\ T <Au G things to look atuF&G0FN ~F^&9GuF&GFݸ2WV~ub&G &WFމVFV&G &W~uKLFFΣLP # tvv^&7D.j  I ()(), "', "' ANSI StandardvVvv&|hw6Lj #^&FPj wFvvRP^STOPLISTAUTHORSJOURNALSDESCRIPT^&Gx$:Q* / :X#k]#kA Press F1 for+O O+OO / /AVpz)Fr /  Saving CO2NEW-A Pre  T%n%.) / /{Ackerly, D.D.//Coleman, J.S.//Morse, S.R.//Bazzaz, F.A.CO2 and Temperature Effects on Leaf Area Production in Two Annual Plant Species Ecology1992731260-1269-Ecology. 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 influenced leaf area production through stem (the plastochron index), and through shifts in the relationship between whole-plant leaf area and the number of main stem nodes. In Abutilon, leaf initiation rate was highest at 38C, but area of individual leaves was greatest at 28C. Total leaf area was greatly reduced at 18C due to slow leaf initiation rates. Elevated CO2 concentration increased leaf initiation rate at 28C, resulting in an increase in whole-plant leaf area. In Amaranthus, leaf initiation rate increased with temperature, and was increased by elevated CO2 at 28C. Individual leaf area was 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 38 C relative to 28C, and elevated CO2 levels resulted in increased leaf area at 28C but decreased leaf area at 38C. The effects on leaf area closely parallel rates of biomass accumulation in the same experiment, suggesting that responses of developme ntal processes to elevated CO2 and interacting factors may play an important role in mediating effects on plant growth./Abutilon theophrasti/Amaranthus retroflexus0controlled environment chambers/old field communities/leaf area development/plastochr on index/temperature\     N X > F q { Acock, B.//Acock, M.C.//Pasternak, D.Interactions of CO2 Enrichment and Temperature on Carbohydrate Production and Accumulation in Muskmelon Leaves Journal of the American Society of Horticultural Science1990115525-529-J. Amer. So c. Hort. Sci.. We examined how temperature and stage of vegetative growth affect carbohydrate production and accumulation in Cucumis 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 starch 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 significantly 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 higher 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]./muskmelon/Cucumis melo0SPAR units/carbohydrates/temperature/growth stages/NAR/growth analysis\*k w Acock, B.//Pasternak, D.Effects of CO2 Concentration on Composition, Anatomy, and Morphology of Plants Enoch, H.Z.//Kimball, B.A. eds. Physiology, Yield and EconomicsBoca Raton, FloridaCRC Press, Inc.1986Vol.II41-52#Carbon Dioxide Enrichment of Greenhouse Crops. In summary, we can say that species differ in their response to high CO2. Plants which are using CAM are relatively unresponsive. Other plants with the C4 pathway show modest dry weight gains but large reductions in transpiration rate. Plants which only have the C3 pathway, or well-watered CAM plants which are behaving like C3 plants, exhibit modest reductions in transpiration rate and large gains in dry weight, resulting in a variety of changes in plant composition, anatomy, and morphology. We know too little to even begin dividing C3 species into response groups. However, we can describe a typical or average response as follows. All organs on the plants become heavier with roots gaining proportionally more dry weight than stems, and stems more than leaves. The additional dry matter in the root is mainly used to increase root length with very little going to increase the density of the root tissue. Additional dry matter going to the stem causes increases in its height and diameter and little increase in the density of the tissue. Additional dry matter going to the leaves causes both a small increase in leaf area and a small increase in leaf thickness. There is an increase in structural dry matter 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, depending 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.0allocation/C3/C4/review\QBazzaz, F.A.//Garbutt, K.//Williams, W.E. In Strain, B.R.//Cure, J.D. eds. Effect of Increased Atmospheric Carbon Dioxide Concentration on Plant CommunitiesWashington, D.C.U.S. Dept. of Energy, Carbon Dioxide Research Division1985DOE/ER-0238#Direct Effects of Increasing Carbon Dioxide on Vegetation0review/community level CO2 responses/species competition/C3/C4/flowering/CO2 enrichment studies\,Arnone, J.A., IIIPhotosynthesis, Carbon Allocation, and Nitrogen Fixation in Red AlderPh.D. DissertationYale University1988(Dissertation Abstracts Vol.50:08-B, p.3244 (96 pp.). 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 nodulation and nitrogen fixation on plant biomass productivity and al location 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 nodulation, 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:sho"ot ratios for plants in all treatments decreased over the course of the experiment. This occurred more rapidly in nodulated plants and was attributed to more rapid attainment 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./Alnus rubra/red alder0nitrogen/nitrogen fixation/allocation/trees/carbon:nitrogen ratio/controlled environment chambers\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. 039 in Green Report Series Effects of Increasing Atmospheric CO2 on the Growth, Water Relations, and% Physiology of Plants Grown under Optimal and Limiting Levels of Water and NitrogenWashington, D.C.U.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture, Agric. Res. Serv.1986#Response of Vegetation to Carbon Dio&xide/cotton/Gossypium hirsutum0open-top chambers/isotope discrimination/ABA/water stress/nitrogen/FIZZ irrigation/FACE/carbohydrates/leaf photosynthesis/growth/yield/water status/pink bollworm/Pectinophora gossypiella/herbivory/insects/exposure meth'ods\ Allen, L.H., Jr.Effects of Increasing Carbon Dioxide Levels and Climate Change on Plant Growth, Evapotranspiration, and Water Resources Committee on Climate Uncertainty and Water Resources Management Managing Water Resources in the West) under Conditions of Climate Uncertainty1990 Nov. 14-16Scottsdale, ArizonaWashington, D.C.National Academy Press1991101-147/soybean/Glycine max0WUE/evapotranspiration/climate change/climate model/agriculture/streamflow/GCM's/modeling/rev*iew\?Baker, J.T.//Jr., L.H. Allen,//Boote, K.J.//Jones, P.//Jones, J.W.Rice Photosynthesis and Evapotranspiration in Subambient, Ambient, and Superambient Carbon Dioxide Concentrations Agronomy Journal199082834-840-Agron. J.. The cu,rrent 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, evapotranspiration, and water use ef-ficiency of rice (Oryza sativa L., cv. IR-30). Rice plants were grown 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. 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 increase in the 160 to 500 umol/mol tr/eatments. 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 leveling off of the response among the s0uperambient [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 response to long-term [CO2] growth treatment. 1 The lack of further photosynthetic response above the 500 umol/mol [CO2] treatment 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 in2 global atmospheric [CO2]./rice/Oryza sativa0pre-industrial CO2 concentration/canopy photosynthesis/transpiration/WUE/light/SPAR units\*  Acock, B.//Reddy, V.R.//Hodges, H.F.//Baker, D.N.//McKinion, J.M.Photosynthetic Response of Soybean Canopies to Full-Season Carbon Dioxide Enrichment Agronomy Journal198577942-947-Agron. J.. Global atmospheric CO2 concentration4 ([CO2]) is increasing as a result of the burning of fossil fuels. At present there is little information about how agronomic crops will respond to future high [CO2]. To investigate the basic process that will be most affected, soybean canopies were 5continuously exposed to various [CO2] and photosynthetic rates were measured throughout the growing season. Soybean was grown to physiological maturity in sunlit controlled-environment chambers in CO2 concentrations of 330, 450, 600 and 800 uL/L. Ca6rbon dioxide fluxes were measured on the canopies at 15-min intervals every day and used to calculate photosynthetic and respiration rates. Gross photosynthetic rate increased with each increment in [CO2] regardless of stage of development, but there7 was considerable day-to-day and seasonal variation. Seasonal changes in photosynthetic rate were associated with developmental changes in the crop. Photosynthetic rates were low during early vegetative development, even after the canopy had closed,8 but increased threefold just before flowering to reach a peak during flowering at stage R2. They then decreased by 30% or more until just before the start of pod expansion (R3) when a 45% increase occurred. Thereafter, photosynthetic rates decrease9d slowly and continuously to final harvest. The daily curves of photosynthetic rate vs. photosynthetic photon flux density were further analyzed to determine canopy light utilization efficiency () and canopy conductance to CO2 transfer (). Plants :grown in 800 uL/L [CO2] had a value of that averaged about 40% higher than that for plants grown in 330 uL/L and a value of that averaged about 24% lower for the season. Differences in between these treatments were significant throughout the se;ason, while initial differences in between treatments became less obvious after late vegetative growth stage VII./soybean/Glycine max0SPAR units/canopy photosynthesis/photosynthesis model/light utilization efficiency/conductance\*' <* Acock, B.; Jr, L.H. Allen, In Strain, B.R.//Cure, J.D. eds. Crop Responses to Elevated Carbon Dioxide ConcentrationsWashington, D.C.Dept. of Energy Carbon Dioxide Research Division1985DOE/ER-0238#Direct Effects of Increasing Ca>rbon Dioxide on Vegetation0review/photosynthesis/transpiration/WUE/environmental interactions/crop model\ Aizawa, K.//Nakamura, Y.//Miyachi, S.Variation of Phosphoenolpyruvate Carboxylase Activity in Dunaliella Associated with Changes in Atmospheric CO2 Concentration Plant Cell Physiology1985261199-1203-Plant Cell Physiol.. In Duna@liella tertiolecta, D. bioculata and D. viridis the activities of phosphoenolpyruvate carboxylase and carbonic anhydrase were higher in the cells grown in ordinary air (low-CO2 cells) than in those grown in air enriched with 1-5% CO2 (high-CO2 cells),A whereas in Porphyridium cruentum R-1 there was no difference in phosphoenolpyruvate carboxylase activity between these two types of cells. Apparent Km (NaHCO3) values for photosynthesis in low-CO2 cells of all species tested were smaller than those iBn high-CO2 cells. Most of the 14C was incorporated into 3-phosphoglycerate, sugar mono- and di-phosphates during the initial periods of photosynthetic NaH14CO3-fixation, indicating that both types of cells in D. tertiolecta are C3 plants./DunaliellaC tertiolecta/Dunaliella bioculata/Dunaliella viridis/Porphyridium cruentum0enzymes/carbonic anhydrase/phosphoenolpyruvate carboxylase/cell culture/algae/aquatic plants\ _ i   D         Akey, D.H.//Kimball, B.AGrowth and Development of the Beet Armyworm on Cotton Grown in an Enriched Carbon Dioxide Atmosphere Southwestern Entomologist198914255-260-Southwestern Entomol.. Growth and development were studied in tFhe beet armyworm (BAW), Spodoptera exigua (Hbner), reared on cotton seedlings at high (640 uL/L) or ambient (320 uL/L) carbon dioxide (CO2) levels and at two fertilizer levels. Under high fertilization, female BAW reared on CO2 enriched seedlings weiGghed significantly less (87.3 mg) than controls (101.0 mg) and had a significantly longer developmental time (14.2 versus 12.4 days for controls). Male BAW followed the same pattern, but the differences were not statistically significant. Combined (Hmale and female) survival rates for BAW reared on CO2-enriched cotton seedlings on a high fertilizer level were 19.1 compared to 41.6% for controls; more females survived than males by a significant ratio of 2:1./cotton/Gossypium hirsutum0open-top cIhambers/Spodoptera exigua/beet armyworm/insects\*   Akey, D.H.//Kimball, B.A.//Mauney, J.R.Growth and Development of the Pink Bollworm, Pectinophora gossypiella (Lepidoptera: Gelechiidae), on Bolls of Cotton Grown in Enriched Carbon Dioxide Atmospheres Environmental Entomology198817K452-455-Environ. Entomol.. The pink bollworm, Pectinophora gossypiella (Saunders), was reared on the bolls of cotton plants grown in CO2-enriched (649 uL/L) and ambient (371 uL/L) chambers and in two open field plots, one with free-air CO2 enrichmeLnt (522 uL/L) and one without enrichment (ambient CO2, 360 uL/L). The effects of increased CO2 levels on growth and development were examined. There was no difference in pupal weights of pink bollworm raised on CO2-enriched cotton compared with thoseM raised on ambient CO2 cotton (26.80 versus 26.64 mg, respectively). Also, there was no difference in developmental time (21-27 d). Analysis of percent seed damage by larvae showed no differences between CO2-enriched and ambient CO2 cotton. These rNesults 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./cotton/Gossypium hirsutum0Pectinophora gossypiella Saunders/pink bollworOm/insects/seeds/carbon:nitrogen ratio/seed damage/open-top chambers\RT m  4 Allen, L.H., JrPlant Responses to Rising Carbon Dioxide and Potential Interactions with Air Pollutants Journal of Environmental Quality19901915-34-J. Environ. Qual.. As global population increases and industrialization expands,Q carbon dioxide (CO2) and toxic air pollutants can be expected to be injected into the atmosphere at increasing rates. This analysis reviews a wide range of direct plant responses to rising CO2, increasing levels of gaseous pollutants, and climate chRange, and potential interactions among the factors. Although several environmental interactions on stomata and foliage temperatures are reviewed briefly, a comprehensive review of effects of potential climatic change on plants is not a major objectivSe of this analysis. Research shows that elevated CO2 increases photosynthetic rates, leaf area, biomass, and yield. Elevated CO2 also reduces transpiration rate per unit leaf area, but not in proportion to reduction of stomatal conductance, because Tfoliage 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 photosynthesisU 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 tVhe 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 chWanges in CO2.0climate change/air pollution/conductance/transpiration/WUE/review\ (Andre, M.//Du Cloux, H.//Richaud, C.Wheat Response to CO2 Enrichment: CO2 Exchanges, Transpiration and Mineral Uptakes MacElroy, R.//Martello, N.V.//Smernoff, D. eds. Controlled Ecological Life Support System: CELLS '85 Workshop1985 YJuly 16-19AMES Research Center, Moffett FieldNASA Report TM882151986405-428/wheat/Triticum aestivum0growth analysis/canopy photosynthesis/transpiration/WUE/water stress/ nutrition/plant density/phosphorus/nitrogen/potassium/controlled enviroZnment chambers\Allen, L.H., Jr.//Bisbal, E.C.//Boote, K.J.