment and due to global warming that may increase minimum winter temperatures, reducing die-back of overwintering stems./ / !N2 &N2 / zr, L- M- N\. O. S. Py. Ty. L- R- L1 1 7@2629^2^Sasek,T W^Strain,B R^1988^1^Effects of Carbon Dioxide Enrichment on the Growth and Morphology of Kudzu (_Pueraria lobata_)^102^36^^28-36^^^^^^^^^^1565^^^^^^^^^^^kudzu/Pueraria lobataata (Willd.) Ohwivjr/FNȋ?~NrFlC^1563^Weed Sci.FpF=t#ˋ6@s˸r &PS~Tf r/F3ۋvq*r r6TDFA^1563^Kudzu (_Pueraria lobata_ Ohwi #4 PUELO) was grown from seeds in controlled-environment chambers at 350, 675, or 1000 uL/L CO2. Biomass and leaf area production, morphological characteristics, and growth analysis components were determined at 14, 24, 45, and 60 days after emergence. At 60 days, plants grown at 1000 uL/L CO2 had 51% more biomass, 58% longer stems, and 50% more branches than plants grown at 350 uL/L CO2. Plants grown at 675 uL/L CO2 were intermediate. Growth analysis components indicated that CO2 enrichment increased growth by compounding effects due to increased net assimilation rates and increased leaf area duration. Relative growth rates were not significantly affected. The large CO2-induced increase in stem height versus stem diameter is in marked contrast to previously reported responses of woody erect growth forms. Possible ecological implications for competitive abilities are discussed.Y[XPSQRVWRS[r&] _^ZY[XPSQVW630^2^Sasek,T W^Strain,B R^1989^1^Effects of Carbon Dioxide Enrichment on the Expansion and Size of Kudzu (_Pueraria lobata_) Leaves^102^37^^23-28^^^^^^^^^^1568^^^^^^^^^^^Pueraria lobata/kudzu^^^^^) Ohwi/kudzu 0=:C^1566^Weed Sci.r;%2iQQprmnsRgt/N3FF@FuRr9FuA^1566^Seedlings of kudzu were grown at 350, 675, or 1000 uL/L CO2 in controlled-environment chambers. At elevated CO2 concentrations, maximum leaf expansion rates were approximately 40% greater, leaves were fully expanded several days sooner, fully expanded leaves were larger at each leaf position, and leaf production rates were increased 12%. Peak starch accumulation was much greater in plants grown at elevated CO2 concentrations. Total xylem water potentials were higher (less negative) at full hydration, and osmotic potentials were decreased (more negative) by CO2 enrichment. At 1000 uL/L CO2, leaf turgor pressure was twice that at 350 uL/L CO2. Results suggest that leaf expansion rates and leaf expansivity may have been increased due to higher turgor pressure at the higher CO2 concentrations. The potential for successful seedling establishment may be enhanced as the atmospheric CO2 concentration continues to rise, increasing kudzu invasiveness.t&\t631^2^Sasek,T W^Strain,B R^1991^1^Effects of CO2 Enrichment on the Growth and Morphology of a Native and an Introduced Honeysuckle Vine^14^78^^69-75^^^^^^^^^^1571^^^^^^^^^^^Lonicera japonica/Japanese honeysuckle/coral honeysuckle/Lonicera sempervirensmpervirens L.ˋ6*6PWS~_XˀO7@S~PRVWv t(,t G&=u׊G ttGċv_^C^1569^Amer. J. Bot.QWVTfF&ZtIWǸv&*<~u FuNF_&ZFtI&ZǸv&A^1569^Japanese honeysuckle (_Lonicera japonica_ Thunb.), introduced to the United States, and the native coral honeysuckle (_Lonicera sempervirens_ L.) were compared to determine how intrinsic differences in their growth characteristics would affect their response to atmospheric carbon dioxide enrichment. Plants of both species grown from cuttings were harvested after 54 days of growth in controlled environment growth chambers at 350, 675, or 1,000 uL/L CO2. The biomass of Japanese honeysuckle was increased 135% at 675 uL/L CO2 and 76% at 1,000 uL/L CO2 after 54 days. Morphologically, the main effect of CO2 enrichment was to triple the number of branches and to increase total branch length six times. Enhanced and accelerated branching also increased total leaf area 50% at elevated CO2 concentrations. In coral honeysuckle, total biomass was only 50% greater in the elevated CO2 treatments. Branching was quadrupled but had not proceeded long enough to affect total leaf area. Main stem height was increased 36% at 1,000 uL/L CO2. The much less significant height response of other woody erect growth forms suggests that vines may increase in importance during competition if atmospheric CO2 concentrations increase as predicted. The impact of Japanese honeysuckle in the United States may become more serious.PFPFP< FV632^2^Sasek,T W^Strain,B R^1990^1^Implications of Atmospheric CO2 Enrichment and Climatic Change for the Geographical Distribution of Two Introduced Vines in the U.S.A^88^16^^31-51^^^^^^^^^^1574^^^^^^^^^^^kudzu/Pueraria lobata/Japanese honeysuckle/Lonicera japonicajaponica Thunb.3ƺ^&9tJ@Pj FVLNPR: VFu=tTƺVЃC^1572^Climatic Change^ءD&GD@^&G_^F;s[jjFVLNPR: VFt=A^1572^The continuing increase in the atmospheric carbon dioxide concentration resulting from fossil fuel combustion and deforestation may change the ecological impact and geographical distribution of kudzu (_Pueraria lobata_ Ohwi) and Japanese honeysuckle (_Lonicera japonica_ Thunb.) in the U.S.A. Both vines were introduced about a century ago from Japan and have become naturalized weeds. Westward range expansion is currently limited by drought during seedling establishment, while northward range expansion is limited by low temperature sensitivity of overwintering stems. Direct effects of CO2 enrichment on growth were assessed by growing the plants in controlled environment chambers at 350, 675, or 1000 uL/L CO2. In both species, CO2 enrichment increased instantaneous water use efficiency by increasing photosynthetic rates and reducing transpiration rates. During a drought stress, CO2 enrichment delayed significant decline in total water potential of kudzu by several days. When grown in a cool temperature regime of 18/12C day/night, the CO2 enrichment significantly increased leaf area and total biomass of both species and plants were taller and had more branches. These results suggested that atmospheric CO2 enrichment may allow westward and northward spread of both species in the U.S.A. Indirect effects of CO2 induced climate change (Greenhouse Effect) on the vines' distribution were assessed. Predictions based on current models of climatic response were used to project changes in winter temperatures at doubled CO2 concentrations. Increases in average and minimum winter temperatures by 3C could allow northward spread of both species by several hundred kilometers. Projected decreases in summer precipitation may minimize westward spread, despite improved water use efficiency and increased drought tolerance.vFFPFv PC tju5 =t^FvFFPF v PC tju5 =t^F633^1^Saxe,H^1986^1^Effects of NO, NO2 and CO2 on Net Photosynthesis, Dark Respiration and Transpiration of Pot Plants^23^103^^185-197^^^^^^^^^^1577^^^^^^^^^^^Ficus elastica/Ficus benjamina/Hedera helix/Hedera canariensis/Hibiscus rosa-sinensis/Dieffenbachia maculata/Nephrolepis exaltataata6PvvtI ;Dt^]3^]UVW~vEFVFVC^1575^New Phytol. u3_^ ^F V &G&WPR* u3_^ 6h6fFPFPFPFP<F V FFPvvvI A^1575^Eight cultivars of the pot plants (_Ficus elastica 'Robusta', Ficus benjamina, Hedera helix 'Anne Marie', Hedera canariensis 'Montgomery', Hibiscus rosa-sinensis 'Red', Hibiscus rosa-sinensis 'Moesiana', Dieffenbachia maculata 'Compacta'_ and _Nephrolepis exaltata 'Bostoniensis'_) most commonly grown in Danish commercial greenhouses were subjected to 4 d exposures to 1 ml/L of CO2, 1 ml/L CO2 + 1 uL/L NO, 1 uL/L NO alone and 1 uL/L NO2 alone. Effects on net photosynthesis and dark respiration of aerial parts and effects on whole plant transpiration were observed before, during and after exposures. The measurements were mathematically transformed to double relative values, to indicate the effects of the different gaseous treatments. Carbon dioxide enrichment enhanced net photosynthesis by 40.9% and subsequent dark respiration by 23.5%, while transpiration was reduced. NO reduced photosynthesis (approximately 20%) and transpiration (the latter at high CO2 only), but did not affect respiration. NO2 rarely had significant effects. All effects of the gaseous treatments on photosynthesis and transpiration were reversible and had independent mechanisms, while effects on respiration were non-reversible. On the average, 1 uL/L NO was four times more inhibitory to photosynthesis than 1 uL/L NO2. Short-term effects (4 d) on photosynthesis of exposure to CO2 + NO correlated significantly (P<0.03) with the long-term effects (four to five months) on dry weight found using the same cultivars in similar treatments.V+&I)A&${_sQW&634^2^Saxe,H^Christensen,O V^1985^1^Effects of Carbon Dioxide with and without Nitric Oxide Pollution on Growth, Morphogenesis and Production Time of Pot Plants^81^38^^159-169^^^^^^^^^^1580^^^^^^^^^^^Ficus elastica/Ficus benjamina/Hedera helix/Hedera canariensis/Hibiscus rosa-sinensis/Dieffenbachia maculata/Nephrolepis exaltataata tL|66rtt t 9L C^1578^Environ. Pollut.^4T~ tO6zu3]^_ZYSQWVZ%:rODEdDF|>HA^1578^Eight of the cultivars of pot plants grown most commonly in Danish commercial glasshouses were subjected to long-term CO2 enrichment with or without nitric oxide pollution. Effects on the morphology and productivity of the plants were determined. The advantage obtained from the use of CO2 was generally reduced by the addition of nitric oxide, although visual damage, such as scorched leaves, was only found in one species.U6rt| t &u]^_XPVU t&635^3^Schapendonk,A H C M^van de Geijn,S C^Dayan,E^1990^3^Effect of CO2 Concentration and Temperature on Photosynthesis and Assimilate Partitioning of a Closed Canopy^The Greenhouse Effect and Primary Productivity in European Agro-ecosystems; 5-10 April 1990; Wageningen, The Netherlands^Pudoc^Wageningen^38-41^^^^^^^^^^^^^^^^^^^^^tomato/Lycopersicon esculentum^^^^^^^^^^Goudriaan,J^van Keulen,H^van Laar,HHar,H HSQRVWU3عӃJur$׎^v*N ^vD636^1^Schlesinger,WH^1993^1^Response of the Terrestrial Biosphere to Global Climate Change and Human Perturbation^123^104-105^^295-305^^^^^^^^^^1584^^^^^^^^^^^^^^^^ t:W&}W_W&}[_W&}__W&} _W&};z_u^>rk>rC^1582^VegetatioSs>rt6rVFA^1587^Atmospheric CO2 concentrations are increasing world-wide and are expected to double within the next century. This study was conducted to determine the combined effects of CO2 enrichment and dehydration stress on development of 'TAM W-101' winter wheat (_Triticum aestivum_ L.) at the tillering stage. Seedlings (one per pot) were grown in growth chambers maintained at 350 (ambient) or 700 (enriched) uL/L CO2, and subjected to three levels of soil moisture (well watered, medium s tress, and severe stress). Plastochron (the developmental time for one leaf) decreased 2 to 3% at all water levels under C O2 enrichment. Averaged over CO2 treatments, water limitation increased plastochron from 90 thermal units under well-water ed conditions to 126 under medium stress and 151 under severe stress. Similarly, water limitation reduced tiller number fr om 26 to 14 and 12 under medium and severe stress, respectively. The ratio of leaf dry wt. to leaf area (specific leaf wt. ) and water use efficiency were significantly higher in plants grown under CO2 enrichment. Although CO2 enrichment had positive effects on growth and development of winter wheat at tillering, these were insufficient to counterbalance the debilitating effects of water limitation.&>3 t u>9l&${^_^XVWu23 uφ ++r 639^2^Schwartz,N^Strain,B R^1990^1^Carbon -- a Plant Nutrient, Deficiency and Sufficiency^72^13^^1073-1078^^^^^^^^^^1592^^^^^^^^^^^wheat/Triticum aestivum/maize/Zea mays/soybean/Glycine max/tomato/Lycopersicon esculentum/lettuce/Lactuca sativa/radish/Raphanus sativus/bean/Phaseolus vulgaristivus L./bean/Phaseolus vulgaris L.%2 t:$rF ]_^ZYXR2QPSWVC^1590^J. Plant Nut.fGN2FvE 6QVgt<^6D6\6T6t6L6DNY ‹F~uF~tA^1590^Toxicity symptoms of carbon dioxide (CO2) have been observed at 10,000 ppm concentration after six days in seven species. Maize is an indicator plant for C-toxicity, developing zebra-like stripes. Full recovery from C-toxicity occurred only in wheat and maize plants. No deficiency symptoms of carbon have been determined. Root exposure during six days to 10,000 ppm CO2 or near zero CO2 had no visible effect, and plants develop normally.2F t:؈FF~uNu640^5^Setter,T L^Waters,I^Wallace,I^Bhekasut,P^Greenway,H^1989^1^Submergence of Rice. I. Growth and Photosynthetic Response to CO2 Enrichment of Floodwater^52^16^^251-263^^^^^^^^^^1595^^^^^^^^^^^rice/Oryza sativaiava L.\t9^=9b~79C^1593^Austr. J. Plant Physiol.T|&;T|^ZY[Ú${s&؛UPQVW wNFvNF~A^1593^Growth and photosynthetic response of lowland rice following complete submergence is related to the concentration of CO2 dissolved in floodwater. Submergence of plants in stagnant solution at low CO2 concentration or solution gassed with air at 0.03 kPa CO2 (equilibrium of 0.01 mol/m3 dissolved CO2) decreased carbohydrates, and little or no growth occurred. Plants submerged in solutions gassed with 3-20 kPa CO2 in air (equilibrium of 0.9-6 mol/m3 CO2) showed at most small decreases in carbohydrates, and growth was up to 100% of the non-submerged plants. At pH 7.5, there was little net photosynthe tic O2 evolution by detached submerged leaves even at high HCO3(-) concentrations, which suggests that these rice leaves c!ould utilise only CO2 and not HCO3(-). At pH 6.5, O2 evolution in solutions in equilibrium with 7.4 Pa CO2 was 3-4 fold hi"gher than in solutions in equilibrium with 0.6 kPa CO2. Photorespiration was indicated by a decrease in the rate of net O2# evolution with increasing external O2. In stagnant solutions this reduction of O2 evolution was pronounced; at a CO2 conc$entration of 0.25 mol/m3 net O2 evolution ceased when the O2 concentration in the water had reached only 0.125 mol/m3. The% requirement of photosynthesis for a combination of high CO2 concentrations and low external O2 was presumably due to slow diffusion of these gases in the unstirred layer of solution around the leaves.:v:v:v]YXPSQRVW'641^1^Shaer,Y A^1985^6^Effect of Carbon Dioxide Enrichment on Diffusive Resistance for Gas Exchange, Water Use, and Water (Use Efficiency of Greenhouse Tomatoes^^Texas A&M University^^Doctoral Dissertation^^^Dissertation Abstracts 47:01-B, p.6 (118 pp.)^^^^^^^1597^^^^^^^^^^^Lycopersicon esculentum/tomatoomatoЊF^@֊=:s$:s:s€kv(&GF*A^1596^Three adjacent ventilated mini-greenhouses (MGH) made of clear polyethylene film, transmitting natural solar radiat+ion, were enclosed in a conventional inflated polyethylene greenhouse. In each MGH, an equal number of tomato plants were ,grown in the Spring and the Fall of 1984, and kept at optimum levels of moisture and nutrients. From 10 to 98 days after e-mergence, CO2 levels in the mini-greenhouses were maintained at about 340, 700, and 1000 ppmv during the daytime. As CO2 l.evels in the MGH air increased from 340 to 1000 ppmv, the crop surface resistance, measured with a porometer, increased fr/om about 30 to 100 s/m. CO2 enrichment also increased the ratio between the internal and the external CO2 levels of the le0aves from 0.70 to 0.85. From the Fall 1984 data, a linear equation was derived to relate surface resistance to the interna1l CO2 level with an R-square value of 0.8. At an air exchange rate of 30 m3/m2/h in the MGH, the aerodynamic resistance, m2easured using a heated brass plate, or as computed by the residual method, averaged 225 s/m. This parameter dominated gas 3exchange by the plants at all CO2 levels. Therefore, the water use as measured by weighing mini-lysimeters (pots) on clear4 days, decreased only slightly, 15-20%, as result of the CO2 enrichment. This occurred in spite of an increase in leaf tem5perature of about 1.5C. The leaf area and stomatal density were not markedly affected by CO2 enrichment. Both the instant6aneous and the seasonal water use efficiency increased markedly, by about 70%, by growing the plants at a CO2 level of 10070 ppmv rather than 340 ppmv. In part, this was due to the reduction of water use, but mainly to the increase in assimilation rate, in total dry matter, and in the mass of fresh fruit harvested, being 70%, 31%, and 50%, respectively.uhf9642^2^Shaer,Y A^van Bavel,C H M^1991^1^Relationships between Stomatal Resistance and CO2 Level around and inside Leaves of Greenhouse Tomatoes^28^26^^72^^^^^^^^^^^^^^^^^^^^^Lycopersicon esculentum/tomatol./tomato^ H&F&DHVC^1598^HortSci.6F6H6B6DB&D &&TD&D&\&T&\&D ^ ܡVvvDBHFsF_^ZY<643^3^Shaish,A^Roth-Bejerano,N^Itai,C^1989^1^The Response of Stomata to CO2 Relates to Its Effect on Respiration and ATP Levels^44^76^^107-111^^^^^^^^^^1602^^^^^^^^^^^Commelina communisnis L.D&DFFHF‹v2fts:C^1600^Phsiol. Plant.&DAFt#F&&D&DF&D&D&D Vv&&|^&&T&|&|^&F&DHIv?A^1600^External ATP enhanced stomatal opening of _Commelina communis_ L. differently from EDTA. ATP was more effective in @opening stomata than EDTA, when both were applied in amounts yielding equivalent free Ca++ concentration. The stimulation Aby ATP depended upon its de-phosphorylation and was not due to the Pi released. Hence an energetical contribution of exterBnal ATP appears possible. Increase in CO2 concentration increased the stimulation of stomatal opening by ATP and diminished the internal ATP level, ATP/(ADP + AMP) ratio and respiration.[XPSQRVWڋEFUE M];w r;shN^ D644^3^Sharkey,T D^Loreto,F^Delwiche,C F^1991^1^High Carbon Dioxide and Sun/Shade Effects on Isoprene Emission from Oak and Aspen Tree Leaves^16^14^^333-338^^^^^^^^^^1605^^^^^^^^^^^red oak/Quercus rubra/quaking aspen/Populus tremuloidesloides M=C^1603^Plant Cell Environ.D&GD詒vC~uV_v'^ FvN 袚^ ą_^ZY[Xxf PGA^1603^Isoprene (2-methyl 1,3-butadiene) is emitted from many plants, especially trees. We tested the effect of growth at Hhigh CO2 partial pressure and sun versus shade conditions on the capacity of _Quercus rubra_ L. (red oak) and _Populus treImuloides_ Michx. (quaking aspen) leaves to make isoprene. Oak leaves grown at high CO2 partial pressure (65 Pa) had twice Jthe rate of isoprene emission as leaves grown at 40 Pa CO2. However, aspen leaves behaved oppositely, with high CO2-grown Kleaves having just 60-70% the rate of isoprene emission as leaves grown in 40 Pa CO2. Similar responses were observed fromL 25 to 35C leaf temperature during assay. The stimulation of isoprene emission by growth at high CO2 and the stimulation Min high temperature resulted in isoprene emission consuming over 15% of the carbon fixed during photosynthesis in high-CO2N grown oak leaves assayed at 35C. Leaves from the south (sunny) sides of trees growing in natural conditions had rates ofO isoprene emission double those of leaves growing in shaded locations on the same trees. This effect was similar in both aPspen and oak. The leaves used for these experiments had significantly different chlorophyll a/b ratios indicating they werQe functionally sun (from the sunny locations) or shade leaves (from the protected locations). Because the metabolic pathwaRy of isoprene synthesis is unknown, we are unable to speculate about how or why these effects occur. However, these effectSs are more consistent with metabolic control of isoprene release rather than a metabolic leak of isoprene from metabolism.T The results are also important for large scale modelling of isoprene emission and for predicting the effect of future increases in atmospheric CO2 level on isoprene emission from vegetation.^FV u yB33؃ʋ؋FVFEichx.t؃FVZY[XPSQRVW u u =y؃FV3ۿY+˃t8.;tw.;wr 3W645^2^Sharkey,T D^Vanderveer,P J^1989^1^Stromal Phosphate Concentration Is Low during Feedback Limited Photosynthesis^17^91^^679-684^^^^^^^^^^1608^^^^^^^^^^^Phaseolus vulgaris^^^^^.{++;s@uVB3 ƋVFt ؃´VF UC^1606^Plant Physiol.3һZ%F3FF u FF@F.~Fہô.~F^ uS.{3ҋN~t ZA^1606^It has been hypothesized that photosynthesis can be feedback limited when the phosphate concentration cannot be bot[h low enough to allow starch and sucrose synthesis at the required rate and high enough for ATP synthesis at the required \rate. We have measured the concentration of phosphate in the stroma and cytosol of leaves held under feedback conditions. ]We used nonaqueous fractionation techniques with freeze-clamped leaves of _Phaseolus vulgaris_ plants grown on reduced pho^sphate nutrition. Feedback was induced by holding leaves in low O2 or high CO2 partial pressure. We found 7 millimolar pho_sphate in the stroma of leaves in normal oxygen but just 2.7 millimolar phosphate in leaves held in low oxygen. Because 1 `to 2 millimolar phosphate in the stroma may be metabolically inactive, we estimate that in low oxygen, the metabolically aactive pool of phosphate is between negligible and 1.7 millimolar. We conclude that halfway between these extremes, 0.856 mbillimolar is a good estimate of the phosphate concentration in the stroma of feedback-limited leaves and that the true conccentration could be even lower. The stromal phosphate concentration was also low when leaves were held in high CO2, which dalso induces feedback-limited photosynthesis, indicating that the effect is related to feedback limitation, not to low oxyegen _per se_. We conclude that the concentration of phosphate in the stroma is usually in excess and that it is sequesterefd to regulate photosynthesis, especially starch synthesis. The capacity for this regulation is limited by the coupling factor requirement for phosphate..658tPSQW8˓Us]_Y[Xs2O66,N6>I8u ptp2&$:&62v,N[L646^2^Shina,G^Seginer,I^1989^1^Optimal Management of Tomato Growth in Greenhouses^15^248^^307-313^^^^^^^^^^^^^^^^^^^^^tomaXC^1609^Act. Hort.,N[88&6[Xð<726>6u>6|B6ˀ>6}6u&6>6|6Bˠ6j647^4^Shishido,Y^Seyama,N^Imada,S^Hori,Y^1989^1^Carbon Budget in Tomato Plants as Affected by Night Temperature Evaluated by Steady State Feeding with 14-CO2^35^63^^357-367^^^^^^^^^^^^^^^^^^^^^tomato/Lycopersicon esculentum^^^^^6\t@hC^1611^Ann. Bot. s61s s6s ǣ6Pښ?N6X_^ˉLT<&6`PQWU>6u66~+>m648^4^Shugart,H H^Antonovsky,M Ya^Jarvis,P G^Sandford,A P^1986^3^CO2, Climatic Change and Forest Ecosystems^The Greenhousen Effect, Climatic Change, and Ecosystems^John Wiley and Sons^Chichester, England^475-521^^^^29^^Scientific Committee on Problems of the Environment^^^^1614^^^^^^^^^^^^^^^^^^^^^Bolin,B^Doos,BR^Jager,J^Warrick,RA^^^^^^^1614uXPSR>7u$>7pA^1613^The forests of the Earth constitute a complex system with many possible responses, both to the direct effects of anq increase in atmospheric CO2 concentration and to the possible changes in climate. These responses may originate from phenromena that operate on very different time and space scales. In general, formidable difficulties are encountered in 'scalinsg-up' the short-term physiological and biochemical responses of leaves and individual plants to estimate the intermediate tand long-term responses of forests. The difficulties arise from the large uncertainties involved in the methods of extrapoulation and from the complex interactions that occur at larger scales. The two uncertainties are presently large enough to vpreclude meaningful discussions of the interactions between CO2 concentrations and climate except in the most general way.w With respect to the direct effects of CO2, these problems of scaling-up are compounded by the lack of experimental evidenxce for relevant forest species, particularly for plants that have been allowed to acclimate to enhanced CO2 concentrationsy over one or more growing cycles. Although higher concentrations of CO2 have been shown to increase CO2 assimilation and, zconsequently, growth rates of individual trees in controlled conditions over the short term, it is highly uncertain whethe{r such effects would be sustained and would lead to increased productivity in actual forest environments over the long ter|m. In uncontrolled environments, the direct CO2 effects are complicated by micrometeorological differences in the degree o}f coupling between forests and atmosphere (within as well as between forest systems), and by species competition and inter~actions. If, indeed, elevated CO2 concentrations do result in long-term growth enhancement, increases in productivity would be more likely to occur in commercial forests than in mature forests in which the capacities for increased carbon storage are more limited. Direct experimentation at this scale, however, is largely impracticable. In order, therefore, to assess the responses of forest systems to both higher CO2 concentrations and changes in climate, experimental studies must be augmented by empirical observation and simulation modelling. With respect to the effects of climatic change, empirical climate-vegetation models and forest simulation models have been used to assess the responses of forests at scales ranging from a single point in a forest to an entire continental system. In general, from the results of a limited number of such studies, together with our understanding of the basic underlying processes, we conclude that: Climatic changes of the order of magnitude predicted by climate models for a doubling of atmospheric CO2 are potentially sufficient to produce substantial intermediate and long-term changes in the composition, size and location of the forests of the world. At continental and regional scales, simulation models indicate considerable spatial heterogeneity in the response of forests. The natural forests of the high latitudes in general and the boreal forests in particular, appear sensitive to predicted temperature changes. Warmer conditions could possibly lead to large reductions in the areal extent of boreal forests and a poleward shift in their boundaries. It is at these latitudes that climate models predict the largest warming to occur as a result of increased concentrations of greenhouse gases, with smaller temperature changes in the lower latitudes. The forests of the tropical and sub-tropical zones would probably be more sensitive to changes in precipitation than temperature. Because of the high uncertainty regarding future changes in precipitation in the tropics, and because of the present lack of models that can be used to simulate the effects of tropical ecosystems to changes in climate variables, our knowledge of the responses of tropical forests to future climatic changes is meagre.8ي8:w:w)tsˆ>78aˀ>649^1^Silvola,J^1990^1^Combined Effects of Varying Water Content and CO2 Concentration on Photosynthesis in _Spagnum fuscum_^107^13^^224-228^^^^^^^^^^1617^^^^^^^^^^^Spagnum fuscum/mossossu  s) XPSQVURW:tY:>[:*68*kC^1615^Holarct. Ecol.:t:tYN<s:*s'8t"&6A^1615^The photosynthesis of _Spagnum fuscum_ (Schimp.) Klinggr. at different water contents and CO2 concentrations was measured in the laboratory. The optimal water content for photosynthesis near the current atmospheric CO2 concentration is 600-800% (percentage of dry weight). The decrease in photosynthesis is very steep towards lower water contents and less steep towards higher water contents. The optimal water content range moves higher and becomes wider with increasing CO2 concentration. At 3000 ppm there is no longer any decrease in photosynthesis with increasing water content. The water content of _S. fuscum_ has a considerable effect on the response of photosynthesis to CO2 concentration. In a moss saturated with water, photosynthesis increases gradually until 8000 ppm CO2, but this saturation concentration becomes lower with decreasing water content, being _c._ 1500 ppm at a water content of 700-800%. An increase in CO2 concentration over 300 ppm will raise photosynthesis very little in dry moss with a water content of only 300-400%.'8uNPSW>[:&68)8qt Y:V650^3^Simon,J-P^Potvin,C^Strain,B R^1989^1^Effects of Temperature and CO2 Enrichment on Kinetic Properties of NADP+ -Malate Dehydrogenase in Two Ecotypes of Barnyard Grass (_Echinochloa crus-galli_ (L.) Beauv.) from Contrasting Climates^34^81^^138-144^^^^^^^^^^1620^^^^^^^^^^^barnyardgrass/Echinochloa crus-galli^^^i (L.) Beauv.ëZPc86878X:tYC^1618^Oecologia!i:b[8tU868Y8tT868Y8 tV868Y8@tW868[8tX868)tWY8>[8 s_A^1618^The apparent energy of activation (_Ea_), Michaelis-Menten constant (_Km_ for oxaloacetate), _Vmax/Km_ ratios and specific activities of NADP+ -malate dehydrogenase (NADP+ -MDH; EC 1.1.1.82) were analyzed in plants of Barnyard grass from Quebec (QUE) and Mississippi (MISS) acclimated to two thermoperiods (28/22C, 21/15C, and grown under two CO2 concentrations, 350 uL/L and 675 uL/L. _Ea_ values of NADP+ -MDH extracted from QUE plants were significantly lower than those of MISS plants. _Km_ values and _Vmax/Km_ ratios of the enzyme from both ecotypes were similar over the range of 10-30C but reduced _Vmax/Km_ ratios were found for the enzyme of QUE plants at 30 and 40C assays. MISS plants had higher enzyme activities when measured on a chlorophyll basis but this trend was reversed when activities were expressed per fresh weight leaf or per leaf surface area. Activities were significantly higher in plants of both populations acclimated to 22/28C. CO2 enrichment did not modify appreciably the catalytic properties of NADP+ -MDH and did not have a compensatory effect upon catalysis or enzyme activity under cool acclimatory conditions. NADP+ -MDH activities were always in excess of the amount required to support observed rates of CO2 assimilation and these two parameters were significantly correlated. The enhanced photosynthetic performance of QUE plants under cold temperature conditions, as compared to that of MISS plants, cannot be attributed to kinetic differences of NADP+ -malate dehydrogenase among these ecotypes.g9 B$:@B651^1^Sinclair,T R^1992^1^Mineral Nutrition and Plant Growth Response to Climate Change^39^43^^1141-1146^^^^^^^^^^1623623C^1621^J. Exp. Bot.X8@ I8s uoR3aR3ҎڢeZ`:DDDDD *D s >N8uU"A^1621^The limiting factor concept has often been used to describe plant growth responses to altered availability of resources. However, even preliminary experiments, where atmospheric CO2 concentrations and solution mineral concentrations were varied, demonstrated that a more complex concept was required to interpret the potential effects of climate change and mineral availability on plant growth. It is proposed that these resources for plant growth may be better viewed as simultaneously limiting. Further, in considering the limitation in plant growth to mineral nutrition it is important to consider both the solution concentration and the total amount of the individual minerals available to the plant. Sustaining a positive response to increased CO2 concentration, for example, requires an increase in plant uptake of the total amount of minerals. Consequently, it is very difficult to predict the plant growth response to climate change because of the large uncertainty about mineral availability. On the one hand, increased CO2 concentrations should stimulate nitrogen fixation by both free-living organisms and symbiotic systems, and improve soil properties for mineral availability as a result of increased organic matter deposition in the soil. On the other hand, increased temperature and altered rainfall patterns may result in increased losses of soil minerals. Even the direction in the net change in available soil minerals is unclear. Realistic evaluations of the effects of climate change on plant growth will be challenged to contend with the large uncertainty and complexities in understanding mineral availability and plant mineral nutrition.ys;r fv~& u u HA;vs;vtq2U_^ZY[XPVWދ>:3;s$&< u&&9u &9Du&9Dtރ_^X652^2^Sionit,N^Kramer,P J^1986^3^Woody Plant Reactions to CO2 Enrichment^Physiology, Yield, and Economics^CRC Press, Inc.^Boca Raton, Florida^69-85^^^^II^^Carbon Dioxide Enrichment of Greenhouse Crops^^^^1625^^^^^^^^^^^^^^^^^^^^^Enoch,H Z^Kimball,B AB AÀO&E&UÀO&E &U &E &U QVJ=O^YÇ&GGÀgGW+D Txu uO@RWww3A^1624^Woody plants constitute an important sink for CO2 and are ecologically important species in forest communities. It is therefore important to characterize their responses to increasing atmospheric CO2 concentration. To reach this major objective with some certainty will require a comprehensive research effort in both laboratory and field. Based on the few data available, doubling the present level of CO2 in the atmosphere would affect physiology, morphology, and biomass production of woody plants, and is likely to have differential effects on the establishment and growth of tree seedlings. However, the responses of plants to increasing CO2 concentration depend on the extent of the growth limitation imposed by other environmental factors such as available supplies of water and nutrients, light and temperature. Most of our information comes from short-term experiments conducted under controlled conditions. Large-scale research projects are needed to more specifically determine the combined effects of CO2 enrichment and other environmental factors.5*r 3A uYD653^3^Sionit,N^Strain,B R^Flint,E P^1987^1^Interaction of Temperature and CO2 Enrichment on Soybean: Photosynthesis and Seed Yield^29^67^^629-636^^^^^^^^^^1628^^^^^^^^^^^soybean/Glycine maxmax (L.) Merr.[ ^P$tttV~VW#^_C^1626^Can. J. Plant Sci.r!t&9U wr&9M s=tQOYsg^DDDXQR &OFV&M&uA^1626^Seed yield and photosynthetic responses of soybean (_Glycine max_ L. Merr. 'Ransom') were studied in growth chambers at day/night temperatures of 18/12, 22/16, and 26/20C and atmospheric CO2 concentrations of 350, 675 and 1000 uL/L. No seeds were produced at 18/12C within any of the CO2 concentrations. Numbers of pods and seeds increased with increasing temperature and CO2 levels. Carbon dioxide enrichment increased seed yield of soybean grown at moderately cool temperatures. This increase was associated with an increase in net photosynthetic rate. Leaf photosynthesis in response to CO2 enrichment increased more at 22/16C than at 26/20C. Increases in temperature and CO2 levels enhanced total growth of plants but hastened senescence of leaves. The extended photosynthetic capacity at cool temperatures did not result in allocating more dry matter to developing pods. CO2 enrichment at 26/20C resulted in greater seed yield increases than CO2 enrichment at lower temperatures.u &}u_^XPVW*rO&Mu &}u_^XPVWr &M&EO_^XPVWr &M&EO_^654^3^Sionit,N^Strain,B R^Flint,E P^1987^1^Interaction of Temperature and CO2 Enrichment on Soybean: Growth and Dry Matter Partitioning^29^67^^59-67^^^^^^^^^^1631^^^^^^^^^^^soybean/Glycine maxmax (L.) Merr.X ${QRWr6ts-C^1629^Can. J. Plant Sci. s_ZYSRWU:=WWPC3_\ tGE fs3҇Tnt*G t ZY[XÃ'QRr5t uC^1632^Can. J. For. Res.u 7X<: ZYPQr#B^rtJrGtoH YXPQȡB u lrBA^1632^Growth and development of native species of trees in response to long-term increases in atmospheric CO2 concentration were studied. Seedlings of two competing perennials, _Pinus taeda_ L. and _Liquidambar styraciflua_ L., were obtained from germinated seeds and grown through one complete growing season at 350, 500, and 650 uL/L CO2. The plants were grown in CO2 controlled greenhouses under natural photoperiods and light regimes, with temperature controlled to simulate mean local climate. Stem length and basal stem diameter increased with increasing CO2 in both species. _Liquidambar styraciflua_ maintained size dominance in all concentrations. The dry weights of stems, roots, and leaves increased in both species. In _P. taeda_, however, the seedlings reached maximum size at 500 uL/L while _L. styraciflua_ continued to increase up to 650 uL/L. _Liquidambar styraciflua_ produced significantly more branches and leaves at the higher CO2 concentrations than at 350 uL/L. Differences in plant shape and responses in growth rate of these two naturally competing tree species suggest that continuing atmospheric CO2 enrichment could affect future interactions between the species and might produce changes in community composition.^sr: _^Y[XPSQRVWxx3r8It*t%Ӌ^ 'rV t 656^1^Slack,G^1986^3^CO2 Enrichment of Tomato Crops^Physiology, Yield, and Economics^CRC Press, Inc.^Boca Raton, Florida^151-163^^^^II^^Carbon Dioxide Enrichment of Greenhouse Crops^^^^1636^^^^^^^^^^^tomato/Lycopersicon esculentum^^^^^^^^^^Enoch,HZ^Kimball,BAall,B AB AG ZEr,^[Zhr*r*u  _^Y[XBr:QRVW3ҹA^1635^The benefits of enriching tomato crops with CO2 were first demonstrated experimentally in the 1920s but the technique was not used commercially until some 40 years later when cheap sources of CO2 became available to the protected crops industry. The practice is now well established and is used by most of the major tomato producers. Increases in yield are highest when enrichment can be maintained for long periods during daylight hours without the need for ventilation. A threefold increase in CO2 concentration increases leaf net photosynthesis by about 50% in both low and high light conditions. In the vegetative phase, enrichment enhances plant growth by increasing net assimilation rate and leaf area. Relative growth rate is increased initially but eventually falls to that of nonenriched plants. There is no significant effect on the rate of leaf production. Dry weight may be increased by 40 to 50% and leaf area by 20 to 25%. The effects in low light are particularly important since large numbers of plants are propagated commercially in late autumn and winter. Increasing CO2 level in these conditions has a similar effect on dry matter production, as does increasing light. Growth responses to enrichment are directly attributable to enhanced photosynthetic activity so there is no effect on seed germination nor from enrichment during the night period. In the reproductive phase, enrichment induces earlier flowering, but the effect is small and is restricted to flowers of the first truss (3 to 9 days). Enrichment also improves flower setting and fruit development of the early trusses in poor light conditions, and a relationship between truss abortion and CO2 concentration has been shown. Increases in both the number and the weight of fruits on individual trusses are seen with enriched plants so that  early and total fruit yields are greater and profitability higher. Published results vary considerably in the size of the  effect but generally quote total yield increases of around 30%. Fruit yield and profitability are maximized when the CO2 c oncentration is maintained at about 1000 uL/L. Data on the effects of elevated CO2 levels on fruit quality is scarce and c onflicting. Large differences in cultivar response were reported in the 1960s but later reports suggest little or no effec t. The response of tomato plant growth and fruit yield to elevated CO2 levels is a function of CO2 concentration and time. Whole-day enrichment would therefore be expected to maximize growth and yield, though there is a possibility that shorter daily periods may be more cost-effective. Results from experiments designed to test this possibility show that some reduction in the duration of daily enrichment during the pre-planting period would be acceptable, although this course of action would not lead to large monetary savings. In the post-planting period, any reduction would be detrimental since the loss of revenue from the crop would far outweigh any savings made from reduced gas usage. The enrichment technique is generally restricted to the winter and early spring periods of the year when ventilation for temperature control is minimal. As ambient temperatures rise and ventilation periods increase, enrichment becomes uneconomic and is stopped. Without enrichment, CO2 levels in the glasshouse decline during the daytime and may be substantially below ambient for long periods in bright light. Recently two techniques have been developed to alleviate this problem. In the first, ventilation is avoided by cooling the CO2-enriched air in evaporative cooling towers and returning it to the glasshouse. This method, compared with a conventionally ventilated (fan and pad) crop grown without enrichment, increased fruit yield by 17 and 48% when CO2 level was controlled at 650 and 1000 uL/L, respectively. The second method assumes that it is uneconomic to practice threefold CO2 enrichment throughout the summer months but that it is worthwhile enriching with CO2 to maintain a level of 350 to 400 uL/L. This technique avoids the detrimental effects of CO2 depletion and has the potential for increasing yield.;t";t'&657^3^Slack,G^Fenlon,J S^Hand,D W^1988^1^The Effects of Summer CO2 Enrichment and Ventilation Temperatures on the Yield, Quality and Value of Glasshouse Tomatoes^19^63^^119-129^^^^^^^^^^1639^^^^^^^^^^^tomato/Lycopersicon esculentumtum Mill.&C^1637^J. Hort. Sci.z&H~TR~@XXf&u1&>u)&u  s&t r&R~&>te&A^1637^The responses of January-sown tomatoes to a range of CO2 concentrations (ambient, 375, 450 and 525 vpm) in summer w ere investigated in two experiments. The first was designed to examine the effects of summer CO2 on the fruit yield of fou!r cultivars planted in two rooting substrates (soil or peat-bags). The aim of the second was to increase the cost-effectiv"eness of the treatment by delaying greenhouse ventilation in order that reductions in the inputs of CO2 might be achieved #at levels of enrichment above ambient. Summer CO2 enrichment was applied for eighteen weeks starting at the end of April. $Fruiting response was linearly related to summer CO2 concentration. The yield response slopes for plants grown in differen%t rooting substrates, ventilation temperatures and seasons were not significantly different. The overall response incremen&t showed that in the range 320 to 526 vpm (the mean measured values), marketable fruit yield increased by 2.65 +/- 0.201 k'g/m2 for each 100 vpm increase in mean CO2 level. Delaying glasshouse ventilation reduced the amount of CO2 supplied to th(e greenhouses by 23 to 35% but total marketable yield fell by 11% and the weight of fruits graded CLass 1 was reduced on average by 20% in the higher temperature regimen making the treatment commercially unacceptable.E E XW>8~_P*658^2^Slack,G^Hand,D W^1985^1^The Effect of Winter and Summer CO2 Enrichment on the Growth and Fruit Yield of Glasshouse Cucumber^19^60^^507-516^^^^^^^^^^1642^^^^^^^^^^^cucumber/Cucumis sativusvus L.&e&e u &E&)'r&F tC^1640^J. Hort. Sci.t&Dt&L2 r Y^&tItY^ZY[** &\&\ *w2SVSV&-A^1640^The responses of January-sown cucumbers to a range of CO2 concentrations in winter and in summer were examined toge.ther with a non-enriched treatment. In winter the CO2 concentration in the glasshouses was ambient, 400 or 1000 vpm, and i/n the summer, 350, 380, 400 or 450 vpm. Winter CO2 enrichment to 1000 vpm produced large increases in growth by early Marc0h. Mean CO2 concentration in the ambient treatment during this period was 370 vpm and there were no differences between th1e effect of this and the 400 vpm treatment. Fruit yield by mid-April was doubled when CO2 level was maintained at 400 vpm 2and trebled when the level was raised to 1000 vpm. Gross monetary value was similarly increased. CO2 enrichment also incre3ased mean fruit weight, by 10% at 400 vpm and 23% at 1000 vpm. During April the mean CO2 concentration in the non-enriched4 treatments averaged 262 vpm with some daily means falling below 200 vpm. With summertime CO2 enrichment fruit yields and 5gross monetary values improved with increasing CO2. Maintaining levels of 350, 380, 400 or 450 vpm CO2 increased total fru6it yields by 5, 11, 15 and 22%. Fruit yield was linearly related to mean CO2 concentration. Between 318 and 455 vpm CO2, f7ruit yield increased by 54 g/m2 for each vpm increase in mean summertime CO2 concentration. The enrichment treatments were cost-effective.S~ t&@ud2T&S~S~HS~t`&u'S~u&& 2T& t S~@)9659^2^Slack,G^Hand,D W^1986^1^The Effects of Propagation Temperature, CO2 Concentration and Early Post-harvest Night Temperature on the Fruit Yield of January-sown Cucumbers^19^61^^303-306^^^^^^^^^^1645^^^^^^^^^^^cucumber/Cucumis sativusvus L.+C^1643^J. Hort. Sci.u=:[s2I^Y[XZPQRVWF3 t&u&Gu&Dt &;t&D@tY&;6uing night temperature reduction (1, 3 and 6 weeks after first harvest) were examined in a glasshouse experiment. Early (4-?week) fruit yield and monetary returns were significantly increased when the higher day temperature treatment was combined@ with the 1600 vpm CO2. The early advantage was soon lost and after 20 weeks harvesting there were no differences between Athe propagation temperature treatments. After two weeks of CO2 treatment total dry weight of aerial parts, leaf area and sBtem length were increased by 88, 73, and 69%, respectively, when the CO2 level was raised from 400 to 1000 vpm. A further Crise from 1000 to 1600 vpm produced no further increases indicating that 1000 vpm is probably near the optimum concentratiDon for growth at the temperatures applied. In the early (4-week) harvest period, fruit yield and gross monetary returns inEcreased by _c._ 30% when CO2 was raised from 400 to 1000 vpm but there was little or no difference between plants grown inF 1000 or 1600 vpm. The early yield advantage from enrichment at 1000 vpm CO2 was maintained throughout the season (20 weekGs of harvesting). The most economic level of CO2 enrichment for January-sown cucumbers was _c._ 1000 vpm. Lowering night tHemperature at the start of harvesting reduced fruit yield and monetary value compared with lowering the temperature 3 or 6I weeks after fruit picking commenced. The estimated savings in fuel from this treatment were too small to offset the loss Jof revenue from the crop. The most economic time to reduce night temperature in the January-sown crop was 3 weeks after the start of harvesting. rZ:[Fj~uYXSY:[PSRVW&|t#PS&[X&D<~u~_^Z[XQ3YQM660^3^Smith,S D^Strain,B R^Sharkey,T D^1987^1^Effects of CO2 Enrichment on Four Great Basin Grasses^37^1^^139-143^^^^^^^^^^1648^^^^^^^^^^^Bromus tectorum/Agropyron smithii/Eragrostis orcuttiana/Oryzopsis hymenoidesnoides&X&T SQRVQKC^1646^Funct. Ecol.>sS~t &S~Y^!&Dt&L2 rY^&tZY[PSQW 3r+@t&! ttwPA^1646^Plants of four Great Basin grass species were grown from seed in two greenhouses at low (340 uL/L) and high (680 uLQ/L) CO2 concentration. In all four species, high CO2 promoted mean increases in the number of basal stems, leaf area, specRific leaf weight and above-ground dry weight. High CO2 resulted in an increase in CO2 assimilation in two C3 grasses but nSot in a C4 grass, while all three species showed decreases in stomatal conductance. Mean increases of 60% in above-ground Tdry weight and 80% in water-use-efficiency are consistent with previously reported high CO2 effects on grasses. No consistUent differential effects of high CO2 were observed when comparing annual _vs_ perennial species. Global CO2 enrichment mayV alter the competitive balance of Great Basin plant communities, possibly enhancing the dominance of _Bromus tectorum_ L. on degraded rangelands.>@~>~.F~Pr=u8sX6V.6&6^ B~. ؜P XX B~. CX661^3^Socias,F X^Medrano,H^Sharkey,T D^1993^1^Feedback Limitation of Photosynthesis of _Phaseolus vulgaris_ L. Grown in Elevated CO2^16^16^^81-86^^^^^^^^^^1651^^^^^^^^^^^Phaseolus vulgaris/bean./bean+މ^& ^& & tDW&suNC^1649^Plant Cell Environ.D_^ZY[rkr 3J øÀ=tGPV&| t::r {::r^X[A^1649^The capacity for photosynthesis is often affected when plants are grown in air with elevated CO2 partial pressure. \We grew _Phaseolus vulgaris_ L. in 35 and 65 Pa CO2 and measured photosynthetic parameters. When assayed at the growth CO2] level, photosynthesis was equal in the two CO2 treatments. The maximum rate of ribulose-1,5-bisphosphate (RuBP) consumpti^on was lower in plants grown at 65 Pa, but the CO2 partial pressure at which the maximum occurred was higher in the high-C_O2-grown plants, indicating acclimation to high CO2. The acclimation of RuBP consumption to CO2 involved a reduction of th`e activity of RuBP carboxylase which resulted from reduced carbamylation, not a loss of protein. The rate of RuBP consumptaion declined with CO2 when the CO2 partial pressure was above 50 Pa in plants grown under both CO2 levels. This was causedb by feedback inhibition as judged by a lack of response to removing O2 from the air stream. The rate of photosynthesis at chigh CO2 was lower in the high-CO2-grown plants and this was correlated with reduced activity of sucrose-phosphate synthase. This is only the second report of O2-insensitive photosynthesis under growth conditions for plants grown in high CO2.Ye662^2^Spencer,W^Bowes,G^1986^1^Photosynthesis and Growth of Water Hyacinth under CO2 Enrichment^17^82^^528-533^^^^^^^^^^1654^^^^^^^^^^^water hyacinth/Eichhornia crassipespes (Mart.) SolmsdS~@uD&|u9&>u&>#w&uSYC^1652^Plant Physiol.&t&6&D@u &|Et&u&Du&Du&L^Y[XPSQV&>uT&>v&6&hA^1652^Water hyacinth (_Eichhornia crassipes_ [Mart.] Solms) plants were grown in environmental chambers at ambient and eniriched CO2 levels (330 and 600 microliters CO2 per liter). Daughter plants (ramets) produced in the enriched CO2 gained 39j% greater dry weight than those at ambient CO2, but the original mother plants did not. The CO2 enrichment increased the nkumber of leaves per ramet and leaf area index, but did not significantly increase leaf size or the number of ramets formedl. Flower production was increased 147%. The elevated CO2 increased the net photosynthetic rate of the mother plants by 40%m, but this was not maintained as the plants acclimated to the higher CO2 level. After 14 days at the elevated CO2, leaf rensistance increased and transpiration decreased, especially from the adaxial leaf surface. After 4 weeks in elevated as comopared to ambient CO2, ribulose bisphosphate carboxylase activity was 40% less, soluble protein content 49% less, and chlorpophyll content 26% less; whereas starch content was 40% greater. Although at a given CO2 level the enriched CO2 plants hadq only half the net photosynthetic rate of their counterparts grown at ambient CO2, they showed similar internal CO2 concenrtrations. This suggested that the decreased supply of CO2 to the mesophyll, as a result of the increased stomatal resistansce, was counterbalanced by a decreased utilization of CO2. Photorespiration and dark respiration were lower, such that thet CO2 compensation point was not altered. The photosynthetic light and CO2 saturation points were not greatly changed, nor uwas the O2 inhibition of photosynthesis (measured at 330 microliters CO2 per liter). It appears that with CO2 enrichment tvhe temporary increase in net photosynthesis produced larger ramets. After acclimation, the greater total ramet leaf area mwore than compensated for the lower net photosynthetic rate on a unit leaf area basis, and resulted in a sustained improvement in dry weight gain.&&& &&.!})u N5TY[XS>g7)u/6T[PSQRVy663^2^Sritharan,R^Lenz,F^1990^1^The Effect of CO2 Concentration and Water Supply on Photosynthesis, Dry Matter Production zand Nitrate Concentrations of Kohlrabi (_Brassica oleracea_ var. gongylodes L.)^15^268^^43-54^^^^^^^^^^1657^^^^^^^^^^^Brassica oleracea/kohlrabiylodes/kohlrabihlrabi$ZX)t&;6u H~u88T)ut}tut&;6ultfC^1655^Act. Hort.R$T&;^[Xu@tH~t3 tH~u&@t&Du&Du€t &u)u&>t+&| t"&}A^1655^Kohlrabi plants were grown under controlled environmental conditions at two levels of CO2 concentration (300 uL/L a~nd 900 uL/L). They were supplied with modified Hoagland solution and subjected to three levels of water supply (100, 50 and 25%) for three weeks. At high CO2 concentration plants produced more leaf area, dry matter and had higher photosynthetic rates than those grown at low CO2. This effect was more pronounced at low water supply though the absolute rates of growth, dry matter, photosynthesis, transpiration and stomatal conductance were reduced. The nitrate concentration in all plant organs were significantly reduced at high CO2. Low water supply resulted in increased NO3 concentrations especially in lamina and tuber. These results indicate that CO2 enrichment and adequate water supply can reduce nitrate concentration considerably in Kohlrabi plants. Possible control mechanisms and effects of CO2 on dry matter production and nitrogen metabolism at water stress are discussed.&&&M;T&H~uR&>tJ$';T:Tȋӡ1 t33;t+H+A+664^2^Stanev,V P^Tsonev,T D^1986^3^CO2 Enrichment in Some Countries of Eastern Europe: Research and Practical Application^Status and CO2 Sources^CRC Press, Inc.^Boca Raton, Florida^35-48^^^^I^^Carbon Dioxide Enrichment of Greenhouse Crops^^^^^^^^^^^^^^^^^^^^^^^^^Enoch,H Z^Kimball,B AB A+F ;TF^^^ ;T+F+^ ;T16FSQ1~Y[QY::TY those of wild type before and after a 14-hour exposure to limiting CO2 concentrations. The four mutants represent two loci involved in the CO2-concentrating system of this unicellular alga. All mutants had a lower photosynthetic affinity for inorganic carbon than did the wild type when grown at an elevated CO2 concentration, indicating that the genetic lesion in each is expressed even at elevated CO2 concentrations. Wild type and all four mutants exhibited adaptive responses to l666^2^Stewart,J D^Hoddinott,J^1993^1^Photosynthetic Acclimation to Elevated Atmospheric Carbon Dioxide and UV Irradiation in _Pinus banksiana_^44^88^^493-500^^^^^^^^^^1662^^^^^^^^^^^Pinus banksiana/jack pinejack pinePSV~F &=u{C^1660^Physiol. Plantarum3FF~&iu<&T u1> u*6;w# @*A^1666^Transgenic tobacco (_Nicotiana tabacum_ L.) plants transformed with 'antisense' _rbcS_ to produce a series of plants with a progressive decrease in the amount of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) have been used to investigate the contribution of Rubisco to the control of photosynthesis at different irradiance, CO2 concentrations and vapour-pressure deficits. Assimilation rates, transpiration, the internal CO2 concentration and chlorophyll fluorescence were measured in each plant. (i) The flux-control coefficient of Rubisco was estimated from the slope of the plot of Rubisco content versus assimilation rate. The flux-control coefficient had a value of 0.8 or more in high irradiance, (1050 umol/m2/s), low vapour pressure deficit (4 mbar) and ambient CO2 (350 ubar). Control was marginal in enhanced CO2 (450 ubar) or low light (310 umol/m2/s) and was also decreased at high vapour-pressure deficit (17 mbar). No control was exerted in 5% CO2. (ii) The flux-control coefficients of Rubisco were compared with the fractional demand placed on the calculated available Rubisco capacity. Only a marginal control on photosynthetic flux is exerted by Rubisco until over 50% of the available capacity is being used. Control increases as utilisation rises to 80%, and approaches unity (i.e. strict limitation) when more than 80% of the available capacity is being used. (iii) In low light, plants with reduced Rubisco have very high energy-dependent quenching of chlorophyll fluorescence (qE) and a decreased apparent quantum yield. It is argued that Rubisco still exerts marginal control in these conditions because decreased Rubisco leads to increased thylakoid energisation and high-energy dependent dissipation of light energy, and lower light-harvesting efficiency. (iv) The flux-control coefficient of stomata for photosynthesis was calculated from the flux-control coefficient of Rubisco and the internal CO2 concentration, by applying the connectivity theorem. Control by the stomata varies between zero and about 0.25. It is increased by increased irradiance, decreased CO2 or decreased vapour-pressure deficit. (v) Photosynthetic oscillations in saturating irradiance and CO2 are suppressed in decreased-activity transformants before the steady-state rate of photosynthesis is affected. This provides direct evidence that these oscillations reveal the presence of 'excess' Rubisco. (vi) Comparison of the flux-control coefficients of Rubisco with mechanistic models of photosynthesis provides direct support for the reliability of these models in conditions where Rubisco has a flux-control coefficient approach unity (i.e. 'limits' photosynthesis), but also indicates that these models are less useful in conditions where control is shared between Rubisco and other components of the photosynthetic apparatus..]&D2 W> uv&t&| uuK6H]3&t t@[W669^1^Strain,B R^1992^1^Atmospheric Carbon Dioxide: A Plant Fertilizer?^108^4^^87-89^^^^^^^^^^1671671> t<C^1669^The New Biologistt؎ t(_^Y[PSQRVW K<}EE&&dFV&&`FVA^1669^Horticulturists have long known that increasing carbon dioxide concentration in greenhouses would increase crop yield under optimal conditions of other environmental factors; hence, some people have proposed that the CO2 emission need not be curbed. In unmanaged systems, however, plant productivity may not always increase with increasing CO2. Rangeland and forest managers, for instance, as well as third world farmers, may not observe significant plant growth increases because nutrients incorporated into plant and litter material may not be recycled at rates sufficient to meet the demand resulting from carbon fertilization. Another proposed benefit of increased CO2 concentration, decreased water loss from plants due to lower leaf stomatal conductance, may be offset by increases in leaf area. Carbon sequestration as a result of tree planting will not be important in reducing CO2 concentrations in the long term. The rate of change predicted to occur if fossil fuel consumption continues to grow unabated may not be tolerable.3E=r3*B2DF^ZY[670^1^Strain,BR,Group Leader^1991^3^Available Technologies for Field Experimentation with Elevated CO2 in Global Change Research^Ecosystem Experiments, Report of the Scientific Committee on Problems of the Environment (International Council of Scientific Unions)^John Wiley and Sons, Ltd.^New York^245-261^^^^45^^^^^^^^^^^^^^^^^^^^^^^^^^^Mooney,HA^Medina,E^Schindler671^1^Strain,B R^1987^1^Direct Effects of Increasing Atmospheric CO2 on Plants and Ecosystems^92^2^^18-21^^^^^^^^^^167567C^1673^Treeb؉dfYh]j l[nWoXpYqZrVs`tbvHxs&4v3&\ &tA^1673^The long term effects of allowing the concentration of CO2 in the global atmosphere to double by the middle of the next century are not yet predictable. However, it is inevitable that there will be a change in climatic and ecological patterns. Increasing the atmospheric CO2 concentration under experimental conditions has been shown to alter the growth rate and reproductive potential of plants, and must ultimately affect interactions at the community level and beyond.Y&]5sF][X^Ú_PWU\${sFF]_XPQUǚ${sFF]YXQPbء${XYPSQRVWUt672^1^Strain,B R^1991^3^Possible Genetic Effects of Continually Increasing Atmospheric CO2^Ecological Genetics and Air Pollution^Springer-Verlag, Inc.^New York^237-244^^^^^^^^^^1677^^^^^^^^^^^^^^^^^^^^^Taylor,G E,Jr^Pitelka,L F^Clegg,MT>rA^1676^This commentary extends the discussion on differential plant sensitivity to air quality changes other than the toxic air pollutants which induce the classic stress syndrome of declining physiology and growth. Global atmospheric changes that differentially increase plant growth and vigor among genotypes of an ecosystem will induce ecological stresses associated with the differential competitive potentials and survival of individuals. If these changes proceed in a unidirectional manner for long periods of time, the genetic structure of populations and communities will likely change.GG2,673^2^Strain,B R^Thomas,R B^1992^1^Field Measurements of CO2 Enhancement and Climate Change in Natural Vegetation^122^64^^45-60^^^^^^^^^^1680^^^^^^^^^^^^^^^^79^^^^^^^^1680;|`V;vZPX[;R|H;wLBX[;D|:;s>4X[;u.;t2(X[;u*;t$҃ N application compared with CO2 enrichment. 2. The dinitrogen-fixing activity which was lower in wild soybean variety thanA^1678^It is generally assumed that healthy, natural ecosystems have the potential to sequester carbon under favorable environmental conditions. There is also evidence that CO2 acts as a plant fertilizer. It is of interest to know if these assumptions are valid and how natural systems might respond under future scenarios of CO2 increase and possible climate changes. Few measurements of the effects of CO2 increase and possible climate changes have been made on 'natural' ecosystems under realistic field conditions. Most measurements have been conducted in the synthetic environments of totally controlled greenhouses and growth chambers. Several lines of evidence indicate that controlled environment studies using plants growing in pots induce experimental artifacts that reduce confidence in the use of results for prediction of future global responses. Open top chambers are being used in several autecological field studies in an attempt to obtain more realistic field environments. A few field microcosm studies have been completed and a system for the free air release of CO2 has been applied in cotton fields. Unfortunately, the requirement of large amounts of CO2 and financial restrictions have precluded the initiation of larger scale field studies in natural vegetation. This paper lists and summarizes the best field studies available but draws heavily on studies from artificial environments and conditions in an attempt to summarize knowledge of global environmental change on forests and other non-agricultural ecosystems. Finally the paper concludes that there is a need for the development and application of equipment for field measurements in several representative natural ecosystems and makes specific recommendation of the creation of a tropical research center.6FÚ6FÚ${Ú6FÚ${Ú${Ú6F674^3^Stuhlfauth,T^Klug,K^Fock,H P^1987^1^The Production of Secondary Metabolites by _Digitalis lanata_ during CO2 Enrichment and Water Stress^109^26^^2735-2739^^^^^^^^^^1683^^^^^^^^^^^Digitalis lanata/woolly foxglovefoxglove*_ubC^1681^Phytochem.&[lDt&&|u&DS^LTM&Y n[rE2&&G&_ S^f[&c&A^1681^The influence of atmospheric CO2 enrichment and water stress on the production of biomass and cardioactive substances by the woolly foxglove _Digitalis lanata_ was investigated. Carbon dioxide enrichment (1000 ppm) had a 'fertilizing' effect in that both biomass and cardenolide content increased to about 160% of the control. The yield of the pharmacologically relevant major product, digoxin, significantly increased following enrichment, whereas two other compounds decreased. Water stress, in the physiological range, reduced fresh weight more than either cardenolide content or dry weight. The amount of digitoxigenin was considerably reduced, whereas the other cardenolides, including digoxin, were less affected. CO2-e nriched plants, which were also subjected to drought, exhibited mixed responses. We conclude from these investigations tha t not only primary, but also secondary metabolism is influenced by variations of the environment. Possible ecological consequences of changes in secondary metabolism due to atmospheric CO2 enrichment and water stress are discussed.t W&|E _V&F&D& K&TM^^ f ~t 676^7^Surano,K A^Daley,P F^Houpis,J L J^Shinn,J H^Helms,J A^Palassou,R J^Costella,M P^1986^1^Growth and Physiological Resp onses of _Pinus ponderosa_ Dougl. ex P. Laws. to Long-term Elevated CO2 Concentration^43^2^^243-259^^^^^^^^^^1689^^^^^^^^^^^Pinus ponderosa/ponderosa pinerosa pine FWt= tN *rwu2^2;sOPDŽ&DŽC^1687^Tree Physiol.k^6DŽ[Ƅ_^mcwW u^NV t7rp^_N]ҍ^ A^1687^Seven-year-old ponderosa pine (_Pinus ponderosa_ Dougl. ex P. Laws.) saplings and one- and two- year-old ponderosa pine seedlings of a Sierra Nevada and a Rocky Mountain seed source, respectively, were exposed to CO2-enriched atmospheres  in an outdoor open-top chamber facility for 2.5 years. Seedling growth (main stem diameter, height, volume) increased wit h increasing CO2 concentration, though the two populations exhibited different patterns of response. By the beginning of t he last growth season, however, the trees under the highest CO2 concentrations showed signs of stress that included accele rated needle abscision, chlorosis, and apparent alteration of tolerance to heat. The stress response is at least partly at tributable to elevated foliar temperatures resulting from CO2-induced stomatal closure, which in turn lowered transpirational cooling of needles.u>Y_XFr,^6K)}M)P siFS^g[6P 677^2^Suzuki,K^Spalding,M H^1989^1^Adaptation of _Chlamydomonas reinhardtii_ High CO2-requiring Mutants to Limiting CO2^17^90^^1195-1200^^^^^^^^^^2048^^^^^^^^^^^Chlamydomonas reinhardtii^^^^^^^^ u"NFuAF;FvFF,F<u2 C^1690^Plant Physiol.FNF~uيFFNFF_ZY[XPSQRVNO${rFvҍ^Fs^^ZY[X 678^3^Szarek,S R^Holthe,P A^Ting,I P^1987^1^Minor Physiological Response to Elevated CO2 by CAM Plant _Agave vilmoriniana_^17^83^^938-940^^^^^^^^^^1694^^^^^^^^^^^Agave vilmorinianaana Berger%Y[X!r;r@Ã[uRO2r&; C^1692^Plant Physiol.cuFtk< &&>P~t ]^yꀌ.DŽXÀNc~u "A^1692^One-year-old plants of the CAM leaf succulent _Agave vilmoriniana_ Berger were grown outdoors at Riverside, Califor #nia. Potted plants were acclimated to CO2-enrichment (about 750 microliters per liter) by growth for 2 weeks in an open-to $p polyethylene chamber. Control plants were grown nearby where the ambient CO2 concentration was about 370 microliters per % liter. When the plants were well watered, CO2-induced differences in stomatal conductances and CO2 assimilation rates ove &r the entire 24-hour period were not large. There was a large nocturnal acidification in both CO2 treatments and insignifi 'cant differences in leaf chlorophyll content. Well watered plants maintained water potentials of -0.3 to -0.4 megapascals. ( When other plants were allowed to dry to water potentials of -1.2 to-1.7 megapascals, stomatal conductance and CO2 uptake ) rates were reduced in magnitude, with the biggest difference in Phase IV photosynthesis. The minor nocturnal response to *CO2 concentration by this species is interpreted to indicate saturated, or nearly saturated, phosphoenolpyruvate carboxyla +se activity at current atmospheric CO2 concentrations. CO2-enhanced diurnal activity of ribulose bisphosphate carboxylase activity remains a possibility.