//Jones, P.H.Soybean Dry Matter Allocation under Subambient and Superambient Levels of Carbon Dioxide Agronomy Journal199183875-883-Agron. J.. Rising atmospheric carbon dioxide concent\ration [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 tw]o reasons: to assess response of plants to prehistoric as well as future 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-environmen^t chambers at CO2 levels of 160, 220, 280, 330, 660, and 990 umol (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 ta_ken 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 components (petioles and stems) increased. At final harvest the respective [CO2`] treatments resulted in 38, 53, 62, 100, 120 and 92% 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 caonfirm not only that rising CO2 should increase plant growth, but also that plant growth was probably seriously limited by atmospheric [CO2] in preindustrial revolution times back to the previous global glaciation./soybean/Glycine max0SPAR units/preb-industrial CO2 concentration/allocation/yield/growth\*  Allen, L.H., Jr.//Boote, K.J.//Jones, J.W.//Jones, P.H.//Valle, R.R.//Acock, B.//Rogers, H.H.//Dahlman, R.C.Response of Vegetation to Rising Carbon Dioxide: Photosynthesis, Biomass, and Seed Yield of Soybean Global Biogeochemical Cyclesd1987I1-14-Global Biogeochem. Cycles. 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 ae 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 tof 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 cgarbon 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./soybean/Glycine max0review/growth model/pre-industrial CO2 hconcentration/carbon cycle/carbon sequestering/deforestation\Allen, L.H., Jr.//Bisbal, E.C.//Campbell, W.J.//Boote, K.J.Carbon Dioxide Effects on Soybean Developmental Stages and Expansive Growth Soil and Crop Science Society of Florida, Proceedings199049124-131-Soil and Crop Sci. Soc. Fla.j Proc.. 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 COk2 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 clontrolled 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 mmainstem 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 nodesn 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 oveor 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 phenoplogy./soybean/Glycine max0SPAR units/phenology/growth/pre-industrial CO2 concentration\*  Allen, L.H., Jr.//Boote, K.J.Vegetation, Effect of Rising CO2New YorkAcademic Press, Inc.1992Vol. 4409-416#Encyclopedia of Earth System Science0review/transpiration/temperature/air pollution/nutrition/climate\Allen, L.H., Jr.//Valle, R.R.//Mishoe, J.W.//Jones, J.W.//Jones, P.H.Soybean Leaf Gas Exchange Responses to CO2 Enrichment Soil and Crop Science Society of Florida, Proceedings199049192-198-Soil and Crop Sci. Soc. Fla. Proc.. Casrbon dioxide concentration of the atmosphere is expected to double within the next century. This study was undertaken to determine the leaf gas exchange responses of soybean (Glycine Max (L.) Merr. cv. Bragg) grown continuously at 330, 450, 600, and t800 L (CO2)/million L (air), or volume parts per million volumes (vpm), in sunlit, controlled-environment chambers. The chambers were secured to soil bins filled with a reconstructed profile of Arredondo fine sand (a loamy siliceous hyperthermic Grosusarenic Paleudult). A gas exchange system was used to measure leaf and air temperatures, flow rates, cuvette input and exit CO2 concentrations and vapor pressures, and incident solar photosynthetically active radiation (PAR). These measurements werev used to calculate the carbon dioxide exchange rate (CER), transpiration rate (TRATE), stomatal resistance (rs), and leaf internal airspace (intercellular) CO2 concentration (Ci) of fully expanded, sunlit leaves held in a flat, horizontal position. Rwesults indicated that leaf CER increased linearly over the CO2 concentration range of 330 to 800 vpm. Differences in leaf transpiration rates between the 800 and 330 vpm CO2 treatment were small. Water-use efficiency, CER/TRATE, increased as CO2 levexl increased, mainly due to an increase in CER. Both leaf stomatal resistance and leaf temperature increased with increasing CO2 concentrations at fixed PAR. The ratio of Ci to external CO2 concentration (Ce) was approximately constant across the ranyge of [CO2] treatments. These findings showed no tendency for CO2-saturation of soybean leaf CER (and hence no evidence of CO2-induced feedback inhibition of photosynthetic rate) over the CO2 concentration range of 330 to 800 vpm./soybean/Glycine mazx0leaf photosynthesis/transpiration/WUE/photosynthetic feedback inhibition/Ci:Ca/SPAR units/carbon/carbon\*  Allen, L.H., Jr.//Vu, J.C.V.//Valle, R.R.//Boote, K.J.//Jones, P.H.Nonstructural Carbohydrates and Nitrogen of Soybean Grown under Carbon Dioxide Enrichment Crop Science19882884-94-Crop Sci.. 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 (L.) Merr. cv. Bragg]. Plants were grown at Gain}esville, FL from seed to maturity in six sunlit, controlled-environment chambers that maintained CO2 at 330, 330, 450, 600, 800, and 800 umol (CO2)/mol (air). Attached lysimeters contained Arredondo fine sand (loamy, siliceous, hyperthermic Grossare~nic Paleudult). Leaflet blades were sampled five times per day at 48 and 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./soybean/Glycine max0SPAR units/carbohydrates/nitrogen/specific leaf weight/allocation\*  Allen, S.G.//Idso, S.B.//Kimball, B.A.//Anderson, M.G.Relationship between Growth Rate and Net Photosynthesis of Azolla in Ambient and Elevated CO2 Concentrations Agriculture, Ecosystems and Environment198820137-141-Agric. Ecosystems Environ.. Azolla pinnata was grown out-of-doors at Phoenix, AZ, U.S.A. in open-topped plastic-walled chambers supplied with either 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 CO2 concentration-environment interaction./Azolla pinnata0open-top chambers/canopy photosynthesis/growth rate/aquatic plants\Rr x    Allen, S.G.//Idso, S.B.//Kimball, B.A.Interactive Effects of CO2 and Environment on Net Photosynthesis of Water-Lily Agriculture, Ecosystems and Environment19903081-88-Agric. Ecosystems Environ.. 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./Nymphaea marliac/water lily0open-top chambers/aquatic plants/canopy photosynthesis/light/temperature\*  "Amthor, J.SRespiration in a Future, Higher-CO2 World Plant, Cell and Environment19911413-20-Plant Cell Environ.. 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' respiration, another major component of the carbon budget of higher plants, may be affected by a change in [CO2] independent of an increase in temperature. Literature pertaining to an impact of [CO2] on respiration rate is reviewed. With an increase in [CO2], respiration rate is increased in some cases, but decreased in others. The effects of [CO2] on respiration rate may be direct or indirect. Mechanisms responsible for various observations are proposed. These proposed mechanisms relate to changes in: (1) levels of nonstructural carbohydrates, (2) growth rate and structural phytomass accumulation, (3) composition of phytomass, (4) direct chemical interactions between CO2 and respiratory enzymes, (5) direct chemical interactions between CO2 and other cellular components, (6) dark CO2 fixation rate, and (7) ethylene biosynthesis rate. Because a range of (possibly interactive) effects exists, and present knowledge is limited, the impact of future [CO2] on respiration rate cannot be predicted. Theoretical considerations and types of experiments that can lead to an increase in the understanding of this issue are outlined.0review/carbon budget/respiration\#Amthor, J.S//Koch, G.W.//Bloom, A.J.CO2 Inhibits Respiration in Leaves of Rumex crispus L. Plant Physiology199298757-760-Plant Physiol.. Curly dock (Rumex crispus L.) was grown from seed in a glasshouse at an ambient CO2 partial pressure of about 35 pascals. Apparent respiration rate (CO2 efflux in the dark) of expanded leaves was then measured at ambient CO2 partial pressure 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 pressure of CO2 typically inhibited respiration by 25 to 30%, whereas a decrease in CO2 elicited a corresponding increase in respiration. These responses were readily reversible. A flexible, sensitive regulatory interaction between CO2 (a byproduct of respiration) and some component(s) of heterotrophic metabolism is indicated./Rumex crispus/curly dock0greenhouse/respiration/Ci:Ca\RK X   $Anderson, I.H.//Dons, C.//Nilsen, S.//Haugstad, M.K.Growth, Photosynthesis and Photorespiration of Lemna gibba: Response to Variations in CO2 and O2 Concentrations and Photon Flux Density Photosynthesis Research1985687-96-Photosynth. Res.. Dry weight and Relative Growth Rate of Lemna gibba were significantly increased by CO2 enrichment up to 6000 uL CO2/L. This high CO2 optimum for growth is probably due to the presence of nonfunctional stomata. The response to high CO2 was less or absent following four days growth in 2% O2. The Leaf Area Ratio decreased in response to CO2 enrichment as a result of an increase in dry weight per frond. Photosynthetic rate was increased by CO2 enrichment up to 1500 uL CO2/L during measurement, showing only small increases with further CO2 enrichment up to 5000 uL CO2/L at a photon flux density of 210 umol/m2/s and small decreases at 2000 umol/m/s. The actual rate of photosynthesis of those plants cultivated at high CO2 levels, however, was less than the air grown plants. The response of photosynthesis to O2 indicated that the enhancement of growth and photosynthesis by CO2 enrichment was a result of decreased photorespiration. Plants cultivated in low O2 produced abnormal morphological features and after a short time showed a reduction in growth./Lemna gibba/duckweed0growth/respiration/canopy photosynthesis/oxygen/light/aquatic plants/controlled environment chambers\Rd o  * &Andre, M.//Cotte, F.//Gerbaud, A.//Massimino, D.//Massimino, J.//Richaud, C.Effect of CO2 and O2 on Development and Fructification of Wheat in Closed Systems Advances in Space Research19899(8)17-(8)28-Adv. Space Res.. The cultivation of wheat (Triticum aestivum L.) was performed in controlled environment chambers with the continuous monitoring of photosynthesis, dark respiration, transpiration and main nutrient uptakes. A protocol in twin chambers was developed to compare the specific effects of low O2 and high CO2. Each parameter is able to influence photosynthesis but different effects are obtained in the development, fructification and seed production, because of the different effects of each parameter on the ratio of reductive to oxidative cycle of carbon. The first main conclusion is that low level of O2, at the same rate of biomass production, strongly acts on the rate of ear appearance and on seed production. Ear appearance was delayed and seed production reduced with a low O2 treatment (about 4%). The O2 effect was not mainly due to the repression of the oxidative cycle. The high CO2 treatment (700 to 900 uL/L) delayed ear appearance by 4 days, but did not reduce 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./Triticum aestivum/wheat0controlled environment chambers/oxygen/seed production/canopy photosynthesis/respiration\*   'Andre, M.//Du Cloux, H.Interaction of CO2 Enrichment and Water Limitations on Photosynthesis and Water-Use Efficiency in Wheat Plant Physiology and Biochemistry199331103-112-Plant Physiol. Biochem.. Wheat plants (Triticum aestivum L. cv. Capitole) were grown in twin closed growth chambers with continuous monitoring of CO2 and water exchanges. During the vegetative stage the effect of CO2 enrichment, from 330 to 660 uL/L, was studied under an irradiance of 660 uE/m2/s with an optimum watering. Comparisons were made with successive experiments in which daily water supply was fixed to a fraction (0.62-0.5-0.25) of the maximal transpiration of previous experiments. In a well watered canopy, the doubling of CO2 decreased transpiration by only 8%. Water use efficiency was increased (factor 1.45) mainly by the stimulation of photosynthesis. Under restricted water supply, photosynthesis of plants was more limited than transpiration. The inhibition of photosynthesis and the increase of water use efficiency can be predicted by a simple diffusion model applied to the response curve of photosynthesis to CO2, measured on canopy in standard conditions of watering. The main hypothesis is that the equivalent stomatal conductance is reduced proportionally to the water availability, without closure by patching. Under enriched CO2, the same reduction of leaf surface by water limitation was observed. Photosynthesis was less affected. Therefore, water use efficiency was again increased. Doubling CO2 concentration can compensate for water stress inhibition on CO2 assimilation. That model also predicts interactions of CO2 and water stress observed on water-use-efficiency which was increased by a factor up to 5 in comparison with well-watered plants in standard atmosphere. The implications of this study on global change models are discussed./wheat/Triticum aestivum0controlled environment chambers/grasses/conductance/water stress/canopy photosynthesis/WUE/transpiration/photosynthesis model\*  )Andre, M.//Ducloux, H.//Richaud, C.//Massimino, D.//Daguenet, A.//Massimino, J.//Gerbaud, A.Etude des Relations entre Photosynthese Respiration, Transpiration et Nutrition Minerale chez le Ble Advances in Space Research19877(4)105-(4)114-Adv. Space Res.. 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./wheat/Triticum aestivum0canopy photosynthesis/respiration/transpiration/nutrition/nitrogen/potassium/phosphorus/controlled environment chambers\* . *Andreeva, T.F.//Strogonova, L.E.//Voevudskaya, S.Yu.//Maevskaya, S.N.//Cherkanova, N.N.Effect of Enhanced CO2 Concentration on Photosynthesis, Carbohydrate and Nitrogen Metabolism, and Growth Processes in Mustard Plants Fiziologiya Rastenii19893640-48-Fiziol. Rast.. 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./mustard/Brassica juncea0photosynthesis/fraction 1 protein/carbohydrates/nitrogen/temperature/controlled environment chambers\*  +Apel, PInfluence of CO2 on Stomatal Numbers Biologia Plantarum (Praha)1989372-74-Biol. Plantarum. 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./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/corn0stomatal density/cultivar responses/controlled environment chambers\-Arnone, J.A., III//Gordon, J.C.Effect of Nodulation, Nitrogen Fixation and CO2 Enrichment on the Physiology, Growth and Dry Mass Allocation of Seedlings of Alnus rubra Bong. New Phytologist199011655-66-New Phytol.. Inoculated and uninoculated Alnus rubra Bong. seedlings were grown for 47 days in atmospheres containing ambient (350 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. Evidence 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./Alnus rubra0trees/nodulation/nitrogen fixation/allocation/controlled environment chambers\R    .Arp, W.JEffects of Source-Sink Relations on Photosynthetic Acclimation to Elevated CO2 Plant, Cell and Environment199114869-875-Plant Cell Environ.. 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.0review/photosynthetic acclimation/source-sink balance/root:shoot ratio/pot volume\0Arp, W.J.//Drake, B.G.Increased Photosynthetic Capacity of Scirpus olneyi after 4 Years of Exposure to Elevated CO2 Plant, Cell and Environment1991141003-1006-Plant Cell Environ.. 