<N剕A?qoc 35 t 3#, uJGusc 3 t -679^2^Telewski,F W^Strain,B R^1987^3^Densitometric and Ring Width Analysis of 3-year-old _Pinus taeda_ L. and _Liquidambar . styraciflua_ L. Grown under Three Levels of CO2 and Two Water Regimes^Proceedings of the International Symposium on Ecolo /gical Aspects of Tree-ring Analysis^NTIS, U.S. Department of Commerce^Springfield, Virginia^^^^^^^^DOE Conf-8608144^^^1696^^^^^^^^^^^Pinus taeda/loblolly pine/Liquidambar styraciflua/sweetgum^^^^^^^^^^Jacoby,GC,Jr^Hornbeck,JWck,JWeetgum; 1A^1695^Trees of _Pinus taeda_ and _Liquidambar styraciflua_ were grown from seed and treated for three years at 350, 500 a 2nd 650 ppm CO2. Water stress was applied to one half of the plants in years 2 and 3. The twelve treatment groups were harv 3ested and measurements were made on total stem diameter, ring width and wood density. In all treatment groups, increased C 4O2 increased stem diameter. Individual ring widths also increased with increase in CO2, the trend being clearer in _Liquid 5ambar styraciflua_. There is no change in latewood density of _L. styraciflua_ with CO2 treatment. There was an apparent i 6ncrease in latewood density in water stressed saplings compared with non-stressed saplings which is independent of CO2 tre 7atment. An apparent increase in latewood density was observed in _P. taeda_, especially in the last growth ring. Because o 8f the great increase in individual ring widths in _L. styraciflua_ the total ring biomass (integral density) increases wit 9h CO2 treatment in well watered trees but decreases with drought. A similar trend was observed in the integral density in :_P. taeda_. No significant changes were observed in average density between any treatment group for either species. It is ;suggested that, at least for 3 year old saplings, ring width and integral density (a measure which includes ring width) ar &22&&8\ t&M'^_ZY[XPQRVWU&@&|&D2&d&L& >680^3^Teramura,A H^Sullivan,J H^Ziska,L H^1990^1^Interaction of Elevated Ultraviolet-B Radiation and CO2 on Productivity a ?nd Photosynthetic Characteristics in Wheat, Rice, and Soybean^17^94^^470-475^^^^^^^^^^1699^^^^^^^^^^^wheat/Triticum aestivum/rice/Oryza sativa/soybean/Glycine maxycine max (L.) Merr.r&2&>&E% tUr~P&}u:FXu؋~ C^1697^Plant Physiol.XPSW$'rFs&|_&DsF_[XPSQRW&_r03ɿ & GGr&>&2 BA^1697^Wheat (_Triticum aestivum_ L. cv Bannock), rice (_Oryza sativa_ L. cv IR-36, and soybean (_Glycine max_ [L.] Merr c Cv Essex) were grown in a factorial greenhouse experiment to determine if CO2-induced increases in photosynthesis, biomass, D and yield are modified by increases in ultraviolet (UV)-B radiation corresponding to stratospheric ozone depletion. The e Experimental conditions simulated were: (a) an increase in CO2 concentration from 350 to 650 microliters per liter; (b) an Fincrease in UV-B radiation corresponding to a 10% ozone depletion at the equator; and (c) a and b in combination. Seed yie Gld and total biomass increased significantly with elevated CO2 in all three species when compared to the control. However, H with concurrent increases in UV-B and CO2, no increase in either seed yield (wheat and rice) or total biomass (rice) was Iobserved with respect to the control. In contrast, CO2-induced increases in seed yield and total plant biomass were mainta Jined or increased in soybean within the elevated CO2, UV-B environment. Whole leaf gas exchange indicated a significant in Kcrease in photosynthesis, apparent quantum efficiency (AQE) and water-use-efficiency (WUE) with elevated CO2 in all 3 spec Lies. Including elevated UV-B radiation with high CO2 eliminated the effect of high CO2 on photosynthesis and WUE in rice a Mnd the increase in AQE associated with high CO2 in all species. Elevated CO2 did not change the apparent carboxylation eff Niciency (ACE) in the three species although the combination of elevated CO2 and UV-B reduced ACE in wheat and rice. The re Osults of this experiment illustrate that increased UV-B radiation may modify CO2-induced increases in biomass, seed yield Pand photosynthetic parameters and suggest that available data may not adequately characterize the potential effect of future, simultaneous changes in CO2 concentration and UV-B radiation.]Y[X^_QVur&"u3}>뀸 R681^1^Thomas,R B^1987^6^Responses of Two Summer Annuals to Interactions of Atmospheric Carbon-dioxide and Soil Nitrogen^^C Slemson University^^Doctoral Dissertation^^^Dissertation Abstracts Vol.49:05-B, p.1508 (187 pp.)^^^^^^^1701^^^^^^^^^^^Chenopodium album/lambsquarters/Amaranthus hybridus/pigweedgweedt&\&"${ ^YXPSQWU싏a&;MuEX&:Mu; UA^1700^An increase in atmospheric CO2 is likely to have profound effects on ecosystems. Responses by plant species to elev Vated CO2 might depend on factors such as the species' photosynthetic pathway. Increased competitiveness of C3 species rela Wtive to C4 species can be anticipated in response to CO2 enrichment due to enhanced carboxylation rates, but when soil nit Xrogen is limiting, C3 plants may be unable to increase carboxylation rates due to enzyme deficiency. The competitive relat Yionship between _Chenopodium album_ L. (C3) and _Amaranthus hybridus_ L. (C4) was investigated in two atmospheric CO2 leve Zls (350 and 600 uL/L) and two soil nitrogen levels (1 and 15 mM NH4NO3). Biomass and leaf surface area of _Amaranthus_ pla [nts did not respond to CO2 enrichment. Only in high nitrogen did _Chenopodium_ plants respond to increased CO2 with greate \r biomass and leaf surface area. Nitrogen use efficiency (NUE) was higher in _Amaranthus_ than in _Chenopodium_ in all tre ]atments except for the high-nitrogen and high-CO2 treatment. Under conditions of high nitrogen and low CO2, _Chenopodium_ ^was a poor competitor, but competition favored _Chenopodium_ in high nitrogen and high CO2. In low nitrogen and high CO2, _competition favored _Chenopodium_ on a dry weight basis, but favored _Amaranthus_ on a seed weight basis, reflecting early ` senescence of _Chenopodium_. In low nitrogen and high CO2, competition favored _Amaranthus_ on a dry weight basis, but fa avored _Chenopodium_ on a seed weight basis. Physiological aspects of the growth of _Chenopodium_ and _Amaranthus_ were stu bdied. Acclimation to elevated CO2 occurred at the enzyme level in _Chenopodium_. Under conditions of high nitrogen and no ccompetition, individual _Chenopodium_ plants responded to elevated CO2 with greater biomass, leaf surface area, and maximu dm net photosynthetic rates. In high nitrogen, leaf nitrogen, soluble protein, and RuBP carboxylase activity of _Chenopodiu em_ decreased and NUE increased when grown in elevated CO2. In low nitrogen without competition, _Chenopodium_ showed no si fgnificant response to CO2 enrichment. _Amaranthus_ grown in high CO2 and low nitrogen without competition showed no signif gicant changes in leaf nitrogen, soluble protein, carboxylase activity, chlorophyll, or NUE in response to CO2 enrichment. hFuture shifts in competitive relationships between C3 and C4 plants will not only be influenced by increasing atmospheric CO2, but will be modified by other environmental factors including availability of nitrogen.ҋN&;Lw9&:Tw3&;Lw3&+L j682^5^Thomas,R B^Richter,D D^Ye,H^Heine,P R^Strain,B R^1991^1^Nitrogen Dynamics and Growth of Seedlings of an N-fixing Tre ke (_Gliricidia sepium_ (Jacq.) Walp.) Exposed to Elevated Atmospheric Carbon Dioxide^34^88^^415-421^^^^^^^^^^1704^^^^^^^^^^^Gliricidia sepiumium (Jack) Walp.&6迸r 2ar: sF ]^_ZY[XPSQRWVU$r_&E tTdؾDu&E&M @C^1702^Oecologiat&>&uHr~r: sF ]^_ZY[XRPWVU˷r觔r&6&D&t&t:ŷrsF nA^1702^Seeds of _Gliricidia sepium_ (Jacq.) Walp., a tree native to seasonal tropical forests of Central America, were ino oculated with N-fixing _Rhizobium_ bacteria and grown in growth chambers for 71 days to investigate interactive effects of patmospheric CO2 and plant N status on early seedling growth, nodulation, and N accretion. Seedlings were grown with CO2 pa qrtial pressures of 350 and 650 ubars (current ambient and a predicted partial pressure of the mid-21st century) and with p rlus N or minus N nutrient solutions to control soil N status. Of particular interest was seedling response to CO2 when gro swn without available soil N, a condition in which seedlings initially experienced severe N deficiency because bacterial N- tfixation was the sole source of N. Biomass of leaves, stems, and roots increased significantly with CO2 enrichment (by 32% u, 15% and 26%, respectively) provided seedlings were supplied with N fertilizer. Leaf biomass of N-deficient seedlings was v increased 50% by CO2 enrichment but there was little indication that photosynthate translocation from leaves to roots or wthat plant N (fixed by _Rhizobium_) was altered by elevated CO2. In seedlings supplied with soil N, elevated CO2 increased x average nodule weight, total nodule weight per plant, and the amount of leaf nitrogen provided by N-fixation (as indicate yd by leaf delta 15N). While CO2 enrichment reduced the N concentration of some plant tissues, whole plant N accretion incr zeased. Results support the contention that increasing atmospheric CO2 partial pressures will enhance productivity and N-fi {xing activity of N-fixing tree seedlings, but that the magnitude of early seedling response to CO2 will depend greatly on plant and soil nutrient status.t̀u4: Nt @suFu^~[XPSRUbۀt.0. }683^2^Thomas,R B^Strain,B R^1991^1^Root Restriction as a Factor in Photosynthetic Acclimation of Cotton Seedlings Grown in Elevated Carbon Dioxide^17^96^^627-634^^^^^^^^^^1707^^^^^^^^^^^cotton/Gossypium hirsutumtum L.WVȃ+fdۡ: lC^1705^Plant Physiol.V& v~F؋N& GG& ~&> & & F& -& $&" $¿ r A^1705^Interactive effects of root restriction and atmospheric CO2 enrichment on plant growth, photosynthetic capacity, an d carbohydrate partitioning were studied in cotton seedlings (_Gossypium hirsutum_ L.) grown for 28 days in three atmosphe ric CO2 partial pressures (270, 350, and 650 microbars) and two pot sizes (0.38 and 1.75 liters). Some plants were transpl anted from small pots into large pots after 20 days. Reduction of root biomass resulting from growth in small pots was acc ompanied by decreased shoot biomass and leaf area. When root growth was less restricted, plants exposed to higher CO2 part ial pressures produced more shoot and root biomass than plants exposed to lower levels of CO2. In small pots, whole plant biomass and leaf area of plants grown in 270 and 350 microbars of CO2 were not significantly different. Plants grown in sm all pots in 650 microbars of CO2 produced greater total biomass than plants grown in 350 microbars, but the dry weight gai n was found to be primarily an accumulation of leaf starch. Reduced photosynthetic capacity of plants grown at elevated le vels of CO2 was clearly associated with inadequate rooting volume. Reductions in net photosynthesis were not associated wi th decreased stomatal conductance. Reduced carboxylation efficiency in response to CO2 enrichment occurred only when root growth was restricted suggesting that ribulose-1,5-bisphosphate carboxylase/oxygenase activity may be responsive to plant source-sink balance rather than to CO2 concentration as a single factor. When root-restricted plants were transplanted int o large pots, carboxylation efficiency and ribulose-1,5-bisphosphate regeneration capacity increased indicating that accli mation of photosynthesis was reversible. Reductions in photosynthetic capacity as root growth was progressively restricted suggest sink-limited feedback inhibition as a possible mechanism for regulating net photosynthesis of plants grown in elevated CO2.G=t${XPSQRVWfFvFvSQ<LY[sV&E'@tiv t_:guZguRF?t;w uEF 684^1^Thompson,G B^1990^6^The Influence of CO2 Enrichment on the Growth, Nitrogen Concentration, and Mildew Infection of Cereals^^University of Cambridge^^Doctoral Dissertation _XPSQVW<f&}D&=tv:/#:v*t 685^3^Thornley,J H M^Fowler,D^Cannell,G R^1991^1^Terrestrial Carbon Storage Resulting from CO2 and Nitrogen Fertilization in Temperate Grasslands^16^14^^1007-1011^^^^^^^^^^1711711F~t~r VV VV_^ZYXPQRVFF3 ~C^1709^Plant Cell Environ.tv&FVvċVVFF ^ZYXPSVW&E't$3&&E ;u _ A^1709^A temperate grassland model has been used to simulate carbon sequestration under various environmental conditions. The results suggest that the CO2 and nitrogen fertilization that has occurred may contribute appreciably to the so-called missing carbon sink, which it has been suggested must exist to balance the global carbon budget.G(PV&u5& 686^2^Tissue,D T^Oechel,W C^1987^1^Response of _Eriophorum vaginatum_ to Elevated CO2 and Temperature in the Alaskan Tussock Tundra^2^68^^401-410^^^^^^^^^^1714^^^^^^^^^^^Eriophorum vaginatumtum L. _^Y[XPSVW&u8&D_= C^1712^Ecologyt;u +yؾ2_^[XPVPV PVPV&u&d &D uGt&dG""2u3 A^1712^Small greenhouses were used in the arctic to maintain _Eriophorum vaginatum_-dominated tussock tundra for 10 wk at ambient CO2 (340 uL/L), elevated CO2 (510 or 680 uL/L), or elevated CO2 and 4C above ambient temperature (680 uL/L, ambie nt + 4C). These treatments represent present levels of atmospheric CO2 and temperature, and those predicted for the next century. Within 3 wk, plants maintained at elevated CO2 exhibited a physiological adjustment of their photosynthetic rate so that plants grown at ambient and elevated CO2 levels had similar photosynthetic rates at their respective growth CO2 co ncentrations. The reduction in photosynthetic capacity for plants grown at elevated CO2 levels did not appear to be due to stomatal closure or end-product inhibition. Other possible mechanisms were not explored. Transpiration rates and water us e efficiency did not differ among treatments in the generally wet environment of tussock tundra. Relative leaf growth rate and the seasonal pattern of growth were also unaltered, suggesting that the growth of mature tillers is not, under normal ambient conditions, limited by temperature or carbohydrate. However, new tiller production was significantly increased at elevated CO2, suggesting that the long-term effect of CO2 enhancement in this sedge may be the production of a greater nu mber of new tillers rather than an increase in the size or productivity of existing tillers. Our results are consistent wi th the notion that growth of _Eriophorum vaginatum_ in the field is more limited by nutrient supply than by photosynthesis . We further suggest that photosynthetic rates reflect the sink activity. It is therefore very difficult to assign cause and effect between growth rates and photosynthetic rates.|t&>t<u6P1=Xu6r>w &>t+}r'l 687^3^Titus,J E^Feldman,R S^Grise,D^1990^1^Submerged Macrophyte Growth at Low pH. I. CO2 Enrichment Effects with Fertile Sediment^34^84^^307-313^^^^^^^^^^1717^^^^^^^^^^^Vallisneria americanaana Michx.2&3ҁ~|u &L&L&;Lt& C^1715^OecologiaO&w6&OIr`t\RQ&Gt&WNYZr;&G&g}r( t~\u%6:"6: A^1715^_Vallisneria americana_ was grown for six weeks in a greenhouse on relatively fertile sediment to test for factors other than nutrient limitation which may slow growth of this submersed macrophyte at pH 5. On the basis of dry mass accumu lated, (1) low pH significantly depressed _Vallisneria_ growth at constant free CO2 levels; (2) free CO2 enrichment, howev er, greatly stimulated _Vallisneria_ growth at pH 5, by 2.8-fold and 10-fold at 3.2 times and 10 times air-equilibrated CO 2 levels, respectively; and (3) growth was greater by far at pH 5 than at higher pH with constant total dissolved inorgani c carbon (DIC). Free CO2 availability was thus an important controller of growth at low pH by _Vallisneria americana_ on f ertile sediment, and low pH was not directly deleterious. Field surveys of acidic lakes in the Adirondack Mountains of New York state revealed that DIC levels in low pH lakes were often well above equilibrium values and could potentially suppor t vigorous macrophyte growth. Aluminum and/or iron toxicity did not appear to impair growth at low pH, and aluminum concen trations in _Vallisneria_ shoots significantly decreased with increasing free CO2 concentrations at pH 5.0, perhaps due to growth dilution. Rosette production (a measure of asexual reproduction), maximum leaf length, and extent of flowering within treatments were positively correlated with plant biomass, rather than with pH or free CO2 levels _per se_.t5&Gc 688^3^Tremblay,N^Yelle,S^Gosselin,A^1987^1^Effects of CO2 Enrichment, Nitrogen and Phosphorus Fertilization on Growth and Yield of Celery Transplants^28^22^^875-876^^^^^^^^^^1720^^^^^^^^^^^celery/Apium graveolensens L.tgb&y >^Ԛ(6: C^1718^HortSci.[+uԡY0u&& +Y+sԋ[&& +Y+s&( +[+uZ[SRb&y >^Ԛ(6: u eԋ_C A^1718^Celery transplants (_Apium graveolens_ L. cv. Florida 683) were fertilized with complete nutrient solutions at thre e N concentrations and three concentrations of P in a factorial combination, both with or without atmospheric CO2 enrichme nt. They then were planted on a muck soil and harvested at the end of July. Carbon dioxide enrichment increased the transp lant leaf area as well as shoot and root dry weight and decreased the leaf area ratio (LAR), but had no significant effect on growth parameters at harvest. Nitrogen affected leaf area, dry weight, leaf area ratio, and dry mater content of trans plant shoots together with root:shoot dry weight ratio. Total, marketable, and side shoot weights at harvest were signific antly increased by the intermediate N concentration (400 ppm N) provided during transplant raising. Phosphorus had no effect on transplant growth but interacted with N on the weight of marketable shoots harvested. 689^3^Tremblay,N^Yelle,S^Gosselin,A^1988^1^Effects of CO2 Enrichment, Nitrogen and Phosphorus Fertilization during the Nursery Period on Mineral Composition of Celery^72^11^^37-49^^^^^^^^^^1723^^^^^^^^^^^celery/Apium graveolensens L.&&&'<' C^1721^J. Plant Nut.(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p( /.,,,,, , , , , ,,, A^1721^This experiment aimed at determining the effects of pretransplanting nutritional conditioning (PNC) on celery eleme ntal composition at planting and harvest time. Celery seedlings (_Apium graveolens_ L. cv. Florida 683) were fertilized wi th complete nutrient solutions at 3 concentrations of urea nitrogen and 3 concentrations of phosphorus in factorial combin ation, both with or without atmospheric CO2 enrichment. They were then planted in a muck soil and harvested at the end of July. CO2 enrichment decreased N, P, K, Mg and B concentrations in seedling shoot. It reduced N and K and increased Mg, bu t had no effect on P, Ca and B concentrations in roots. Nitrogen fertilization increased N concentration in shoot and root s but decreased P, K and Ca concentration in roots. The low urea-N level resulted in low shoot P concentration. Phosphorus fertilization increased P concentration in seedling shoot and roots but depressed K in shoot. Maximum Ca and Mg concentra tions in shoot were measured at low P fertilization. At harvest, shoot N concentration was found to have increased linearl y with the P fertilization rate provided during seedling preparation. Therefore, PNC can modify the nutritional status of celery plants not only at planting time but also for the entire growing season.bclrDUdu end save 1200 72 div dup scal 690^4^Tripp,K E^Kroen,W K^Peet,M M^Willits,D H^1992^1^Fewer Whiteflies Found on CO2-enriched Greenhouse Tomatoes with High C:N Ratios^28^27^^1079-1080^^^^^^^^^^1726^^^^^^^^^^^tomato/Lycopersicon esculentumtum Mill., C^1724^HortSci.com  A^1724^Eight tomato (_Lycopersicon esculentum_) cultivars were grown for 16 weeks in greenhouses enriched for an average o f 8.1 hours daily to 1000 uL CO2/L of air or in greenhouses maintained at ambient CO2. Carbon dioxide enrichment significa ntly decreased the mean number of greenhouse whiteflies [_Trialeurodes vaporariorum_ (Westward), Homoptera: Aleyrodidae] a s measured by counts from commercial yellow sticky traps. The number of whiteflies present was negatively correlated with both seasonal foliar C:N ratio and percent C but positively correlated with percent N in the foliage. Thus, CO2 enrichment apparently alters plant composition in such a way as to reduce significantly the population growth of greenhouse whiteflies.DDDDDDDDDDDDDDDDDDDDDDDDDDDDD@DDDDDDDD@DDDDDDDDDDDD@@TDDQUPATUPPPUUUUUUUUUU 691^4^Tripp,K E^Peet,M M^Willits,D H^Pharr,D M^1991^1^CO2-enhanced Foliar Deformation of Tomato: Relationship to Foliar Starch Concentration^3^116^^876-880^^^^^^^^^^1729^^^^^^^^^^^tomato/Lycopersicon esculentumtum Mill.f7:N7:T7:]7: C^1727^J. Amer. Soc. Hort. Sci.7:7:7:7:"b_ZK u& A^1727^Two cultivars of greenhouse tomato (_Lycopersicon esculentum_ Mill.) were grown with ambient or 1000 uL CO2/L durin g Jan.-June 1987 and 1988. In both years, CO2-enrichment increased foliar deformation and foliar starch, but during the se ason, foliar starch levels decreased while deformation increased. 'Laura' had more deformation, while 'Michigan-Ohio' had higher foliar starch concentration. During an entire season, there was no significant relationship between foliar starch c oncentration and deformation severity. Foliar C exchange rates in the lower canopy were not affected by severity of deform ation. Data from these experiments do not support the hypothesis that excess foliar starch is responsible for foliar deformation at elevated CO2..8|HHUy ma Y\t8RDaeP 692^5^Tripp,K E^Peet,M M^Pharr,D M^Willits,D H^Nelson,P V^1991^1^CO2-enhanced Yield and Foliar Deformation among Tomato Genotypes in Elevated CO2 Environments^17^96^^713-719^^^^^^^^^^1732^^^^^^^^^^^tomato/Lycopersicon esculentumtum Mill.bZ C^1730^Plant Physiol. \5҉c5҉.҉5҉5҉;;҉4>҉ /҉S>҉6b"b A^1730^Yield increases observed among eight genotypes of tomato (_Lycopersicon esculentum_ Mill.) grown at ambient CO2 (ab out 350) or 1000 microliters per liter CO2 were not due to carbon exchange rate increases. Yield varied among genotypes wh ile carbon exchange rate did not. Yield increases were due to a change in partitioning from root to fruit. Tomatoes grown with CO2 enrichment exhibited nonepinastic foliar deformation similar to nutrient deficiency symptoms. Foliar deformation varied among genotypes, increased throughout the season, and became most severe at elevated CO2. Foliar deformation was po sitively related to fruit yield. Foliage from the lower canopy was sampled throughout the growing season and analysed for starch, K, P, Ca, Mg, Fe, and Mn concentrations. Foliar K and Mn concentrations were the only elements correlated with def ormation severity. Foliar K decreased while deformation increased. In another study, foliage of half the plants of one gen otype received foliar applications of 7 millimolar KH2PO4. Untreated foliage showed significantly greater deformation than treated foliage. Reduced foliar K concentration may cause CO2-enhanced foliar deformation. Reduced K may occur following decreased nutrient uptake resulting from reduced root mass due to the change in partitioning from root to fruit. 693^2^Troeng,E^Ackzell,L^1990^1^Effects of Carbon Dioxide Enrichment on Bud Formation and Growth of Coniferous Seedlings^15^268^^179-189^^^^^^^^^^1735^^^^^^^^^^^Picea abies/Norway spruce/Pinus contorta/longleaf pine/Pinus sylvestris/Scots pine tris L./Scots pine C^1733^Act. Hort. A^1733^First-year seedlings of _Pinus sylvestris, Pinus contorta_ and _Picea abies_ were exposed to elevated (900 ppm or 1 800 ppm) or ambient atmospheric carbon dioxide levels before or during budset. Total seedling biomass increased at high ca rbon dioxide concentrations, root dry weight increasing more than shoot dry weight. Formation of needle primordia in the b ud was not influenced by carbon dioxide enrichment. _Pinus contorta_ showed a high percentage Lammas growth when exposed t o high carbon dioxide concentrations. For _Picea abies_, nutrient supply, temperature regimes and winter hardening were al so studied in relation to carbon dioxide supply during bud formation. The number of needle primordia formed was strongly influenced by air temperature. Lack of nutrients during bud formation had a slightly negative effect on frost hardiness.694^2^Tsuzuki,M^Miyachi,S^1991^1^CO2 Syndrome in _Chlorella_^54^69^^1003-1007^^^^^^^^^^^^^^^^^^^^^Chlorella spp. C^1736^Can. J. Bot.!695^5^Tsuzuki,M^Ohnuma,E^Sato,N^Takatu,T^Kawaguchi,A^1990^1^Effects of CO2 Concentration during Growth on Fatty Acid CompoMsition in Microalgae^17^93^^851-856^^^^^^^^^^1740^^^^^^^^^^^Chlorella vulgaris/Dunaliella tertiolecta/Anacystis nidulans/C!C^1738^Plant Physiol.!A^1738^The degree of unsaturation of fatty acids was higher in _Chlorella vulgaris_ 11h cells grown with air (low-CO2 cell!s) than in the cells grown with air enriched with 2% CO2 (high-CO2 cells). The change in the ratio of linoleic acid to alp!ha-linolenic acid was particularly significant. This change of the ratio was observed in four major lipids (monogalactosyl!diacylglycerol, digalactosyldiacylglycerol, phosphatidylcholine, and phosphatidylethanolamine). The relative contents of l! ipid classes were essentially the same both in high-CO2 and low-CO2 cells. After high-CO2 cells were transferred to low CO! 2 condition, total amount of fatty acids remained constant but the relative content of alpha-linolenic acid increased duri! ng a 6-hour lag phase in growth with concomitant decreases in linoleic and oleic acids. When low-CO2 cells were transferre! d to high CO2 condition, total amount of fatty acids and relative content of oleic acid increased significantly. The amoun! t of alpha-linolenic acid remained almost constant, while the amounts of palmitic, oleic, and linoleic acids increased. Si!milar, but smaller, changes in fatty acid compositions were observed in two species of green algae _Chlamydomonas reinhard!tii_ and _Dunaliella tertiolecta_. However, no difference was found in _Euglena gracilis, Porphyridium cruentum, Anabaena variabilis_, and _Anacystis nidulans_.DP >Frd>$"8>F^^^^^2꤀D^^Hf^H^dz"L`fF>?꤀DF>?꤀DF>?꤀!696^2^Tyree,M T^Alexander,J D^1993^1^Plant Water Relations and the Effects of Elevated CO2: A Review and Suggestions for Future Research^123^104/105^^47-62^^^^^^^^^^1743^^^^^^^^^^^^^^^^o}?>?(꤀D F>?Ў꤀D=ioxide^^xide^^VegetatiodMD#=>== # =!A^1741^Increased ambient carbon dioxide (CO2) has been found to ameliorate water stress in the majority of species studied!. The results of many studies indicate that lower evaporative flux density is associated with high CO2-induced stomatal cl!osure. As a result of decreases in evaporative flux density and increases in net photosynthesis, also found to occur in hi!gh CO2 environments, plants have often been shown to maintain higher water use efficiencies when grown at high CO2 than wh!en grown in normal, ambient air. Plants grown at high CO2 have also been found to maintain higher total water potentials, !to increase biomass production, have larger root-to-shoot ratios, and to be generally more drought resistant (through avoi!dance mechanisms) than those grown at ambient CO2 levels. High CO2-induced changes in plant structure (i.e., vessel or tra!cheid anatomy, leaf specific conductivity) may be associated with changes in vulnerability to xylem cavitation or in envir!onmental conditions in which runaway embolism is likely to occur. Further study is needed to resolve these important issues. Methodology and other CO2 effects on plant water relations are discussed.  WordPerfect A^1217^In Dutch. H M^1991^1^Radial and Vertical Heat Conduction in Stem and Trunk Flow Gauges^28^26^^72^   ! 698^1^Van Berkel,N^1986^3^CO2 Enrichment in the Netherlands^Status and CO2 Sources^CRC Press, Inc.^Boca Raton, Florida^17-33^^^^I^^Carbon Dioxide Enrichment of Greenhouse Crops^^^^^^^^^^^^^^^^^^^^^^^^^Enoch,H Z^Kimball,B AB A !"699^4^van de Staaij,J W M^Lenssen,G M^Stroetenga,M^Rozema,J^1993^1^The Combined Effects of Elevated CO2 Levels and UV-B Ra!#diation on Growth Characteristics of _Elymus athericus_ (= _E. pycnanathus_)^123^104/105^^433-439^^^^^^^^^^1748^^^^^^^^^^^Elymus athericus^^^^^) Kerguelen^^^^^OGIN_NAMESHELL001@K,Error: File not found. wrong version number or invaloxide^^^^105; Vegetatioigher is required $ Error: 80286 or higher CPU is required $ !&A^1746^_Elymus athericus_ (Link) Kerguelen, a C3 grass, was grown in a greenhouse experiment to determine the effect of en!'hanced atmospheric CO2 and elevated UV-B radiation levels on plant growth. Plants were subjected to the following treatmen!(ts: a) ambient CO2-control UV-B, b) ambient CO2-elevated UV-B, c) double CO2-control UV-B, d) double CO2-elevate UV-B. Ele!)vated CO2 concentrations stimulated plant growth, biomass production was 67% higher than at ambient CO2. Elevated UV-B rad!*iation had a negative effect on growth, biomass production was depressed by 31%. Enhanced CO2 combined with elevated UV-B !+levels caused a biomass depression of 8% when compared with the control plants. UV-B induced growth depression can be modi!,fied by a growth stimulus caused by high CO2 concentrations. Growth analysis has been performed and possible physiological mechanisms behind changing growth parameters are discussed.SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS!.700^2^van de Geijn,S C^van Veen,J A^1993^1^Implications of Increased Carbon Dioxide Levels for Carbon Input and Turnover in Soils^123^104/105^^283-292^^^^^^^^^^1751^^^^^^^^^^^^^^^^SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS^^749^104/105; VegetatioSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS!1A^1749^The complexity of the plant-soil system in its interactions with the changing climate is discussed. It is shown tha!2t processes at the level of organic matter inputs into the soil and the fluxes and pools involved in the global cycle are !3not known in sufficient detail to allow an estimation of the future quantitative shifts. Even the direction in which the l!4evel of stored carbon in the soil organic matter pool will develop is not clear. The importance of the nitrogen cycle, whi!5ch is intimately coupled to the carbon cycle through the turnover of soil organic matter is underlined. In its turn, the m!6ineralisation of soil organic matter takes place at a rate which is highly dependent on the nature of inputs and the avail!7ability of mineral nutrients. Aspects of shifts in temperature, changes in cultivation practices (reduced tillage) and uni!8ntended spreading of inputs in chemical N-fertilizers are of great importance at a regional and global scale. The complexi!9ty of the interactions in the process of mineralisation do require further studies to clarify the point whether a substant!:ial and durable additional storage of carbon in soil organic matter is likely, or that shifts in temperature will cause an overriding acceleration of the mineralisation, and trigger corresponding net release of carbon.SSSSSSSSSSSSSSSSSSSSSSSSS!<701^1^van Keulen,H^1990^3^The Impact of the Greenhouse Effect on Factors Limiting Primary Production^The Greenhouse Effect!= and Primary Productivity in European Agro-ecosystems; 5-10 April 1990; Wageningen, The Netherlands^Pudoc^Wageningen^62-63^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^Goudriaan,J^van Keulen,H^van Laar,H HSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS!?702^3^Van Oosten,J-J^Afif,D^Dizengremel,P^1992^1^Long-term Effects of a CO2 Enriched Atmosphere on Enzymes of the Primary Carbon Metabolism of Spruce Trees^20^30^^541-547^^^^^^^^^^1755^^^^^^^^^^^Norway spruce/Picea abiesies L. Karst.SSSSSSSSS!C^1753^Plant Physiol. Biochem.SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS!BA^1753^The long-term effects of an enriched CO2 atmosphere on the primary carbon metabolism of 4-year-old spruce trees (_P!Cicea abies_ L. Karst) were examined. Eight key enzymes were studied in 1-year-old needles of trees submitted for two years!D in open-top chambers to three CO2 levels (350, 480 and 570 ppmV). The specific activity and quantity of ribulose-1,5-bisp!Ehosphate carboxylase/oxygenase (RuBisCO, EC 4.1.1.39), and the specific activities of photorespiratory enzymes, glycolate !Foxidase (EC 1.1.3.15) and hydroxypyruvate reductase (HPR, EC 1.1.1.29) showed a significant decrease in the CO2-enriched a!Gtmospheres. By contrast, a net increase was found for the specific activities of the mitochondrial enzymes, NAD-malic enzy!Hme (NAD-ME, EC 1.1.1.39) and especially fumarase (EC 4.2.1.2). The specific activity of phosphofructophosphotransferase (P!IFP, EC 2.7.1.90), a glycolytic enzyme, did not change while a slight decrease of the activity of glucose 6-phosphate dehyd!Jrogenase (G6PDH, EC 1.1.1.49), a pentose phosphate pathway enzyme, was observed. The carboxylating enzyme, phosphoenolpyru!Kvate carboxylase (PEPC, EC 4.1.1.31) showed a marked decrease in activity. These results clearly demonstrate both increase!Ls in enzyme activities linked to the respiratory process and decreases in activites of CO-fixing enzymes as a result of long-term exposure to less than twice the ambient level of CO2.. /qs /i=WP51 /d-C:\WP60\S&d)s@+&s^^^J!N703^4^Van Oosten,J-J^Laitat,E^Dizengremel,P^Gerant,D^1992^3^The Effects of CO2 Enrichment on the Biochemistry of Photosynt!Ohesis and Photorespiration of Spruce Trees Cultivated in Open-top Chambers^Responses of Forest Ecosystems to Environmental!P Changes^Elsevier Applied Science^London^655-656^^^^^^^^^^^^^^^^^^^^^Picea abies/Norway spruce^^^^^^^^^^Teller,A^Mathy,P^Jeffers,JNRJeffers,J N R! V0 pdTf!d???????????!R704^4^van Veen,J A^Liljeroth,E^Lekkerkerk,L J A^van de Geijn,S C^1991^1^Carbon Fluxes in Plant-soil Systems at Elevated CO2 Levels^85^1^^175-181^^^^^^^^^^17597593d|W>T= F@&F$ 6Fi?5T5Zr45!