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 observed in other species growing in the field, which suggests that photosynthesis of certain field grown plants will continue to respond to elevated levels of atmospheric CO2./sedge/Scirpus olneyi0leaf photosynthesis/photosynthetic acclimation/open-top chambers\*< J 2Artus, N.N.Two Mutants of Arabidopsis thaliana That Become Chlorotic in Atmospheres Enriched with CO2 Plant, Cell and Environment199013575-580-Plant Cell Environ.. 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 leaves and spreads to the tips. The injurious effects of CO2 seem to be restricted to photosynthetic tissues, since root elongation 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 mutations do not impose a requirement for photorespiration. The possibilities that the high CO2-sensitive phenotypes are caused by an effect of CO2 in stomata, on ethylene synthesis, or on mineral uptake are discussed but are considered unlikely./Arabidopsis thaliana0mutant/controlled environment chambers\R /   4Aston, A.R.The Effect of Doubling Atmospheric CO2 on Streamflow: a Simulation Journal of Hydrology198467273-280-J. Hydrol.. There is a potential for atmospheric CO2 to rise four- or six-fold, and at some time in the foreseeable future a doubling 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 stremflow 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.0streamflow/hydrologic model\Burnett, R.B.//Chaudhuri, U.N.//Kanemasu, E.T.//Kirkham, M.B. 024 in Green Report Series Sorghum at Elevated Levels of CO2Washington, D.C.U.S. Dept. of Energy, Carbon Dioxide Research Division1985#Response of Vegetation to Carbon Dioxide/sorghum/Sorghum bicolor0rhizotron/outdoor growth chambers/growth stages/yield/evapotranspiration/C4/roots/root:shoot ratio/allocation/WUE\kBiswas, P.K.//Hileman, D.R.//Allen, J.R.//Bhattacharya, N.C.//Lu, J.Y.//Pace, R.D.//Rogers, H.H. 022 in Green Report Series Field Studies of Sweet Potatoes and Cowpeas in Response to Elevated Carbon DioxideWashington, D.C. and Tuskegee, AlabamaU.S. Dept. of Energy, Carbon Dioxide Research Division, and Tuskegee University1985#Response of Vegetation to Carbon Dioxide/sweet potato/cowpea/Ipomoea batatas/Vigna unguiculata0open-top chambers/nitrogen/conductance/growth/yield/nitrogen fixation//crops\ Acock, B.//Trent, A. 017 in Green Report Series The Soybean Crop Simulator GLYCIM: Documentation for the Modular Version 91Washington, D.CU.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture, Agric. Res. Serv.1991#Response of Vegetation to Carbon Dioxide/soybean/Glycine max0generic model/crop model/simulation\Acock, B.//Acock, M.C.//Reddy, V.R.//Baker, D.N. 011 in Green Report Series The Simulation, with GLYCIM, of Soybean Crops Grown in the Field and at Various CO2 Concentrations in Open-top Chambers during 1982Washington, D.C.U.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture, Agric. Res. Serv.1985#Response of Vegetation to Carbon Dioxide/soybean0open-top chambers/modeling/crop model/simulation\Doyle, T.W.//Taylor, F.G.//Parker, M.L.//Cooper, C.F.//West, D.C. 025 in Green Report Series Preliminary Ring-Width and Ring-Density Data for Deriving Wood Mass Chronologies of Coniferous Species from the Northwest U.S. and CanadaWashington, D.C. and Oak Ridge, TennesseeU.S. Dept. of Energy, Carbon Dioxide Research Division, and Environmental Sciences Division, Oak Ridge National Laboratory1985#Response of Vegetation to Carbon Dioxide/white spruce/red pine/Douglas-fir/Western hemlock/Western red cedar/Engelmann spruce/lodgepole pine/yellow cedar/black spruce0trees/tree-ring analysis\Graybill, D.A. 026 in Green Report Series Western U.S. Tree-Ring Index Chronology Data for Detection of Arboreal Response to Increasing Carbon DioxideWashington, D.C., and Oak Ridge, TennesseeU.S. Dept. of Energy, Carbon Dioxide Research Division, and Environmental Sciences Division, Oak Ridge National Laboratory1985#Response of Vegetation to Carbon Dioxide/Pinus longaeva/Pinus aristata/Pinus flexilis0trees/trees/tree-ring analysis/altitude\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. 027 in Green Report Series Effect of Increasing Atmospheric CO2 on the Yield and Water Use of CropsWashington, D.C.U.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture, Agric. Res. Serv.1985#Response of Vegetation to Carbon Dioxide/cotton/Gossypium hirsutum0open-top chambers/yield/conductance/water status/photosynthetic acclimation/leaf photosynthesis/carbohydrates/soil respiration/exposure methods\sReynolds, J.F.//Bachelet, D.//Leadley, P.//Moorhead, D. 028 in Green Report Series Assessing the Effects of Elevated Carbon Dioxide on Plants: Towards the Development of a Generic Plant Growth ModelWashington, D.C.U.S. Dept. of Energy, Carbon Dioxide Research Division1986#Response of Vegetation to Carbon Dioxide0generic model/modeling/growth model\Chaudhuri, U.N.//Burnett, R.B.//Kanemasu, E.T//Kirkham, M.B. 029 in Green Report Series Effect of Elevated Levels of CO2 on Winter Wheat under Two Moisture RegimesWashington, D.C.U.S. Dept. of Energy, Carbon Dioxide Research Division1986#Response of Vegetation to Carbon Dioxide/wheat/Triticum aestivum0rhizotron/outdoor growth chambers/water stress/WUE/yield/roots/evapotranspiration/water status/conductance\lBiswas, P.K.//Hileman, D.R.//Bhattacharya, N.C.//Ghosh, P.P.//Bhattacharya, S.//Johnson, J.H.//Mbikayi, N.T. 030 in Green Report Series Growth, Yield and Plant Water Relationships in Sweet Potatoes in Response to Carbon Dioxide EnrichmentWashington, D.C. and Tuskegee, AlabamaU.S. Dept. of Energy, Carbon Dioxide Research Division, and Tuskegee University1986#Response of Vegetation to Carbon Dioxide/sweet potato/Ipomoea batatas0open-top chambers/growth analysis/yield/water status/leaf photosynthesis/water stress\Allen, L.H., Jr.//Boote, K.J.//Jones, J.W.//Mishoe, J.W.//Jones, P.H.//Valle, R.R//Bisbal, E.C. 031 in Green Report Series Subambient and Superambient Carbon Dioxide Effects on Growth, Nonstructural Carbohydrates, Biochemistry of Photosynthesis and Transpiration of Soybeans. 1984 Progress ReportWashington, D.C.U.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture, Agric. Res. Serv.1985#Response of Vegetation to Carbon Dioxide/soybean/Glycine max0SPAR units/pre-industrial CO2 concentration/growth/carbohydrates/photosynthesis/transpiration/ribulose bisphosphate carboxylase\Cure, J.D.//Galloway, L.F.//Israel, D.W.//Jr., T.W. Rufty, 033 in Green Report Series Influence of Nutrition on Vegetation Response to Carbon Dioxide. I. Interactions of Nitrogen and Phosphorus Supply on Soybean Growth and Nutritional ParametersWashington, D.C.U.S. Dept. of Energy, Carbon Dioxide Research Division1986#Response of Vegetation to Carbon Dioxide/soybean/Glycine max0controlled environment chambers/nutrition/nitrogen/phosphorus/growth/yield\Drake, B.//Arp, W.//Curtis, P.S.//Leadley, P.W.//Sager, J.//Whigham, D. 034 in Green Report Series Effects of Elevated CO2 on Chesapeake Bay Wetlands. I. Description of the Study SiteWashington, D.C.U.S. Dept. of Energy, Carbon Dioxide Research Division1986#Response of Vegetation to Carbon Dioxide/Spartina patens/Distichlis spicata/Scirpus olneyi0open-top chambers/salt marsh/litter quality/water status/aquatic plants/halophytes/exposure methods\+Oechel, W.C.//Riechers, G.H.//Beyers, J.//Cowles, S.//Grulke, N.//Hastings, S.//Oberbauer, S//Prudhomme, T.//Sionit, N. 037 in Green Report Series Response of a Tundra Ecosystem to Elevated Atmospheric Carbon DioxideWashington, D.C.U.S. Dept. of Energy, Carbon Dioxide Research Division1986#Response of Vegetation to Carbon Dioxide/Vaccinium vitis-idaea/Eriophorum vaginatum/Ledum palustre/Carex bigelowii/Betula nana0tracking chambers/tundra/allocation/soil respiration/photosynthetic acclimation/leaf photosynthesis/nutrition/exposure methods\Drake, B.G.//Arp, W.//Craig, J.//Curtis, P.S.//Leadley, P.W.//Whigham, D. 038 in Green Report Series Effects of Elevated CO2 on Chesapeake Bay Wetlands. II. Gas Exchange and Microenvironment in Open Top ChambersWashington, D.C.U.S. Dept. of Energy, Carbon Dioxide Research Division1987#Response of Vegetation to Carbon Dioxide/Scirpus olneyi/Spartina patens/Distichlis spicata0open-top chambers/salt marsh/canopy photosynthesis/conductance/photosynthetic acclimation/aquatic plants/halophytes/exposure methods\Chaudhuri, U.N.//Burnett, R.B.//Kanemasu, E.T//Kirkham, M.B. 040 in Green Report Series Effect of Elevated Levels of CO2 on Winter Wheat under Two Moisture RegimesWashington, D.C.U.S. Dept. of Energy, Carbon Dioxide Research Division1987#Response of Vegetation to Carbon Dioxide/wheat/Triticum aestivum0rhizotron/water stress/roots/outdoor growth chambers/transpiration/conductance/fluorescence/allocation/carbohydrates/yield\vReynolds, J.F.//Skiles, J.W.//Moorhead, D.L. 041 in Green Report Series SERECO: A Model for the Simulation of Ecosystem Response to Elevated CO2Washington, D. C.U.S. Dept. of Energy, Carbon Dioxide Research Division1987#Response of Vegetation to Carbon Dioxide0modeling/ecosystem model/ecosystem level CO2 responses/generic model/scaling\<Baker, J.T.//Jr., L.H. Allen,//Boote, K.J.//Rowland-Bamford, A.J.//Jones, J.W.//Jones, P.H.//Bowes, G.//Albrecht, S.L. 043 in Green Report Series Response of Rice to Subambient and Superambient Carbon Dioxide Concentrations. 1986-1987 Progress ReportWashington, D.C.U.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture, Agric. Res. Serv.1988#Response of Vegetation to Carbon Dioxide/rice/Oryza sativa0SPAR units/pre-industrial CO2 concentration/gr owth stages/yield/allocation/canopy photosynthesis/transpiration/carbohydrates/stomatal density/ribulose bisphosphate carboxylase/Cyanobacteria/Anabaena variabilis\uReynolds, J.F.;Dougherty, R.L.;Tenhunen, J.D.;Harley, P.C. 042 in Green Report Series A Model for the Simulation of Plant Response to Elevated CO2Washington, D.C.U.S. Dept. of Energy, Carbon Dioxide Research Division1988#Response o f Vegetation to Carbon Dioxide0modeling/photosynthesis model/generic model\/Hendrey, G.R.//Lewin, K.F.//Lipfert, F.//Kolber, Z.//Daum, M. 045 in Green Report Series Free-Air Carbon Dioxide Enrichment (FACE) Facility Development: I. Concept, Prototype Design and PerformanceWashington, D.C.U.S. Dept. of Energy,  Carbon Dioxide Research Division1988#Response of Vegetation to Carbon Dioxide0FACE/exposure methods\0Hendrey, G.R.//Lipfert, F.W.//Kimball, B.A.//Hileman, D.R.//Bhattacharya, N.C. 046 in Green Report Series Free Air Carbon Dioxide Enrichment (FACE) Facility Development: II. Field Tests at Yazoo City, MS, 1987Washington, D.C.U.S. Dept. of Energy, Carbon Dioxide Research Division1988#Response of Vegetation to Carbon Dioxide/cotton/Gossypium hirsutum0FACE/leaf photosynthesis/conductance/open-top chambers/modeling/growth model/exposure methods\Cure, J.D.//Galloway, L.F.//El Dodo, M.//Israel, D.W.//Jr., T.W. Rufty, 048 in Green Report Series Growth and Carbon Budgets of Soybean Leaves Exposed to Elevated Carbon DioxideWashington, D.C.U.S. Dept. of Energy, Carbon Dioxide Research Division1989#Response of Vegetation to Carbon Dioxide/soybean/Glycine max0controlled environment chambers/growth/carbon budget/source-sink balance/leaf area development/leaf photosynthesis/remobilization/assimilate partitioning\Kimball, B.A.//Mauney, J.R.//Akey, D.H.//Hendrix, D.L.//Allen, S.G.//Idso, S.B.//Radin, J.W.//Lakatos, E.A. 049 in Green Report Series Effects of Increasing Atmospheric CO2 on the Growth, Water Relations, and Physiology of Plants Grown under Optimal and Limiting Levels of Water and NitrogenWashington, D.C.U.S. Dept. of Energy, Carbon Dioxide Research Division and U.S. Dept. of Agriculture, Agric. Res. Serv.1987#Response of Vegetation to Carbon Dioxide/cotton/Gossypium hirsutum0open-top chambers/water stress/nitrogen/beet armyworm/FACE/FIZZ irrigation/growth model/leaf photosynthesis/stomata/exposure methods\Chaudhuri, U.N.//Kanemasu, E.T.//Kirkham, M.B. 050 in Green Report Series Effect of Elevated Levels of CO2 on Winter Wheat under Two Moisture RegimesWashington, D.C.U.S. Dept. of Energy, Carbon Dioxide Research Division1989#Response of Vegetation to Carbon Dioxide/wheat/Triticum aestivum0rhizotron/outdoor growth chambers/water stress/growth stages/transpiration/yield/WUE\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.//Ziska, L. 051 in Green Report Series Effects of Elevated CO2 on Chesapeake Bay Wetlands. IV. Ecosystem and Whole Plant Responses. April-November 1988.Washington, D.C.U.S. Dept. of Energy, Carbon Dioxide Research Division1989#Response of Vegetation to Carbon Dioxide/Scirpus olneyi/Spartina patens/Distichlis spicata/Glycine max/soybean/Lycopersicon esculentum/tomato/Manihot esculentum/Amaranthus hypochondriacus/amaranth/Acacia mangium/Ficus obtusifolia/Paspallum conjugatum/Pharus latifolia/Psychotria limonensis/Tabebuia rosea0open-top chambers/salt marsh/aquatic plants/roots/nitrogen/growth/leaf photosynthesis/canopy photosynthesis/photosynthetic acclimation/respiration/carbon budget/evapotranspiration/C3/C4/species competition/community level CO2 responses/litter quality//litter decomposition/halophytes\~Kimball, B.A.//Akey, D.H.//Mauney, J.R.//Idso, S.B.//Allen, S.G.//Hendrix, D.L.//Radin, J.W 052 in Green Report Series Elevated CO2: Modeling Crop Response, Interaction with Temperature, Effects on Trees and InsectsWashington, D.C.U.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture, Agric. Res. Serv.1988#Response of Vegetation to Carbon Dioxide/cotton/Gossypium hirsutum/Agave vilmoriniana/Citrus aurantium/orange trees/sorghum/Sorghum bicolor0open-top chambers/trees/modeling/crop model/temperature/insects/herbivory/FACE/Spodoptera exigua/beet armyworm/CAM/FIZZ irrigation\@Baker, J.T.//Jr., L.H. Allen,//Boote, K.J.//Rowland-Bamford, A.J.//Jones, J.W.//Jones, P.H.//Bowes, G.//Laugel, F. 053 in Green Report Series Temperature and CO2 Effects on Rice. 1988 Progress ReportWashington, D.C.U.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture, Agric. Res. Serv.1989#Response of Vegetation to Carbon Dioxide/Oryza sativa/rice0SPAR units/temperature/growth stages/yield/canopy photosynthesis/evapotranspiration/respiration/c arbohydrates/ribulose bisphosphate carboxylase/sucrosephosphate synthase\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, D. 055 in Green Report Series Effects of Elevated CO2 on Chesapeake Bay Wetlands. V. Eco"system and Whole Plant Responses. April-November 1989Washington, D.C.U.S. Dept. of Energy, Carbon Dioxide Research Division1990#Response of Vegetation to Carbon Dioxide/Scirpus olneyi/Spartina patens0open-top chambers/salt marsh/water status/#WUE/canopy photosynthesis/methane/evapotranspiration/nitrogen/ecosystem level CO2 responses/leaf photosynthesis/roots/quantum requirement/respiration/halophytes\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. 056 in Green Report Series Rangeland-Plant Response to Elevated CO2Washington, D%.C.U.S. Dept. of Energy, Carbon Dioxide Research Division1990#Response of Vegetation to Carbon Dioxide/Andropogon gerardii/big bluestem0outdoor growth chambers/tallgrass prairie/grasses/sedges/Forbs/leaf photosynthesis/transpiration/conductance&/growth/rangeland\Allen, L.H., Jr.