@C^1757^Ecol. Appl.! t )2}S&dd/$2}63$/3k&sq!UA^1757^The flow of carbon from photosynthesizing tissues of higher plants, through the roots and into the soil is one of t!Vhe key processes in terrestrial ecosystems. An increased level of CO2 in the atmosphere will likely result in an increased!W input of organic carbon into the soil due to the expected increase in primary production. Whether this will lead to accum!Xulation of greater amounts of organic carbon in soil depends on the flow of carbon through the plant into the soil and its!Y subsequent transformation in the soil by microorganisms. In this paper the major controls of carbon translocation via roo!Zts into the soil as well as the subsequent microbial turnover of root-derived carbon are reviewed. We discuss possible consequences of an increased CO2 level in the atmosphere on these processes.WPC(@"! [H.!\705^4^Vassey,T L^Quick,W P^Sharkey,T D^Stitt,M^1991^1^Water Stress, Carbon Dioxide, and Light Effects on Sucrose-phosphate synthase Activity in _Phaseolus vulgaris_^44^81^^37-44^^^^^^^^^^1762^^^^^^^^^^^Phaseolus vulgaris/bean./bean-vX_-!SC^1760^Phsiol. Plant.vX}1vX2vXV2vXf2vX 3vX!3vX,3vXg3vX<5vXg5vXq5vXx5vX5vX5vX5vX5vX5vX5vX5vX5vX 6vXG6vX6vX6vX6!_A^1760^The characteristics of sucrose-phosphate synthase (SPS; EC 2.4.1.14) activity in leaves of _Phaseolus vulgaris_ L. !`cv. Linden was studied in plants subjected to water stress and various CO2 and light treatments. When water was withheld f!aor 3 days causing mild water stress (-0.9 MPa), the activity of SPS measured in crude extracts was reduced ca 50%. The eff!bect of water stress was most evident when the enzyme was assayed with saturating amounts of its substrates fructose-6-phos!cphate and UDP glucose. Placing a water-stressed plant in an atmosphere containing 1% CO2 reversed the effect of water stre!dss on SPS activity over 5 h even though the water stress was not relieved. Holding unstressed leaves in low CO2 partial pr!eessure reduced the extractable activity of SPS. After 1 h of low CO2 treatment the effect of low CO2 could be reversed by !f20 min of 5% CO2. However, after 24 h of low CO2 treatment, less SPS activity was recovered by the 20 min. treatment. The !gcytosolic protein synthesis inhibitor cycloheximide prevented the slow recovery of SPS activity, but did not affect the ra!hpid recovery of SPS. We conclude that the effect of water stress on SPS activity was a consequence of the inhibition of ph!iotosynthesis caused by stomatal closure. Responses of _Phaseolus vulgaris_ SPS to light were similar to the response to lo!jw CO2 in that the effects were most pronounced under Vmax assay conditions. This is the first report of this type of light response of SPS in a dicotyledonous species.n to lose part of your document. Do you really want to cancel? (Y/N) NށPr!l706^3^Vessey,J K^Henry,L T^Raper,CD,Jr^1990^1^Nitrogen Nutrition and Temporal Effects of Enhanced Carbon Dioxide on Soybean Growth^12^30^^287-294^^^^^^^^^^1765^^^^^^^^^^^soybean/Glycine maxmax L. Merr.5ӂ &:`!]C^1763^Crop Sci.%@5 %$3D 2436352'ڃ.0S1!oA^1763^Plants grown on porous media at elevated CO2 levels generally have low concentrations of tissue N and often appear !pto require increased levels of external N to maximize growth response. This study determines if soybean [_Glycine max_ (L.!q) Merr. 'Ransom'] grown hydroponically at elevated CO2 requires increases in external NO3(-) concentrations beyond levels !rthat are optimal at ambient CO2 to maintain tissue N concentrations and maximize the growth response. This study also inve!sstigates temporal influences of elevated CO2 on growth responses by soybean. Plants were grown vegetatively for 34 d in hy!tdroponic culture at atmospheric CO2 concentrations of 400, 675, and 900 uL/L and during the final 18 d at NO3(-) concentra!utions of 0.5, 1.0, 5.0 and 10.0 mM in the culture solution. At 675 and 900 uL/L CO2, plants had maximum increases of 31 an!vd 45% in dry weight during the experimental period. Plant growth at 900 uL/L CO2 was stimulated earlier than at 650 uL/L. !wDuring the final 18 d of the experiment, the relative growth rates (RGR) of plants grown at elevated CO2 declined. Elevate!xd CO2 caused increases in total N and total NO3(-)-N content and leaf area but not leaf number. Enhancing CO2 levels also !ycaused a decrease in root:shoot ratios. Stomatal resistance increased by 2.1- and 2.8-fold for plants at the 675 and 900 u!zL/L CO2, respectively. Nitrate level in the culture solutions had no effect on growth or on C:N ratios of tissues, nor did!{ increases in CO2 levels cause a decrease in N concentration of plant tissues. Hence, increases in NO3(-) concentration of!| the hydroponic solution were not necessary to maintain the N status of the plants or to maximize the growth response to elevated CO2.!~707^1^Vugts,H F^1993^1^The Need for Micrometeorological Research of the Response of the Energy Balance of Vegetated Surfaces to CO2 Enrichment^123^104/105^^321-328^^^^^^^^^^1768^^^^^^^^^^^^^^^^de^^6^104/105; Vegetatio!A^1766^A Penman-Monteith equation has been use to evaluate a change in canopy resistance on the evapotranspiration of a sa!vannah and agricultural area in Botswana. After a short introduction, some problems concerning the K-theory of 'first orde!r closure' are indicated when one uses it for transport modelling within and above a canopy. The Penman-Monteith equation !was used to calculate the canopy resistance for a savannah vegetation and sorghum under the same environmental conditions.! After that, by changing the stomatal resistance due to an increase of the CO2 content, the change in the evapotranspirati!on was estimated. Finally some recommendations for future research are given and an outline of a proposed FACE experiment is presented.!708^2^Wallick,K^Zinnen,T M^1990^1^Basil Chlorosis: a Physiological Disorder in CO2-enriched Atmospheres^110^74^^171-173^^^^^^^^^^1771^^^^^^^^^^^Ocimum basilicum/basilsil!mC^1769^Plant Dis.  ^8BTT@=Ks!A^1769^Basil (_Ocimum basilicum_) grown commercially in a hydroponic facility under high-pressure sodium lights in a CO2-e!nriched atmosphere developed a distinct interveinal chlorosis. Attempts to transmit the disease mechanically or by graftin!g to unaffected, greenhouse-grown basil and certain other plant species failed. Affected basil that was transferred from t!he hydroponic facility to a greenhouse and grown in potting mix produced new, chlorosis-free leaves. Under experimental co!nditions, basil became chlorotic in 1,000 ppm CO2, but not when in ambient CO2. This was true whether the basil was grown !hydroponically or in pots, or under fluorescent or high-pressure sodium lights. Electron microscopy revealed no detectable! pathogens, but large starch grains were observed in chloroplasts of chlorotic leaves. Elevated CO2 concentrations apparently induced basil chlorosis.o:d !709^4^Wang,Y-P^Gifford,R M^Farquhar,G D^Wong,S C^1991^3^Direct Effect of Elevated CO2 on Canopy Leaf Area Development of a! Wheat Crop from Sowing to Anthesis^Climatic Variation and Change: Implications for Agriculture in the Pacific Rim; 1989 J!une 20-28 and 1990 September 24-28; University of California, Davis, USA and University of Melbourne, Australia^The Public! Service Research and Dissemination Program, University of California, Davis, USA; and the Faculty of Agriculture, University of Melbourne, Australia^^19-26^^^^^^^^^^1773^^^^^^^^^^^Triticum aestivum/wheat^^^^^^^ @ @ WPC4!A^1772^A simple model of wheat canopy leaf area development from sowing to anthesis was developed and tested. The model wa!s used to analyse the sensitivity of canopy leaf area development to double present carbon dioxide concentration in the at!mosphere at different temperature patterns, which were simulated by adding 0 to 3C to the controlled temperature pattern.! It is concluded that the direct beneficial effect of elevated carbon dioxide (680 mmol/mol) will counterbalance the detri!mental effect of a 3C rise in daily mean air temperature when a crop is grown under a condition of 680 mmol/mol carbon dioxide concentration without water stress and nutrient deficiency..!710^1^Ward,D A^1987^1^The Temperature Acclimation of Photosynthetic Responses to CO2 in _Zea mays_ and Its Relationship to! the Activities of Photosynthetic Enzymes and the CO2-concentrating Mechanism of C4 Photosynthesis^16^10^^407-411^^^^^^^^^^1776^^^^^^^^^^^Zea mays/corn^^^^^n!C^1774^Plant Cell Environ.!A^1774^Associations between photosynthetic responses to CO2 at rate-saturating light and photosynthetic enzyme activities !were compared for leaves of maize grown under constant air temperatures of 19, 25 and 31C. Key photosynthetic enzymes ana!lysed were ribulose bisphosphate (RuBP) carboxylase, phosphoenolpyruvate (PEP) carboxylase, NADP-malic enzyme and pyruvate!, Pi dikinase. Rates of CO2-saturated photosynthesis were similar in leaves developed at 19C and 25C but were decreased !significantly by growth at 31C. In contrast, carboxylation efficiency differed significantly between all three temperatur!e regimes. Carboxylation efficiency was greatest in leaves developed at 19C and decreased with increasing temperature dur!ing growth. The changes of carboxylation efficiency were highly correlated with changes in the activity of pyruvate, Pi di!kinase (_r_=0.95), but not with other photosynthetic enzyme activities. The activities of these latter enzymes, including !that of RuBP carboxylase, were relatively insensitive to temperature during growth. The sensitivity of quantum yield to O2! concentration was lower in leaves grown at 19C than in leaves grown at 31C. These observations support the novel hypoth!esis that variation in the capacity for CO2 delivery to the bundle sheath by the C4 cycle, relative to the capacity for net assimilation by the C3 cycle, can be a principal determinant of C4 photosynthetic response to CO2.}WPC{.APPWP}WPC{.D0R!711^3^Warrick,R A^Gifford,R M^Parry,M L^1986^3^CO2, Climatic Change and Agriculture^The Greenhouse Effect, Climatic Change!, and Ecosystems^John Wiley and Sons^Chichester, England^393-473^^^^29^^Scientific Committee on Problems of the Environment^^^^1778^^^^^^^^^^^^^^^^^^^^^Bolin,B^Doos,BR^Jager,J^Warrick,RA^^^^^^^1778{E.MRG*.WPPWP}WPC{.WAVMT32.MIDWP{WPC}.LCN!A^1777^A 'doubling' of ambient CO2 concentrations has a positive effect on growth and yield of major food and fibre crops.! These may range from 10% to 50% for C3 plants to 1% to 10% for C4 plants. Globally, the potential benefits of CO2-enhance!d yields might well be unevenly distributed because of the differences in where C3 and C4 crops are grown. The positive gr!owth and yield response from elevated CO2 levels is obtained under most environmentally stressful as well as optimal condi!tions. Thus both the core and the margins of crop regions could benefit from increased CO2 relative to current yield level!s. In relative terms, the growth and yield response is actually higher under some stressful environmental conditions, like! moisture stress. In absolute terms, yield response to increased CO2 concentrations is greatest under good growing conditi!ons. In many developing countries where soil nutrient shortage is a chronic problem, the full benefits of enhanced yields !may not be realized, particularly if phosphorus is deficient. As yet, the regional patterns of climatic change cannot be f!orecast reliably. This presents the major obstacle to predicting actual crop yield and production impacts from climate cha!nge. However, in crop impact analyses, employing GCM-derived crop-climate models, a number of studies have found that, in !the absence of managerial adjustments or direct CO2 effects: for the _core_ areas of the North American and European mid-l!atitude grain regions, the probable effect of an instantaneous increase in average temperatures would be to decrease crop !yields (3%-17% for 2C). The negative impact of higher temperature on grain yield derives from associated increases in eva!potranspiration, and from accelerated rates of plant development and a shortening of the period of yield formation. Increa!ses in precipitation would tend to offset the reduction in grain yield from warming; decreases in precipitation would acce!ntuate them. The impacts of climate warming at the margins of production could be less than, greater than, or in the oppos!ite direction from those observed at the core areas. Few systematic studies of the impacts of possible changes in climate !have been conducted for the tropics and sub-tropics. At all latitudes, the potential for severest adverse (or most benefic!ial) impacts of climatic change on crops may, in fact, be located in the marginal areas, variously defined. The impacts of! climatic change in marginal areas of agriculture might well be expected to elicit spatial shifts in crop areas or practic!es -- the concern of the 'marginal-spatial approach' to impact assessment. Shifts in crop boundaries could be on the order! of hundreds of kilometres per C change. Spatial readjustment, of course, is only one way in which agriculture could resp!ond to increasing CO2 and climatic change. Other response capability is internal to agriculture: feedback mechanisms can h!elp to self-regulate the system to environmental change over time. The question, how much? is addressed by 'agricultural s!ector analyses'. One approach is to link models in a sequential fashion to identify, estimate and integrate the 'cascade' !of impacts which may occur at the regional scale. At national and international scales, global models that focus on agricu!ltural production, consumption and trade are one means of examining the interactions within the entire system. Based on li!mited applications, it can be suggested that: A large proportion of any potential adverse effects on yields and production! as a result of gradual change in climate can be absorbed through policy and market feedback mechanisms. The disruption fr!om single extreme years could cause over-reaction in the system with oscillating impacts in subsequent years. The impacts !of climatic change on production in one region could be transferred to another over time through the network of global mar!ket and trade. The general lesson from agricultural sector analyses is that close attention needs to be paid to the _dynam!ics_ of the system. Furthermore, the response of the system depends critically on the assumed _rate_ of environmental change. (Abridged)YZ!):-):YZ$U':%0:'^':(a':,X': [':#M,:$S,:%P,:$S,:%P,:$:$:#:E[J[!712^5^Warrick,R A^Shugart,H H^Antonovsky,M Ja^Tarrant,J R^Tucker,C J^1986^3^The Effects of Increased CO2 and Climatic Chan!ge on Terrestrial Ecosystems^The Greenhouse Effect, Climatic Change, and Ecosystems^John Wiley and Sons^Chichester, Englan!d^363-392^^^^29^^Scientific Committee on Problems of the Environment^^^^1780^^^^^^^^^^^^^^^^^^^^^Bolin,B^Doos,BR^Jager,J^Warrick,RA^^^^^^1780FsFsBDs(DsEsCs3%:6%:)EsCsEs\Ds<%:Es9%:B%:Gs!%:?%:Gs HsHsJHsHsHsH!A^1779^There are no firm grounds for believing that the net effects of increased CO2 and climatic change will be adverse r!ather than beneficial. At the extreme, some assessments like the _Global 2000 Report to the President_ (U.S. Council on En!vironmental Quality and Department of State, 1980) see future changes in climate coinciding with deteriorating conditions !in agriculture, forests and other resources, and thus paint a very gloomy picture indeed. In contrast, Simon and Kahn (198!4) examine the same issues and in a strongly optimistic tone, reach just the opposite conclusions. In fact, at a global sc!ale the uncertainties that are involved in both sets of analyses are large enough to accommodate both views. If, in this (!and subsequent) chapters, we tend to emphasize the potential negative impacts, it is only because those are the ones which! are of most immediate concern to society and which the scientific community should hope to identify and predict. The list! of possible adverse consequences of climate-related ecosystem changes is long and speculative, and the following represen!t a sample. _Conservation._ There are many natural parks and reserves that are refuges for rare and endangered plant and a!nimal species. Often these parks occupy a relatively small area in a setting of non-park land. If an environmental change !made such parks unsuitable as habitats for these species, it is uncertain whether alternative refuges could be found or wh!ether it would even be possible to transport species to new sites. The risk of widespread extirpation of rare species (par!ticularly those with local distributions) could be high as a result of climatic change. _Forestry._ Forestry as a predicti!ve science used in a management context is highly dependent on data or local knowledge of forest response to specific mana!gement treatments. Under a sufficiently large change in climate, this local knowledge base would have to be used outside i!ts calibration range and the consequences of management actions would be less certain. _Related ecological processes._ The! global pattern of many of the ecological processes in natural systems could be altered if the climate changed. Insect pes!ts, pathogenic organisms and wildfire frequencies could all change. While the prediction of such changes is highly uncerta!in, their potential impacts are quite large. _Hydrological systems._ The impact of climatic change on regional ecosystems !(particularly forests) could alter the hydrological characteristics of watersheds. Decreases in transpiration rates from t!he direct effects of increased CO2 on vegetation might increase runoff, for instance, and enhance the effects of precipita!tion increases or offset the effects of precipitation decreases (Wigley and Jones, 1985). Changes in flooding and river fl!ow rates could have pronounced effects on the rivers themselves, on the ecosystems adjoining the rivers, and on the variou!s human activities that depend on reliable quantity and quality of water. If, on the other hand, the impacts of increased !CO2, trace gases and climatic change on agriculture, forests and other ecosystems prove, on balance, favourable, all the b!etter. In summary, this chapter has set the stage for a more detailed examination of the effects of increased CO2 and clim!atic change by outlining the major issues and dimensions of the problem in the global context, with an emphasis on agricul!ture and forest ecosystems. For both agriculture and forests the basic questions are similar: How would crop yields or cro!p types or forest composition be altered, particularly at the margins of production or at ecological transition zones? How! might these effects, integrated over time and space, change global patterns of forests or agricultural production, taking! into consideration the interactive natural and human processes that make both systems very dynamic? In order to derive me!aningful, credible answers, it is necessary to interface scenarios of environmental change with research procedures or mod!els capable of testing the sensitivity of the systems. What approaches are available? How have they been used and what que!stions have been asked of them? What have we learned so far from their specific applications to problems of increased CO2 concentrations and climatic change?R!713^1^Weinstein,D A^1992^1^Use of Simulation Models to Evaluate the Alteration of Ecotones by Global Carbon Dioxide Increases^111^92^^379-383^^^^^^^^^^1782^^^^^^^^^^^^^^^^C:\WP60\DOCS\RUSSIA\CLOUDS.1ST!A^1781^In the series analytic: Landscape boundaries: Consequences for biotic diversity and ecological flows/edited by A.J. Hansen and F. de Castri.89^1^Environmental Effects on Photorespiration of C3-C4 Species. I. Influence of CO2 and O2 dur"714^3^Wheeler,R M^Tibbitts,T W^Fitzpatrick,A H^1991^1^Carbon Dioxide Effects on Potato Growth under Different Photoperiods and Irradiance^12^31^^1209-1213^^^^^^^^^^1785^^^^^^^^^^^Solanum tuberosum/potatopotatoT;z9&EvC\"A^1783^Carbon dioxide concentration can exert a strong influence on plant growth, but this influence can vary depending on" irradiance. To study this, potato plants (_Solanum tuberosum_ L.) cultivars 'Norland', 'Russet Burbank', and 'Denali' wer"e grown in controlled-environment rooms at different levels of CO2 and irradiance. Carbon dioxide levels were maintained e"ither at 350 or 1000 umol/mol and applied in combination with 12- or 24-h photoperiods at 400 or 800 umol/m2/s photosynthe"tic photon flux. Air temperatures and relative humidity were held constant at 16C and 70%, respectively, and plants were "harvested 90 d after planting. When averaged across all cultivars, CO2 enrichment increased tuber yield and total plant dr"y weight by 39 and 34%, respectively, under a 12-h photoperiod at 400 umol/m2/s; 27 and 19% under 12 h at 800 umol/m2/s; 9" and 9% under 24 h at 400 umol/m2/s. It decreased dry weights by 9 and 9% under 24 h at 800 umol/m2/s. Tuber yield of Dena" li showed the greatest increase (21%) in response to increased CO2 across all irradiance treatments, while tuber yields of" Russet Burbank and Norland were increased 18 and 9%, respectively. The results show a pattern of greater plant growth from CO2 enrichment under lower PPF and a short photoperiod.ãhR+Ãzu6&Du2rráN" 715^2^Wheeler,R M^Tibbitts,T W^1989^1^Utilization of Potatoes for Life Support Systems in Space. IV. Effect of CO2 Enrichment^112^66^^25-34^^^^^^^^^^1788^^^^^^^^^^^Solanum tuberosum/potatoatofjiP`d\hbf^jGXC^1786^Amer. Potato J. ŀ>tP*Xr t$ ^Y[SR3ɡ`rAw ٚ%*Z[SQV6oK"A^1786^Potatoes (_Solanum tuberosum_ L.) cvs. Norland and Russet Burbank were grown in solid stands in separate controlled" environment rooms at two CO2 levels, 365 umol/mol (ppm) and 1000 umol/mol. Rooms were maintained under continuous fluores"cent light (450 umol/s/m2 PPF), 16 C and 70% relative humidity. Norland plants were grown for 110 days and Russet Burbank" plants for 126 days. CO2 assimilation rates (net photosynthetic rates) of exposed, upper canopy leaves were measured at w"eekly intervals beginning at 21-days-age for Norland and 28-days-age for Russet Burbank. Elevation of CO2 increased CO2 as"similation rates of Norland leaves by approximately 24% but decreased rates of Russet Burbank leaves by approximately 12%." Assimilation rates of Norland leaves under the high CO2 decreased as plants matured so that their rates were similar to r"ates under the low CO2 levels after 70-days-age. Assimilation rates of Russet Burbank leaves under high CO2 remained depre"ssed in comparison to low CO2 plants throughout the period of measurements. Yield data showed only marginal benefits from "CO2 enrichment: tuber dry weight increased 2% for Norland and 12% for Russet Burbank, total plant dry weight was increased" 6% for Norland and 4% for Russet Burbank. The best productivity obtained in this study (21.9 g tuber dry wt/m2/day from N"orland at 1000 umol/mol of CO2) indicates that the dietary energy needs of one human in space could be supplied from 34 m2 of potatoes.^X SS C| ξu%T&[Q$?ȸY RR2RQVPY^YZSQRV"716^1^Whipps,J M^1985^1^Effect of CO2-concentration on Growth, Carbon Distribution and Loss of Carbon from Roots of Maize^39^36^^644-651^^^^^^^^^^2047^^^^^^^^^^^maize/Zea mays/corn^^^^^n^^^^^FhsIrt, 's(hrrs#"C^1789^J. Exp. Bot.st-ߒ@u&R t:< t< ur: Ëqk”:ZXfuPRTG;u;ZXW^^^^^2050^^^^^^^^^^^Spartina alterniflora^^^^^^^^:_ PSVPSV|r3 xes(?r&**r"$718^4^Williams,M L^Jones,D G^Baxter,R^Farrar,J F^1992^3^The Effect of Enhanced Concentrations of Atmospheric CO2 on Leaf R"%espiration^Molecular, Biochemical and Physiological Aspects of Plant Respiration^SPB Academic Publishing^The Hague^541-545^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^Lambers,H^Van der Plas,L H Wst[Xu!lkuu>} P$f-_s_^YP6iȓ&SP&֒P:X֒&X&SȓiXÀ+ &"!C^1794^OecologiaP uXPS3g^r.pft} **rt >u^s>gt[XPS",A^1794^Tree saplings, two groups of three species from each of two deciduous tree communities, were grown in competition a"-t three CO2 concentrations and two light levels. After one growing season, biomass was measured to assess the effect of CO".2 on community structure, and nitrogen and phosphorus concentrations were measured for leaves, stems, and roots of all tre"/es. Gas-exchange measurements were made on the same species grown under the same CO2 concentrations. Photosynthetic capaci"0ty (rate of photosynthesis at saturating CO2 and light) tended to decline as CO2 concentration increased, but differences "1were not statistically significant. Stomatal conductance declined significantly as CO2 increased. Nitrogen and phosphorus "2concentrations generally declined as CO2 increased, but there were some unexpected patterns in roots and stems. CO2 concen"3tration did not significantly affect the overall growth of either community after one season, but the relative biomass of each species changed in a complex way, depending on CO2, light level and community.ki)NXP,NfnTL"5720^3^Williams,W E^Garbutt,K^Bazzaz,FA^1988^1^The Response of Plants to Elevated CO2. V. Performance of an Assemblage of S"6erpentine Grassland Herbs^76^28^^123-130^^^^^^^^^^1799^^^^^^^^^^^Agoseris heterophylla/Lasthenia glabrata/Layia platyglossa/Micropus Californicus/Microseris sp./Plantago erectaifornicus F. & M./Microseris sp./Plantago erecta Morris..L/Gossypium hirsutum^Bot.:_^ZY[XPR Dt&<;Trw;r+T u;Ԓw 6+ZXSQRW&#FFVF"9A^1797^Six species of herbs from the serpentine grassland of Jasper Ridge Nature Preserve (Stanford, California) -- _Micro":seris_ sp., _Plantago erecta, Micropus Californicus, Agoseris heterophylla, Layia platyglossa_ and _Lasthenia glabrata_ --"; were grown individually and in competitive arrays, under three levels of CO2: 350, 500 and 700 uL/L. CO2 affected the bio"had a statistically significant effect on nitrogen content, higher CO2 resulted in lower nitrogen content. Competition app"?eared to decrease the effects of CO2. Our results suggest that in this community, competitive networks and adaptations to "@a low-resource habitat may strongly damp the effects of CO2. These results contrast with our previous work on annuals of a higher stature system and agree with recent results on Arctic tundra species.${XPRU&E=t ښ${rGV"B721^5^Willits,D H^Nelson,P V^Peet,M M^Depa,M A^Kuehny,J S^1992^1^Modeling Nutrient Uptake in Chrysanthemum as a Function of Growth Rate^3^117^^769-774^^^^^^^^^^1802^^^^^^^^^^^Dendranthema grandiflorum/Chrysanthemum morifoliumolium:0:qal carbon cycle.oc. Hort. Sci.:3k`~;u0:%6& st:-t(0J>ft&"EA^1800^The results of six experiments conducted over 3 years were analyzed to develop a relationship between nutrient upta"Fke rate and growth rate in hydroponically grown _Dendranthema x grandiflorum_ (Ramat.) Kitamura, cv. Fiesta. Plants subjec"Gted to two levels of CO2 and three levels of irradiance in four greenhouses were periodically analyzed for growth and the "Hinternal concentration of 11 mineral elements. The resulting data were used to determine relative accumulation rate and re"Ilative growth rate, which were included in linear regression analyses to determine the dependence of uptake on growth. The"J regression equations were significant, with a slight trend toward nonlinearity in some elements. This nonlinearity seems "Kto be related to the aging of the plant and suggests a process in the plant capable of controlling uptake rate, perhaps as a result of changes in the rate of formation of different types of tissues.t7):*D):<t <u "M722^5^Willits,D H^Nelson,P V^Peet,M M^Depa,M A^Kuehny,J S^1992^3^Nutrient Uptake in Chrysanthemum as Affected by Light, CO"N2 Level and Age^ASAE Meeting; 1992 June 21-24; Charlotte, North Carolina^American Society of Agricultural Engineers^St. Joseph, Michigan^^^^^^^^^^^1804^^^^^^^^^^^Dendranthema grandiflorum/Chrysanthemum morifolium^^^^^^t@k8St D"PA^1803^Data from six chrysanthemum growth studies were analyzed and the relative accumulation rate (RAR) of eleven mineral"Q elements modeled. The plants were grown hydroponically under 3 different light levels and 2 different CO2 levels. RAR was"R found to depend primarily on relative growth rate (RGR) but a significant dependence on age was observed, suggesting that"S nutrient uptake rate may be controlled by the quantity and type of tissue being formed. Light and CO2 were found to have no effect on RAR independent of that on RGR.k&~^̀@&Y7Y7> u _^ZY[ FSY7>Y7@u ~Mu6Y7>Y7u*"U723^5^Willits,D^Peet,M^Depa,M^Kuehny,J^Nelson,P^1990^3^Modulation of Nutrient Uptake in Chrysanthemum by Irradiance, CO2, "VSeason and Developmental Stage^Proceedings of a Symposium, Mechanisms of Plant Perception and Response to Environmental St"Wimuli; 1989 August 6-10; Arlington, Virginia^British Society for Plant Growth Regulation^^59-65^^^^^^^Monograph No. 20^^^1806^^^^^^^^^^^chrysanthemum^^^^^^^^^^Thomas,TH^Smith,ARRnthemumu t @t Ê2|u >t |u"YA^1805^Leaf tissue concentrations of most elements decreased in chrysanthemum as growth rates were increased by irradiance"Z or CO2. Data from six experiments were fit to linear models of relative accumulation rate of nutrients (RAR) on relative "[growth rate (RGR), with and without considering changing plant age and environmental factors affecting growth rate. For mo"\st elements, RAR was linearly related to RGR with a slope approximating 1 and an intercept approximating 0. Closer examina"]tion of these relationships revealed, however, that chrysanthemum possesses the ability to modify its nutrient uptake rate"^ to match its internally regulated needs and that these needs appear to change with maturity. In addition to the maturity "_effect, a growth effect was discovered which seems to be related to the effect of RGR on RAR, independent of maturity. The mechanism by which the plant is correcting RAR as a function of maturity and growth is not known.EuT]X"a724^2^Willits,D H^Peet,M M^1989^1^Predicting Yield Responses to Different Greenhouse CO2 Enrichment Schemes: Cucumbers and Tomatoes^46^44^^275-293^^^^^^^^^^1809^^^^^^^^^^^cucumber/Cucumis sativus/tomato/Lycopersicon esculentumlentum Mill.!P"C and perhaps provide insight into the extent to which soil organic matter can accommodate the 'missing' carbon in the glob"dA^1807^Data from six years of carbon dioxide (CO2) enrichment studies at North Carolina State University were analyzed in "ean attempt to develop predictive relationships for plant responses to different enrichment schemes and CO2 levels (600-500"f0 uL/L). Cucumbers (_Cucumis sativus_ L.) and tomatoes (_Lycopersicon esculentum_ Mill.) were enriched using: (i) closed-l"goop cooling to extend enrichment periods beyond that generally practicable and (ii) elevated CO2 levels to compensate for "hshort enrichment times normally encountered in conventional enrichment. Yields of nine cultivars of cucumber and seven of "itomato, from both ground bed and bag culture, were regressed against solar energy, number of enrichment hours, fractional "jenrichment time, CO2 set point concentration (i.e., target concentration), and actual daily CO2 concentration. Absolute yi"kelds for cucumber were found to be strongly related to the solar energy received and, to a lesser degree, the number of en"lrichment hours. CO2 concentration, either set point or actual, was significant only when included in quadratic form. The r"melationship developed suggests that the optimum concentration is inversely related to the length of the enrichment period "nand that the product of the number of enrichment hours and the set point concentration should equal 14,400 uL-h/L. Absolut"oe yields for tomato were also highly dependent upon solar energy, and to a lesser degree, either actual CO2 concentration,"p number of enrichment hours, or fractional enrichment time. Weight gain advantages for cucumber were found to be a linear "qfunction of fractional enrichment time (enrichment time divided by solar daylength), reaching a maximum value of 54% when "rcontinuously enriched during daylight hours. Weight gain advantages for tomato were found to be a non-linear function of fractional enrichment time with values of fractional enrichment time less than 0.5 producing little or no gain.uPx=725^1^Wittwer,S H^1985^1^Carbon Dioxide Levels in the Biosphere: Effects on Plant Productivity^8^2^^171-198^^^^^^^^^^1812"bopic studies on FACE experiments in different ecosystems should permit more definitive assessment of carbon turnover rates"vA^1810^Human society is now inadvertently conducting a great biological and environmental experiment, the outcome of which"w is not known. Atmospheric carbon dioxide (CO2) is increasing at the rate of 1.5 parts per million (ppm) per year. It has "xrisen from 315 ppm to 340 ppm in the past 25 years -- a 9% increase. Because CO2 is among the factors which can limit the "ygrowth of plants, the increase may be beneficial. An increase in plant growth due to 'fertilization' of extra CO2 has not "zbeen measured, but a 5 to 10% increase may already have occurred. Current data indicate that plants growing at higher than"{ normal CO2 levels are more tolerant of water, temperature, light and atmospheric pollutant stresses. There are effects on"| carbon metabolism, plant growth and development, microbial activity, and terrestrial and aquatic plant communities. The c"}urrent rising level of atmospheric CO2 represents a dramatic change in a resource base and can affect the total biological"~ productivity of the earth. A global change in a fundamental element of all plant life mandates the establishment of a res"earch agenda for the assessment of unexplored frontiers. Increasing levels of atmospheric CO2 will likely have major effects on food and the production of other renewable resources in the decades to come.F3 tKS:7122 .X ~ ˃>}u2< w Vl!