//Beladi, S.E. 057 in Green Report Series Free-Air CO2 Enrichment (FACE): Analysis of Gaseous Dispersion Arrays for the Study of Rising Atmospheric CO2 Effects on Vegetation. 1983-1989 Progress ReportWashington, D.C.U.(S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture, Agric. Res. Serv.1990#Response of Vegetation to Carbon Dioxide0FACE/exposure methods\8Bailly, J.//Coleman, J.R.Effect of CO2 Concentration on Protein Biosynthesis and Carbonic Anhydrase Expression in Chlamydomonas reinhardtii Plant Physiology198887833-840-Plant Physiol.. The effect of external inorganic carbon (*Ci) concentrations on protein biosynthesis and carbonic anhydrase (CA) mRNA abundance were examined in the eukaryotic alga Chlamydomonas reinhardtii. Transfer of high CO2 (5%) grown algae to air levels of CO2 resulted in the transitory synthesis of t+wo polypeptides of approximately 49,000 and 52,000 daltons as well as prolonged synthesis and accumulation of the 37,000 dalton CA monomer and an unidentified 20,000 dalton polypeptide. The gene coding for carbonic anhydrase was isolated from a genom,ic expression library and subjected to restriction endonuclease analysis. Southern blot analysis of chromosomal DNA indicates that only a single copy of the gene is present. The 2.5 kilobase DNA fragment hybridizes specifically to a 1.4 kilobase tra-nscript in RNA isolated from air-grown cells and from cells grown on 5% CO2 that have been exposed to air levels of CO2. Maximum mRNA abundance was observed after 1 to 3 hours of exposure to air. Transfer of air-grown cells to a high CO2 environment. resulted in the elimination of the CA transcript after 60 minutes of exposure. Changes in CA transcript abundance in response to external Ci concentrations occurred in the presence or absence of light./Chlamydomonas reinhardtii0algae/enzymes/carbo/nic anhydrase/gene expression/aquatic plants/cell culture\Rs  f  ;Baker, J.T.//Jr., L.H. Allen,//Boote, K.J.Growth and Yield Responses of Rice to Carbon Dioxide Concentration Journal of Agricultural Science, Cambridge1990115313-320-J. Agric. Sci., Camb.. Rice plants (Oryza sativa L., cv. IR301) were grown in paddy culture in outdoor, naturally sunlit, controlled-environment, plant growth chambers at Gainesville, Florida, USA, in 1987. The rice plants were exposed throughout the season to subambient (160 and 250), ambient (330) or superamb2ient (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 increase occurring between the 160 and 500 umol CO2/mol air treatm3ents. Early in the growing season, root:shoot biomass ratio increased with increasing CO2 concentration; although the ratio decreased during the growing season, net assimilation rate increased with increasing CO2 concentration and decreased during th4e 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 amon5g CO2 treatments. Doubling the CO2 concentration from 330 to 660 umol CO2/mol air resulted in a 32% increase in grain yield. These results suggest that important changes in the growth and yield of rice may be expected in the future as the CO2 concen6tration of the earth's atmosphere continues to rise./rice/Oryza sativa0growth analysis/pre-industrial CO2 concentration/allocation/SPAR units\*  >Baker, J.T.//Jr., L.H. Allen,//Boote, K.J.Response of Rice to Carbon Dioxide and Temperature Agricultural and Forest Meteorology199260153-166-Agric. For. Meteorol.. The current increase in atmospheric carbon dioxide concentrati8on ([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 yield of food crops. This study was conducted to determine the effects and po9ssible 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, naturally sunlit, controlled-environment, and plant growth chambers. Temperature treatmen:ts 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] treatments of 330 and 660 umol CO2/mol air. In the 40/33/37C temperature treatment, plan;ts in the 330 umol/mol [CO2] treatment died during stem extension while the [CO2] enriched plants survived but produced sterile panicles. Plants in the 34/27/31C temperature treatments accumulated biomass and leaf area at a faster rate early in the <growing season than plants in 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 yie=ld 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 decli>ned by an average of 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 som?e areas if air temperatures increase, especially under conditions of low solar irradiance./rice/Oryza sativa0temperature/growth/yield/SPAR units\*4 @ ABaker, J.T.//Jr., L.H.Allen,//Boote, K.J.Temperature Effects on Rice at Elevated CO2 Concentration Journal of Experimental Botany199243959-964-J. Exp. Bot.. The continuing increase in atmospheric carbon dioxide concentration ([ACO2]) and projections of possible future increases in global air temperatures have stimulated interest in the effects of these climate variables on agriculturally important food crops. This study was conducted to determine the effects of [CO2] and teBmperature on rice (Oryza sativa L., cv. 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 temperatCure/night-time dry bulb air temperature/paddy water temperature) and [CO2] of 660 umol CO2/mol air. An ambient chamber was maintained at a [CO2] of 330 umol/mol and temperature regime of 28/21/25C. Carbon dioxide enrichment at 28/21/25C increased Dboth 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 tEhis temperature range, the number of panicles/plant nearly doubled while the number of seeds/panicle declined sharply. These results indicate that while future increase in atmospheric [CO2] are likely to be beneficial to rice growth and yield, potentFially large negative effects on rice yield are possible if air temperatures also rise./rice/Oryza sativa0temperature/growth/yield/seed production/SPAR units\*  =Baker, J.T.//Jr., L.H. Allen,//Boote, K.J.//Jones, P.//Jones, J.W.Response of Soybean to Air Temperature and Carbon Dioxide Concentration Crop Science19892998-105-Crop Sci.. Documented increases in global atmospheric CO2 concenHtration 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 conducted to determine the effects and interactions of CO2 concentraItion and air temperature on the development, growth, total nonstructural carbohydrate (TNC), and final seed yield of soybean [Glycine max (L.) Merr., cv. Bragg] grown season-long in naturally lit, controlled-environment chambers. Day/night air temperJatures of 26/19, 31/24 and 36/29C were maintained in CO2 treatments of 330 and 660 umol CO2/mol air. Both CO2 enrichment and increasing air temperature decreased main stem plastochron interval, while increasing air temperature increased final mainstKem 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 temperature in leaf area, aboveground biomass, and plastochron interval was attributed to the Lhighest temperature treatment being near or above the optimum for soybean growth and development. Seed yield increased with CO2 enrichment due mainly to an increase in seed number rather than weight per seed. Individual seed weight decreased, while Mseed number increased with increasing temperature. Leaflet TNC was relatively stable throughout the day. Stem TNC was less affected by CO2 than by temperature treatment and decreased with increasing temperature. These results indicate that the respoNnse of soybean to elevated CO2 concentration is highly temperature dependent./soybean/Glycine max0seeds/reproduction/temperature/yield/carbohydrates/SPAR units\*d o :Baker, J.T.; Jr., L.H. Allen,;Boote, K.J.; Jones, P.; Jones, J.W.Developmental Responses of Rice to Photoperiod and Carbon Dioxide Concentration Agricultural and Forest Meteorology199050201-210-Agric. For. Meteorol.. The documePnted increase in the carbon dioxide concentration of the Earth's atmosphere has stimulated interest in the effects of CO2 on plants and in particular the future prospects for the world's food supplies. While rice is a major food crop, relatively littQle 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 geographic region. The objectiRve of this study was to determine the developmental responses of a modern, improved rice cultivar (Oryza sativa, cultivar 'IR-30') to a range of CO2 concentrations under two contrasting photoperiods. Rice plants were grown season-long in an outdoor, Snaturally lit, computer-controlled environment, plant growth chambers in CO2 concentrations of 160, 250 (subambient), 330 (ambient), 500, 660 and 900 (superambient) umol CO2/mol air. The entire experiment was conducted twice during 1987. The first oTr early planted rice (EPR) experiment was conducted with photoperiod extension lights during the vegetative phase of development, while the second or late-planted rice (LPR) experiment was conducted using only naturally occurring photoperiod. In bothU experiments, mainstem leaf developmental rates were greater during vegetative rather than reproductive growth stages and leaf appearance rates increased with CO2 treatment during vegetative development. In the LPR experiment, panicle initiation and Vboot 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 development with increasing CO2 treatment was associated with a COW2-induced decrease in the number of mainstem leaves formed during 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 photopeXriod during the EPR experiment forcing a delay in the onset of reproductive development particularly in the superambient treatments. The CO2-induced acceleration of development and shortening of total growth duration should become a topic of interestY for rice agronomists and breeders involved with selecting rice cultivars and agronomic practices for a particular geographic region in view of the continued increases in global atmospheric CO2 concentration./rice/Oryza sativa0growth stages/photoperZiod/pre-industrial CO2 concentration/SPAR units\*D P CBaker, R.G.E.;Boatman, D.J.Some Effects of Nitrogen, Phosphorus, Potassium and Carbon Dioxide Concentration on the Morphology and Vegetative Reproduction of Sphagnum cuspidatum Ehrh. New Phytologist1990116604-611-New Phytol.. F\ive experiments are described which were designed to investigate the effects of varying the concentrations of nitrate, phosphate, potassium and carbon dioxide in the culture solution on the morphology and vegetative reproduction of Sphagnum cuspidatum] Ehrh. The plants were grown axenically from spores sown on agar containing inorganic salts and then transferred to aqueous culture solutions through which air containing enhanced concentrations of carbon dioxide was passed. In three of the experi^ments the plants were grown in a balanced inorganic salt solution at various dilutions and in two of these the concentration of carbon dioxide in the gas bubbled through the solution was varied. The concentrations of nitrogen, phosphorus and potassiu_m were varied independently and in combination in the remaining experiments while the concentration of carbon dioxide was kept constant. In some of the experiments the minimum concentrations of nitrogen and potassium supplied were considerably belo`w the minimum average concentrations recorded in rain but the minimum concentration of phosphorus supplied was within the upper part of the range recorded in rain. Within the ranges supplied the concentrations of all three elements and of carbon dioxaide affected interfascicle length and vegetative reproduction (innovation formation) but it was concluded that the element limiting innovation formation in natural conditions is phosphorus./Sphagnum cuspidatum0nutrition/nitrogen/phosphorus/potassiumb/vegetative reproduction/controlled environment chambers\R    BBaker, J.T.// Laugel, F.// Boote, K.J.// Jr., L.H. Allen,Effects of Daytime Carbon Dioxide Concentration on Dark Respiration in Rice Plant, Cell and Environment199215231-239-Plant Cell Environ.. Rising atmospheric carbon dioxidde concentration ([CO2]) has generated considerable interest in the response of agricultural crops to [CO2]. The objectives of this study were to determine the effects of a wide range of daytime [CO2] on dark respiration of rice (Oryza sativa L. cv. IeR-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 areaf basis (Rd) increased with increasing [CO2] treatments and was very similar 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 descgribed for photosynthesis. Specific respiration rate (Rdw) decreased with time during the growing season and was higher in the subambient than the ambient and superambient [CO2] treatments. This greater Rdw in the subambient [CO2] treatments was attrhibuted to a higher specific maintenance respiration rate and was associated with higher plant tissue nitrogen concentration./rice/Oryza sativa0SPAR units/pre-industrial CO2 concentration/nitrogen/respiration\*  iDBaldocchi, D.D.//White, R.//Johnston, J.W.A Wind Tunnel Study to Design Large, Open-top Chambers for Whole-tree Pollutant Exposure Experiments Journal of the Air Pollution Control Association198939549-1556-JAPCA. A wind tunnel kstudy was conducted to determine the optimal design features of a large, open-top chamber, as needed for pollution exposure studies on mature trees. An optimally-designed, open-top chamber must minimize the incursion of ambient air through its openinlg and maintain a uniform treatment concentration throughout the chamber. The design features of interest are the diameter and height of the chamber and the deflection angle and opening size of any frustum that may be mounted on top of a model chamberm. Design specifications depend on the turbulence regime about the chamber, which is influenced by the nature of the surrounding vegetation. Consequently, our investigation was performed on scale-model, open-top chambers in a wind tunnel populated wnith a model coniferous forest. Turbulence measurements demonstrated the similarity between the turbulence regime of the model and a natural forest. A hydrocarbon tracer was injected into the wind tunnel flow to characterize chamber performance. Tohe main design features of open-top chambers are the velocity of air exiting through the top and the relationship between the length scale of the turbulence and the diameter of the chamber opening. As exit velocities increase, the proportion of eddieps with sufficient force to penetrate into the chamber decrease. Therefore, for equal volumetric air flows, smaller opening sizes increase the exit velocities and reduce the number and extent of ambient air incursions. Almost total exclusion of ambieqnt 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 reduced when the diameter of the chamber opening is smarller than the characteristic length scale of the turbulence, a measure 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 perforsmance 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 for a smoother transition in the wind velocity streamline and is tless apt to cause wake turbulence, as is the case with steeper frusta. Knowledge of the turbulence characteristics of plant canopies are readily available in the literature and can aid scientists and engineers in designing the optimal chamber and furusta dimensions for their particular application. Therefore, the empirical approach to chamber design can be