^S,2؎[˃>}u t Vlk*^SRV726^1^Wittwer,S H^1990^1^Implications of the Greenhouse Effect of Crop Productivity^28^25^^1560-1567^^814l֏s^^^^^HortSci.lt<wAltdltvr|sT"729^1^Wong,S-C^1993^1^Interaction between Elevated Atmospheric Partial Pressure of CO2 and Humidity on Plant Growth: Compa"rison between Cotton and Radish^123^104/105^^211-221^^^^^^^^^^1822^^^^^^^^^^^Gossypium hirsutum/cotton/Raphanus sativus/radish^^^^^^^^^^XW9dsԒ)d_W9ds))d_;Tu;Dwr׈t uLioxide^^ Dioxide^^tatioRы;w+t-sZYWd)&_;Tu;Ds)L\r ;Tu;DvDT׈u+"A^1820^Cotton plants (_Gossypium hirsutum_ L. var Deltapine 90) and radish plants (_Raphanus sativus_ L. var Round Red) we"re grown under full sunlight using a factorial combination of atmospheric CO2 concentrations (350 umol/mol and 700 umol/mo"l) and humidities (35% and 90% RH at 32C during the day). Cotton plants showed large responses to increased humidity and "to doubled CO2. In cotton plants, the enhanced dry matter yield due to doubled CO2 concentration was 1.6-fold greater at l"ow humidity than at high humidity. Apart from the direct effect of elevated CO2 level on photosynthesis, the greater effec"t of doubled CO2 concentration on dry matter yield at low humidity was probably due to: (1) increased leaf water potential" caused by reduction of transpiration resulting from the negative CO2 response of stomata to increased CO2 concentration t"he consequence being greater leaf area expansion; (2) reduction of CO2 assimilation rate at low humidity and normal CO2 co"ncentration as a result of humidity response of stomata causing reduction of intercellular CO2 concentration. In contrast," apart from the very early stage of development, radish plants do not respond to increased humidity but had a relatively l"arge response to doubled CO2 concentration. Furthermore, due to the determinate growth pattern as well as having a prominent storage root, the extra photoassimilate derived at doubled CO2 level is allocated to the storage root.NF .P.J"730^2^Wong,S-C^Dunin,F X^1987^1^Photosynthesis and Transpiration of Trees in a Eucalypt Forest Stand: CO2, Light and Humidity Responses^52^14^^619-632^^^^^^^^^^1825^^^^^^^^^^^Eucalyptus spp.Sdہ>*}؎Ë&&G$[PVWd^^^23^Aust. J. Plant Physiol.؉_^XPd؀ t'ـ>'9~o.' &ـ>&9~_&0/٣1-%ـ>%9~E%0#ـ>#9"A^1823^Exchange of water vapour and CO2 was measured on a small group of trees in a 12-year-old regenerating forest domina"ted by _Eucalyptus_ spp. in Kioloa State Forest, south-eastern New South Wales. The trees were growing in a weighing lysim"eter (10.3 m2 ground area) with the dominant tree about 10 m high. A 12 m high enclosure made of polyethylene film was ere"cted to enclose the trees on the lysimeter. Air was impelled in from the bottom of the enclosure by four fans at a total f"low rate of 4.6 m3/s. Air samples for infrared gas analysers were taken 1, 4, 7 and 10 m above the ground. Pure CO2 (up to" 1000 litres/min) was injected to obtain the response of rates of photosynthesis and transpiration at various levels of CO"2 in the enclosure environment. At normal ambient partial pressure of CO2, the photosynthetic rate of the canopy (28 umol/"m2 ground area/s) was found to be saturated at about half of full sunlight. At midday, the foliage in the layers 1-4 m, 4-"7 m and 7-10 m from the ground level contributed 10.7, 44.3, and 34% of the total carbon assimilated by the canopy, respec"tively. Canopy conductance was reduced with increasing vapour pressure difference between leaves and the air on the basis "that internal partial pressure of CO2 was decreased. Light intensity required to saturate photosynthesis increased with in"creasing ambient partial pressure of CO2. At 680 ubar ambient partial pressure of CO2 and at saturating light intensity, t"here was a 50% increase in photosynthetic rate and a 30% reduction in transpiration rate, resulting in a reduction in tran"spiration ratio of 80%. The apparent quantum yield derived at 340 and 680 ubar CO2 was 0.049 and 0.071, respectively. The light compensation point also decreased at higher ambient partial pressure of CO2.9w Ó t<s> u r5~w"731^3^Wong,S C^Kriedemann,P E^Farquhar,G D^1992^1^CO2 x Nitrogen Interaction on Seedling Growth of Four Species of Eucalyp"t^25^40^^457-472^^^^^^^^^^1828^^^^^^^^^^^Eucalyptus camaldulensis/Eucalyptus cypellocarpa/Eucalyptus pauciflora/Eucalyptus pulverulentapreng./Eucalyptus pulverulenta Sims2uCC;t w!r;t&;ZY[PSV:uC u^[X^^^^^^^^^^Primula obconica^^^^^S\2SP>;#8A^1845^The influence of recent historical changes in atmospheric CO2 have been investigated by two methods: 1, the respons#9es of leaf development and physiology as indicated by leaves stored in herbaria and 2, by investigating the differential g#:rowth responses of populations originating from naturally different CO2 concentrations. Herbarium leaves indicate that sto#;matal density and leaf nitrogen have decreased over the last 150 to 200 years, while water use efficiency, estimated from # grown in the controlled environment, using seeds originating from populations occurring in the different CO2 mole fractio#?ns. Plants from the different ambient CO2 mole fractions showed different rates of growth and different non-linear respons#@es of the shoot to root ratio in response to changes in the CO2 mole fraction from 350 to 675 umol/mol. The proposal that #Aplants originating from high altitude will show greater stimulations of growth with an increase in CO2, than plants from l#Bow altitude, was rejected in experiments which simulated the atmospheric pressure at altitudes of 0 and 2000 m at CO2 mole fractions of 350 and 700 umol/mol and on populations of _Plantago major_ originating from altitudes of 0 and 3335 m. #D739^1^Woodward,F I^1987^1^Stomatal Numbers Are Sensitive to Increases in CO2 from Pre-industrial Levels^77^327^^617-618^^^^^^^^^^1850^^^^^^^^^^^Acer pseudoplatanus/sycamore maple/Quercus robur/Rhamnus catharticus/Rumex crispus/curly docks L./c#Fsion). There was no effect of HPS on the easy-to-root cultivar Blood of China. Irradiance from HPS either at 45 umol/s/m2 #.for 16 hr/day or at 75 umol/s/m2 CO2 mist inhibited rooting of both cultivars when applied in fall propagation. In spring,#HA^1848^Recent measurements of atmospheric CO2 levels in ice cores have shown that global CO2 has increased by about 60 umo#Il/mol over the past 200 years. Evidence for the response of plants in the field to this change in CO2 levels is here prese#Jnted in the form of a significant change in stomatal density -- an anatomical response of considerable ecophysiological im#Kportance. A 40% decrease in density of stomata was observed in herbarium specimens of leaves of eight temperate arboreal s#Lpecies collected over the last 200 years. This decline was confirmed for some of the species observed as herbarium specime#Mns by experiments under controlled environmental conditions. In these an increase in the mole fraction of CO2 from 280 umo#Nl/mol to the current ambient level of 340 umol/mol was found to cause a decrease in stomatal density of 67%. Experiments h#Oave shown that the combination of this previously unreported response of stomatal density to the level of CO2 with the kno#Pwn responses of stomatal aperture, cause water use efficiency to be much lower than expected at low CO2 and over a wide range of humidities.#R740^3^Woodward,F I^Thompson,G B^McKee,I F^1991^1^The Effects of Elevated Concentrations of Carbon Dioxide on Individual Plants, Populations, Communities and Ecosystems^35^67 (Supplement 1)^^23-28^^^^^^^^^^1853^^^^^^^^^^^^^^^^A^1690^Photosynthetic characteristics of four high-CO2-requiring mutants of _Chlamydomonas_ _reinhardtii_ were compared to#UA^1851^Changes in the atmospheric concentration of CO2, over periods of millennia, are positively correlated with the temp#Verature of the world. It is expected that this positive correlation will be manifested in the future, warmer 'greenhouse w#World' with higher concentrations of CO2. The predicted changes in temperature and precipitation are expected to cause sign#Xificant changes in the distribution patterns of the world's terrestrial vegetation (Woodward and McKee, 1991). In addition#Y to this indirect effect, CO2 influences plants directly and an increase in the concentration of CO2 may increase the rate#Z of photosynthesis in plants with the C3 pathway of fixation. Experimental observations often differ in the degree and len#[gth of this stimulation, reflecting the stronger impact of other photosynthetic limitations. Where photosynthetic stimulat#\ion does occur there is a general decrease in leaf protein, which may stimulate rates of leaf herbivory. The well establis#]hed and associated increase in the C/N ratio of individual leaves should reduce rates of leaf decomposition. However the f#^ew community experiments at elevated CO2 suggest little change in the rate of nutrient cycling in communities. Stomatal op#_ening is generally reduced as CO2 concentration increases. This feature scales up through to the community level, however,#` it appears that the total volume of water used by a community is unlikely to alter with CO2 alone, because plants tend to#a develop leafier canopies. This change, plus enhanced rates of root development, indicate a greater potential for carbon s#bequestration by terrestrial ecosystems. Monthly observations of atmospheric CO2 concentration above the tundra over the la#cst 14 years indicate these expected increases in the rates of CO2 drawdown by the northern ecosystems of the tundra and th#de boreal and temperate deciduous forests. However, some of this change may be due to interactions with the warmer climate of the 1980s and perhaps an increased aerial supply of pollutant nitrogen.Gu&E,Z;G&s&EZ;G$ry&DG.&T>#f741^1^Wray,S M^1987^6^Competitive Interactions of Two Old-field Perennials, _Aster pilosus_ and _Andropogon virginicus_ un#gder Carbon-dioxide Enrichment^^Duke University^^Doctoral Dissertation^^^Dissertation Abstracts Vol. 48:05-B, p.1232 (180 pp.)^^^^^^^1855^^^^^^^^^^^Aster pilosus/aster/Andropogon virginicus/broomsedge>Erk~ $_G>VtqO@t#iA^1854^Differential response of species to CO2 enrichment may change future community structure in natural ecosystems. In #jold fields of the North Carolina Piedmont, aster (_Aster pilosus_ Willd., C3) is usually the dominant perennial two years #kafter abandonment. Broomsedge (_Andropogon virginicus_ L., C4) outcompetes and replaces aster during the next several year#ls. When grown individually, aster responds positively to CO2 enrichment, whereas broomsedge does not. Thus it was hypothes#mized that the competitive interaction between these species would change if the atmospheric CO2 concentration was increase#nd. Aster and broomsedge were grown in simplified de Wit replacement series experiments in the Duke Phytotron at 350, 500 a#ond 650 uL/L CO2. The suppression of broomsedge by aster was always greater with CO2 enrichment so that broomsedge grown wi#pth aster had 69% less dry weight than in monoculture at 650 uL/L CO2. Aster had 49% more dry weight when grown with brooms#qedge than in monoculture at 650 uL/L CO2. Broomsedge was more drought tolerant than aster and under ambient conditions had#r a higher water use efficiency. However, under water-limited conditions, broomsedge was not a stronger competitor than ast#ser. With CO2 enrichment aster comprised 75% of total pot biomass under both water-limited and well-watered conditions. The#tre could also be competition between established broomsedge and a second generation of aster seedlings in old fields. In t#uhe Phytotron when broomsedge was grown for six weeks before aster emerged, aster seedlings did not suppress the growth of #vbroomsedge even with CO2 enrichment. These studies have shown that competitive interactions between these old-field perenn#wials change under CO2 enrichment when grown in a controlled environment. Future increases in atmospheric CO2 concentration#x may slow the rate of succession in old fields under both drought and nondrought conditions. However, aster will not neces#ysarily eliminate broomsedge from the perennial herbaceous community as broomsedge ultimately will reach a size where compe#ztition with aster seedlings does not delay its growth. It is hoped that these studies will contribute to the understanding of the dynamics of community structure in the face of environmental change.NEP>Vu w;6uNXPRV t&G@u#|742^2^Wray,S M^Strain,B R^1987^1^Competition in Old-field Perennials under CO2 Enrichment^2^68^^1116-1120^^^^^^^^^^1858^^^^^^^^^^^Aster pilosus/aster/Andropogon virginicus/broomsedgeL./broomsedgeT N3\LDT^VtVt>Vt 333@ V2333@^YøBu! t\tGvWxŀtGzW|@tG#A^1862^_Aster pilosus_ Willd. (aster, C3) and _Andropogon virginicus_ L. (broomsedge, C4) were grown in growth chambers at# 26/20 C day/night temperatures with a PPFD of 1,000 umol/s/m2. Water was withheld for a 2-wk drought period under three C#O2 concentrations (approximately 380, 500, and 650 uL/L). There were significant effects of CO2 enrichment on aster so tha#t drought stress did not occur in plants grown with CO2 enrichment. Non-watered plants with CO2 enrichment had greater lea#f water potentials, greater photosynthetic rates, and greater total dry wt than non-watered plants grown at 380 uL/L CO2. #The response of broomsedge to drought was the same in all CO2 treatments and there was no significant interaction of CO2 e#nrichment and drought. The decreased severity of drought stress and the increased growth of aster with CO2 enrichment may #increase its competitive ability during droughts, allowing it to persist for longer periods during succession in abandoned fields.&E/&Et&E$h&E8Vs&L5&u/#forces the effect of CO2 on _g_ and counteracts the effect of CO2 on _E_, because the driving force for transpiration is e#749^4^Yandell,B S^Najar,A^Wheeler,R^Tibbitts,T W^1988^1^Modeling the Effects of Light, Carbon Dioxide, and Temperature on the Growth of Potato^12^28^^811-818^^^^^^^^^^1878^^^^^^^^^^^Solanum tuberosum/potatopotatot~uLDXtL+~0#r, owing to thermal and hydrologic feedbacks, an increase in CO2 leads to a considerable increase in VPD-leaf-air. This en#A^1876^This study examined the effects of light, temperature and carbon dioxide on the growth of potato (_Solanum tuberosu#m_ L.) in a controlled environment in order to ascertain the best growing conditions for potato in life support systems in# space. 'Norland' and 'Russet Burbank' were grown in 6-L pots of peat-vermiculite for 56 d in growth chambers at the Unive#rsity of Wisconsin Biotron. Environmental factor levels included continuous light (24-h photoperiod) at 250, 400, and 550 #umol/m2/s PPF; constant temperature at 16, 20, and 24C; and CO2 at approximately 400, 1000 and 1600 uL/L. _Separate effec#ts analysis_ and _ridge analysis_ provided a means to examine the effects of individual environmental factors and to deter#mine combinations of factors that are expected to give the best increases in yields over the central design point. The res#ponse surface of Norland indicated that tuber yields were highest with moderately low temperature (18.7C), low CO2 (400 u#L/L) and high light (550 umol/m2/s PPF). These conditions also favored shorter stem growth. Russet Burbank tuber yields we#re highest at moderately low temperature (17.5C), high CO2 (1600 uL/L) and medium light (455 umol/m2/s PPF). Models gener#ated from these analyses will be used to project the most efficient conditions for growth of potatoes in closed ecological life support systems (CELSS) in space colonies.&M7rFN@IvVFtJGjWlGjWl;Vu;FsFGhGfGp#750^3^Yelle,S^Gosselin,A^Trudel,M-J^1987^1^Effect of Atmospheric CO2 Concentration and Root-zone Temperature on Growth, Mi#neral Nutrition, and Nitrate Reductase Activity of Greenhouse Tomato^3^112^^1036-1040^^^^^^^^^^1881^^^^^^^^^^^Lycopersicon esculentum/tomatol./tomatoodD($@Fd(~EREOu ES*EPER?2MPwr&E $&EF&E&EN~9FwFM#ation) and by 4 - 7% at low _g_ (dark weather), at least if VPD would remain constant. In a greenhouse-crop system, howeve#A^1879^Tomato plants (_Lycopersicon esculentum_ Mill. cvs. Vendor and Carmelo) were exposed to two CO2 levels (330 or 800 #uL/L) and five root-zone temperatures (12, 18, 24, 30, or 36C). The enhancement of shoot growth from CO2 enrichment i#ncreased with root-zone temperature (RZT) to 30C. Enhancement of root growth decreased. The response to high CO2 level wa#s larger with 'Vendor' than 'Carmelo'. A concentration of 800 uL/L of CO2 increased N and K uptake by 58% and 45% respecti#vely. The largest P uptake was obtained with plants grown at 800 uL/L CO2 and 36 RZT. Leaf NO3 concentration decreased at# 800 uL/L of CO2 and at a RZT of 12. At low RZT, CO2 enrichment increased growth but did not increase the translocation o#f NO3 to the leaf. There was no significant relationship between nitrate reductase activity (NRA) and leaf NO3 content, im#plying that the 'inactive NO3' (which does not affect NRA) was at higher levels in leaves exposed to 330 uL/L CO2 than in #those exposed to 800 uL/L CO2. There was also a decrease in N concentration of leaves subjected to 800 uL/L CO2, possibly #caused by a reduction of NO3 transport toward leaves rather than a decrease in NO3 reduction within leaves. Therefore, the best response to CO2 enrichment at 30 appears to be related to increased NO3 translocation.FZX&M~t:Nt5&m #751^3^Yelle,S^Gosselin,A^Trudel,M-J^1987^1^Effets a Long Terme de l'Enrichissement Carbone sur la Tomate de Serre Cultivee avec ou sans Eclairage d'Appoint^29^67^^899-907^^^^^^^^^^1884^^^^^^^^^^^Lycopersicon esculentum/tomatol./tomatoE+t=#ith the equation it was estimated that a 10% decrease in _g_ would reduce _E_ by 1.5 - 3% at high levels of _g_ (high radi#A^1882^Tomato (_Lycopersicon esculentum_ Mill. 'Vedettos') was grown under three different concentrations of atmospheric C#O2 (330, 900 and 1500 ppm) and two lighting intensities (natural and natural plus 30 W/m2 PAR) provided by high-pressure s#odium lights (HPS). Results show a reduction in CO2 efficiency after eight weeks of enrichment. The higher the CO2 concent$ration, the more serious is this reduction. Our results show the potential of CO2 enrichment and supplementary lighting as$ well as their synergetic effect on productivity (yield increases of 32, 73 and 122%, respectively). Supplementary lightin$g does not compensate for the reduction of CO2 efficiency. Concentrations of 900 and 1500 ppm increased the plants' water-use efficiency. In French.&/u&7u &3u&;XV t?&>v4 t-&6u &L&L&|t &L&t&$752^2^Zeroni,M^Gale,J^1988^1^Response of Sonia Roses to Continuous Daytime CO2 Supplementation under Controlled Environment Conditions^116^39^^863-870^^^^^^^^^^1887^^^^^^^^^^^Rosa hybrida/roseose~w ~DDE~ԋDDE萪~ܪ#ion were highly correlated to radiation and were in reasonable accordance with the Penman-Monteith combination equation. W$A^1885^Rose plants (_Rosa hybrida_ cv. Sonia, Syn. Sweet Promise) were placed in growth chambers under conditions resembli$ng winter in a controlled environment greenhouse in the desert: mild temperature, high incident photosynthetic photon flux$ density (PPFD), high air humidity and 10.5 h daylength. Concentrations of CO2 in the air were maintained throughout the d$ ay at 320, 600 or 1200 uL/L with approximately 350 L/L at night. Plant growth (length, fresh and dry weight), development $ (breaks, blindness), flower yield and flower quality (flower bud diameter, fresh weight and cane length) indices were moni$ tored throughout three consecutive flowering cycles. CO2 supplementation caused an increase in leaf resistance to water va$ pour diffusion, accompanied by a reduction in the rate of transpiration per unit leaf area. Total leaf area increased at h$igher CO2 concentrations. Water use per plant did not change. Plant water potentials increased with rising CO2 concentrati$ons. Growth, development, flower yield and flower quality were greatly enhanced in the CO2-enriched atmosphere. The respon$se of growth and development to CO2 supplementation tended to decrease slightly with time when calculated per branch, but $increased when calculated per plant. Flower yield and quality did not change with time. The highest CO2 treatment resulted$ in a sustained, approximately 50% increase in yield, and doubling of the above quality indices throughout the three growth cycles.>[~;s;+&>[F+ƙ~;vf+ tǙvNȃ~tًFF+FHƋF+t2v uv$753^2^Zeroni,M^Gale,J^1989^1^Response of 'Sonia' Roses to Salinity at Three Levels of Ambient CO2^19^64^^503-511^^^^^^^^^^1890^^^^^^^^^^^Rosa hybrida/roseose+׋+L+y 33+Uu8PRDz+r;v;w\ $_g_ by about 3%, at any level of CO2, VPD and PAR, if VPD and PAR would remain constant. Measured rates of crop transpirat$A^1888^The effect of prolonged exposure of plants to a combination of both salinity and high CO2 concentration ([CO2]) is $not easy to predict. The purpose of this work was to contribute to the clarification of this question for roses. 'Sonia' r$ose plants were placed in growth chambers for three consecutive flowering cycles, under conditions simulating winter in a $controlled environment greenhouse in the desert. Plants were grown at three levels of [CO2] and four levels of salinity. P$lants died or stopped growing when treated with 3,436 g/m3 salt. Subsequently, the highest concentration used was 2,577 g/$m3 total soluble salt. Salinity tolerance increased at high [CO2]. Some combinations of CO2 and salt gave higher yields th$an those obtained with CO2 alone, due to a decrease in blindness. This suggests that salt, in the presence of high [CO2], $changed the distribution of assimilates. Under high [CO2], salinity did not change plant water potential, but leaf diffusi$on resistance to water vapour (r) increased. The r did not correlate well with the measured rates of transpiration. This s$ uggests that the r of leaves of different ages react differently to the combination of salinity and high [CO2]; evidently, the leaves used to measure r were not representative of the entire plant.+ ၀>Vt +EK_W.W'PSQRV$"754^2^Ziska,L H^Bunce,J A^1993^1^Inhibition of Whole Plant Respiration by Elevated CO2 as Modified by Growth Temperature^44^87^^459-466^^^^^^^^^^1893^^^^^^^^^^^orchardgrass/Dactylis glomerata/Medicago sativa/alfalfa./alfalfa udN[$g_, were fitted to the measured data. The fitted regression curves demonstrated that 100 umol/mol increase in CO2 reduced $%A^1891^Plants of alfalfa (_Medicago sativa_) and orchard grass (_Dactylus glomerata_) were grown in controlled environment$& chambers at two CO2 concentrations (350 and 700 umol/mol) and 4 constant day/night growth temperatures of 15, 20, 25 and $'30C for 50-90 days to determine changes in growth and whole plant CO2 efflux (dark respiration). To facilitate comparison$(s with other studies, respiration data were expressed on the basis of leaf area, dry weight and protein. Growth at elevate$)d CO2 increased total plant biomass at all temperatures relative to ambient CO2 but the relative enhancement declined (_P_$* ambient and elevated CO2 conditions continued until October. In contrast to the C3 sedge, the C4 grass showed no significant photosynthetic increase to elevated CO2 except at the beginning of the 1988 season.~t3~5:F#0~E=$@756^4^Ziska,L H^Hogan,K P^Smith,A P^Drake,B G^1991^1^Growth and Photosynthetic Response of Nine Tropical Species with Long$A-term Exposure to Elevated Carbon Dioxide^34^86^^383-389^^^^^^^^^^1899^^^^^^^^^^^Ananas comosus/pineapple/Aechmea magdalen$Bae/Pharus latifolia/Paspallum conjugatum/Manihot esculentum/cassava/Ficus obtusifolia/Psychotria limonensis/Tabebuia rosea/Acacia mangium^^^^^^^^VnF t!7:rRN<6FrGNF6Fr:uRpd>;u$d758^2^Ziska,L H^Teramura,A H^1992^1^Intraspecific Variation in the Response of Rice (_Oryza sativa_) to Increased CO2 - Photosynthetic, Biomass and Reproductive Characteristics^44^84^^269-276^^^^^^^^^^1905^^^^^^^^^^^Oryza sativa/rice./riceM>$RA^1218^The effects of carbon dioxide concentration (CO2) in the range of 300-1100 umol/mol on leaf conductance (_g_) and r$gA^1903^Two rice (_Oryza sativa_ L.) cultivars of contrasting morphologies, IR-36 and Fujiyama-5, were exposed to ambient ($h360 uL/L) and ambient plus 300 uL/L CO2 from time of emergence until ca 50% grain fill at the Duke University Phytotron, D$iurham, North Carolina. Exposure to increased CO2 resulted in about a 50% increase in the photosynthetic rate for both cult$jivars and photosynthetic enhancement was still evident after 3 months of exposure to a high CO2 environment. The photosynt$khetic response at 5% CO2 and the response of CO2 assimilation (A) to internal CO2 (Ci) suggest a reallocation of biochemic$lal resources from RuBP carboxylation to RuBP regeneration. Increases in total plant biomass at elevated CO2 were approxima$mtely the same in both cultivars, although differences in allocation patterns were noted in root/shoot ratio. Differences i$nn reproductive characteristics were also observed between cultivars at an elevated CO2 environment with a significant incr$oease in harvest index for IR-36 but not for Fujiyama-5. Changes in carbon allocation in reproduction between these two cul$ptivars suggest that lines of rice could be identified that would maximize reproductive output in a future high CO2 environment.3FXZ^E UvXZ^EUu XZ^Uuۃ~u E u ~t FFFXZ^EU v$r759^8^Allen,S G^Idso,S B^Kimball,B A^Baker,J T^Allen,L H,Jr^Mauney,J R^Radin,J W^Anderson,M G^1990^5^Effects of Air Temper$sature on Atmospheric CO2-Plant Growth Relationships^NTIS, U.S. Dept. of Commerce, Springfield, Virginia^^^^^^^^^^^^^^^^^^^^^^^^^^TR048 in Yellow Report Series^DOE/ER-0450T^Dept. of Energy, Carbon Dioxide Research Program^Uv]lsVRPv~$u760^2^Baker,J T^Allen,L H,Jr^1993^1^Contrasting Crop Species Responses to CO2 and Temperature: Rice, Soybean and Citrus^12$v3^104/105^^239-260^^^^^^^^^^1909^^^^^^^^^^^rice/Oryza sativa/soybean/Glycine max/citrus/Citrus sinensis/Poncirus trifoliata^^^^^^ifoliata^^^^^ t<| t <| t)u F v  v F ZYX_^[VWPSQR"Dioxide^^ Dioxide^^atio&D$EFFދEFEFEFE FEFEFEFEFEFE FEFE"FVFދ$yA^1907^The continuing increase in atmospheric carbon dioxide concentration ([CO2]) and projections of possible future incr$zeases in global air temperatures have stimulated interest in the effects of these climate variables on plants and, in part${icular, on agriculturally important food crops. Mounting evidence from many different experiments suggests that the magnit$|ude and even direction of crop responses to [CO2] and temperature is almost certain to be species dependent and very likel$}y, within a species, to be cultivar dependent. Over the last decade, [CO2] and temperature experiments have been conducted$~ on several crop species in the outdoor, naturally-sunlit, environmentally controlled, plant growth chambers by USDA-ARS a$nd the University of Florida, at Gainesville, Florida, USA. The objectives for this paper are to summarize some of the maj$or findings of these experiments and further to compare and contrast species responses to [CO2] and temperature for three $diverse crop species: rice (_Oryza sativa_, L.), soybean (_Glycine max_, L.) and citrus (various species). Citrus had the $lowest growth and photosynthetic rates but under [CO2] enrichment displayed the greatest percentage increases over ambient$ [CO2] control treatments. In all three species the direct effect of [CO2] enrichment was always an increase in photosynth$etic rate. In soybean, photosynthetic rate depended on current [CO2] regardless of the long-term [CO2] history of the crop$. In rice, photosynthetic rate measured at a common [CO2], decreased with increasing long-term [CO2] growth treatment due $to a corresponding decline in RuBP carboxylase content and activity. Rice specific respiration decrease from subambient to$ ambient and superambient [CO2] due to a decrease in plant tissue nitrogen content and a decline in specific maintenance r$espiration rate. In all three species, crop water use decreased with [CO2] enrichment but increased with increases in temp$erature. For both rice and soybean, [CO2] enrichment increased growth and grain yield. Rice grain yields declined by roughly 10% per each 1C rise in day/night temperature above 28/21C.twJ\tsQ\tNP>Vt]K7\t$761^5^Baker,J T^Allen,L H,Jr^Boote,K J^Jones,P^Jones,J W^1990^1^Developmental Responses of Rice to Photoperiod and Carbon Dioxide Concentration^46^50^^201-210^^^^^^^^^^1912^^^^^^^^^^^rice/Oryza sativaiva L.QRVW\tm>56D D ue reason for long-term yield increases in roses when grown in enriched environments.^ZYXRRPQVWUp pqF $A^1910^The documented increase in the carbon dioxide concentration of the Earth's atmosphere has stimulated interest in th$e effects of CO2 on plants and in particular the future prospects for the world's food supplies. While rice is a major foo$d crop, relatively little is known about the effects of CO2 concentration on the timing of physiological growth stages and$ total growth duration, which are important aspects of a rice cultivar's adaptability to the environment of a particular g$eographic region. The objective of this study was to determine the developmental responses of a modern, improved rice cult$ivar (_Oryza sativa_, cultivar 'IR-30') to a range of CO2 concentrations under two contrasting photoperiods. Rice plants w$ere grown season-long in an outdoor, naturally lit, computer-controlled environment, plant growth chambers in CO2 concentr$ations of 160, 250 (subambient), 330 (ambient), 500, 660 and 900 (superambient) umol CO2/mol air. The entire experiment wa$s conducted twice during 1987. The first or early planted rice (EPR) experiment was conducted with photoperiod extension l$ights during the vegetative phase of development, while the second or late-planted rice (LPR) experiment was conducted usi$ng only naturally occurring photoperiod. In both experiments, mainstem leaf developmental rates were greater during vegeta$tive rather than reproductive growth stages and leaf appearance rates increased with CO2 treatment during vegetative devel$opment. In the LPR experiment, panicle initiation and boot stage occurred earlier and total growth duration was shortened $for rice plants in the superambient compared with ambient and subambient CO2 treatments. This acceleration of plant develo$pment with increasing CO2 treatment was associated with a CO2-induced decrease in the number of mainstem leaves formed dur$ing the vegetative phase of growth. The reduced developmental response of rice plants to CO2 in the EPR compared with the $LPR experiment was attributed to the artificially extended photoperiod during the EPR experiment forcing a delay in the on$set of reproductive development particularly in the superambient treatments. The CO2-induced acceleration of development a$nd shortening of total growth duration should become a topic of interest for rice agronomists and breeders involved with s$electing rice cultivars and agronomic practices for a particular geographic region in view of the continued increases in global atmospheric CO2 concentration.