avoided, and substantial savings can be realized.0open-top chambers/air pollution/exposure methods\FBarlow, E.W.R//Conroy, J.Influence of Elevated Atmospheric Carbon Dioxide on the Productivity of Australian Forestry Plantations Pearman, G.I. ed. Greenhouse: Planning for Climate ChangeNew YorkE.J. Brill1988520-533. Australwia produced $2.7 billion worth of forest products in 1983-84 but a further $1.3 billion worth, principally softwood, were imported. Because of this ever increasing demand for softwood, there is a move away from utilization of native hardwoods and by x2020 AD, when the atmospheric CO2 concentration is likely to be greater than 450 ppmv, 75% of forest products are projected to come from coniferous plantations. This move towards Pinus radiata is a result of both demand for softwood and lack of indepyth 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 rzepeated episodes of drought are common. Consequently, we are investigating the growth response of pines to elevated CO2 at a range of phosphorus and water levels. When phosphorus was adequate, doubling CO2 concentration more than doubled the rate of{ photosynthesis and increased the total plant dry weight by about 40%. However, there was no response when phosphorus was deficient. In contrast, there was a slightly higher response under simulated drought conditions. A further possible effect o|f rising CO2 levels is that the climatic range of P. radiata may be altered due to a reduction in water use or an increase in the drought tolerance of the trees. We found that CO2 enrichment did not affect either of these factors but the water-use ef}ficiency 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 elevated CO2 at two phosphorus levels, we have identifie~d a considerable variation between the families in their response to CO2 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 phosphorus fertilization is adequate. If the rise in CO2 results in climatic change the range of P. radiata may be even further 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 phosphorus and water to enable more accurate prediction of the productivity and water use of Australian native forests and eucalyptus plantations./Pinus radiata0review/allocation/conductance/family responses/growth/nutrition/phosphorus/pot volume/trees/WUE/water stress/leaf photosynthesis/forest\   c p   " ,    n  x HBarr, A.G.//King, K.M.//Thurtell, G.W//Graham, M.E.DHumidity and Soil Water Influence the Transpiration Response of Maize to CO2 Enrichment Canadian Journal of Plant Science199070941-948-Can. J. Plant Sci.. The impact of increasing atmospheric CO2 on the productivity of C4 crops may vary with soil water availability. This study investigates the hypothesis that elevating CO2 in Zea mays L. reduces the degree to which transpiration is limited by soil water at high vapor pressure deficits or low soil water contents. Plants growing in controlled environments at 300 and 600 umol/mol CO2 were exposed daily to five levels of vapor pressure deficit as water was withheld and the soil dried over an 8-d period. Doubling CO2 caused an overall reduction of 23% in the transpiration rate and 34% in the leaf conductance, but the effect of CO2 on transpiration and leaf conductance was greatest at high soil water content and low vapor pressure deficit, when soil water least limited transpiration. Implications for the productivity of C4 crops in the field are discussed./corn/Zea mays0C4/VPD/water stress/conductance/transpiration/controlled environment chambers/humidity\*  IBarson, M.M.//Gifford, R.M.Carbon Dioxide Sinks: The Potential Role of Tree Planting in Australia Swain, D.J. ed. Greenhouse and EnergyAustraliaCSIRO1990433-443. Reforestation has been suggested as a possible policy option at several recent international "greenhouse effect" forums. 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. Although forestry cannot in principle offer a permanent solution to continuous emission of CO2 from fossil fuel burning, its expansion 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 sequestration 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.0trees/modeling/reforestation\JBauerle, W.L.//Kretchman, D.//Tucker-Kelly, L.CO2 Enrichment in the U.S. Enoch, H.Z.//Kimball, B.A. eds. Status and CO2 SourcesBoca Raton, FloridaCRC Press, Inc.1986Vol.I49-57#Carbon Dioxide Enrichment of Greenhouse Crops0commercial use of CO2/greenhouse\MBazzaz, F.A.The Response of Natural Ecosystems to the Rising Global CO2 Levels Annual Review of Ecology and Systematics199021167-196-Ann. Rev. Ecol. Syst.0review/physiological CO2 responses/environmental interactions/species competition/family responses/population level CO2 responses/community level CO2 responses/ecosystem level CO2 responses/soil microorganisms/herbivory/species range/CO2 enrichment studies\NBazzaz, F.A.//Ackerly, D.D.//Woodward, F.I.//Rochefort, L.CO2 Enrichment and Dependence of Reproduction on Density in an Annual Plant and a Simulation of Its Population Dynamics Journal of Ecology199280643-651-J. Ecol.. 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 of demography and reproduction. Variables measured included survivorship, proportion of plants flowering and fruiting, number 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 production 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 produced 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 simulated 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./Abutilon theophrasti0controlled environment chambers/old field communities/population model/plant density/reproduction/simulation/survivorship/modeling\*  OBazzaz, F.A.//Coleman, J.S.//Morse, S.R.Growth Responses of Seven Major Co-occurring Tree Species of the Northeastern United States to Elevated CO2 Canadian Journal of Forest Research1990201479-1484-Can. J. For. Res.. 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 from 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 pine, hemlock, sugar maple) under CO2 levels of 400 or 700 uL/L. Plants were then harvested for biomass and growth determinations. 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. Furthermore, 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 CO2 concentrations were the shade-tolerant species (i.e., beech, sugar maple, and hemlock). Thus, elevated CO2 levels may enhance 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 seedlings greatly affected their response to elevated CO2 concentration./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 canadensis0trees/growth/shade tolerance/species competition/controlled environment chambers\G X n          $ 4 PBazzaz, F.A.//Fajer, E.D.Plant Life in CO2-Rich World Scientific American199226668-74-Sci. Amer.0review/photosynthesis/insects/C3/C4/ecosystem level CO2 responses/CO2 enrichment studies\LBazzaz, F.A./Garbutt, K.The Response of Annuals in Competitive Neighborhoods: Effects of Elevated CO2 Ecology198869937-946-Ecology. Four members of an annual community were used to investigate the effects of changing neighborhood complexity and increased 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 moisture 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 general, 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./Ambrosia artemisiifolia/Abutilon theophrasti/Amaranthus retroflexus/Setaria faberii0sunlit controlled environment chambers/old field communities/C3/C4/species competition\W k   = G I ` SBazzaz, F.A.//Garbutt, K.//Reekie, E.G.//Williams, W.E.Using Growth Analysis to Interpret Competition between a C3 and a C4 Annual under Ambient and Elevated CO2 Oecologia198979223-235-Oecologia. Detailed growth analysis in conjunction with information on leaf display and nitrogen uptake was used to interpret competition 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 other. Competition caused a reduction in growth in both species, but for different reasons. In Abutilon, decreases in leaf area ratio (LAR) were responsible, whereas decreased unit leaf rate (ULR) was involved in the case of Amaranthus. Mean canopy 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./Abutilon theophrasti/Amaranthus retroflexus0sunlit controlled environment chambers/species competition/growth analysis/root:shoot ratio/nitrogen/old field communities/C3/C4\2R f y      < F L T v      M W       C K     $ ,         c k      (  2 KBazzaz, F.A./McConnaughay, K.D.M.Plant-plant Interactions in Elevated CO2 Environments Australian Journal of Botany199240547-563-Austr. J. Bot.. Increasing atmospheric carbon dioxide concentrations present a novel resource condition for plant communities. In order 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 consequence, 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 competitors as a result of CO2 enrichment, contrary to expectations based on their photosynthetic pathways. It is now clear that individually 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 is incomplete. We urgently need information about how elevated CO2 atmospheres influence stand formation and population dynamics, specifically with regard to the identities, numbers, sizes and reproductive fitnesses of individuals within single and multiple species stands, if we are to make multi-generational predictions concerning the fate of populations and communities in an elevated CO2 world.0review/community level CO2 responses/plant-plant interactions/temperature/environmental interactions\QPolley, H.W.//Johnson, H.B.//Mayeux, H.S.Carbon Dioxide and Water Fluxes of C3 Annuals and C3 and C4 Perennials at Subambient CO2 Concentration Functional Ecology19926693-703-Funct. Ecol.. 1. The C3 annuals, Avena sativa and Brassica kaber, and C3 and C4 perennials, Prosopis glandulosa and Schizachyrium 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 [CO2] gradient. 2. The ratio of night respiration (Rn) to daytime net assimilation (Pd) was greatest in A. sativa/B. kaber exposed to mean [CO2] below 200 umol/mol, while Rn/Pd differed little among five stands of P. glandulosa/S. scoparium that were grown at mean [CO2] from 219 to 331 umol/mol. 3. Evapotranspiration was reduced and water-use efficiency (WUE) was increased in A. sativa/B. kaber stands by higher [CO2]. 4. Pd and WUE of P. glandulosa/S. scoparium were not related to [CO2] across either of two growing seasons. Both Pd and WUE, however, were greater at higher [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./Avena sativa/oat/Brassica kaber/field mustard/Prosopis glandulosa/mesquite/Schizachyrium scoparium/little bluestem0gradient exposure tunnel/C3/C4/pre-industrial CO2 concentration/WUE/evapotranspiration/respiration\2     ( - D       F G I J q   , L M Z t   TBeer, S.The Fixation of Inorganic Carbon in Plant Cells Enoch, H.//Kimball, B.A. eds. Physiology, Yield, and EconomicsBoca Raton, FloridaCRC Press, Inc.1986Vol.II3-11#Carbon Dioxide Enrichment of Greenhouse Crops. 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 for 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 mitochondrial 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 plants, this occurs in mesophyll cells. Malate or aspartate is then transported to bundle sheath cells where it is decarboxylated, 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.0review/photosynthesis/C3/C4/CAM/enzymes/metabolites\YBellamy, L.A.//Kimball, B.A.CO2 Enrichment Duration and Heating Credit as Determined by Climate Enoch, H.Z.//Kimball, B.A. eds. Physiology, Yield, and EconomicsBoca Raton, FloridaCRC Press, Inc.1986Vol.II168-197#Carbon Dioxide Enrichment of Greenhouse Crops. To determine if it is economical to invest in CO2 enrichment equipment, a detailed economic analysis considering the increases in income and operating expenses should be performed. The procedure for such an analysis is straightforward (e.g., Chapter 13) but it is necessary to make estimates of the percent increase in yield, the amount of CO2 used, and of any reduction in heating energy requirements resulting from a combustion-type CO2 generator. For any given greenhouse and crop, these three factors will vary with the local climate and in particular, with the outside air temperature, and global solar radiation. It is practical to enrich with CO2 only while a greenhouse is closed and not ventilated. Therefore, CO2 enrichment duration equals day length minus ventilation time. Using Kimball's MEB program curves were generated which show the ventilation time fraction a 0.05 m3/m2/s capacity (47 greenhouse volume changes per hour) fan would need to operate to maintain a given set point temperature as a function of transmitted solar radiation for various ambient air temperatures. Similar curves were generated showing the heating credit from a CO2 generator rated at 42.5 W/m2 (CO2 output 9.5 g/m2/h). Hourly solar radiation and temperature data for days typical of each month of the year for six climate regions were generated using simple models from values of monthly mean minimum and maximum temperatures and mean total daily global radiation. Such data should be available nearby to most greenhouse locations. The hourly climate data for each of the typical monthly days were used in conjunction with the ventilation time fraction curves to compute the ventilation requirement throughout the year for six locations--Oslo, Norway; De Bilt, Netherlands; Milan, Italy; Columbus, Ohio, U.S.; Tokyo, Japan; Tel Aviv, Israel. The number of hours at which the greenhouse operated in five ventilation classes (0%, 0 to 20%, 20 to 50%, 50 to 100%, 100%) for a 30C ventilation temperature setpoint were plotted. For all sites except Tel Aviv, enrichment is possible throughout the whole day during winter. At Oslo, a greenhouse can remain unventilated and enriched for up to 7 months of the year. The areas in each ventilation class were measured to estimate the corresponding annual number of hours of possible CO2 enrichment. From these CO2 enrichment duration values, the required amounts of CO2 can be estimated. The amount of solar radiation received by the crop during each of the ventilation classes was also determined, so that the percent increase in yield due to CO2 enrichment could be calculated. A greenhouse in Oslo can remain closed and CO2 enriched for 79% of the total annual daylight hours, yet only 51% of the total radiation is received by the crop during this time. Using the 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 increased 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%, respectively. 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.0commercial use of CO2/greenhouse\ZBentley, B. L.//Johnson, N.D.Plants as Food for Herbivores: The Roles of Nitrogen Fixateion and Carbon Dioxide Enrichment Price, P.W.//Lewinsotin, T.M.//Fernandes, G.W.//Benson, W.W. eds. Plant-Animal Interactions: Evolutionary Ecology in Tropical and Temperate RegionsJohn Wiley & Sons, Inc.1990257-2720review/herbivory/insects/nitrogen fixation/carbon:nitrogen ratio\[Berntson, G.M.//Woodward, F.I.The Root System Architecture and Development of Senecio vulgaris in Elevated CO2 and Drought Functional Ecology19926324-333-Funct. Ecol.. 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./Senecio vulgaris0water stress/roots/growth analysis/root:shoot ratio/rhizotron/greenhous\ O _  !       +   \Besford, R.T.The Greenhouse Effect: Acclimation of Tomato Plants Growing in High CO2, Relative Changes in Calvin Cycle Enzymes Journal of Plant Physiology1990136458-463. 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 dehydrogenase (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 apparent differences in the other two Calvin cycle enzymes at this stage of expansion. With subsequent leaf development in high CO2 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 normal and high-CO2 grown plants. This specific immunoassay estimated a 75% reduction of LSU in the high-CO2 grown leaf at full expansion./Lycopersicon esculentum0enzymes/photosynthetic acclimation/Calvin cycle enzymes/controlled environment chambers\^Besford, R.T.//Hand, D.W.The Effects of CO2 Enrichment and Nitrogen Oxides on some Calvin Cycle Enzymes and Nitrite Reductase in Glasshouse Lettuce Journal of Experimental Botany198940329-336-J. Exp. Bot.. 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./Lactuca sativa0enzymes/Calvin cycle enzymes/air pollution/nitrogen oxides/metabolites/phosphoenolpyruvate carboxylase/greenhouse\_Besford, R.T.//Ludwig, L.J.//Withers, A.C.The Greenhouse Effect: Acclimation of Tomato Plants Growing in High CO2, Photosynthesis and Ribulose-1, 5-Bisphosphate Carboxylase Protein Journal of Experimental Botany199041925-931-J. Ex p. Bot.. 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-bisphosphate carboxylase (RuBPco) E.C. 4.1.1.39 protein and activity throughout leaf development of the unshaded 5th leaf above the cotyledons. The high  CO2 concentration during growth did not appreciably affect the rate of leaf expansion or final leaf area but did increase the fresh weight per unit area of leaf. With short-term CO2 enrichment, i.e. only during the photosynthesis measurements, the l ight-saturated photosynthetic rate (Pmax) of young leaves did not increase while those reaching full expansion more than doubled their net rate of CO2 fixation. However, with longer term CO2 enrichment, i.e. growing the crop in high CO2, the plants di d 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 ontogenetic 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 protein and Pmax in 300 vpm CO2 and Pmax in 1000 vpm CO2 were similarly reduced. The loss of RuBPco protein may be a major factor associated with the accelerated fall in Pmax since it was close to that predicted from the amount and kinetics of RuBPco assuming RuBP saturation. In the oldest leaves examined grown in high CO2 additional factors may be limiting photosynthesis since RuBPco kinetics marginally overestimated Pmax in 300 vpm CO2 and the initial slope of photosynthesis in response to intercellular CO2 was also less than expected from the extractable RuBPco./Lycopersicon esculentum0photosynthetic acclimation/ribulose bisphosphate carboxylase/enzymes/leaf photosynthesis/controlled environment chambers\R  H K  `Betsche, T.//Morin, F.//Cotte, F.//Gaugain, F.//Andr, M.Gas Exchanges, Chlorophyll a Fluorescence, and Metabolite Levels in Leaves of Trifolium subterraneum during Long-term Exposure to Elevated CO2 VIII th International Congress on Photosynthesis1989Stockholm, Sweden1989#Progress in Photosynthesis Research. 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./Trifolium subterraneum0photosynthetic feedback inhibition/fluorescence/metabolites/phosphorus/carbohydrates/greenhouse\zW X   , - aBhattacharya, N.C.Prospects of Agriculture in a Carbon Dioxide-enriched Environment Geyer, R.A. ed. A Global Warming Forum: Scientific, Economic and Legal OverviewBoca Raton, FloridaCRC Press, Inc.1992. 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 unman aged ecosystems, these effects of elevated CO2 may cause marked changes.0review/photosynthesis/temperature/water stress/nutrition/carbohydrates/agriculture/weeds/herbivory\ cBhattacharya, N.C.//Bhattacharya, S.//Strain, B.R.//Biswas, P.K.//Tolbert, M.E.M.An Insight into the Mechanism of Auxin Action in Rooting Hypocotyl Cuttings of Impatiens balsamina Grown in Phytotron under Enriched CO2 Environment Wilson," W.C. ed. Thirteenth Annual Meeting3-7 Aug. 1986St. Petersburg Beach, Florida198692#Plant Growth Regulator Society of America/Impatiens balsamina0rooting/auxin/growth regulators/controlled environment chambers\* # bBhattacharya, N.C.//Bhattacharya, S.//Strain, B.R.//Biswas, P.K.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 Journal of Plant Physiology1989135261-266-J. Plant Physiol.. 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 cond&itions. The effect of CO2 enrichment on carbohydrate concentrations in 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 da'ys after planting as compared to stems and roots receiving increased 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./Ipomoea batatas/sweet potato0carbohydrates/proteins/growth stages/controlled environment chambers\R  M \ eBhattacharya, N.C.//Biswas, P.K.//Bhattacharya, S.//Sionit, N.//Strain, B.R.Growth and Yield Response of Sweet Potato to Atmospheric CO2 Enrichment Crop Science198525975-981-Crop Sci.. Tuber growth of sweet potato (Ipomoea batat+as) 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 undertake,n 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 s-tem 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 1.08 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./sweet potato/1Ipomoea batatas0source-sink balance/growth analysis/yield/tubers/controlled environment chambers\*  fBhattacharya, N.C.//Ghosh, P.P.//Bhattacharya, S.//Hileman, D.R.//Biswas, P.K.Effects of Abscisic Acid on Rooting Stem Cuttings of Sweet Potato in Open Top Chambers under Enriched CO2 Environment Biologia Plantarum (Praha)1988302043-209-Biol. Plantarum. 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 chambe4rs 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 5364 cm3/m3 CO2./sweet potato/Ipomoea batatas0rooting/growth regulators/ABA/open-top chambers\*7 F gBhattacharya, N.C.//Hileman, D.R.//Ghosh, P.P.//Musser, R.L.//Bhattacharya, S.//Biswas, P.K.Interaction of Enriched CO2 and Water Stress on the Physiology of and Biomass Production in Sweet Potato Grown in Open-top Chambers Plant, Cell a7nd Environment199013933-940-Plant Cell Environ.. The objective of this study was to investigate the effects of water stress in sweet potato (Ipomoea batatas L. [Lam.] 'Georgia Jet') on biomass production and plant-water relationships in an e8nriched 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 9higher in plants grown in a CO2 concentration 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 grow:n 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 with 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./sweet potato/Ipomoea batatas0water stress/growth/tubers/open-top chambers\*  <dBhattacharya, N.C.//Bhattacharya, S.//Strain, B.R.Isozyme Polymorphism during Rooting at Elevated CO2 HortScience198924302-305-HortSci.. The effects of CO2 enrichment and IAA on adventitious root formation of hypocotyl cuttings> of Impatiens balsamina L. 'Camellia' were examined. Root numbers increased significantly at 675 and 1000 uL CO2/L compared to 350 uL/L. In the presence of IAA, the number of roots increased at 675 and 1000 uL CO2/L and the effect was most pronounce?d with 5 ug IAA/ml at 675 uL CO2/L. IAA-treated cuttings, compared to those in deionized water, exhibited slightly increased intensities of some of the isoperoxidases coinciding with root initiation and development in a CO2-enriched atmosphere. The @data also indicate that at least two isozymes of peroxidase are associated with root development./Impatiens balsamina0growth regulators/enzymes/IAA/rooting/controlled environment chambers/peroxidase\*  hBhattacharya, S.//Bhattacharya, N.C.//Biswas, P.K.//Strain, B.R.Response of Cow Pea (Vigna unguiculata L.) to CO2 Enrichment Environment on Growth, Dry-matter Production and Yield Components at Different Stages of Vegetative and ReproductBive Growth Journal of Agricultural Science, Cambridge1985105527-534-J. Agric. Sci. Camb.. This study examines the effects of increased atmospheric carbon dioxide concentrations on vegetative and reproductive growth and partitioning of biomasCs during pod and seed development of cow pea in controlled environment chambers at 350, 675, and 1000 uL CO2/L. The length of main stem and branches, the number of leaves and branches, and leaf area were all greater at high CO2 than at low CO2 concDentration. The appearance of flowers was 10-12 days earlier in high CO2 than in ambient CO2 atmosphere. The senescence of leaves started about 7 days earlier in plants grown at 675 and 1000 uL CO2/L than in those grown at 350 uL CO2/L. The rate of Eleaf senescence was more rapid in 1000 uL/L than in 675 uL CO2/L. The dry weight of roots, stems and leaves increased with CO2 enrichment, being greater in 675 uL/L than in 1000 uL CO2/L. Plants grown in 675 and 1000 uL/L produced more pods and seedFs than in 350 uL CO2/L. Total seed weight and number of pods, as well as number of seeds per pod, were significantly greater in CO2 enriched atmosphere than ambient CO2 level. Although CO2 enrichment caused a significant increase in the total numberG 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 investigation that CO2 enrichment significantly enhanced vegetaHtive as well as reproductive growth resulting in the increase in yield and early plant maturation in this leguminous crop./cowpea/Vigna unguiculata0growth analysis/yield/growth stages/allocation/seed production/reproduction/controlled environment chIambers\*V g jBhattacharya, S.//Eatman, J.F.//Biswas, P.K.//Tolbert, M.E.M.CO2 Enrichment and its Relationship to Bioconversion of Cellulosic Biomass of Sweet Potato (Ipomoea batatas L.) into Fermentable Sugars Biomass198815259-268-Biomass. SKweet potatoes (Ipomoea batatas L. (Lam.) 'Georgia-Jet') were grown in open field plots and open top chambers at CO2 concentrations of 354, 531, 506 and 659 uL/L for 90 days. The leaves and stems after the harvest were used as substrates for the produLction of fermentable sugars. Elevated CO2 concentrations increased the cellulose content of stems, being most pronounced at 506 uL/L. Hemicellulose content of leaves and stems as well as lignin content of stems decreased as a result of CO2 enrichmenMt. The increase in cellulosic biomass in plants grown in CO2 enriched environment resulted in increased conversion of cellulose into fermentable sugars. The saccharification was greater in stems than in leaves. It was also found that chemical pretrNeatment of stems and leaves enhanced the enzymatic hydrolysis and the yields of glucose were higher than those from untreated stems and leaves./sweet potato/Ipomoea batatas0biomass conversion/open-top chambers\R  O   iBhattacharya, S.//Bhattacharya, N.C.//Strain, B.R.Rooting of Sweet Potato Stem Cuttings under CO2-enriched Environment and with IAA Treatment HortScience1985201109-1110-HortSci.. Stem cuttings of sweet potato (Ipomoea batatas LQ. 'Georgia Jet') with intact apex and leaves were cultured in water or in different concentrations of IAA and were maintained in controlled environment chambers at 350, 675, or 1000 ppm CO2. The temperature was 20C during a 14-hr day and 14 duringR a 10-hr dark period. The photosynthetic photon flux density was 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 SCO2 atmosphere./sweet potato/Ipomoea batatas0IAA/growth regulators/rooting/controlled environment chambers\*  mBlack, C.C., JrEffects of CO2 Concentration on Photosynthesis and Respiration of C4 and CAM Plants Enoch, H.Z.//Kimball, B.A. eds. Physiology, Yield, and EconomicsBoca Raton, FloridaCRC Press, Inc.1986Vol.II29-40#Carbon DioxUide Enrichment of Greenhouse Crops. With C4 plants, CO2 enrichment will have a small, probably less than 25%, enhancement of plant growth or biomass production. However, water use efficiency will increase severalfold with a doubling or tripling ofV air CO2 levels. With CAM plants, CO2 enrichment should be done at night. Little daytime CO2 uptake occurs in most CAM plants, but enrichment late in the day and at night likely will be beneficial to growth. No long-term growth work has been doneW with CO2 enrichment and the production of CAM plants, but the available research indicates night enrichment should be beneficial.0review/C4/CAM/photosynthesis/respiration/enzymes/metabolites\n Bolin, B.//Doos, B.R.//Jager, J.//Warrick (eds.), R.A. The Greenhouse Effect, Climatic Change, and EcosystemsNew YorkJohn Wiley & Sons19860oddsybol/review/climate/CO2 enrichment studies\oBoone, M.Y.L.//Rickman, R.W.//Whisler, F.D.Leaf Appearance Rates of Two Winter Wheat Cultivars under High Carbon Dioxide Conditions Agronomy Journal199082718-724-Agron. J.. The mechanisms describing leaf appearance and tillerinZg are vital to the modeling of wheat canopy development. How these two factors will be affected by increasing global atmospheric [CO2] in cool or warm climates is not fully understood. Two southeastern USA adapted wheat (Triticum aestivum L.) cultiv[ars, Coker 762 and Stacy, were grown under nearly nonlimiting conditions including elevated [CO2] (600 uL/L) and under six air temperature regimes (ranging from 4/-1 to 18/7C d/night and progressively increasing to 16/4 to 29/18C d/night during the \season) to observe leaf and tiller appearance rates and to compare tillering rates to those predicted by the Fibonacci series as approximated by Binet's equation. Both cultivars exhibited an abrupt one-time change in their phyllochron interval for al]l six temperatures. This change occurred just prior to double ridge formation. The vegetative growth phase phyllochron interval of the two cultivars was significantly different only in the 21/10C temperature treatment. In the two lowest temperatur^e treatments (16/4 and 18/7C), the cultivars differed in phyllochron interval during the reproductive growth phase. The tillering rate of wheat followed closely the theoretical development predicted by Binet's equation during the vegetative phase of_ development./wheat/Triticum aestivum0growth model/temperature/growth stages/controlled environment chambers\*   pBottner, P.//Couteaux, M.M.Effect of Plant Activity on Decomposition: Soil-plant Interactions in Response to Increasing Atmospheric CO2 Concentration van Breemen, N. ed. Ecosystem Research Report No.1, Decomposition and Accumulation ofa Organic Matter in Terrestrial Ecosystems: Research Priorities and Approaches1991 Sept. 2-4Doorwerth, The Netherlands19910rhizosphere/litter decomposition/litter quality/modeling\qBottner, P.//Couteaux, M.M.Reponse de la Matiere Organique des Sols Landmann, G. ed. Les Recherches en France sur les Ecosystemes Forestiers.ParisMinistere de l'Agriculture et de la Foret199225-26.In French.0soil microorganiscms\tBowes, G.Growth at Elevated CO2: Photosynthetic Responses Mediated through Rubisco Plant, Cell and Environment199114795-806-Plant Cell Environ.. The global uptake of CO2 in photosynthesis is about 120 gigatons (GT) of carbon peer 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 alsof 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 usuaglly 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,h 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 fielid 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 maintjains 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 dkisruption. 