& ŀtI?PQ&DrѾҍ^rĉFvF&D&Tv^ YI:rȋFFXr$762^3^Baker,J T^Allen,L H,Jr^Boote,K J^1990^1^Growth and Yield Responses of Rice to Carbon Dioxide Concentration^40^115^^313-320^^^^^^^^^^1915^^^^^^^^^^^rice/Oryza sativaiva L.s3Y[I^E&D&;D|&uEM&&DE&DE&D$ations. The maintenance of Rubisco and CA activities with prolonged exposure to CO2-enriched atmospheres is proposed as th$A^1913^Rice plants (_Oryza sativa_ L., cv. IR30) were grown in paddy culture in outdoor, naturally sunlit, controlled-envi$ronment, plant growth chambers at Gainesville, Florida, USA, in 1987. The rice plants were exposed throughout the season t$o subambient (160 and 250), ambient (330) or superambient (500, 660, 900 umol CO2/mol air) CO2 concentrations. Total shoot$ biomass, root biomass, tillering, and final grain yield increased with increasing CO2 concentration, the greatest increas$e occurring between the 160 and 500 umol CO2/mol air treatments. Early in the growing season, root:shoot biomass ratio inc$reased with increasing CO2 concentration; although the ratio decreased during the growing season, net assimilation rate in$creased with increasing CO2 concentration and decreased during the growing season. Differences in biomass and lamina area $among CO2 treatments were largely due to corresponding differences in tillering response. The number of panicles/plant was$ almost entirely responsible for differences in final grain yield among CO2 treatments. Doubling the CO2 concentration fro$m 330 to 660 umol CO2/mol air resulted in a 32% increase in grain yield. These results suggest that important changes in t$he growth and yield of rice may be expected in the future as the CO2 concentration of the earth's atmosphere continues to rise.J\ ;Vu;Lu++\ BT \L&T ;Vt\L }\\ J\LT _YA;N}jFËv~NI3҈Vz$763^8^Baker,J T^Allen,L H,Jr^Boote,K J^Rowland-Bamford,A J^Jones,J W^Jones,P H^Bowes,G^Albrecht,S L^1988^5^Response of Ric$e to Subambient and Superambient Carbon Dioxide Concentrations 1986-1987 Progress Report^U.S. Dept. of Energy, Carbon Diox$ide Research Division, and U.S. Dept. of Agriculture, Agric. Res. Serv., Washington, D.C^^^^^^^^^^^^^^^^^^^^^^^^rice/Oryza sativa^^043 in Green Report Series^Response of Vegetation to Carbon Dioxide^^^^^V݋^~^Fv&4^s X@;F$764^5^Baker,J T^Allen,L H,Jr^Boote,K J^Jones,P^Jones,J W^1989^1^Response of Soybean to Air Temperature and Carbon Dioxide Concentration^12^29^^98-105^^^^^^^^^^1919^^^^^^^^^^^soybean/Glycine maxmax L. Merr.46RQ$not change and that there were no characteristic adaptations to long-term growth (up to 20 weeks) at elevated CO2 concentr$A^1917^Documented increases in global atmospheric CO2 concentration have stimulated interest in the direct effects of CO2 $on plant growth and yield as well as the interactive effects of CO2 with other major climatic variables. This study was co$nducted to determine the effects and interactions of CO2 concentration and air temperature on the development, growth, tot$al nonstructural carbohydrate (TNC), and final seed yield of soybean [_Glycine max_ (L.) Merr., cv. Bragg] grown season-lo$ng in naturally lit, controlled-environment chambers. Day/night air temperatures of 26/19, 31/24 and 36/29C were maintain$ed in CO2 treatments of 330 and 660 umol CO2/mol air. Both CO2 enrichment and increasing air temperature decreased main st$em plastochron interval, while increasing air temperature increased final mainstem node number. Leaf area and above-ground$ biomass increased with CO2 enrichment and with temperature from 26/19C to 31/24C. The nonlinear increase with temperatu$re in leaf area, aboveground biomass, and plastochron interval was attributed to the highest temperature treatment being n$ear or above the optimum for soybean growth and development. Seed yield increased with CO2 enrichment due mainly to an inc$rease in seed number rather than weight per seed. Individual seed weight decreased, while seed number increased with incre$asing temperature. Leaflet TNC was relatively stable throughout the day. Stem TNC was less affected by CO2 than by tempera$ture treatment and decreased with increasing temperature. These results indicate that the response of soybean to elevated CO2 concentration is highly temperature dependent.u Da`tT|r ZʃO${sFҍ^${rF3$v3Dj u $765^3^Baker,J T^Allen,L H,Jr^Boote,K J^1992^1^Response of Rice to Carbon Dioxide and Temperature^46^60^^153-166^^^^^^^^^^1922^^^^^^^^^^^rice/Oryza sativaiva L.^_ZY[XPSQRWD;D u L33TrID ;D|1+D ;Du&L33ɉ L\rO$ured in the enzyme activites between the two CO2 concentrations. The results suggest that the photosynthetic capacity did $A^1920^The current increase in atmospheric carbon dioxide concentration ([CO2]) along with predictions of possible future $increases in global air temperatures have stimulated interest in the effects of [CO2] and temperature on the growth and yi$eld of food crops. This study was conducted to determine the effects and possible interactions of [CO2] and temperature on$ the growth and yield of rice (_Oryza sativa_ L., cultivar IR-30). Rice plants were grown for a season in outdoor, natural$ly sunlit, controlled-environment, and plant growth chambers. Temperature treatments of 28/21/25, 34/27/31, and 40/33/37C$ (daytime dry bulb air temperature/night-time dry bulb air temperature/paddy water temperature) were maintained in [CO2] t$reatments of 330 and 660 umol CO2/mol air. In the 40/33/37C temperature treatment, plants in the 330 umol/mol [CO2] treat$ment died during stem extension while the [CO2] enriched plants survived but produced sterile panicles. Plants in the 34/2$7/31C temperature treatments accumulated biomass and leaf area at a faster rate early in the growing season than plants i$n the 28/21/25C temperature treatments. Tillering increased with increasing temperature treatment. Grain yield increases $owing to [CO2] enrichment were small and non-significant. This lack of [CO2] response on grain yield was attributed to the$ generally lower levels of solar irradiance encountered during the late fall and winter when this experiment was conducted$. Grain yields were affected much more strongly by temperature than [CO2] treatment. Grain yields declined by an average o$f approximately 7-8% per 1C rise in temperature from the 28/21/25 to 34/27/31C temperature treatment. The reduced grain $yields with increasing temperature treatment suggests potential detrimental effects on rice production in some areas if air temperatures increase, especially under conditions of low solar irradiance.MK>JtFF&3K9&Mu]^ZY[X_$766^5^Baker,J T^Allen,L H,Jr^Boote,K J^Jones,P^Jones,J W^1990^1^Rice Photosynthesis and Evapotranspiration in Subambient, Ambient, and Superambient Carbon Dioxide Concentrations^4^82^^834-840^^^^^^^^^^1925^^^^^^^^^^^rice/Oryza sativava L.+y$hoot development and at different positions within the plant canopy. Generally, there were no significant differences meas$A^1923^The current global rise in atmospheric carbon dioxide concentration [CO2], has stimulated interest in the response $of agricultural crops to [CO2]. The objectives were to determine the effects of [CO2] on photosynthesis, evapotranspiratio$n, and water use efficiency of rice (_Oryza sativa_ L., cv. IR-30). Rice plants were grown in naturally sunlit, plant grow$th chambers in subambient (160 and 250), ambient (330), or superambient (500, 660, and 900 umol CO2/mol air) [CO2] treatme$nts. Photosynthetic light response curves were analyzed to obtain estimates of canopy light utilization efficiency () and$ canopy conductance to CO2 transfer (). Estimates of increased with increasing [CO2] treatment with the greatest increa$se in the 160 to 500 umol/mol treatments. Estimates of were more variable than those of and were not different among [$CO2] treatments. Photosynthetic rates increased with increasing [CO2] treatment from 160 to 500 umol/mol followed by a lev$eling off of the response among the superambient [CO2] treatments. Evapotranspiration decreased while water-use efficiency$ increased with increasing [CO2]. Short-term cross-switching of [CO2] among the chambers revealed a profound adaptive resp$onse to long-term [CO2] growth treatment. The lack of further photosynthetic response above the 500 umol/mol [CO2] treatme$nt appears to indicate a need to select or screen rice cultivars for increased response to superambient [CO2] in order to more fully take advantage of future increases in global atmospheric [CO2].F ^SH${sF ^>^5&6$767^8^Baker,J T^Allen,L H,Jr^Boote,K J^Rowland-Bamford,A J^Jones,J W^Jones,P H^Bowes,G^Laugel,F^1989^5^Temperature and CO2$ Effects on Rice. 1988 Progress Report^U.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of Agricultu$re, Agric. Res. Serv., Washington, D.C^^^^^^^^^^^^^^^^^^^^^^^^Oryza sativa/rice^^053 in Green Report Series^Response of Vegetation to Carbon Dioxide^^^^36U32&&6U32&!&6U 32&%&#^ZY[XPSQRV6D 6e$768^3^Baker,J T^Allen,L H,Jr^Boote,K J^1992^1^Temperature Effects on Rice at Elevated CO2 Concentration^39^43^^959-964^^^^^^^^^^1929^^^^^^^^^^^rice/Oryza sativaiva L.L &&~A;N}<&VB3NN&u| t| t I&$ental lighting for 2 years. Measurements of initial and Mg++-CO2-activated activities of Rubisco and CA were made during s$A^1927^The continuing increase in atmospheric carbon dioxide concentration ([CO2]) and projections of possible future incr$eases in global air temperatures have stimulated interest in the effects of these climate variables on agriculturally impo$rtant food crops. This study was conducted to determine the effects of [CO2] and temperature on rice (_Oryza sativa_ L., c$v. IR-30). Rice plants were grown season-long in outdoor, naturally sunlit, controlled-environment, plant growth chambers $in temperature regimes ranging from 25/18/21C to 37/30/34C (daytime dry bulb air temperature/night-time dry bulb air tem$perature/paddy water temperature) and [CO2] of 660 umol CO2/mol air. An ambient chamber was maintained at a [CO2] of 330 u$mol/mol and temperature regime of 28/21/25C. Carbon dioxide enrichment at 28/21/25C increased both biomass accumulation $and tillering and increased grain yield by 60%. In the 660 umol/mol [CO2] treatment, grain yield decreased from 10.4 to 1.$0 Mg/ha with increasing temperature from 28/21/25C to the 37/30/34C temperature treatment. Across this temperature range$, the number of panicles/plant nearly doubled while the number of seeds/panicle declined sharply. These results indicate t$hat while future increase in atmospheric [CO2] are likely to be beneficial to rice growth and yield, potentially large negative effects on rice yield are possible if air temperatures also rise.VԉF6M3~(6M +&+&6M&+&$769^4^Baker,J T^Laugel,F^Boote,K J^Allen,L H,Jr^1992^1^Effects of Daytime Carbon Dioxide Concentration on Dark Respiration in Rice^16^15^^231-239^^^^^^^^^^1932^^^^^^^^^^^rice/Oryza sativaiva L.&>u&>uPSQRVW+@F&+$2 years at ambient and 900 uL CO2/L during winter and spring with 75 umol/m2/s photosynthetically active radiation supplem%A^1930^Rising atmospheric carbon dioxide concentration ([CO2]) has generated considerable interest in the response of agri%cultural crops to [CO2]. The objectives of this study were to determine the effects of a wide range of daytime [CO2] on da%rk respiration of rice (_Oryza sativa_ L. cv. IR-30). Rice plants were grown season-long in naturally sunlit plant growth %chambers in subambient (160 and 250), ambient (330), or superambient (500, 660 and 900 umol CO2/mol air) [CO2] treatments.% Canopy dark respiration, expressed on a ground area basis (Rd) increased with increasing [CO2] treatments and was very si%milar among the superambient treatments. The trends in Rd over time and in response to increasing daytime [CO2] treatment %were associated with and similar to trends previously described for photosynthesis. Specific respiration rate (Rdw) decrea%sed with time during the growing season and was higher in the subambient than the ambient and superambient [CO2] treatment%s. This greater Rdw in the subambient [CO2] treatments was attributed to a higher specific maintenance respiration rate and was associated with higher plant tissue nitrogen concentration.G^ N F+@VsF_^ZY[XPSQRVWfF% 770^3^Bultot,F^Dupriez,G L^Gellens,D^1988^1^Estimated Annual Regime of Energy-Balance Components, Evapotranspiration and Soil Moisture for a Drainage Basin in the Case of a CO2 Doubling^88^12^^39-56^^^^^^^^^^1934F&)3& x&6DV3% A^1933^Assuming a doubling of the atmospheric CO2 concentration, parameters of an empirical formula for calculating the da% ily net terrestrial radiation under the climatic conditions of Belgium are determined. The developed method takes into acc%ount information yielded by climate models about the CO2 impact. Annual regimes of the energy balance components are calcu%lated for a drainage basin in Belgium. A daily step conceptual hydrological model (developed at the Royal Meteorological I%nstitute of Belgium) was run to estimate the effective evapotranspiration and the soil moisture in the 2xCO2 case; results of this simulation are compared with the present day condition.d@ЋF zR3ҋNJ 2RF3ҊL*؊$Z€%771^3^Campbell,W J^Allen,L H,Jr^Bowes,G^1987^3^Effects of Short-term and Long-term Exposures to Varying CO2 Concentrations% on Soybean Photosynthesis^Progress in Photosynthesis Research^Martinus Nijhoff Publishers^Dordrecht, The Netherlands^IV.5.253-IV.5.256^^^^IV^^^^^^1937^^^^^^^^^^^soybean/Glycine max^^^^^^^^^^Biggens,J^Biggens,J Merr.6GE6GE66W#ot) was lost from the roots at all CO2 concentrations at all times but the amounts of carbon lost per unit weight of plant%A^1935^Soybean plants grown at twice atmospheric concentrations of CO2 had greater leaf photosynthesis rates than plants g%rown at atmospheric concentrations of CO2, across a range of measurement CO2 levels. Several explanations for this were explored.F _^ZY[XPI&2K.h&d&&d@.hPSQRVWHF2VV ^2;Vu tF;VtA~%772^3^Campbell,W J^Allen,L H,Jr^Bowes,G^1988^1^Effects of CO2 Concentration on Rubisco Activity, Amount, and Photosynthesis in Soybean Leaves^17^88^^1310-1316^^^^^^^^^^1940^^^^^^^^^^^soybean/Glycine maxmax (L.) Merr.wNFvNF~$) and carbonic anhydrase (CA) of greenhouse roses were studied. Plants of _Rosa_ x _hybrida_ 'Red Success' were grown for %A^1938^Growth at an elevated CO2 concentration resulted in an enhanced capacity for soybean (_Glycine max_ L. Merr. cv Bra%gg) leaflet photosynthesis. Plants were grown from seed in outdoor controlled-environment chambers under natural solar irr%adiance. Photosynthetic rates, measured during the seed filling stage, were up to 150% greater with leaflets grown at 660 %compared to 330 microliters of CO2 per liter when measured across a range of intercellular CO2 concentrations and irradian% ce. Soybean plants grown at elevated CO2 concentrations had heavier pod weights per plant, 44% heavier with 660 compared t%!o 330 microliters of CO2 per liter grown plants, and also greater specific leaf weights. Ribulose 1,5-bisphosphate carboxy%"lase/oxygenase (rubisco) activity showed no response (mean activity of 96 micromoles of CO2 per square meter per second ex%#pressed on a leaflet area basis) to short-term (about 1 hour) exposures to a range of CO2 concentrations (110-880 microlit%$ers per liter), nor was a response of activity (mean activity of 1.01 micromoles of CO2 per minute per milligram of protei%%n) to growth CO2 concentration (160-990 microliters per liter) observed. The amount of rubisco protein was constant, as gr%&owth CO2 concentration was varied, and averaged 55% of the total leaflet soluble protein. Although CO2 is required for act%'ivation of rubisco, results indicated that within the range of CO2 concentrations used (110-990 microliters per liter), rubisco activity in soybean leaflets, in the light, was not regulated by CO2.BsDԊ423$2:v$2:v2%)773^3^Campbell,W J^Allen,L H,Jr^Bowes,G^1990^1^Response of Soybean Canopy Photosynthesis to CO2 Concentration, Light and Temperature^39^41^^427-433^^^^^^^^^^1943^^^^^^^^^^^soybean/Glycine maxmax (L.) Merr.??_x_yvߟ?z_{%A^183^The effect of prolonged CO2 enrichment on the activities of ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco%,A^1941^Photosynthetic rates of outdoor-grown soybean (_Glycine max_ L. Merr. cv. Bragg) canopies increased with increasing%- CO2 concentration during growth, before and after canopy closure (complete light interception), when measured over a wide%. range of solar irradiance values. Total canopy leaf area was greater as the CO2 concentration during growth was increased%/ from 160 to 990 mm3/dm3. Photosynthetic rates of canopies grown at 330 and 660 mm3 CO2/dm3 were similar when measured at %0the same CO2 concentrations and high irradiance. There was no difference in ribulose _bis_phosphate carboxylase/oxygenase %1(rubisco) activity or ribulose 1,5-_bis_phosphate (RuBP) concentration between plants grown at the two CO2 concentrations.%2 However, photosynthetic rates averaged 87% greater for the canopies grown and measured at 660 mm3 CO2/dm3. A 10C differe%3nce in air temperature during growth resulted in only a 4C leaf temperature difference, which was insufficient to change %4the photosynthetic rate or rubisco activity in canopies grown and measured at either 330 or 660 mm3 CO2/dm3. RuBP concentr%5ations decreased as air temperature during growth was increased at both CO2 concentrations. These data indicate that the i%6ncreased photosynthetic rates of soybean canopies at elevated CO2 are due to several factors, including: more rapid develo%7pment of the leaf area index; a reduction in substrate CO2 limitation; and no downward acclimation in photosynthetic capacity, as occur in some other species.NfV2>Pu8: 6PL^PSQRVW >E u uhf%9774^2^Cornic,G^Briantais,J-M^1991^1^Partitioning of Photosynthetic Electron Flow between CO2 and O2 Reduction in a C3 Leaf%: (_Phaseolus vulgaris_ L.) at Different CO2 Concentrations and during Drought Stress^51^183^^178-184^^^^^^^^^^1946^^^^^^^^^^^Phaseolus vulgaris/bean./beanB&D &&TD&D&\&T&\&D ^ ܡVvvDBHFsF_^ZY^^^^^^^^^^^Solanum melongena/eggplanthh|hh|h;uN VNVG 33^ A+f%=A^1944^Photosystem II chlorophyll fluorescence and leaf net gas exchanges (CO2 and H2O) were measured simultaneously on be%>an leaves (_Phaseolus vulgaris_ L.) submitted either to different ambient CO2 concentrations or to a drought stress. When %?leaves are under photorespiratory conditions, a simple fluorescence parameter delta F/Fm (B. Genty et al. 1989, Biochem. B%@iophys. Acta 990: 87-92; delta F = difference between maximum, Fmv and steady-state fluorescence emissions) allows the cal%Aculation of the total rate of photosynthetic electron-transport and the rate of electron transport to O2. These rates are %Bin agreement with the measurements of leaf O2 absorption using 18-O2 and the kinetic properties of ribulose-1,5-bisphospha%Cte carboxylase/oxygenase. The fluorescence parameter, delta F/Fm, showed that the allocation of photosynthetic electrons t%Do O2 was increased during the desiccation of a leaf. Decreasing leaf net CO2 uptake, either by decreasing the ambient CO2 %Econcentration or by dehydrating a leaf, had the same effect on the partitioning of photosynthetic electrons between CO2 an%Fd O2 reduction. It is concluded that the decline of net CO2 uptake of a leaf under drought stress is only due, at least fo%Gr a mild reversible stress (causing at most a leaf water deficit of 35%), to stomatal closure which leads to a decrease in%H leaf internal CO2 concentration. Since, during the dehydration of a leaf, the calculated internal CO2 concentration remained constant or even increased we conclude that this calculation is misleading under such conditions.DhIDN.S&X-%J775^5^Cure,J D^Galloway,L F^El Dodo,M^Israel,D W^Rufty,T W,Jr^1989^5^Growth and Carbon Budgets of Soybean Leaves Exposed t%Ko Elevated Carbon Dioxide^U.S. Dept. of Energy, Carbon Dioxide Research Division, Washington, D.C^^^^^^^^^^^^^^^^^^^^^^^^soybean/Glycine max^^048 in Green Report Series^Response of Vegetation to Carbon Dioxide^^ Dioxide^^esponse of Vegetation%M776^4^Cure,J D^Galloway,L F^Israel,D W^Rufty,T W,Jr^1986^5^Influence of Nutrition on Vegetation Response to Carbon Dioxide%N. I. Interactions of Nitrogen and Phosphorus Supply on Soybean Growth and Nutritional Parameters^U.S. Dept. of Energy, Car%Obon Dioxide Research Division; Washington, D.C^^^^^^^^^^^^^^^^^^^^^^^^soybean/Glycine max^^033 in Green Report Series^Response of Vegetation to Carbon Dioxide^^ Dioxide^^rA[Yr9XYуr0[Yуr%[Ãr tڃ؃]_[YË%Q777^3^Cure,J D^Rufty,T W,Jr^Israel,D W^1989^1^Alterations of Soybean Leaf Development and Photosynthesis in a CO2-Enriched Atmosphere^84^150^^337-345^^^^^^^^^^1951^^^^^^^^^^^soybean/Glycine maxmax (L.) Merr.UWVQS03 u t` y ؃ nment and translocate labeled compounds into the shoot.t؃[Y^_]QSF^N ȋNuFᓋFf؋F%TA^1949^This study was conducted to characterize changes in the canopy photosynthetic leaf area of developing soybean (_Gly%Ucine max_ [L.] Merr. cv. Lee) exposed to a CO2-enriched atmosphere. Young, vegetative plants were exposed to 350 or 700 uL%V/L CO2 for 15 d. Plant dry mass and total leaf area were greater in the CO2-enriched environment. Emergence and expansion %Wrates of main stem leaves increased at high CO2, but the areas of individual leaves at full expansion were affected very l%Xittle (5-10% greater than controls). More rapid leaf expansion rates occurred in the light and dark. Under CO2-enriched co%Ynditions, the net CO2 exchange rates of all leaves on the main stem were higher before and after full expansion. Stomatal %Zconductance was lower in high CO2 only after leaves approached full expansion. Leaf development on the lateral branches al%[so was increased at high CO2, accounting for 40% of the total increase in leaf area by the end of the experiment. We concl%\ude that more rapid rates of leaf development under CO2 enrichment likely resulted from increased photosynthesis rates and that both direct and indirect effects were involved.7&a``TmT6:r: ٚ${s6:U36:sB${%^778^3^Cure,J D^Rufty,T W,Jr^Israel,D W^1987^1^Assimilate Utilization in the Leaf Canopy and Whole-Plant Growth of Soybean during Acclimation to Elevated CO2^84^148^^67-72^^^^^^^^^^1954^^^^^^^^^^^soybean/Glycine maxmax L. Merr.66c 6P%Rnd leaf area. Applications of 14-CO2 to the root zone demonstrated that 14C eggplant roots absorb CO2 from the soil enviro%aA^1952^Young vegetative soybeans (_Glycine max_ 'Ransom') were exposed to control (350 uL/L CO2) or CO2 enriched (700 uL/L%b CO2) environments continuously for 22 days. Alterations in carbon acquisition, assimilate utilization by the leaf canopy %cand whole-plant growth were followed to characterize plant acclimation at high CO2. Whole-plant dry weight (DW) progressiv%dely increased at high CO2 relative to the control throughout the experiment. The initial DW increases were associated with%e the accumulation of nonstructural assimilates in leaves and increased specific leaf weight (SLW). After 3 days, however, %fDW began to accumulate rapidly in stems and roots under high CO2, and SLW no longer increased relative to controls. Total %gleaf area did not increase significantly at high CO2 until 13 days after the start of treatments. Net assimilation rates d%heclined under both CO2 conditions but remained higher at 700 uL/L CO2 throughout the experiment. The increases in stem and%i root DW during week 1 at high CO2 were accompanied by (1) an early increase in the estimated rate of assimilate utilizati%jon in the canopy during the dark phase of the diurnal cycle and (2) a later increase in the estimated rate of assimilate u%ktilization during the light phase. The results indicate that dark mobilization of assimilates from source leaves responded%l to variations in assimilate accumulation but that export of assimilates from source leaves in the light adjusted more slowly and appeared to be coordinated with large changes in sink activity in the whole plant.Us66+>6;>bUs߷6%n779^3^Cure,J D^Rufty,T W,Jr^Israel,D W^1991^1^Assimilate Relations in Source and Sink Leaves during Acclimation to a CO2-Enriched Atmosphere^44^83^^687-695^^^^^^^^^^1957^^^^^^^^^^^soybean/Glycine maxmax L. Merr. 7NuXPSR>7u$>7%_long day/warm temperature conditions. Under periods of short days and low light levels, 15% CO2 reduced total dry weight a%qA^1955^Evidence from previous studies suggested that adjustments in assimilate formation and partitioning in leaves might %roccur over time when plants are exposed to enriched atmospheric CO2. We examined assimilate relations of source (primary u%snifoliate) and developing sink (second mainstem trifoliate) leaves of soybean [_Glycine max_ (L.) Merr. cv. Lee] plants fo%tr 12 days after transfer from a control (350 uL/L) to a high (700 uL/L) CO2 environment. Similar responses were evident in%u the two leaf types. Net CO2 exchange rate (CER) immediately increased and remained elevated in high CO2. Initially, the a%vdditional assimilate at high CO2 levels in the light was utilized in the subsequent dark period. After approximately 7 day%ws, assimilate export in the light began to increase and by 12 days reached rates 3 to 5 times that of the control. In the %xdeveloping sink leaf, high rates of export in the light occurred as the leaf approached full expansion. The results indica%yte that a specific acclimation process occurs in source leaves which increases the capacity for assimilate export in the light phase of the diurnal cycle as plants adjust to enriched CO2 and a more rapid growth rate.t>ktJ8):rC=u7%{780^3^Cure,J D^Rufty,T W,Jr^Israel,D W^1988^1^Phosphorus Stress Effects on Growth and Seed Yield Responses of Nonnodulated Soybean to Elevated Carbon Dioxide^4^80^^897-902^^^^^^^^^^1960^^^^^^^^^^^soybean/Glycine maxmax L. Merr.rQW>7M%ostently increased stem diameter while a significant increase in plant total dry weight and leaf area only occurred during %~A^1958^The influence of P availability on plant responses to elevated atmospheric CO2 concentrations has received limited %research attention. Therefore, an experiment was conducted to examine the effect of a wide range of P availabilities on pl%ant response to enriched atmospheric CO2. Nonnodulating soybean [_Glycine max_ (L.) Merr., 'Lee'] plants were grown from g%ermination to maturity in controlled environment chambers at 350 or 700 uL/L CO2 and supplied with a complete nutrient sol%ution containing either 0.005, 0.10, 0.25, 0.50, or 1.00 mM P. Growth and seed yield were maximized at the 0.25 and 0.50 m%M P concentrations at 350 and 700 uL/L CO2, respectively. Growth and yield were significantly increased by CO2 enrichment %at all except the lowest P concentration. The stimulation of growth at high CO2 was consistently associated with increased% leaf area, net assimilation rate, P uptake, and P utilization efficiency in the production of dry matter. When averaged o%ver the four highest P levels, total root mass was increased 63% by CO2 enrichment, but P uptake efficiency per unit root %mass was decreased 22%. The yield enhancement of 23 to 57% at high CO2 was associated with increases in the number and siz%e of seed. Carbon dioxide enrichment had no significant effect on harvest index. The results indicate that CO2 enrichment %can result in stimulation of growth and yield of nonnodulated, NO3-fed soybean plants, even at concentrations of P that limit plant growth at ambient CO2 concentration.78 u a,s <.t uO3Nv3=:*6=:Naˋ6v76x%781^5^Curry,R B^Peart,R M^Jones,J W^Boote,K J^Allen,L H,Jr^1990^1^Response of Crop Yield to Predicted Changes in Climate and Atmospheric CO2 Using Simulation^118^33^^1383-1390^^^^^^^^^^1963^^^^^^^^^^^soybean/Glycine maxmax (L.) Merr.XSW:%|entration in the soil on the growth of eggplant (_Solanum melongena_ L.). Elevated CO2 levels in the root atmosphere consi%A^1961^Soybean growth and yield for 19 locations in southeastern U.S.A. were simulated for 30 years (1951-80) of climate d%ata. Three different climate change scenarios, with and without supplemental irrigation, were used with the SOYGRO crop mo%del. The three climate scenarios were standard historic data and two scenarios based on changes predicted by two general c%irculation models (GCM) for a doubling of atmospheric carbon dioxide. Results were analyzed for four different conditions:% normal weather, doubled CO2 alone, climate change alone, and the combined effect of climate change and doubled CO2. Resul%ts indicate 1) yields vary widely with climate scenario; 2) increased water use and irrigation need for the combined case of doubled CO2 and climate change; and 3) simulation is a useful tool for this type of study.X::u N: %782^5^Doyle,T W^Taylor,F G^Parker,M L^Cooper,C F^West,D C^1985^5^Preliminary Ring-Width and Ring-Density Data for Deriving% Wood Mass Chronologies of Coniferous Species from the Northwest U.S. and Canada^U.S. Dept. of Energy, Carbon Dioxide Rese%arch Division, Washington, D.C., and Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee^%^^^^^^^^^^^^^^^^^^^^^^^white spruce/red pine/Douglas-fir/Western hemlock/Western red cedar/Engelmann spruce/lodgepole pine/yellow cedar/black spruce^^025 in Green Report Series^Response of Vegetation to Carbon Dioxide^^rgRu ]8g9 B$:@B%785^7^Hileman,D R^Ghosh,P P^Bhattacharya,N C^Biswas,P K^Allen,L H,Jr^Peresta,G^Kimball,B A^1992^1^A Comparison of the Uniformity of an Elevated CO2 Environment in Three Different Types of Open-top Chambers^8^11^^195-202^^^^^^^^^^1972972%on boron is necessary to confirm this hypothesis. Fruit production was significantly higher (24%) at high CO2 than low CO2%A^1970^Carbon dioxide levels were determined at various points inside three different types of open-top chambers (square, %round without frustum and round with frustum), to compare the variability in CO2 concentrations among the different types %of chambers. At similar rates of injection of CO2 into the fan housings of the three chambers, CO2 levels were highest in %the round chamber with a frustum and lowest in the square chamber. The lower enrichment levels in the square chamber were %most likely due to greater air movement by the fan. Variability in CO2 concentration was lowest in the round chamber with %a frustum. Variability was similar in the round (without frustum) and square chambers, except at the upper heights, where %variability was somewhat greater in the shorter, square chamber. These trends were true both for variability from point to% point within chambers and for variability over time. In both the square chamber and the round chamber without a frustum, %CO2 levels were frequently lower and more variable in the downwind side of the chamber than in the upwind side. The round chamber with the frustum showed no evidence of a wind direction effect.6:t:_ZYXP8@ 8A t Ȋ8%786^2^Hocking,P J^Meyer,C P^1985^1^Responses of Noogoora Burr (_Xanthium occidentale_ Bertol.) to Nitrogen Supply and Carbon Dioxide Enrichment^35^55^^835-844^^^^^^^^^^1975^^^^^^^^^^^Xanthium occidentale/cocklebur^ol.)/cocklebur:_^ZY[XPSQ%s caused by reduced translocation to young, fast growing leaves, because of reduced transpiration. More specific research %A^1973^We studied the responses of _Xanthium occidentale_ (Bertol.) (cocklebur or Noogoora burr), a noxious weed, to atmos%pheric CO2 enrichment and nitrate-N concentrations in the root zone ranging from 0.5 to 25 mM. CO2 enrichment (1500 cm3/m3%) increased dry-matter production to about the same extent (18 per cent) at all levels of supplied N: most of the incremen%t in dry matter was distributed equally between leaves and roots so that there was little effect on shoot-to-root dry-weig%ht ratios. Growth was stimulated greatly by N and plateaued at 12 mM supplied N. Shoot-to-root dry-weight and total N rati%os increased with increasing N supply. CO2 enrichment had no effect on the total amount of N accumulated by plants, but in%creased the N-use efficiency of leaves. Enriched plants had lower concentrations and quantities of N in their leaves than %controls, and therefore lower shoot-to-root total N ratios. Little free NO3 accumulated in organs of control or enriched p%lants. NO3 was a major form of N in xylem sap from detopped plants at low supplied NO3-N, but amino N was equal in importa%nce at high supplied NO3-N in control and enriched plants. Concentrations of NO3 were lower in the xylem sap of CO2 enrich%ed plants. It was concluded that the better N-use efficiency of CO2 enriched plants could result in increased growth of _X. occidentale_ in regions of marginal soil fertility as atmospheric levels of CO2 increase.tO@+GtsRVWUP%787^3^Idso,S B^Kimball,B A^Mauney,J R^1988^1^Atmospheric CO2 Enrichment and Plant Dry Matter Content^46^43^^171-181^^^^^^^%^^^1978^^^^^^^^^^^carrot/Daucus carota/cotton/Gossypium hirsutum/radish/Raphanus sativus/soybean/Glycine max/water fern/Azolla pinnata/water hyacinth/Eichhornia crassipes/Agave vilmoriniana/tomato/Lycopersicon esculentumniana Berger/tomato/Lyc%on content was lower in leaves with LTC than in other leaves and was lower in leaves from high CO2 than in those from low %CO2. These results, in combination with observed reduction in leaf conductance (part I), support the hypothesis that LTC i%A^1976^Fresh and dry plant weights were measured throughout a number of different CO2 enrichment experiments with six terr%estrial plants and two aquatic species. Similar data were also extracted from the literature for 18 additional plants. In %general, CO2 enrichment had little effect on plant percentage dry matter content, except under conditions conducive to starch accumulation in leaves, and then it caused an increase in percentage dry matter content.GXr u wt;Gr P%788^3^Israel,D W^Rufty,T W,Jr^Cure,J D^1990^1^Nitrogen and Phosphorus Nutritional Interactions in a CO2 Enriched Environment^72^13^^1419-1433^^^^^^^^^^1981^^^^^^^^^^^soybean/Glycine maxmax (L.) Merr.VWrWr_^Y˃'QVWrr t%uplicate, in four glasshouse compartments (16m x 16m). LTC was significantly more severe at high than at low CO2. Leaf bor%A^1979^Nonnodulated soybean plants (_Glycine max_ [L.] Merr. 'Lee') were supplied with nutrient solutions containing growt%h limiting concentrations of N or P to examine effects on N- and P- uptake efficiencies (mg nutrient accumulated/gdw root)% and utilization efficiencies in dry matter production (gdw2/mg nutrient). Nutritional treatments were imposed in aerial e%nvironments containing either 350 or 700 uL/L atmospheric CO2 to determine whether the nutrient interactions were modified% when growth rates were altered. Nutrient-stress treatments decreased growth and N- and P- uptake and utilization efficien%cies at 27 days after transplanting (DAT) and seed yield at maturity (98 DAT). Atmospheric CO2 enrichment increased growth% and N- and P-utilization efficiencies at 27 DAT and seed yield in all nutritional treatments and did not affect N- and P-%uptake efficiencies at 27 DAT. Parameter responses to nutrient stress at 27 DAT were not altered by atmospheric CO2 enrichment and vice versa. Nutrient-stress treatments lowered the relative seed yield response to atmospheric CO2 enrichment.QR%789^2^Ke,D^Saltveit,M E,Jr^1989^1^Carbon Dioxide-induced Brown Stain Development as Related to Phenolic Metabolism in Iceberg Lettuce^3^114^^789-794^^^^^^^^^^1984^^^^^^^^^^^Lactuca sativa/lettuceettuceeDEDG@N_^[SQV t%ena_ L., cv. Cosmos) was investigated in the spring of 1991. Two levels of CO2 (413 and 663 umol/mol) were maintained in d%A^1982^Controlled atmospheres containing air + 11% CO2 caused tissue injury and induced phenylalanine ammonia-lyase (PAL, %EC 4.3.1.5) activity in iceberg lettuce (_Lactuca sativa_ L.) midrib tissue. Injury symptoms included brown stain (brownin%g of epidermal tissue) and sunken epidermal areas (pitting) a few millimeters in diameter. Pitting occurred in high-CO2 at%mospheres at 5C with no increase in phenolic content, but browning did not develop until the tissue had been transferred t%o air at 25C. Browning developed within several hours of transfer to air and the degree of browning was correlated with th%e soluble phenolic content. The oxidation of soluble phenolic compounds to brown substances by polyphenol oxidase (PPO, EC% 1.10.3.2) could account for tissue browning. Lignification was associated with cell wall thickening in discolored tissue %and was accompanied by an increase in ionically bound and soluble peroxidase (POD, EC 1.11.1.7) activities. Exposure of ti%ssue to elevated CO2 increased ionically bound indoleacetic acid (IAA) oxidase activity, but reduced soluble IAA oxidase a%ctivity. Application of an aqueous solution of 1.0 mM IAA to the tissue before treatment did not significantly reduce brow%ning. Lettuce tissue exposed to 1.5% O2 + 1% CO2 had reduced PAL activity and lower soluble phenolic content than lettuce %exposed to air + 11% CO2. Depending on the sensitivity of the lettuce tissue to CO2 injury, low-O2 atmospheres either reduced or slightly retarded browning induced by 11% CO2.CCC>CC.CCCC_^[YPSQRVWC tȡ%790^3^Kimball,B A^Pinter,P J,Jr^Mauney,J R^1992^1^Cotton Leaf and Boll Temperatures in the 1989 FACE Experiment^8^11^^233-240^^^^^^^^^^^^^^^^^^^^^cotton/Gossypium hirsutumtum L.crTGFG Fwr?Ft r3Cu,CPFnXrGW%A^1211^The effect of CO2 on leaf boron content, Leaf Tip Chlorosis (LTC) and fruit production of eggplant (_Solanum melong%791^8^Kimball,B A^Mauney,J R^Guinn,G^Nakayama,F S^Pinter,P J,Jr^Clawson,K L^Reginato,R J^Idso,S B^1983^5^Effects of Increa%sing Atmospheric CO2 on the Yield and Water Use of Crops^U.S. Dept. of Agriculture, Agric. Res. Serv., Washington, D.C^^^^^^^^^^^^^^^^^^^^^^^^cotton/Gossypium hirsutum^^021 in Green Report Series^Response of Vegetation to Carbon Dioxide^^^^Z%792^9^Kimball,B A^Mauney,J R^Guinn,G^Nakayama,F S^Pinter,P J,Jr^Clawson,K L^Idso,S B^Butler,G D^Radin,J R^1984^5^Effects o%f Increasing Atmospheric CO2 on the Yield and Water Use of Crops^U.S. Dept. of Energy, Carbon Dioxide Research Division, a%nd U.S. Dept. of Agriculture, Agric. Res. Serv., Washington, D.C^^^^^^^^^^^^^^^^^^^^^^^^cotton/Gossypium hirsutum^^023 in Green Report Series^Response of Vegetation to Carbon Dioxide^^^^ и  _^YXPV= uCt+C uC ͘*rZ,%793^4^Koch,K E^Allen,L H,Jr^Jones,P^Avigne,W T^1987^1^Growth of Citrus Rootstock (Carrizo Citrange) Seedlings During and After Long-term CO2 Enrichment^3^112^^77-82^^^^^^^^^^1991^^^^^^^^^^^Citrus sinensis/Poncirus trifoliata/Carrizo citrangee% crop submodel calculates leaf photosynthesis, crop photosynthesis, dry matter production and fresh weight production. As yet, the production of a tomato and of a cucumber can be simulated.so${dDDDXQQR tȃO$%&ZYWr&>&;>rr & &U&_Q& d${r&YV r&T^Ir&;6s &; t%^^^^^Pinus ponderosa Laws./ponderosa pine FWt= tN *rwu2^2;sOPDŽ&DŽ%^1687^Tree Physiol.k^6DŽ[Ƅ_^mcwW u^NV t7rp^_N]ҍ^&^1687^Seven-year-old ponderosa pine (_Pinus ponderosa_ Dougl. ex P. Laws.) saplings and one- and two- year-old ponderosa ine seedlings of a Sierra Nevada and a Rocky Mountain seed source, respectively, were exposed to CO2-enriched atmosphere&A^1989^Carrizo citrange seedlings [_Citrus sinensis_ (L.) Osbeck x _Poncirus trifoliata_ (L.) Raf.] were grown in field en&closures for 17 weeks during 1984 at 330, 660, or 990 uL/L CO2 and then transferred to ambient air for 10 weeks to examine& growth during and after these treatments. Immediately, after the CO2 treatment period, plants grown at the highest CO2 le&vel had accumulated about 120% more total dry matter than those at 330 uL/L CO2, compared to a mean increase of 67% at 660& uL/L. Shoot length, leaf area, and leaf number were also increased 71%, 55%, and 39%, respectively, at 990 uL/L CO2 and s&omewhat less at 660 uL/L. Percentage gains from CO2 enrichment decreased during the posttreatment period, but absolute dif&ferences were maintained or increased for at least 10 more weeks. During the treatment period, dry matter partitioning amo& ng leaves, stems, and roots did not vary with CO2 level, but root growth after transplanting and transfer to ambient air o& ccurred at the expense of shoot growth in plants that had been grown at ambient CO2 levels. Plant growth, in terms of dry & weight, shoot length, leaf area, and leaf number, was advanced 1.0 to 3.5 weeks after 17 weeks at elevated CO2 levels, and& fresh weight per centimeter of stem length was about 1 month ahead. This last parameter can be used as an approximate ind& icator of readiness for scion budding, suggesting that CO2 enrichment could represent a considerable value to the citrus n&ursery industry. Data are also consistent with the hypothesis that a greater response to elevated CO2 is likely to occur w&here a high sink demand and/or low levels of leaf starch are maintained. Both such demand and low leaf starch occur in citrus seedlings, which have a pronounced juvenility period and capacity for continuous flush-type growth.&794^4^Kuehny,J S^Peet,M M^Nelson,P V^Willits,D H^1991^1^Nutrient Dilution by Starch in CO2-enriched Chrysanthemum^39^42^^711-716^^^^^^^^^^1994^^^^^^^^^^^Chrysanthemum morifolium/chrysanthemumysanthemum(-((((((((((---(K:5::52>>(>5K:>%demand for heat and the necessity for ventilation. Both these factors are related to the CO2 fluxes to the greenhouse. The&A^1992^Increasing growth irradiance and CO2 generally decreases foliar nutrient concentration on a dry weight basis and in&creases foliar starch concentration. However, the extent to which starch concentrations 'dilute' foliar nutrient concentra&tions when the latter are expressed on a dry weight basis is not known. To determine the importance of differential starch& accumulation in calculating nutrient concentrations on a dry weight basis, leaf nutrient and starch concentrations were m&easured in _Chrysanthemum x morifolium_ 'Fiesta' (Ramat.) cuttings grown at three irradiance levels and two CO2 levels for& eight weeks in both winter and spring. On a dry weight basis, foliar concentrations of most nutrients were lower in both &seasons as a result of the elevated CO2 and irradiance levels, and total dry weights were higher. Per cent starch was grea&ter at the high CO2 level in both seasons but was only greater at higher irradiances in the winter experiment. When starch& was subtracted from the leaf dry weights, the differences between CO2 and irradiance treatments disappeared with respect to N, P, K, Ca, Mg, S, and B but not for Fe, Mn, Zn, and Cu.&795^11^Leavitt,S W^Paul,E A^Kimball,B A^Hendrey,G R^Mauney,J R^Rauschkolb,R^Rogers,H^Lewin,KF^Nagy,J^Pinter,PJ,Jr^Johnson,"7HB^1994^1^Carbon Isotope Dynamics of Free-Air CO2-Enriched Cotton and Soils^46^(in press)^^^^^^^^^^^^1997^^^^^^^^^^^cotton&greenhouse on the basis of outside weather data and specific setpoints for the greenhouse climate. It also calculates the &!A^1995^A role for soils as global carbon sink or source under increasing atmospheric CO2 concentrations has been speculati&"ve. Free-air carbon dioxide enrichment (FACE) experiments with cotton, conducted from 1989 to 1991 at the Maricopa Agricul&#tural Center in Arizona, maintained circular plots at 550 umol/mol CO2 with tank CO2 while adjacent ambient control plots &$averaged about 370 umol/mol CO2. This provided an exceptional test for entry of carbon into soils because the petrochemica&%lly-derived tank CO2 used to enrich the air above the FACE plots was depleted in both radiocarbon (14C content was 0% mode&&rn carbon [pmC] and 13C ([delta] 13C = about -36 per mil) relative to background air, thus serving as a potent isotopic tr&'acer. Flask air samples, and plant and soil samples were collected in conjunction with the 1991 experiment. Most of the is&(otopic analyses on plants were performed on the holocellulose component. Soil organic carbon was obtained by first removin&)g carbonate with HCl, floating off plant fragments with a NaCl solution, and picking out remaining plant fragments under m&*agnification. The [delta] 13C of the air above the FACE plots was approximately -15 to -19 per mil, i.e., much more 13C de&+pleted than the background air of approximately -7.5 per mil. The [delta] 13C values of plants and soils in the FACE plots&, were 10-12 per mil and 2 per mil [delta] 13C-depleted, respectively, compared with their control counterparts. The 14C co&-ntent of the FACE cotton plants was approximately 40 pmC lower than the control cotton, but the 14C results from soils wer&.e conflicting and therefore not as revealing as the [delta] 13C of soils. Soil stable-carbon isotope patterns were consist&/ent, and mass balance calculations indicate that about 10% of the present organic carbon content in the FACE soil derived &0from the 3 year FACE experiment. At a minimum, this is an important quantitative measure of carbon turnover, but the prese'nce of 13C-depleted carbon, even in the recalcitrant 6N HCl resistant soil organic fraction (average age 2200 years before&2796^2^Mauney,J R^Hendrix,D L^1988^1^Responses of Glasshouse Grown Cotton to Irrigation with Carbon Dioxide-saturated Water^12^28^^835-838^^^^^^^^^^^^^^^^^^^^^cotton/Gossypium hirsutumx]x]xxSnIoJnIx]o.x]xJ]Ao8xSxSxqSx]oJA..S48&cisions on investments in CO2 and heating equipment. The greenhouse climate submodel calculates the conditions inside the &5797^3^Nijs,I^Impens,I^Behaeghe,T^1989^1^Leaf and Canopy Responses of _Lolium perenne_ to Long-term Elevated Atmospheric Carbon-dioxide Concentration^51^177^^312-320^^^^^^^^^^2002^^^^^^^^^^^Lolium perenne/perennial ryegrassegrassxxxx8SxS]S&3 submodel and a crop submodel. The purpose of the model is to use it as a management system, which can be consulted for de&8A^2000^The relationship between leaf photosynthetic capacity (Pn,max), net canopy CO2- and H20-exchange rate (NCER and Et,&9 respectively) and canopy dry-matter production was examined in _Lolium perenne_ L. cv. Vigor in ambient (363 +/-30 uL/L) &:and elevated (631 +/-31 uL/L) CO2 concentrations. An open system for continuous and simultaneous regulation of atmospheric&; CO2 concentration and NCER and Et measurement was designed and used over an entire growth cycle to calculate a carbon and&< a water balance. While NCERmax of full-grown canopies was 49% higher at elevated CO2 level, stimulation of Pn,max was onl&=y 46% (in spite of a 50% rise in one-sided stomatal resistance for water-vapour diffusion), clearly indicating the effect &>of a higher leaf-area index under high CO2 (approx. 10% in one growing period examined). A larger amount of CO2-deficient &?leaves resulted in higher canopy dark-respiration rates and higher canopy light compensation points. The structural compon&@ent of the high-CO2 effect was therefore a disadvantage at low irradiance, but a far greater benefit at high irradiance. H&Aigher canopy dark-respiration rates under elevated CO2 level and low irradiance during the growing period are the primary &Bcauses for the increase in dry-matter production (19%) being much lower than expected merely based on the NCERmax differen&Cce. While total water use was the same under high and low CO2 levels, water-use efficiency increased 25% on the canopy lev&Del and 87% on a leaf basis. In the course of canopy development, allocation towards the root system became greater, while &Estimulation of shoot dry-matter accumulation was inversely affected. Over an entire growing season the root/shoot production ratio was 22% higher under high CO2 concentration.fffffffffffffffffSJ8"/6=Dz&G798^2^Radoglou,K M^Jarvis,P G^1990^1^Effects of CO2 Enrichment on Four Poplar Clones. I. Growth and Leaf Anatomy^35^65^^617-626^^^^^^^^^^2005^^^^^^^^^^^Populus trichocarpa/Populus euroamericana/Populus deltoidesdes&&H8H2H2H2H2H8H8H8H8>,B2H2&6A^725^In order to calculate the CO2 and heat demand in greenhouses, a simulation model is composed of a greenhouse climate&JA^2003^The poplar clones Columbia River, Beaupre, Robusta and Raspalje have been investigated under the present (350 umol/&Kmol) and double the present (700 umol/mol) atmospheric CO2 concentration. Cuttings were planted in pots and were grown in &Lopen-top chambers inside a glasshouse for 92 d. The number of leaves, total length of stem, total leaf area, overall growt&Mh rate, total leaf, stem and root d. wt responded positively to increased CO2, but the leaf size and biomass allocation sh&Nowed no change with CO2 enrichment. Beaupre and Robusta showed a larger growth response than either Columbia River or Rasp&Oalje. The effects of CO2 enrichment were restricted to the early phase of growth at the beginning of the growth season. Le&Paf cell numbers in all the clones were not affected by CO2 enrichment. Leaf thickness was affected; this was mainly the result of larger mesophyll cells and more extensive intercellular spaces.SS88Y!92^u#HHddd2Hdd9HHYYddd&R799^2^Radoglou,K M^Jarvis,P G^1993^1^Effects of Atmospheric CO2 Enrichment on Early Growth of _Vicia faba_, a Plant with Large Cotyledons^16^16^^93-98^^^^^^^^^^2008^^^^^^^^^^^Vicia faba/broad bean^^^^^^^^^^./broad beandddddddddddddHHddddddDC^2006^In Press; Plant Cell Environ.HHHHddddddHH&UA^2006^Seedlings of _Vicia faba_ L. were grown in open-top growth chambers at present (P = 350 umol/mol) and at elevated (&VE = 700 umol/mol) atmospheric CO2 concentration. The effects of CO2 enrichment on the first phase of growth after germinat&Wion were examined over 45 days. There were no positive effects of CO2 enrichment on growth of the seedlings during this ea&Xrly phase. No differences were observed in leaf area or in total dry weight. No differences were found in morphology or an&Yatomy of the leaves. The numbers of stomatal and epidermal cells, thickness of leaf of epidermis and of mesophyll cell-lay&Zers were unaffected by CO2 enrichment. Also no differences were observed in leaf concentrations of chlorophyll, reducing c&[arbohydrates or starch. These results contrast markedly with results from similar experiments on poplar hybrids and _Phase&\olus vulgaris_ obtained in the same growth facility. It seems that the initial growth is under internal control such that &]the atmospheric CO2 concentration has no effects. The lack of response in this case may be attributed to the presence and longevity of the large cotyledons which provided available substrate for growth.ddddddddddddddddHHddddddWC=NdHddd&_800^4^Rowland-Bamford,A J^Baker,J T^Allen,L H,Jr^Bowes,G^1991^1^Acclimation of Rice to Changing Atmospheric Carbon Dioxide Concentration^16^14^^577-583^^^^^^^^^^2011^^^^^^^^^^^rice/Oryza sativa^^^^L.^^^^HHHHHHHHHHH795-803^^^^^^^^^^2055^^^^^^^^^^^Solanum melongena/eggplant^^^^^,'J,C8^8U,C2W,H=?2=22C,F,C=L8N===L=?'Y,'W,F,,==,==&bA^2009^The effects were studied of season-long (75 and 88 d) exposure of rice (_Oryza sativa_ L. cv. IR-30) to a range of &catmospheric CO2 concentrations in outdoor, computer-controlled, environment chambers under natural solar radiation. The CO&d2 concentrations were maintained at 160, 250, 330, 500, 660 and 900 umol/mol air. Photosynthesis increased with increasing&e growth CO2 concentrations up to 500 umol/mol, but levelled off at higher CO2 values. Specific leaf area also increased si&fgnificantly with increasing CO2. Although leaf dry weight and leaf area index increased, the overall response was not stat&gistically significant. Leaf nitrogen content dropped slightly with elevated CO2, but the response was not statistically si&hgnificant. The specific activity of ribulose bisphosphate carboxylase/oxygenase (rubisco) declined significantly over the &iCO2 concentration range 160 to 900 umol/mol. When expressed on a leaf area basis, rubisco activity decreased by 66%. This &jwas accompanied by a 32% decrease in the amount of rubisco protein as a fraction of the total soluble leaf protein, and by&k 60% on a leaf area basis. For leaves in the dark, the total rubisco activity (CO2/Mg(++)-activated) was reduced by more t&lhan 60%. This indicates that rice accumulated an inhibitor in the dark, probably 2-carboxyarabinitol 1-phosphate (CA-1-P).&m However, the inhibitor did not seem to be involved in the acclimation response. The degree of carbamylation of the rubisc&no enzyme was unchanged by the CO2 growth regime, except at 900 umol/mol where it was reduced by 24%. The acclimation of ri&oce to different atmospheric CO2 conditions involved the modulation of both the activity and amount of rubisco protein in the leaf.+!!!!F0F0F0F0F0F0F0F0F0F0F+F0F/F0F0F060F+F+F+@+@+@+@+F=<+<+<+<+F0F0F0F0F0F0F0F0!!!!D6%F0<<'<'Zahov}    % , %\  `$Times NewRoman'V& 8Document[8]Document Style0..8` ..` 'V8Document[4]Document Style.. . 'U!  W   X ORNL/CDIAC67  \ '@EnvironmentalSciencesDivision  @(  CarbonDioxideInformatio'sisCenter:     @ FY1993Activities  M  @Robert'hman@hand@FrederickW.Stoss*@Q CarbonDioxideInformationAnalysisCenter'EnvironmentalSciencesDivision@PublicationNo.4169@cDatePublished:October1993'9 *Energy,Environment,andResourcesCenter@TheUniversityofTennessee!Knoxville 'eparedfortheGlobalChangeResearchProgramEnvironmentalSciencesDivisionOfficeofHealthandEnvironmentalResearch'epartmentofEnergyBudgetActivityNumberKP0500000    PreparedbytheCarbonDioxideInform'nalysisCenterOakRidgeNationalLaboratoryOakRidge,Tennessee378316335managedbyMartinMariettaEnergySystems,I'theU.S.DepartmentofEnergyundercontractDEAC0584OR21400  i/+3  ' ;&-&&&-;X-X&;&-7&&d&&d7@'! TableofContents   !( Page   ! X'"X!ListofFigures"*.n 7v ^  ListofTables<"(.* 6vii 0 '#Acknowledgments#+. 7  ~  Abstract#+.T0 P  Introdu'$#+.4 "  Highlights"*.21 x OrganizationandStaff'%*. >3 J RequestResponseRecords(R3)System"*.UL7  '&DirectoryofGlobalChangeResearchersandPolicymakersH").e33 j SystemsH").''37 < CommunicationsH"). 639  CollaborativeEffortswithChina'().)H43 d NumericDataDistributionH").2 A45 6 Networking').l261 !  QuantitativeLinksSupportH").V B67 "V" OceanData'*.g269 $(!$ ARMNewsletterH"). 671 ~&"& WorldDataCenterA'+ ;73 P($(    +'+ bXb@. List',res    <X-X+X;X-Figure !( Page   '-X #X#*.1.0  CDIACorganization(September30,1993)#+.'.^  (# (# .2.0  Request/responseactivitiesworldmapforFY1993#+'/0  (# (# .3.0  Request/responseactivitiespiechartforFY1993'0n ~  (# (# .4.0  Request/responseactivitiesworldmapFY1985throu'1993#+.azP  (# (# .5.0  Request/responseactivitiespiech'21985throughFY1993#+.z"  (# (# .6.  Request/response'3iesgraphFY1985throughFY1993#+.wu x .7.  Countriesrepre'4intheWorldDirectory#+.h J .8.0  WorldDirectoryaffiliatio'5FY1993#+.9d (# (# .9.0  Numericdatarequestsworldmap'61993#+.^hj (# (# -10.0  Numericdatadistributionworld'71985throughFY1993#+.x< (# (# -11.  Numericdatadi'8iongraphFY1985throughFY1993#+.at  -12.  Numericdata'9equentlyrequestedsince1985#+.m d   M @j':ddListofTablesdd    =X-X+X<X-Table !(';e   .1.0  CDIACstaffFY1993#+.3Ou (# '<.2.  Request/responseactivities#+.W G  .3.0 '=DOEreportsdistribution#+.T   (# (# .4.0  CDIACreport'>ibution#+.V g  (# (# .5.0  Netadditionsintotalparticip'?#+._9  (# (# .6.0  Alphabeticallistingofcountriesandthe'@yingterritories#+.|  (# (# .7.0  Numericdatarequests'Atry#+.\a (# (# .8.0  Requestsfornumericdata#+'B3 (# (#     =- +X=X-@'C hhAcknowledgments hh  >- I=-Aswithanyco'Deeffort,thisreporthasbeenpreparedwiththehelpofmanypeople.CDIAC'sgreatestdebtistothecontributinginves'EsandresearcherswhosedatacomposethecoreofCDIAC'sinformationanalysisanddatapackaging.Wealsoextendourtha'Fthelaboratories,datacenters,agencies,institutions,andorganizationsthathavesupportedtheeffortsofthisresearc'Gnity.Wereitnotforthevoluntarycooperationanddedicationofthisgroupofresearchers,CDIAC,aswellasitsderiv'Hrmationproducts,comprehensiveinformationservices,andspecialtypublications,couldnotexist.Ourthanksarealsoe'ItothethousandsofpeoplefromaroundtheworldwhohavesoughtassistancefromCDIACoverthepastyear.CDIACwasfo'Jiththeintentofprovidingbroadinformationservicestoamultidisciplinaryaudiencewithdivergentinterestsandneeds'Kontinuetobedelightednotonlywiththeresponsereceivedfromtheresearchcommunityfortheseservicesbutalsobyth'LaseinrequestsforCDIACservicesbypolicyandsocialscientists,educators,andothersinterestedinvariousaspectso'Mlenvironmentalissues,includingclimatechange.WewouldliketoexpressourgratitudetothefollowingpersonnelinC'NOakRidgeNationalLaboratoryandMartinMariettaEnergySystems,Inc.Theircollectiveeffortshavebroughtthisrepor'Obeing.OurdeepestthanksgotoSonjaJones,LauraMorris,DebbieShepherd,andTimStamm,whohandleinformationreques'PrespondtorequestsforCDIAC'spublications,numericdatapackages,andcomputermodelpackages,andwhoserecordkeepin'Qsasthecoreforproducingthestatisticsreportedinthisdocument.WealsothankMarvelBurtisforherspecializedde'Rublishing,design,andproductionskills.WeacknowledgetheworkofRichDaniels,DaleKaiser,BobSepanski,RussVose,'SmmyWhite,who,underthesupervisionofTomBoden,areresponsibleforthedetailedinformationanalysisandpackagingo'Ticdata.WethankGreggMarland,who"withTomBoden"annuallysynthesizesthedatafromvarioussourcesintothegl'UdcountrybycountryCO2emissionsdatabasethatissoimportanttotheglobalchange  communit'VwethankDonLueandDavidSill,whomaintainCDIAC'scomputingsystem,underTommyNelson'sdirection.Finally,wetha'WyCrabtree,CDIACsecretary,andPennyHarmon,CDIACtelephonereceptionist,forkeepingtheofficepaperworkandtelepho'Xficflowingsmoothly.Sadly,wenotethatJodyDaltonandHelenGraveshaveleftCDIACforotherpursuits.Weexpressa'YthankstoTomGross,programmanagerwiththeU.S.DepartmentofEnergy'sOfficeofHealthandEnvironmentalResearch,E'ZentalSciencesDivision,GlobalChangeResearchProgram.Tomhaslongsupportedinternationalexchangeofscientificinf'[namonganaudiencewithmultidisciplinaryinterests.Hisvisionarypromotionofthevalueaddedprocessofprovidingin'\onhasbeenamainstayindevelopingCDIAC'sservicesandderivedinformationproducts.WethankAriPatrinos,director']DOEEnvironmentalSciencesDivision,andprogrammanagersRogerDahlmanandMikeRichesfortheircontinuedsupportofCD'^ivities.WealsothankPaulKanciruk,formerCDIACdirectorandcurrentlymanageroftheEnvironmentalInformationAnaly'_gramintheEnvironmentalSciencesDivision(ESD),atOakRidgeNationalLaboratory(ORNL);FranSharples,headoftheOR'`EnvironmentalAnalysesSection;andBobVanHook,directorofORNLESD,fortheirconstantencouragement.CDIACissuppo'atheU.S.DepartmentofEnergy'sOfficeofHealthandEnvironmentalResearch,EnvironmentalSciencesDivision,GlobalCha'bearchProgram.CDIACishousedintheEnvironmentalSciencesDivisionatOakRidgeNationalLaboratory,whichismanaged'ctinMariettaEnergySystems,Inc.,fortheU.S.DepartmentofEnergyunderContractDEAC0584OR21400.CarbonDioxide'dation )&&0 AnalysisCenter:FY1993ActivitiesisORNLPublicationNumberORNL/CDIACj67jand'ePublication *&1 No.4169lXXXXl.  ,J)4   >&-&I>'f?&-&&>&-@S Abstract   3XT #'g #3 ?- &?&-@- I?-CUSHMAN,R.M.,andF.W.STOSS .1993.Ca'hoxideInformationAnalysisCenter:FY1993 a 0  Activities,ORNL/CDIACXX,OakRidgeNational'itory,OakRidge,Tennessee.XXpp. (#(# Duringthecourseofafiscalyear,OakRidgeNationalLabora'jCarbonDioxideInformationAnalysisCenter(CDIAC)distributesthousandsofspecialtypublications"numericdatapackag'ks),computermodelpackages(CMPs),technicalreports,publiccommunicationpublications,newsletters,articlereprints,'lerencebooks"inresponsetorequestsforinformationrelatedtoglobalenvironmentalissues,primarilythosepertainin'mimatechange.CDIAC'sstaffalsoprovidestechnicalresponsestospecificinquiriesrelatedtocarbondioxide(CO2'nrtracegases,andclimate.Hundredsofreferralstootherresearchers,policyanalysts, i  information'olists,ororganizationsarealsofacilitatedbyCDIAC'sstaff.Thisreportprovidesanaccountoftheactivitiesaccompl'pyCDIACduringtheperiodOctober1,1992toSeptember30,1993.AnorganizationaloverviewofCDIACanditsstaffissu'qtedbyadetaileddescriptionofinquiriesreceivedandCDIAC'sresponsetothoseinquiries.Ananalysisanddescription'rpreparationanddistributionofnumericdatapackages,computermodelpackages,technicalreports,newsletters,factshe'secialtypublications,andreprintsisprovided.CommentsanddescriptionsofCDIAC'sinformationmanagementsystems,pro'talnetworking,andspecialbilateralagreementsarealsodescribed. Keywords: airpollution,ambienttemperature,'uhericchemistry,carboncycle,carbondioxide,climate, 9 climatechange,dataanalysis,dataexchange,'vanagement,earthatmosphere,emissions,fossilfuels,environmentaleffects,geophysicalsurveys,globalaspects,global'w,greenhouseeffect,informationanalysis,informationmanagement,meteorology,methane,monitoring,regionalanalysis,t'xuremonitoring,temperaturesurveys,tracegases  !m  ^7'yd&&d7^@&-&I@-A&-&&@&-@ I'ztion   A- &A&-B- IA-TheCarbonDioxideInform'{enter(CDIAC)wasestablishedbytheU.S.DepartmentofEnergy(DOE)in a 1982tosupportitsCarbonDi'|esearchProgram,nowtheGlobalChangeResearchProgram(GCRP).GCRP'srolewithinDOEhasbeentostudyhowatmospheric'}trationsofcarbondioxidechangeinresponsetofossilfuelemissionsandothersourcesofCO2andwhattherespon'~heEarth'sclimatesystem  mightbe.Initially,CDIAC'smissionwastoprovideidentification,collec'ualityassurance,documentation,anddistributionforinformationonthebiogeochemistryofcarbondioxideandtheeffect'2ontheearth's I  climate.Asthisresearchareamatured,sodidthescopeofCDIAC,toinclude'dglobalchangetopics(e.g.,othergreenhousegasesandtheeffectsofclimatechangeontheenvironment).Theflowof'tionintoandoutofCDIAC"numericdata,journalarticles,agencyreports,bibliographicdata"hasparalleledthein'ginterestinthe"greenhouse"issue.Suchabroadresearchprogram,involvingmanyscientistsnotonlyintheUnitedSt'taroundtheworld,couldonlysucceediftherewasanexplicitrecognitionofthevalueofinformation,inallitsforms'fmeasuresweretakentoensurethatthisinformationwouldbefreelyexchanged.CDIAC'smissiongoesbeyondsupporting'earchcommunity.Theeducationcommunity"teachersandprofessorsfromelementaryschoolstouniversitygraduatedepar'aswellastheirstudents"alsohastobeinvolvedinthisinformationexchange,iftomorrow'sscientistsaretobepr'toworkonthislongtermissue.ThisreportsummarizesCDIAC'sactivitiesincollectinganddistributinginformationdu'1993,itstwelfthyearofexistence.FormoreinformationaboutCDIACortorequestinformationproductsfromCDIAC,co'heCarbonDioxideInformationAnalysisCenter,OakRidgeNationalLaboratory,OakRidge,TN378316335U.S.A.;telephone'0390,FAX6155742232;TELEX854478;electronicmailCDP@ORNLSTC(Bitnet),CDP@ORNL.GOV(Internet),orCDIAC(Omnet).'5 7B-B d&&d7^^  D'C- IB-7C-C dBId7@ 'hlights  D 3X #XT #30  TheU.S.National'yofSciencesannouncedthattheWorldDataCenterA(WDCA)forAtmospheric  TraceGaseshasbeenest'datOakRidgeNationalLaboratory(ORNL).ThenewdatacenterwillbeintegratedintoCDIACatORNL.PaulKancirukis'ectorofCDIAC'sWorldDataCenter.WDCAforAtmosphericTraceGasesisthenewestadditiontotheinternationalCounci'ientificUnions'WorldDataCenterWDCAcomplex,comprisingtheWorldDataCenterslocatedintheUnitedStates.Thisc'ascreatedinresponsetotheneedbytheinternationalscientificcommunityforacentertomanagecriticaldatarelated'cegascycling.Thisnewcenterwillacquire,qualityassure,document,archive,anddistributedataandinformationon'dyofatmospherictracegases,particularlythoseimportanttotheanalysisofglobalchangeissues. (#(# '0  CDIACwasabletoalert85researchersindevelopingregionstotheavailabilityoffundsfromtheU.S. '  undertheU.S.CountryStudiesInitiative,whichiscoordinatedbytheU.S.DepartmentofState'sOfficeofGloba'e. (#(# 0  CDIAC,incollaborationwiththeAllRussianResearchInstituteofHydrometeoro'Information"World   DataCenter(RIHMIWDC)inObninsk,hasproducedthefirstinaseriesoffour'nguagebibliographiesofimportantRussianclimatechangeliterature.SelectedTranslatedAbstractsofRussian ' ^ o+ ^LanguageClimateChangePublications:I.SurfaceEnergyBudget(ORNL/CDIAC57;P'ngsof 9 RIHMIWDC,Issue58)wascompiledbyCDIAC'sMarvelD.Burtis,basedonabstractstranslatedi'lishbyRIHMIWDC'sCarolinaB.Ravina.Thisreport,whichfeaturessidebysideRussianandEnglishabstracts,resultsf'evenmonthguestassignmentofMs.RavinaatCDIAC.Additionalbibliographiesareplannedforthetopicalareasofclouds'ols,andgeneralcirculationclimatemodels.Thistranslationprojectwasconductedundertheauspicesofa1972USUSSR'ntonprotectionoftheenvironment. (#(# 0  CDIAC,incollaborationwiththeScrippsInst'ofOceanography(SIO),hascompiled,qualityassured, o anddocumentedanextensivedatabaseofocean'urementsimportanttoglobalchangestudies.Surface {7 WaterandAtmosphericCarbonDioxideandNitr'deObservationsbyShipboardAutomatedGasChromatography:ResultsfromExpeditionsbetween1977and1990,compiledby'sRobertJ.   SepanskibasedondatacontributedbySIO'sR.F.Weiss,F.A.VanWoy,andP.K.Salameh'ntsmeasurementsthatwillbeusefulforunderstandingexchangesoftwoimportantgreenhousegasesbetweentheoceansand'mosphere. (#(# 0  CDIACisparticipatingintheGlobalEmissionsInventoryActivity(GEIA)'InternationalAtmospheric  # Chemistry(IGAC)Project.IGACisacoreprojectoftheInternationalGeo'BiosphereProgram.CDIAC'sprojectunderGEIA,whichisbeingundertakenbySeniorScientistGreggMarlandandpostdocto'lowRobertAndres,consistsofproducinga1$x1$globaldatabaseofcarbondioxideemissionsfromthecombustion'silfuelsandmanufactureofcement.ThisdatabasewillfurtherIGAC'smissiontomeasure,understand,andpredictchan'globalatmosphericchemistryduringthenext100years. (#(# 0  CDIAC,incollaborationwi'InstituteofAtmosphericPhysics(Beijing),theStateUniversityofNew 7'!