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. Overl 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. Herme 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 COn2. 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.0review/photosynthesis/ribulose bisphosphate carboxylase/enzymoes/photosynthetic feedback inhibition/photorespiration\uBowes, G.//Rowland-Bamford, A.J.//Jr, L. H. Allen,Regulation of Rubisco Activity of Carboxyarabinitol-1-Phosphate and Elevated Atmospheric CO2 in Rice and Soybean Cultivars Baltscheffsky, M. ed.The NetherlandsKluwer Academic Publishqers1990Vol.III399-402#Current Research in Photosynthesis. The degree of rubisco dark inhibition not only shows species, but also intercultivar, and development differences. As with total activity, rubisco activation is developmentally influrenced; 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 rusbisco activity may be compounded by elevated atmospheric CO2./rice/Oryza sativa/soybean/Glycine max0Calvin cycle enzymes/enzymes/growth stages/cultivar responses/light/ribulose bisphosphate carboxylase/temperature/photosynthetic feedback inhibition/tRuBP/SPAR units/controlled environment chambers\vBowman, W.D.//Strain, B.R.Interaction between CO2 Enrichment and Salinity Stress in the C4 Non-halophyte Andropogon glomeratus (Walter) BSP Plant, Cell and Environment198710267-270-Plant Cell Environ.. Increasing atmospheric COv2 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 of salt marshes, plants were grown at 3w50, 500 and 650 cm3/m3 CO2 with 0 or 100 mol/m3 NaCl watering treatments. Increases 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 plantsx. Tillering increases substantially with increasing CO2 in salt-stressed plants, resulting in the increased biomass. Six weeks following initiation of treatments, there was no difference in photosynthesis on a leaf area basis with increasing CO2 in ysalt-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 may have improved the diurnal water status of the plants.z Concentrations of Na+ and Cl- were higher in salt- stressed plants, 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 (non-stomatal) conductance./Andropogon glomeratus0C4/salt stress/leaf photosynthesis/conductance/controlled environment chambers\Rj  y | wBown, A.W.CO2 and Intracellular pH Plant, Cell and Environment19858459-465-Plant Cell Environ.. The experimental determination of cytoplasmic and vacuolar pH values is discussed. Despite variation in these values evidence indi~cates 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.0review/intracellular pH/phosphoenolpyruvate carboxylase\xBravdo, B.Effect of CO2 Enrichment on Photosynthesis of C3 Plants Enoch, H.Z.//Kimball, B.A. eds. Physiology, Yield, and EconomicsBoca Raton, FloridaCRC Press, Inc.1986Vol.II13-27#Carbon Dioxide Enrichment of Greenhouse Crops0review/C3/conductance/leaf photosynthesis/photosynthesis model\yBreen, P.J.//Hesketh, J.D.//Peters, D.B.Field Measurements of Leaf Photosynthesis of C3 and C4 Species under High Irradiance and Enriched CO2 Photosynthetica198620281-285-Photosynthetica. Leaf net photosynthetic CO2 exchange rates (Pn) were measured on field-grown C3 (Glycine max L. Merr., Gossypium hirsutum L., Phaseolus vulgaris L., and Vigna unguiculata L. and C4 (Amaranthus hybridus L.) dicotyledonous species at available sunlight, available sunlight plus an additional 1000 umol (photon)/m2/s at the bottom surface of the leaf, and in CO2 air mixtures of 370, 780, 1500 and 3000 cm3/m3. Three kinds of Pn:CO2 responses were encountered: (1) hyperbolic up to 3000 cm3/m3, (2) hyperbolic up to 1500 cm3/m3, with less than predicted Pn at 300 cm3/m3, and (3) almost no response between 370 and 3000 cm3/m3 CO2 in air. The shapes of these response curves varied with growth stage. In general, leaves of all C3 species approached the same CO2 and radiant energy saturation Pn value of 70-75 umol CO2/m2/s, but some required higher CO2 concentrations than others before such rates were attained./Glycine max/soybean/Gossypium hirsutum/cotton/Phaseolus vulgaris/bean/Vigna unguiculata/cowpea/Amaranthus hybridus/pigweed0light/leaf photosynthesis/C3/C4/growth stages\    + = B T ] n z  zBrooks, A.//Woo, K.C.//Wong, S.C.Effects of Phosphorus Nutrition on the Response of Photosynthesis to CO2 and O2, Activation of Ribulose Bisphosphate Carboxylase and Amounts of Ribulose Bisphosphate and 3-Phosphoglycerate in Spinach Leaves Photosynthesis Research198815133-141-Photosynth. Res.. Phosphorus-deficient spinach plants were grown by transferring them to nutrient solutions without PO4. Photosynthetic rates were measured at a range of intercellular CO2 partial pressures from 50-500 ubar and then the leaves were freeze-clamped in situ to measure ribulose bisphosphate carboxylase (Rubisco) activity and metabolite concentrations. Compared with control leaves, deficient leaves had significantly lower photosynthetic rates, percentage activation of Rubisco, and amounts of ribulose bisphosphate and 3-phosphoglycerate at all CO2 partial pressures. After feeding 10 mM PO4 to the petioles of detached deficient leaves, all these measurements increased within 2 hours. At atmospheric CO2 partial pressure the photosynthetic rate was stimulated in 19 mbar O2 compared with 200 mbar. At higher CO2 partial pressures this stimulation was less but the percentage stimulation in deficient leaves was no different from controls in either CO2 partial pressure. It was concluded that phosphorus deficiency affects both Rubisco activity and the capacity for ribulose bisphosphate regeneration, and possible causes are discussed./spinach/Spinacia oleracea0phosphorus/nutrition/leaf photosynthesis/ribulose bisphosphate carboxylase/metabolites/RuBP/oxygen\Combe, L.//Kobilinsky, A.Effet de la Fumure Carbonee sur la Photosynthese de Radis (Raphanus sativus) en Serre en Hiver Photosynthetica198519550-560-Photosynthetica. Carbon dioxide dependence of net photosynthetic rate [Pn(C) curves] was studied in Raphanus sativus L. plants grown in a greenhouse with and without CO2 enrichment [ca. 1000 and 350 cm3 (CO2)/m3] for a week. Pn decreased with increasing 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 measurement), Pn increased unless the plants were very young (6d). The effect of I was higher in old plants and under CO2 enrichment. 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 one day and disappeared 3 d after the treatment had been stopped. In French./radish/Raphanus sativus0leaf photosynthesis/light/senescence/oddsymbol/greenhouse\U e           % & z |     1 3 > ? WBeerling, D.J.//Chaloner, W.G.//Huntley, B.//Pearson, J.A.//Tooley, M.J.//Woodward, F.I.Variations in the Stomatal Density of Salix herbacea L. under the Changing Atmospheric CO2 Concentrations of Late- and Post-glacial Time Philosophical Transactions of the Royal Society, London (Series B)1992336215-224-Phil. Trans. R. Soc. Lond. B.. The rapidly rising CO2 concentration of the past 200 years has been shown to be accompanied by a fall in stomatal density in the leaves of temperate trees. The present study attempts to investigate the relationship of atmospheric CO2 change and stomatal density in the arctic-alpine shrub, Salix herbacea, over the longer time span of 11,500 years offered by fossil leaves from post-glacial deposits. Comparisons of fossil material from Scotland and Norway are made with leaves from living populations growing in Austria, Greenland and Scotland. The Austrian material, from an altitudinal gradient between 2000 and 2670 m above sea level, gives added comparisons of contemporary differences of CO2 partial pressure with altitude. The results of our investigation indicate, rather surprisingly, that the rising CO2 concentration of the past 11,500 years has been accompanied by an increase in the stomatal density of S. herbacea in contrast to the shorter-term observations on the herbarium material of temperate trees. The most likely explanation appears to centre on the temperature and water availability of the early post-glacial environment overriding the effect of the lower CO2 regime. However, the scale of the time interval involved may also be significant. Natural selection over the 11,500 year period concerned may have favoured 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./Salix herbacea0pre-industrial CO2 concentration/stomatal density\z  |    |Brown, K.REffects of Nitrogen Availability and Atmospheric Carbon Dioxide Enrichment on Growth, Water Use, and Nutrition of Seedlings of Boreal TreesPh.D. DissertationUniversity of Alberta1989(Dissertation Abstracts Vol. 50:07-B, p.2703. 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 grown 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, medium-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 mass of low-N Picea after 100 days. High CO2 increased mass, height, and leaf area of Populus at 30 days in the high-N regime, 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 treatments) 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./Populus tremuloides/Picea glauca0trees/successional communities/nitrogen/growth/nutrition/growth analysis/controlled environment chambers\Z. A z      1 8     U Z r y    u z     ; @ \ c }Brown, K.//Higginbotham, K.O.Effects of Carbon Dioxide Enrichment and Nitrogen Supply on Growth of Boreal Tree Seedlings Tree Physiology19862223-232-Tree Physiol.. 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 seedlings 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./Picea glauca/white spruce/Populus tremuloides/aspen0trees/nitrogen/growth/allocation/growth analysis/nutrition/controlled environment chambers\Rv    ~Brugink, G.T.//Wolting, H.G.//Dassen, J.H.A.//Bus, V.G.M.The Effect of Nitric Oxide Fumigation at Two CO2 Concentrations on Net Photosynthesis and Stomatal Resistance of Tomato (Lycopersicon lycopersicum L. cv. Abunda) New Phytologist1988110185-191-New Phytol.. 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 not recover in the dark after the daily fumigation treatment, the level to which photosynthesis was reduced at the end of the day being the level at which it started the next day. The decrease in photosynthesis could not be explained by an increased stomatal resistance, and the plants did not show visible symptoms of injury. Practical implications of the results are discussed./Lycopersicon lycopersicum0air pollution/greenhouse/nitrogen oxides/photosynthesis/conductance/canopy photosynthesis\R  > W Brugnoli, E.//Hubick, K.T.//von Caemmerer, S.//Wong, S.C.//Farquhar, G.D.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 Dioxide Plant Physiology1988881418-1424-Plant Physiol.. 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. and Phaseolus vulgaris L.) were kept in the dark for 24 hours to decrease contents of starch and sugar in leaves. Then gas exchange measurements were made with constant conditions for 8 hours, and subsequently starch and soluble sugars were extracted for analysis of carbon isotope composition. The ratio of intercellular, Pi, and atmospheric, Pa, partial pressures of CO2 was calculated from gas exchange measurements, integrated over time and weighted by assimilation rate, for comparison with the carbon isotope ratios in soluble sugars and starch. Carbon isotope discrimination in soluble sugars correlated strongly (r=0.93) with Pi/Pa in all species, as did delta in leaf starch (r=0.84). Starch was found to contain significantly more 13C than soluble sugar, and possible explanations are discussed. The strong correlation found between [delta] and Pi/Pa suggests that carbon isotope analysis in leaf starch and soluble sugars may be used for monitoring, indirectly, the average of Pi/Pa weighted by CO2 assimilation rate, over a day. Because Pi/Pa has a negative correlation with transpiration efficiency (mol CO2/mol H20) of isolated plants, delta in starch and sugars may be used to predict differences 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./Populus nigra/Populus deltoides/Gossypium hirsutum/Phaseolus vulgaris0isotope discrimination/carbohydrates/Ci:Ca/leaf photosynthesis/greenhouse\       - \ ^ q s       s x   6 ; Bugbee, B.G.//Salisbury, F.B.Exploring the Limits of Crop Productivity. I. Photosynthetic Efficiency of Wheat in High Irradiance Environments Plant Physiology198888869-878-Plant Physiol.. The long-term vegetative and reproductive growth rates of a wheat crop (Triticum aestivum L.) were determined in three separate studies (24, 45, and 79 days) in response to a wide range of photosynthetic photon fluxes (PPF, 400-2080 micromoles per square meter per second; 22-150 moles per square meter per day; 16-20-hour photoperiod) in a near-optimum, controlled-environment. The CO2 concentration was elevated to 1200 micromoles per mole, and water and nutrients were supplied by liquid hydroponic culture. An unusually high plant density (2000 plants per square meter) was used to obtain high yields. Crop growth rate and grain yield reached 138 and 60 grams per square meter per day, respectively; both continued to increase up to the highest integrated daily PPF level, which was three times greater than a typical daily flux in the field. The conversion efficiency of photosynthesis (energy in biomass/energy in photosynthetic photons) was over 10% at low PPF but decreased to 7% as PPF increased. Harvest index increased from 41 to 44% as PPF increased. Yield components for primary, secondary, and tertiary culms were analyzed separately. Tillering produced up to 7000 heads per square meter at the highest PPF level. Primary and secondary culms were 10% more efficient (higher harvest index) than tertiary culms; hence cultural, 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./wheat/Triticum aestivum0light/growth rate/harvest index/yield/controlled environment chambers\*   Bultot, F.//Dupriez, G.L.