+ York"Albany,andtheNatio'maticDataCenter(Asheville,NorthCarolina),haspublishedClimaticDataBasesofthePeople'sRepublicofChina,1841'(DOE/NBB0091T).CDIAC'sDaleKaiser,withShiyanTao,CongbinFu,ZhaomeiZeng,QingyunZhang,WeiChyungWang,andTh'rl,producedthisdatabaseunderajointresearchagreementbetweentheU.S.DepartmentofEnergyandtheChineseAcadem'iences.Thedatabaseincludesrecordsfrom296stationsandincludesbarometricpressure,surfaceairtemperature,pre'ionamount,relativehumidity,sunshineduration,cloudamount,winddirectionandspeed,andnumberofdayswithsnowco'or ,k'2(#(# 0  sixteenstations,theperiodofrecordbeginsbefore1900.Thesedatasets'ntthemostcomprehensive,longterminstrumentalChineseclimatedatacurrentlyavailableandwillbeusefulforstudies'balandregionalclimatechange. (#(#  0  ORNLCommunityDayd (#(# ' TheCarbonDioxideInformationAnalysisCenter(CDIAC)participatedinOakRidgeNationalLaboratory'sCommunity'demonstratingapersonalcomputerbasedmodelforpredictingemissionsofcarbondioxideandmethane,twoimportantgree'gases,overthenextcentury.OnCommunityDay,thepublicwasinvited,forthefirsttime,totourORNL.CDIAC'sMarvel'demonstratedtheEdmondsReillymodel,oneofCDIAC'smostpopularproducts,andallowedinterestedvisitorstoobserveh'gesindemographic,technological,andeconomicfactorscoulddrasticallyaltergreenhousegasemissions. (#'0  NewNDP4 (#(# 0  TheCarbonDioxideInformationAnalysisCenter(CDIAC'ollaborationwiththeResearchInstituteofHydrometeorologicalInformation(RIHMI,Obninsk,Russia)andtheNationalCli'ataCenter(Asheville,NorthCarolina),hascompletedqualityassuranceanddocumentationofthedatabaseDailyTempe'andPrecipitationDatafor223USSRStations.Thisdatabaseisbeing  publishedasCDIACnumericd'kageNDP040.CDIAC'sRussellVose,withRIHMI'sV.N.Razuvayev,E.G.Apasova,andR.A.Martuganov,documentedthisdata'partofCDIAC'sparticipationina1972bilateralagreementonenvironmentalprotection.Thedatabase,coveringtheyea'1989,includesdataonminimum,mean,anddailytemperatures;dailyprecipitationamount;andextensivestationinventor'ionhistory,andqualityassuranceinformation. (#(# 0  NewNDPCatalogQ' 0  TheCarbonDioxideInformationAnalysisCenterhaspublisheditsCDIACCatalogofNumericData ' PackagesandComputerModelPackages(ORNL/CDIAC62).Thiscatalog,authoredbyThomasA.  'FrederickM.O'Hara,Jr.,andFrederickW.Stoss,providesasummaryofthe45dataandmodelpackagesproducedanddistr'byCDIAC(datacontributors,datadescription,filesize,andillustrativefigure),describeshowCDIACdevelopsitsdata'delpackages,andoffersdetailedinstructionsonhowtoobtainthepackagesfromCDIAC,includingbyftp(filetransfer'l)electronictransmission.TheCDIACCatalogofNumericDataPackagesandComputerModelPackages "'uldgreatlyexpandCDIAC'sinformationoutreachfunctions,therebyenhancingthedistributionofDOE'sglobalchangedata' (#(# 0  WorkshopinJapan"&(#(# 0  TheCarbonDioxideInforma'alysisCenterparticipated,byinvitation,inaworkshoponDataManagementforGlobalEnvironmentalStudies,aspartof'APIAHS'93meetinginYokohama,Japan.CDIACdirectorRobertM.Cushmanpresentedthepaper"TheRoleofCDIACinProvid'ormationfortheGlobalClimateChangeIssue."OtherpresentationswerefromresearchanddatacentersinJapan,China,I'ermany,andSwitzerland. (#(# 0  CDIACpublishesfromtheSecondU.S./JapanWorkshop'#.(#(# 0  TheCarbonDioxideInformationAnalysisCenterpublished,onbehalfoftheU.S.Committee'handEnvironmentalSciences,AReportfromtheSecondU.S./JapanWorkshoponGlobalChange +L&1 Resear'ironmentalResponseTechnologies(MitigationandAdaptation)(CONF930285).The Y,'2 reportpresentsth'edingsofaworkshopheldinHonoluluinFebruary1993undertheauspicesoftheUnitedStatesJapanScienceandTechnolo'ement. (#(# 0  SecondRussianabstracttranslationsvolumenearcompletionz/6*6'(#  B0*7 0  TheCarbonDioxideInformationAnalysisCenter(CDIAC),incollaborationwithth'ussianResearchInstituteofHydrometeorologicalInformationWorldDataCenter(RIHMIWDC)(Obninsk,Russia),hascompile'itationsforthesecondoffourduallanguagevolumesinitsseries,Selected  TranslatedAbstracts'sianLanguageClimateChangePublications.Thefirstvolume Y (ORNL/CDIAC57;ProceedingsofRIHMIW'ue158)coversthetopicoftheEarth'ssurfaceenergybudget,thesecond(ORNL/CDIAC64;ProceedingsofRIHMIWDC,Issue'oversclouds;volumesthreeandfourareplannedtocoveraerosolsandgeneralcirculationmodels,respectively.Thefirs'olumesintheserieswerecompiledbyCDIAC'sMarvelD.Burtis,basedonabstractstranslatedintoEnglishbyRIHMIWDC's'naB.Ravina.Theseriesopensuptowesternresearchersawealthofclimatechangeliteraturethathaspreviouslybeena'eonlyinRussian. (#(#      @ OrganizationandStaff  ' @ Fig.1.CDIACorganization(March31,1993).  ";% ' Table1.CDIACstaffFY1993   >]'' x'> y 0,X #0"`-'``" ' Staff      ,  Title  - >]'''  xd>   -\-"' B& & '``" \ ThomasA.Boden  TaskLeader,DataSystems  B  \ M'.Burtis  EditorialAssistant  n  \ PatriciaJ.Crabtree  Secretary '  \ RobertM.Cushman  Director,CDIAC     \ RichardC.Daniels* 'taPackagingSpecialist 6  \ PennyL.Harmon  Secretary/TelephoneReceptionist '   \ SonjaB.Jones  RequestResponseCoordinator J   \ DaleP.Kaiser' DataPackagingSpecialist v  0 \ PaulKanciruk0\(#\(#Director,WDCAforAtmo'TraceGases (#(#  \ AlexanderV.Kozyr  DataPackagingSpecialist ' \ DonaldL.Lue*  PersonalComputingSpecialist >  \ GreggMarland 'SeniorScientist j&  \ LauraJ.Morris  DataPackagingAssistant R '\ TommyR.Nelson**  TaskLeader,ComputerSystems ~   \ RobertJ.Sepanski* 'ataPackagingSpecialist "  \ DeborahE.Shepherd  DataPackagingAssistant '  \ JamesW.Simmons***  WorkstationSpecialist F&  \ TimothyW.Stamm*' RequestResponseAssociate r.(  \ FrederickW.Stoss*  TaskLeader,InformationSy' Z*  \ RussellS.Vose*  DataPackagingSpecialist ,  \ Tamm'ite  GeographicInformationSystemsSpecialist  . >]''' xd> ""0 ̀*Energy,Environment,andResourcesCenter,UniversityofTennessee'illè**ComputingApplicationsDivision,ORNL***ComputingandTelecommunicationsServices,ORNL  & 6 'X #\- ProfessionalDevelopment D  DuringtheyearCDIACstaffaree'edtoattendvariousworkshopsandtrainingprograms.Theseopportunitiesallowstafftogainnewskillsandimprovethe'rtiseinareasrelatedtoCDIAC'soperations.ThefollowingisalistofCDIACstaffprofessionaldevelopmentactivities'efirsthalfofFY1993. Training    0  RichDanielsattendedtheIntroductio'C/INFOtrainingcourseinRedlands,California,January1993. @(#(# 0  DebbieSh'andLauraMorristookIntroductiontoUNIXcourseheldOctober12!14,Inhousetraining.  (#'0  SonjaJones,LauraMorris,andDebbieShepherdattendedtheHighImpactCommunicationSkillssemin' d  heldJanuary13,1993,offeredbyCareerTrack,inKnoxville. (#(# 0  Tammy'completedtheFranklinTimeManagementcourseatEnergySystemsTrainingand   DevelopmentonOctober2';DebbieSheperdcompletedthecourseonDecember8,1992;PattyCrabtreecompletedthecourseonJanuary13,1993;andF'ss,SonjaJonesandLauraMorriscompletedthecourseonJanuary22,1993. (#(# 0  Debbie'dattendedtheseminar"HowtoMakeitWork"on11/19/92;RebeccaRice,Consultant;In  R ' Rhousetraining[cosponsoredbytheHonorsandAwardsOffice,MMESandtheOakRidgeChapter,ProfessionalSec'sInternationalinrecognitionofthoseatMMESholdingtheCertifiedProfessionalSecretary(CPS)designation] (# 0  SonjaJonescompletedtheEndUserFoxPro2.0Level1courseatTrainingSystems,Inc.,Oak(  January5!6,1993,andtheEndUserFoxPro2.0Level2courseonJanuary11!12,1993.(X(#(# 0  PattyCrabtreecompletedDesktopPublishingwithWordPerfectonFebruary24,1(feredbyMMES . TrainingandDevelopment. (#(#  0  SonjaJonescomplet(CareerPlanningWorkshoponAugust27,1993.D(#(# 0  SonjaJonesattendedasemina(essionalTelephoneSkills"onMay19,1993.!(#(#  PublicationsandPresentations  ($ 0  RichDanielssubmittedapaperdealingwiththecoastalhazardsintheManteoNagsHead,NorthC( #& area(partiallybasedonNDP43AtotheJournalofCoastalResearch).#'(#((0  RichDanielswroteseveralprogramsforStewardC.Sutherland,LamontDohertyGeologicalObservatory,( % ) ColumbiaUniversity.ProgramsandmacrosutilizedtheARC/INFOgeographicinformationsystemhereatCDIACto( isolinetransectmapsofCO2SO2,temperature,etc.forQApurposes(e.g.,showingthe &!+ di( einCO2concentrationsbelowtheoceanssurface).MeasurementsweretakenbytheSSMeteor 'n", re( vesselduringacruiseintheAntarctic. (#(# Ѐ0  CloudAmountandSunshineDurationin( ople'sRepublicofChina,1954!88waspresentedbyDale  *$/ Kaiseratapostersessionofthe8thC(ceonAppliedClimatology,January1993,Anaheim,California.Thepaperispublishedinthepreprintvolumeoftheconfe( (#(# 0  FredStosspresentedapaper,TheCarbonDioxideInformationAnalysisCenter:(ngSupportfor ,-'3 DOE'sGlobalChangeResearchProgram,attheDOE/OSTIannualtechnicalinformation(, -(4 INFOTech,heldinOctoberatOSTI'sfacilitiesinOakRidge. (#(# 0  (tossgaveapresentationontheproposedNationalInstitutesfortheEnvironmentincludingtheNational P0 +7 (aryfortheEnvironmentbeforeajointmeetingoftheSouthernAppalachianchapterofSpecialLibrariesAssociationandt(TennesseechapterofAmericanSocietyforInformationScience. (#(# 0  FredStosshadam(pt,"TheCarbonDioxideInformationAnalysisCenter:RespondingtoChanging X InformationNeeds,"publ(ntheGreenLibraryJournal1(3):199. (#(# 0  BobCushmanandFredStosshadamanuscript,(tutions:CDIAC,"publishedinEnvironment   34(4):5,45. (#(# 0  Finalc(thetechnicalreportClimateDataBasesofthePeople'sRepublicofChina,1841!1988was L   pub(inJanuary1993asDOE/NBB0091T,TR055.Itscontentshavebeendescribedintheprevioussemiannualreport. ( 0  SonjaJones,LauraMorris,DebbieShepherd,andTimothyStammsubmittedtheabstract,CDIAC'sPC( n*  R n*  RBasedInformationManagementSystem,whichwasacceptedtothe10thOffic(mationTechnology 8  Conference,tobeheldJuly13!15,1993,inKnoxville,Tennessee. (#(****    0  BobAndres,GreggMarland,TomBoden,SteveBischofsubmittedCarbonDiox(ssionsfrom N  FossilFuelConsumptionandCementManufacture,1751!1991;andAnEstimateofTh(topic [ CompositionandLatitudinalDistributionforpublicationinabooktobepublishedbyCambri( $ UniversityPress.Marlandpresentedthispaperatthe1993GlobalChangeInstituteinSnowmass,Colorad(!) (#(# 0  Gornitz,V.,R.C.Daniels,T.W.White,andK.R.Birdwell.Thedevelopmentof("talrisk E assessmentdatabasefortheU.S.southeast.J.CoastalRes.(inpress).  (##(#  0  TammyWhitepresentedAnIntroductiontoGIStoEnvironmentalSciencesDivision,Octo($92.Y(#(# 0  TammyWhitepresentedAnoverviewoftheESDGISTeamFacilities(%SforMartinMarietta . EnergySystems,Inc.SpecialTaskForceforSelfDirectedWorkTeams,Novemb(&. (#(#  0  ThomasC.Peterson(NCDC)andRussVose(CDIAC)hadamanuscript,"The('Historical C ClimatologyNetwork:PresentandFuture"publishedintheProceedingsoftheSeventeenthA((limateDiagnosticsWorkshop,whichwasheldinNorman,OklahomainOctober,1992. (#(# 0  ()sehadamanuscript,"TheGlobalHistoricalClimatologyNetwork:LongTermMonthly  c# Temperature,Preci(*n,andPressureData"publishedintheProceedingsoftheFourthSymposiumonGlobalChangeStudies,whichtookplacein(+,1993inAnaheim,California.. (#(# 0  ThomasC.Peterson(NCDC),DavidR.Easterling(NC(,ssVose(CDIAC),andJonK.Eischeid #' (CIRES)hadamanuscript,"TheGlobalHistoricalClimatologyNet(-ecipitationData",publishedintheProceedingsoftheSymposiumonPrecipitationandEvaporation,whichwasheldinBrat(.SlovakiainSeptember,1993. (#(# 0  ThomasC.Peterson(NCDC),DavidR.Easterling(NC(/ssVose(CDIAC),andJonK.Eischeid 'k", (CIRES)submittedamanuscripttotheAmericanMeteorologicalSo(0994AnnualMeeting,whichwillbeheldinNashville,TennesseeinJanuary,1994.Thepaperisentitled"HomogeneousGlob(1TemperatureTimeSeries." (#(# 0  DebbieShepherdpresentedCDIAC'sPCBasedInf(2nManagementSystembySonjaJones,Laura +S&1 Morris,DebbieShepherd,andTimothyStammatthe10thO(3nformationTechnologyConference,HolidayInn"World'sFairSite,July14(July1315,1993).Proceedingswerepublish(4heformofamultimediaCD. (#(# 0  FredStossandSonjaJoneshadapaper"Performanceof(5rbonDioxideInformationAnalysis /<*6 Center(CDIAC)"acceptedforpresentationatthe1993Infotech(Inf(6nTechnology)meeting H0+7 sponsoredbyDOEandtheOfficeofScientificandTechnicalInformation. (7(#  "x `, , 'xx" MeetingsAttended   ` 0  TomBoden(8hDanielsattendedameetingattheGoddardInstituteforSpaceStudies,Manhattan,New 4  York.Meetin(9esignedtocoordinatetheresearcheffortsoftheDOElanduseresearchteamconsistingofI.Fung,S.Brown,J.Richards(:int,D.Skole,C.Hall,R.Houghton,andR.Dahlman(DOE).ThedatabeingcompiledforNDP46wasproducedfor/bythist(; (#(# 0  BobSepanskiattendedtheannualmeetingoftheNOAAClimateMonitoringandDiagnost(<oratory   (CMDL)March3!4,Boulder,Colorado.Obtainedanumberofnewdatasetstobeincludedin(=ndsoras   NDPs.TheseincludedatafromtheNOAA/CMDLhalocarbonflasknetwork,thehalocarboncon(>monitoringnetwork,andtheatmosphericaerosoldatafromtheNOAA/CMDLcontinuousmonitoringsites. (#(#(?0  GreggMarlandattendedaworkshoponInventoriesofNetAnthropogenicEmssionsofGHGinS o (@JosdosCampos,Brazil,March9!11. (#(#  0  FredStossattendedtheinauguralSIG(AeetinghostedbytheUSGSinReston,Virginia.Morethan ^ 250peoplemettohearthelatestonWAISt(Bgiesandthedevelopmentandimplementationofelectronicnetworking. (#(#  0  Gregg(CattendedtheadvisorygroupmeetingonAssessmentofDataBasesonENergyDemand ~: andSupplyinTerms(DirAdequacyforUseinStudiesofGreenhouseGasEmissionsinVienna,Austria,April5!7. (#(# (EZ'xZx"0  BobAndresattendedNASAEarthSciencesummerschool,ProcessesofGlobalChange(Fadena,  California,August9!13. (#(# 0  TammyWhiteattendedthe(GanAssociationofGeographers(AAG),Atlanta,Georgia,April4!7.n*(#(# 0  Tammy(HattendedtheAnnualEnvironmentalSystemsResearchInstitute(ESRI)User ! Conference,PalmSprings,Ca(Ia,May22!28. (#(# 0  RussVoseattendedtheannualmeetingoftheAmericanMeteorologi(Jiety,whichwasheldin V"$ Anaheim,CaliforniainJanuary1993.Whileatthemeeting,hepresentedapa(KheGlobalHistoricalClimatologyNetwork:LongTermMonthlyTemperature,Precipitation,andPressureData." (#(L0  RussVoseattendedtheannualmeetingoftheAssociationofAmericanGeographers,whichwasheldin(Mv%2 ( Atlanta,GeorgiainApril1993.ContactswithseveralusersoftheGHCNdatabase(i.e.,NDP041)weremade.(N(#(# 0  (R#,(#(# 0  &*$.(#(# (OommitteesandAppointments  +r&0 0  FredStosswasnamedascochairoftheCommitteefor(PlInstitutesoftheEnvironmentSteering F-(2 CommitteefortheNationalLibraryfortheEnvironment.He(QarolWatts(NOAA)andBruceGritton(MontereyBayAquariumResearchInstitute)inthisposition. (#(# (R FredStosswasaskedtoserveafifthyearasamemberoftheAdvisoryBoardofEnvironmentAbstracts, f(SwhichispublishedbyA&IBowker,adivisionofR.R.BowkerPublishers. (#(#  ***** (T0  TammyWhiteservedathirdtermcochairpersonontheESDGISOperationsCommitteeandUser (UTeam. (#(# 0  TammyWhitewasamemberoftheESDGISTEAMHiringcommitteewhochosean(VTeam   FacilitiesManager,PatScarbrough. (#(#  AwardsandHonors  (W 0  ThreeCDIACproductsreceivedawardsfromthe1993competitionoftheEastTennesseeChapterofthe(X `  SocietyforTechnicalCommunications.ARMOutreach(FredO'Hara;FredStoss;andLawrenceLivermore(Yl(  NationalLaboratory'sMarvDickerson)receivedanawardforAchievementinPromotionalMaterials;Trends(Z6  '91:ACompendiumofDataonGlobalChange(TomBoden,BobSepanski,andFredStoss)wasawarded ([ MeritinTechnicalReports;andDOEResearchSummary(MarvelBurtis,BobCushman,andFredStoss)was (\ awardedAchievementinWholePeriodicals.Additionally,CDIAC'sLauraMorris(withtheORNLPublicationsDivision'sG(]eLogsdonandEnvironmentalScienceDivision'sMontyRoss)receivedanawardforAchievementinHouseDocumentsforES(^tationHandbook.$(#(# *** 0  RichDanielsandTammyWhite,asmembersofthe(_ographicInformationSystems(GIS) r Committee,receivedWorldClassTeamworkawardsfromtheORNLValu(`ittee(April). (#(# 0  TheESDElectronicsCommunicationsCommitteewastherecipientoft(aTeamAward",  September14,1993,withDebbieShepherdservingaschairman. (#(#  (b0  (#(# @  RequestResponseRecords(R3)System  (c WhenCDIACbeganin1982,greenhousewarmingwasatopicstillprimarilyintheresearcharenaandCDIAC'srolewa(dthemostpart,oneofdistributingdatafromresearcherstoresearchers.By1990,however,when s(egreenhousewarmingwasfrontpagenews,thesubjectofnewsmagazineleadstories,congressionalattention,andinternati(fnferences;CDIAC'srole"anditsusercommunity"hadbroadenedconsiderably.CDIAChasbeenfieldinginformationreq(gromcongressionalstaffersdraftingorevaluatinglegislation,frompublicRRschoolstudentsworkingonscience(hrojects,andfromsciencereporterscompilingdataforstories,aswellasfromresearchscientists.Table2isasummar(iIACrequest/responseactivitiesforthefirsthalfofFY1993.` ` 6@x(jX #6@  Table2.Request/responseactivities  }  C-(k-D, C->]'' ` d> f  (lx2 v 'xv x"$@hh$  Numberofrequests>]''(md>   "ux4  'u u"   (nYear1993  Total x4  " 9 '2 2">]''hj(od>"29  '2 2"    FY1985 (p  * h^ *  Category h Qtrs12  Qtrs34(ql0todate  >]'' ` d> w(r"H'HH"0f^ h^0DiscussionsaAEE((((((((((s """"""""""""""""""""""""A  1,2601,260718,(t  "!'!!"DOEreports211w211(u5,631  "!r'!r!"CDIACreports651w(v7,127  "!uT'!T!"Otherreports61(w61886 u "!Wz6z'!6!"Dataprocessing7(x7289 W "!}9\\'!!"Articles37(y37488 }9 "!_>>'!!"NDPsb395(zw3952,784 _ "!A  '!!"CMPs40({40496 A "!#'!!"Trends(|79196 # (ondiskette)"!a'!a!""(}'!!"Directorysearches715w7154,640 (~ Miscellaneous126w126219 d  Networking(3838H43 i%! " *  '!!">]''( d>>]'' d>>]''( d >>]''  d >"!*  (!" * " "d Z: : 'dd"ԀTotal3,62030(0740,836    Z# >]'' ` a!d >(_!$ "6!ao!+o!'6+6""H!!a!'HaH" D, D(F- D,aDiscussionsincludetelephoneconversations,letters,andinterofficecorrespo(that !% pertaintoDOEdeliverablesorotherglobalchange-relatedmatters.Itdoesnotincludeday-to-(rationsatCDIAC."H'$##'HH" bRequestsforCDROMincluded. '$( (` ` -X #f^-F- ~ F-G- I(-0  CDIACrespondedto3,620requestsfrom1,260individualsforCDIACproductsandservicesfrom58(& + countries:Algeria,Antingua/Barbuda,Argentina,Australia,Austria,Bahrain,Bangladesh,Belgium,Brazil,Bulg(anada,Colombia,CostaRica,Cuba,Egypt,Ethiopia,Finland,France,Germany,Greece,Guyana,Iceland,India,Indonesia,(,Israel,Italy,Japan,Kenya,Luxembourg,Malaysia,Mexico,Monaco,Mongolia,Netherlands,NewZealand,Niger,Nigeria,(People'sRepublicofChina,Poland,Romania,Russia,SaudiArabia,Singapore,SouthAfrica,SouthKorea,Spain,SriLank(en,Switzerland,Taiwan,Trinidad/Tobago,Turkey,UnitedKingdom,UnitedStates,Vietnam,andZimbabwe(Fig.2). ((#   Y,'3 0  DuringthefirsthalfofFY1993CDIACreceivedatotalof923requestsfor(s(DOE,CDIAC,and   othersrepresentingslightlymorethan25percentofCDIAC'srequestresponseacti((Fig.3).Theserequestsforreportsinclude (#(# < m` z jX( m   DOEreports m    ` E211  requests (  m    ` E518  copiesdistributed  x  m ( CDIACreports m    ` E651  requests     (   ` C5,071  copiesdistributed    0 m 0m(#(Otherreports (#(#  m    ` F61  requests 4( m    ` E149  copiesdistributed    m ( Totalreportsdistributed:5,7380 m Atotalof40,836requestsfrom104countrieshavebeenfilledfrom(5todate(Fig.4).m(#m(# 0 m Since1985,requestsrepresentavarietyofresponses(IACstaff,thelargestbeingdiscussions(44%), h distributionofCDIACreports(18%),anddistribution(reports(14%)(Fig.5). m(#m(# 0 m RequestresponseactivitiesforthefirsthalfofFY1993(tobedecliningwhichisattributedtothe  occurrenceoflargeractivitiesassociatedwiththedistr(ofTrends'90inFY1991andm(#m(# 0 m Trends'91inFY1992(Fig.6).(Rm(#m(#      D   D   D   D( D 8>]''<)d >>]''(<)d >@7 Table3.DOEreportsdistribution  D >]'(-d> - 0 m` z x0"(=='" PFY1993"M'HMH"ԈP<T( M ! !0!P8Report"'Y''22">]''(Pd>"2Y'''22"ԈPFY1985P Remaining( Y 0L!0P8numberP qTitleandcontentsP(Qtrs12PQtrs34PRTotalPtodateP)!copies ! >('d>"`I '``"<B 2z"(< I  B001 B WorkshopontheGlobal  (z 26!%N/A Y     B EffectsofCarbonDio(   B FromFossilFuels,May1979B002 B SummaryoftheCarbon(z 12!%N/A y 5     B DioxideEffectsand(  B AssessmentProgramB003 B TheRoleofTemperateZone2(z 25!%N/A U     B ForestsintheWorldCarbon ( B Cycle,February1980B004 B TheRoleofOrganicSoils2( 25!%N/A u     B intheWorldCarbonCycle, (B February1980B005 B CarbonDioxideResearch2z( 49!%N/A     B ProgressReport,April1980B006(B EnvironmentalControlk12'1 19]"'7 1(   B TechnologyforAtmospheric   B CarbonDioxide,May1980B007 (TheRoleofTropical2z 58!%N/A Q  (  B ForestsintheWorld   B CarbonCycle,August1980B008 B (ehensivePlanfor2z 44!%N/A q-!  ( B EffectsResearchand   B Assessment,Part1:The   B GlobalCarbon(nd   B ClimaticEffectsofIn-   B creasingCarbonDioxideB009 (WorkshoponEnvironmentalk22'2 98 "&46 #(   B andSocietalConsequences   B ofaPossibleCO2-Induced y%5 *(   B ClimateChange,September   B 1980B010 B Measurement(gesin2z 13]"'5 (U#.    (TerrestrialCarbonUsing   B RemoteSensingB011 B ProceedingsoftheCarbon(k12'1 51 "&24 +u&2    B Di(ndClimate   B ResearchProgramConference,   B December1980  .(5 (]''<)d>>]''#<)d>@( Table3.(continued)  D >]''-d>( - - B 2z -"=='" (FY1993"M'HMH"ԈP<Total M ! !(8Report"'Y''22">]''Pd>"('''22"ԈPFY1985P Remaining Y 0L!(0P8numberP qTitleandcontentsPQtrs12PQtrs34PR(PtodateP)!copies ! >]''d("`I '``"<B 2z"L< I  (12 B ProceedingsoftheInter-2z 43!%N/A(Y     B nationalMeetingonStable   B IsotopesinTree-Ring  (B Research,December1980B013 B EnvironmentalandSocietal2( 23!%N/A A      B ConsequencesofaPossible  (B CO2-InducedClimateChange-      B AResearchAgenda,VolumeI ( B (December1980).   B VolumeII(VariousDatesfor   B 16Parts,Decembe(   B Part12zQ 4!%N/A (    B Part22zQ 1!%N/A (    B Part32z 50!%N/A(]    B Part42z 58 "&19( 1    B Part52z 62!%( }    B Part62z 82!%( Q     B Part72z 69(243     B Part82z 82(%139 q-!    B Part92z 6( "&83  #    B Part102z (!%123 !M%    B Part112z(57 "&97 !#'    B Part122z( 64!%155 $m)    B Part132z( 74!%163 A& +    B Part142( 58!%206 '"-    B Part162( 63!%209 a)$/    B Part172(z 76!%163 *%1 B014 B SomeAspectsoftheRol(2z 86!%N/A ,='3    B of(allowOceanin   B GlobalCarbonDioxide   B Uptake,January1981  .)6(>]''<)d>>]''#<)d>( Table3.(continued)  D >]''-d( - - B 2z -"=='" (PFY1993"M'HMH"ԈP<Total M ! !(P8Report"'Y''22">]''Pd>"('''22"ԈPFY1985P Remaining Y 0L(0P8numberP qTitleandcontentsPQtrs12PQtrs34PR(alPtodateP)!copies ! >]''d("`I '``"<B 2z"L< I  (015 B CarbonBalanceinNorthern2z 21!%N( Y     B EcosystemsandthePotential   B EffectofCarbonDioxide-(  B InducedClimaticChange,   B January1981B016 B FluxofOrga(bonbyk22'2 57 "&43      ( RiverstotheOceans,   B April1981B017 B WorkshoponOceanicCO2(k12'1 62!%195 )  0  0B #(Standardization,February B #B #    B 1982B018 B Proceedingso(orkshop2z 56!%N/A I   ( onFirstDetectionofCarbon   B DioxideEffects,May1982B019 B Global(sofBiospheric2z 15!%N/A i%  ( B Carbon,July1982B020 B EffectofCO2onMammalian2(z 19!%N/A }    B Organisms,December1982(021 B Proceedings:CarbonDioxide2z 43!%(     B ResearchConference:Carbon   B Dioxide,Scienceand ( B Consensus,February1983B022 B Conf8608144Proceedingsk32('3 60 "&22  #    B oftheInternational (B SymposiumofEcological   B AspectsofTreeRingAnalysisB023 B Conf(2Proceedings2z 40!%N/A #(  ( B fromthe2ndAnnualScience   B MeetingoftheUSDOEand   B PRCASJo(earchProgramB024 B WorkshoponSeaLevelRisek22'2(177 "&54 '"-    B andCoastalProcesses,March   B )#@CONF B ProceedingsoftheInter2z 46)!%N/A *%1 %?890525 B nationalConferenceonGlobal +u&2 ) B andRegionalEnvironmental ,='3    B AtmosphericChemistry,  ) Beijing,China,May310,   B 1989  .)6 >]''<))d>>]''#<)d>@ Table3.(continued) ) D >]''-d> - - )2z -"=='" PFY1993"M)H"ԈP<Total M ! !0!P8Report"'Y')2">]''Pd>"2Y'''22"ԈPFY)  Remaining Y 0L!0P8numberP ) tleandcontentsPQtrs12PQtrs34PRTotalPtodateP)!co)  ! >]''d>"`I '``"<) B 2z"L< I  #@CONF B GlobalClimateFeedba) 11211 123!%N/A Y  >9006)B ProceedingsoftheBrookhaven !  E B NationalLaboratoryWorkshop )    B June36,1990I@TR001 B OnPossibleChangesink2)'2 152 "&24 A      B GlobalSeaLeveland)   B PotentialCauses,March1983I@TR002 B EffectsofApproximatek)2'2 95 "&13 a     B RadiationTreatm)edin   B theClimateModelsonthe   B ClearSkyThermalRadiation  ) Flux:ItsPerturbationDue   B toCO2Increase,January1983 I I)003 B CarbonDioxideEmissionsk62'6 201 "&44)     B fromFossilFuels:A   B ProcedureforEstimation  )B andResultsfor1950-1981,   B June1983I@TR004 B CarboninLiveVegetat)k52'5 213!%161 E    B )ajorWorldEcosystems,   B June1983I@TR005 B DeforestationMeasuredk)2'5 211 "&11 e     B byLANDSAT)Toward   B aMethodJune1983I@TR006 B ResponseoftheNorthk2)2'2 143 "&36  $    B AmericanCornBel)   B ClimateWarming,August1983I@TR007 B AnAnalysisofConceptsk)2'5 298 "&31 #(    B forControlling)heric   B CarbonDioxideI@TR008 B CarbonateChemistryofthe) z 111 "&15  '!,    B WeddellSea)!TR009 B ResponseofUnmanagedk22'2 165 "&10)" a)$/    B ForeststoCO2-Induced )*$0    B ClimateCh)#Available   B Information,InitialTests,   B andDataRequirementsI@)$ B ComputerImplementationofk62'6 206!%157)% .(5    B aGloballyAveragedModel   B oftheWorldCarbonCycle  )&+8 >]''<)d >>]''#<)d)'>@ Table3.(continued)  D >]''-)("> - - B 2z -"=='" ))PFY1993"M'HMH"ԈP<Total M ! )*0!P8Report"'Y''22">]''Pd)+"2Y'''22"ԈPFY1985P Remaining Y 0L),!0P8numberP qTitleandcontentsPQtrs12PQtrs34)-RTotalPtodateP)!copies ! >]'').$>"`I '``"<B 2z"L< I )/I@TR011 B HistoricalCarbonDioxide:k12'1 133)0 "&20 Y     B AbundancesDerivedfromthe   B SmithsonianSp)1logramsI@TR012 B SeasonalClimateScenariok12'1)242 "&25 y 5     B forEuropeandNorthAmerica   B in)3h-CO2,WarmerWorld    I@TR013 B AnAnalysisofPossiblek3)4'3 205 "&33 U     B FutureAtmospheric)5  B RetentionofFossilFuelCO2 )  I@TR014 B TheChangingPatt)6k32'3 204 "&13 u     )7ssilFuelCO2Emissions = I@TR015 B AProposedReferenceSetk)82'4 149 "&18     B ofScenariosfo)9  B RadiativelyActive   B AtmosphericConstituentsI@TR016 B A):sStudyforthek42'4 243 "&79   ); B Removal,Recoveryand   B DisposalofCarbonDioxide   B fromFossi)<Power   B PlantsintheUS.I@TR017 B AClimaticDataBankfork7)=2'7 224!%150 e     B NorthernHemisph)>d   B Areas,1851-1980I@TR018 B AGlobalPaleoclimatick5)?'5 164 "&50  $    B DataBasefor6000Year)@I@TR019 B CarbonDynamicsofk22'2 112)A13 !#'    B NorthernHardwoodForests:   B GasExchangeCharacter)BI@TR020 B ReconstructionofPastk32'3 126)C"&36 A& +    B AtmosphericCO2Contents  '!,    )DfromtheChemistryofthe   B ContemporaryOcean:An   B EvaluationI@)E1 B ATwoDimensionalCO2-k22'2 120 "&)F *%1    B OceanModelIncludingthe   B BiologicalProcesses  )G >]''<)d%>>]''#<)d)H@ Table3.(continued)  D >]''-d)I> - - B 2z -"=='" )JPFY1993"M'HMH"ԈP<Total M ! )K0!P8Report"'Y''22">]''Pd()L2Y'''22"ԈPFY1985P Remaining Y 0L)M!0P8numberP qTitleandcontentsPQtrs12PQtrs34P)NTotalPtodateP)!copies ! >]'')O)>"`I '``"<B 2z"L< I  )PI@TR022 B AGridPointSurfaceAirk52'5 138)Q16 Y     B TemperatureDataSetfor   B theNorthernHemispher)RI@TR023 B TheEffectofElevatedk62'6 204)S13 y 5     B AtmosphericCO2onPlant A      B )TunitiesI@TR024 B MethodsofUncertaintyk52'5 )U "&17 U     B AnalysisforaGlobal   B CarbonDioxid)VI@TR025 B TheStabilityofLow-k22'2 79)W&48 u     B AltitudeSeaSurface   B Temperatures:AnEvalua)X   B oftheCLIMAPReconstruction   B withEmphasisonthe   B P)YSSTAnomaliesI@TR026 B CarbonateChemistryof2z)Z61 "&36 1    B theBeringSeaI@TR027 B AGrid)[urfaceAirk32'3 142 "&18 E  )\B TemperatureDataSetfor   B theSouthernHemisphereI@TR028 B Defini)]dCharacteri-k22'2 68!%101 e   )^ B zationofDataNeedsto   B DescribethePotential   B EffectsofInc)_Atmo-   B sphericCO2onMarine  $    B Fisheriesfromthe)`  B NortheastPacificOceanI@TR029 B PreliminaryDataReportfor)az 48 "&90 #(    B theINDIGO1/INDIVAT3)b  B CruisesintheIndianOceanI@TR030 B EffectsofEnergyTechk7)c'7 361 "&82  '!,    B nologyonGlobalCO2)d '"-    B EmissionsI@TR031 B ImpactofClimateChangek)e2'4 336 "&13 )*$0    B fromIncreased)fheric   B CarbonDioxideonAmerican   B AgricultureI@TR032 )gComparisonofTropicalk12'1 150 "&73 .(5)h  B ForestSurveys  /]*7 >]''<)d*>)i'#<)d+>@ Table3.(continued)  D )j]''-d,> - - B 2z -)k=='" PFY1993"M'HMH"ԈP)lTotal M ! !0!P8Report"'Y''22">])mPd->"2Y'''22"ԈPFY1985P Re)n Y 0L!0P8numberP qTitleandconten)oQtrs12PQtrs34PRTotalPtodateP)!copies !)p>]''d.>"`I '``"<B 2z)qL< I  I@TR033 B HighAccuracyStandards)rz 75!%100 Y     B andReferenceMethodol)s  B forCarbonDioxideinAirI@TR034 B CarbonateChemistryofthek1)t2'1 80 "&62 y 5     B NorthPacificOce)uI@TR035 B AnAnnotatedInventoryofk82'8 217)v'8      B ClimaticIndicesandData   B SetsI@)w B UncertaintyinFutureGlobalk42'4 314!%20)x      B EnergyUseandFossilFuel   B CO2Emissions1975to20)y =    B AppendicesforTR0362z 5)z "&19  I@TR037 B MonthlyMeanPressurek52){5 106 "&47 ]    B ReconstructionsforEurope )|B (Backto1780)andNorth   B America(to1958)I@TR038 B DataBankof)}tick22'2 61!%114 E    )~SurfaceTemperatureand   B PressureDataI@TR039 B TheProspectofSolving)82'8 513 "&30 e     B th)2ProblemThrough q-!    B GlobalReforestationI@TR040 B A)onGreenhouse13213X 1095 "&64  $ )  B GasesI@TR041 B RegionalIntercomparisonsk92') 448!%236 !#'    B ofGeneralCirculation   )delPredictionsand   B HistoricalClimateDataI@TR042 B SurfaceEnergyBalan)k32'3 186 "&14  '!,    B)eeGeneralCirculation   B Models:CurrentClimateand   B ResponsetoIncreasing)  B CO2 )*$0 I@TR043 B TheUseofStatisticalk8)'8 151!%229 +u&2    B ClimateCropModel)   B SimulatingYieldtoProject   B theImpactsofCO2Induced .()   B ClimateChange  /]*7 >]''<)d/>)]''#<)d0>@ Table3.(continued)  D)]''-d1> - - B 2z )=='" PFY1993"M'HMH"ԈP)Total M ! !0!P8Report"'Y''22">)Pd2>"2Y'''22"ԈPFY1985P )ing Y 0L!0P8numberP qTitleandcon)PQtrs12PQtrs34PRTotalPtodateP)!copies !)>]''d3>"`I '``"<B 2)"L< I  I@TR044 B DocumentationofIAPTwok)2'2 60 "&22 Y     B LevelAtmospheri)al   B CirculationModelI@TR045 B APreliminaryAnalysisofk6)'6 583!%476 y 5     B U.S.CO2Emi) A      B ReductionPotentialfrom   B EnergyConservationandthe)  B SubstitutionofNaturalGas   B forCoalinthePeriod   B to20)I@TR046 B GlobalLakeLevelVariationsk82'8 119)!%186 u     B from18,000to0YearsAgo:   B APaleoclima)lysisI@TR047 B AnEvaluationoftheRelationk82'8)170 "&99     B shipBetweentheProduction   B a)ofEnergyandAtmo   B sphericMethaneEmissionsI@TR048 B EffectsofAirTem)e17217 171 "&30 }    )onAtmosphericCO2Plant E    B GrowthRelationshipsI@TR049) SimulatingClimatewithTwok32'3 62!%119 )    B DifferentNumericalSchemesI@TR050 B ModelingpCO2intheUppe)k62'6 121 "&22 9"    B )AReviewofRelevant   B Physical,Chemical,and   B BiologicalProcesses)TR051 B AComprehensive16216 147 "&45)!#'    B PrecipitationDataSet   B forGlobalLandAreasI@TR)B ProcessesforIdentifying23223 52 "&77)& + E B RegionalInfluencesofand2z)!$Sets  '!, E B ResponsestoIncreasing '"- E)B AtmosphericCO2andClimate (U#. E B Change"TheMINKProject. ) E B Thisdocumentisineight )*$0 E B volumes(TR052A)) *%1 I@TR053 B TheDeterminationofTotalk12')Q 2 "&92 ,='3 E B DissolvedInorganicCarbonin ) E B SeaWaterUsingExtraction/ .(5 E B Coulometry:Th)Stage .)6 E B ofaCollaborativeStudy /]*7   i0%+8 )''<)d4>>]''#<)d5>@) Table3.(continued)  D >]''-d6>)- - B 2z -"=='" )FY1993"M'HMH"ԈP<Total M ! !0!)8Report"'Y''22">]''Pd7>"2)''22"ԈPFY1985P Remaining Y 0L!)0P8numberP qTitleandcontentsPQtrs12PQtrs34PRTo)todateP)!copies ! >]''d8>)`I '``"<B 2z"L< I  I@)4 B ModelingtheResponseofPlants48248 97 "&) Y  E B andEcosystemstoElevatedCO2 !  E) andClimateChange   I@TR0550 B ClimateDataBasesofthek3)'3Q 3!%173y 5 B #B # E0 B People's)icofChinaA  B #B # 0  0B ##1841!1988 B #B # >)/ER- B CarbonDioxideResearch2z 328 "&17)U  @0178 B Plan"Summary a  >DOE/ER B CO)imateResearchPlan2z 157 "&17   )@0186>DOE/ER B VegetableResponsek12'1)75 "&13 I @0187 B CarbonDioxide  >)R- B CarbonCycleResearchPlan2z 108 "&13) ] @0188>DOE/ER- B DetectingtheClimatic2)z 521]"'2  @0235 B EffectsofIncreasing)}    B CarbonDioxide   B (Hardbound=HB)>DOE/ER- B)ectingtheClimatic10210X 1608!%208 )@0235 B EffectsofIncreasing e     B CarbonDioxide  )B (Softbound=SB)>DOE/ER B Characterizationof102) 547 "&53  $ @0236 B InformationRequirements )    B forStudiesofCO2Effects: Y"&    B WaterResources)ulture,   B Fisheries,ForestsandHuman   B Health(HB)>DOE/ER) Characterizationof2zX 1680!%N/A A& +)@0236 B InformationRequirements  '!,    B forStudiesofCO2)cts: '"-    B WaterResources,Agriculture,   B Fisheries,Forests)man   B Health(SB)>DOE/ER- B ProjectingtheClimatic2)z 521!%N/A +u&2 @0237 B EffectsofIncrea) ,='3    B CarbonDioxide(HB)  .(5 >]''<)d9>>]''#<)d:>@ Table3.(continued)) D >]''-d;> - - )B 2z -"=='" PFY1993"M)'HMH"ԈP<Total M ! !0!P8Report"'Y)'22">]''Pd<>"2Y'''22"ԈP)85P Remaining Y 0L!0P8numberP)TitleandcontentsPQtrs12PQtrs34PRTotalPtodateP)!)es ! >]''d=>"`I '``")B 2z"L< I  >DOE/ER- B Projectingthe)ic10210X 1637!%105 Y  @) B EffectsofIncreasing !     B CarbonDioxide(SB)>DOE/ER-)B DirectEffectsofk42'4 526]"'8 y 5 )@0238 B IncreasingCarbonDioxide A      B onVegetation(HB))>DOE/ER- B DirectEffectsof13213X 1695 "&) U  @0238 B IncreasingCarbonDioxide a     B )etation(SB)>DOE/ER- B AtmosphericCarbonDioxide2z) 516!%N/A u  @0239 B andtheGlobalCarbonCycle =)   B (HB)>DOE/ER B AtmosphericCarbonDioxide162)16X 1709 "&64  @0239 B andtheGlobalCarbon) ]    B (SB)>DOE/ER B MasterIndexoftheCarbon)2z 566 "&63  @0316 B Dioxid)rchStateof }    B theArtReportSeries(HB)>DOE/ER B M)ndexoftheCarbonk92'9 773!%191  )@0316 B DioxideResearchStateof     B theArtReportSeries(S)y>DOE/EV- B CarbonDioxideandClimate:2z 153) "&16 9" @0202 B SummariesofResearchin  #   ) FY1983andFY1984y>DOE/EV- B CarbonDioxideandClimate:2) 113 "&16 Y"& >0202/1 B SummariesofResearchin)#'    B FY1985>DOE/ER B CarbonDioxideSummaries)z 59 "&19 y%5 * @0299 B ofResearchinF) A& + y>DOE/EV- B ResearchIssuesand2z) "&11 '"- @0129 B SupportingResearchofthe (U#. )  B NationalProgramonCarbon   B Dioxide,Environmentand   B So)FY1980>DOE/ER- B CarbonDioxide&Climate:2z)190 "&13 ,='3 @0347 B SummariesofResearchin I-(4 )  B FY1987  /]*7 >]''<)d>>>]'')#<)d?>@ Table3.(continued)  D >]'')-d@> - - B 2z -")='" PFY1993"M'HMH"ԈP<Total) M ! !0!P8Report"'Y''22">]'')PdA>"2Y'''22"ԈPFY1985P Remaining) 0L!0P8numberP qTitleandcontentsP)rs12PQtrs34PRTotalPtodateP)!copies ! >])dB>"`I '``"<B 2z") 10% per each 1C rise in day/night temperature above 28/21C.VtwJ\tsQ\tNP>Vt]K7\t)61^5^Baker,J T^Allen,L H,Jr^Boote,K J^Jones,P^Jones,J W^1990^1^Developmental Responses of Rice to Photoperiod and Carbon *ioxide Concentration^46^50^^201-210^^1911^^^^^^^^1912^^^^^^^^^^^rice/Oryza sativa L.QRVW\tm>56D D u%^1910^Agric. For. Meteorol.^`bH6dN;} ;}N>5L ul sF _^ZYXRRPQVWUp pqF