//Gellens, D.Estimated Annual Regime of Energy-Balance Components, Evapotranspiration and Soil Moisture for a Drainage Basin in the Case of a CO2 Doubling Climatic Change19881239-56. Assuming a doubling of the atmospheric CO2 concentration, parameters of an empirical formula for calculating the daily net terrestrial radiation under the climatic conditions of Belgium are determined. The developed method takes into account information yielded by climate models about the CO2 impact. Annual regimes of the energy balance components are calculated for a drainage basin in Belgium. A daily step conceptual hydrological model (developed at the Royal Meteorological Institute 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.0climate model/simulation/hydrologic model/radiation\Bunce, J.A.Stomatal Conductance, Photosynthesis and Respiration of Temperate Deciduous Tree Seedlings Grown Outdoors at an Elevated Concentration of Carbon Dioxide Plant, Cell and Environment199215541-549. Seedlings of temperate deciduous tree species were grown outdoors at ambient and at an elevated concentration of carbon dioxide to examine how aspects of their gas exchange would be altered by growth at elevated carbon dioxide concentration. Leaf conductances to water vapour and net carbon dioxide exchange rates were determined periodically near midday. Whole-plant carbon dioxide efflux rates in darkness were also determined. The stomatal conductance of leaves of plants grown and measured at 700 cm3/m3 carbon dioxide did not differ from that of plants grown and measured at 350 cm3/m3 in Malus domestica, Quercus prinus and Quercus robur at any measurement time. In Acer saccharinum, lower conductances occurred for plants grown and measured at elevated carbon dioxide concentration only at measurement temperature above 33C. Photosynthetic 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./Acer rubrum/Acer saccharinum/Quercus prinus/Quercus robur/Malus domestica0trees/conductance/leaf photosynthesis/respiration/open-top chambers/controlled environment chambers\ + : < J O \ z  s { Bunce, J.A.Short- and Long-Term Inhibition of Respiratory Carbon Dioxide Efflux by Elevated Carbon Dioxide Annals of Botany199065637-642-Ann. Bot.. Dark carbon dioxide efflux rates of recently fully expanded leaves and whole plants of Amaranthus hypochondriacus L., Glycine max (L.) Merr., and Lycopersicon esculentum Mill. grown in controlled environments at 35 and 70 Pa carbon dioxide pressure were measured at 35 and 70 Pa carbon dioxide pressure. Harvest data and whole-plant 24-h carbon dioxide exchange were used to determine relative growth rates, net assimilation rates, leaf area ratios, and the ratio of respiration to photosynthesis under the growth conditions. Biomass at a given time after planting was greater at the higher carbon dioxide pressure in G. max and L. esculentum, but not the C4 species, A. hypochondriacus. Relative growth rates for the same range of masses were not different between carbon dioxide treatments in the two C3 species, because higher net assimilation rates at the higher carbon dioxide pressure were offset by lower leaf area ratios. Whole plant carbon dioxide efflux rates per unit of mass were lower in plants grown and measured at the higher carbon dioxide pressure in both G. max and L. esculentum, and were also smaller in relation to daytime net carbon dioxide influx. Short-term responses of respiration 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./tomato/soybean/Lycopersicon esculentum/Glycine max/Amaranthus hypochondriacus/amaranth0C3/C4/respiration/canopy photosynthesis/growth analysis\B     . E      : L     Bunce, J.A.Light, Temperature and Nutrients as Factors in Photosynthetic Adjustment to an Elevated Concentration of Carbon Dioxide Physiologia Plantarum199286173-179-Physiol. Plant.. The short-term stimulation of the net rate of carbon dioxide exchange of leaves by elevated concentrations of CO2 usually observed in C3 plants sometimes does not persist. Experiments were conducted to test whether the patterns of response to the environment during growth were consistent with the hypothesis that photosynthetic adjustment to elevated CO2 concentrtion is due to (1) feedback inhibition or (2) nutrient stress. Soybean [Glycine max (L.) Merr. cv. Williams] and sugar 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 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 leaf of sugar beet had finished expanding. Net rates of CO2 exchange of the most recently expanded leaves were then measured at both 350 and 700 uL/L CO2. Plants grown at the elevated CO2 concentration had net rates of leaf CO2 exchange which were reduced by 33% in sugar beet and 23% in soybean when measured at 350 uL/L CO2 and when averaged over all treatments. Negative photosynthetic adjustment to elevated CO2 concentration was not greater at 20 than at 25C, was not greater with limiting nutrients. Furthermore, in soybean, negative photosynthetic adjustment could be induced by a single night at elevated CO2 concentration, with net rates of CO2 exchange the next day equal to those of leaves of plants grown from seed at the 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./soybean/Glycine max/sugar beet/Beta vulgaris0nutrition/photosynthetic acclimation/photosynthetic feedback inhibition/temperature/controlled environment chambers/leaf photosynthesis\Ru    Bunce, J.A.//Caulfield, F.Reduced Respiratory Carbon Dioxide Efflux During Growth at Elevated Carbon Dioxide in Three Herbaceous Perennial Species Annals of Botany199167325-330-Ann. Bot.. 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. Plants were grown at 35 and 70 Pa carbon dioxide pressure. Dark carbon dioxide efflux rates were determined for whole plants during the first 40 d of growth in the controlled environment chambers, and for the ecosystems during the first year of growth in the field. Elevated carbon dioxide increased the rate of biomass accumulation in all species. In controlled environments, 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 growth 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./Dactylis glomerata/Lolium perenneMedicago sativa0respiration/growth analysis/growth/open-top chambers/controlled environment chambers\ ' ) 7 < K w    ~      S \   Burch, D.W.Economics of CO2 Enrichment in Greenhouses Enoch, H.Z.//Kimball, B.A. eds. Physiology, Yield, and EconomicsBoca Raton, FloridaCRC Press, Inc.1986Vol.II199-209#Carbon Dioxide Enrichment of Greenhouse Crops. 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.0review/greenhouse/commercial use of CO2\Burger, J.//Miyachi, S.//Galland, P.//Senger, H.Quantum Requirements of Photosynthetic Oxygen Evolution and 77K Fluorescence Emission Spectra in Unicellular Green Algae Grown under Low-and High-CO2-Conditions Botanica Acta1988101229-232-Bot. Act.. 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 the 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 quantum requirements under low- and high-CO2 conditions./Dunaliella tertiolecta/Chlamydomonas reinhardtii/Chlorella vulgaris/Chlorella pyrenoidosa0algae/fluorescence/oxygen evolution/aquatic plants/quantum requirement/cell culture\          E O Q ^ c n 7 E   J U Butler, G.D.//Kimball, B.A.//Mauney, J.R.Populations of Bemisia tabaci (Homoptera: Aleyrodidae) on Cotton Grown in Open-top Field Chambers Enriched with CO2 Environmental Entomology19861561-63-Environ. Entomol.. 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 photosynthesis, which is currently li mited 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 sticky traps placed in a field experim ent 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 th at 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./Gossypium hirsutum/cotton0insects/herbivory/open-top chambers/Bemisia tabaci/sweet potato white fly\R9 G   Campagna, M.A.//Margolis, H.A.Influence of Short-term Atmospheric CO2 Enrichment on Growth, Allocation Patterns, and Biochemistry of Black Spruce Seedlings at Different Stages of Development Canadian Journal of Forest Research198919773-782-Can. J. For. Res.. 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 significant 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 allocation 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 carbohydrates to free amino acids increased and the values for k decreased. The effect of CO2 enrichment on these two factors is discussed. 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 individual tree seedlings./Picea mariana/black spruce0trees/allocation/growth stages/carbohydrates/amino acids/root:shoot ratio/commercial use of CO2/greenhouse\# 0       Campbell, D.E.//Young, R.Short-term CO2 Exchange Response to Temperature, Irradiance, and CO2 Concentration in Strawberry Photosynthesis Research1986831-40-Photosynth. Res.. 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), and CO2 (300 to 600 uL/L) on successive days of study. Plants were otherwise maintained at 21C, 300 uE/m2/s PAR and 300-360 uL/L CO2 as standard conditions. Treatment was restricted to the mean interval of 14 h daily illumination and the first 3-4 days of each test week over a 12-week cultivation period. CO2 exchange rates were followed with each step-change in environmental 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./strawberry/Fragaria ananassa0canopy photosynthesis/photosynthesis model/temperature/respiration/light/oxygen/environmental interactions\*/ "@ Campbell, W.J.//Jr., L.H. Allen,//Bowes, G.Effects of Short-term and Long-term Exposures to Varying CO2 Concentrations on Soybean Photosynthesis Biggens, J. ed.Dordrecht, The NetherlandsMartinus Nijhoff Publishers1987Vol.IVIV.$5.253-IV.5.256#Progress in Photosynthesis Research. Soybean plants grown at twice atmospheric concentrations of CO2 had greater leaf photosynthesis rates than plants grown at atmospheric concentrations of CO2, across a range of measurement CO2 lev%els. Several explanations for this were explored./soybean/Glycine max0SPAR units/leaf photosynthesis/ribulose bisphosphate carboxylase/enzymes\Campbell, W.J.//Jr., L.H. Allen,//Bowes, G.Effects of CO2 Concentration on Rubisco Activity, Amount, and Photosynthesis in Soybean Leaves Plant Physiology1988881310-1316-Plant Physiol.. Growth at an elevated CO2 concentration r'esulted in an enhanced capacity for soybean (Glycine max L. Merr. cv Bragg) leaflet photosynthesis. Plants were grown from seed in outdoor controlled-environment chambers under natural solar irradiance. 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 irradiance. Soybean plants grown at elevated CO2 concentrations had h)eavier pod weights per plant, 44% heavier with 660 compared to 330 microliters of CO2 per liter grown plants, and also greater specific leaf weights. Ribulose 1,5-bisphosphate carboxylase/oxygenase (rubisco) activity showed no response (mean activity* of 96 micromoles of CO2 per square meter per second expressed on a leaflet area basis) to short-term (about 1 hour) exposures to a range of CO2 concentrations (110-880 microliters per liter), nor was a response of activity (mean activity of 1.01 micr+omoles of CO2 per minute per milligram of protein) to growth CO2 concentration (160-990 microliters per liter) observed. The amount of rubisco protein was constant, as growth CO2 concentration was varied, and averaged 55% of the total leaflet soluble, protein. Although CO2 is required for activation 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./soybean/G-lycine max0enzymes/ribulose bisphosphate carboxylase/leaf photosynthesis/proteins/metabolites//photosynthetic acclimation/SPAR units\* # Campbell, W.J.//Jr., L.H. Allen,//Bowes, G.Response of Soybean Canopy Photosynthesis to CO2 Concentration, Light and Temperature Journal of Experimental Botany199041427-433-J. Exp. Bot.. Photosynthetic rates of outdoor-grown so/ybean (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 ar0ea 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 the same CO2 concentrations and high irradiance. There was n1o difference in ribulose bisphosphate carboxylase/oxygenase (rubisco) activity or ribulose 1,5-bisphosphate (RuBP) concentration between plants grown at the two CO2 concentrations. However, photosynthetic rates averaged 87% greater for the canopies g2rown and measured at 660 mm3 CO2/dm3. A 10C difference in air temperature during growth resulted in only a 4C leaf temperature difference, which was insufficient to change the photosynthetic rate or rubisco activity in canopies grown and measured a3t either 330 or 660 mm3 CO2/dm3. RuBP concentrations decreased as air temperature during growth was increased at both CO2 concentrations. These data indicate that the increased photosynthetic rates of soybean canopies at elevated CO2 are due to seve4ral factors, including: more rapid development of the leaf area index; a reduction in substrate CO2 limitation; and no downward acclimation in photosynthetic capacity, as occur in some other species./soybean/Glycine max0canopy photosynthesis/photosy5nthetic acclimation/ribulose 1,5-bisphosphate/light/temperature/ribulose bisphosphate carboxylase/SPAR units\z    @ C Caporn, S.J.M.//Mansfield, T.A.//Hand, D.W.The Critical Influence of Temperature on the Inhibition of Photosynthesis by Oxides of Nitrogen in Lettuce Acta Horticulturae1990268103-110-Act. Hort.. The photosynthetic response of l7ettuce to the oxides of nitrogen (NOx) generated during enrichment with CO2 has been studied at different temperatures. The steady rates of net photosynthesis of lettuce fell within several minutes following the addition of nitric oxide to the cuvett8e. 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 exchange by a small stand of lettuce was measured in a 9novel growth chamber with fine thermal control. In high CO2 (1000 vpm) and at 16, 10 and 6C a transient fumigation with 2.0 vpm NO reduced CO2 uptake by 7, 11 and 29% respectively. Deposition of NO 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 w;hich vent the flue gases from the burners directly into the glasshouse air may not be entirely suitable for winter crops grown at low temperatures./lettuce/Lactuca sativa0nitrogen oxides/leaf photosynthesis/temperature/air pollution/conductance/comm<ercial use of CO2\Caporn, S.J.M.//Mansfield, T.A.//Hand, D.W.Low Temperature-enhanced Inhibition of Photosynthesis by Oxides of Nitrogen in Lettuce (Lactuca sativa L.) New Phytologist1991118309-313-New Phytol.. The response of photosynthetic gas> exchange to oxides of nitrogen (NOx) was studied in leaves of lettuce (Lactuca sativa L.) at different temperatures. Exposure to high concentrations (e.g. 1.3 umol NOx/mol), similar to those often found in commercial glasshouses, caused a rapid inhi?bition of the net assimilation of CO2. This appeared to be by a direct effect on photosynthesis rather than by a change in the stomatal conductance. In ambient CO2 (345 umol/mol), the percentage inhibition 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, Aalways less in high than in low CO2. The results suggest that when 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./lettuce/LactucBa sativa0leaf photosynthesis/air pollution/nitrogen oxides/temperature/conductance/controlled environment chambers/commercial use of CO2\R  3 A Caporn, S.J.M.The Effects of Oxides of Nitrogen and Carbon Dioxide Enrichment on Photosynthesis and Growth of Lettuce (Lactuca sativa L.) New Phytologist1989111473-481-New Phytol.. The response of glasshouse crops to the nitrogDen 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 highE 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 tFhe 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 reductiGon 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 Hphotosynthetic capacity of single leaves when measured in NOx-free air. The decrease in photosynthetic rate as the fourth leaf aged occurred earlier in plants grown in CO2-enriched air than in those from the low CO2 treatment. Leaves which developedI in the CO2-enriched air containing NOx did not suffer any long-term damage to photosynthetic activity in comparison with those of the 'clean' high CO2. In mature leaves the principal long-term effect of enrichment (with or without NOx) was to reduceJ 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 of NOx on the photosynthetic capacity suggested that photosynthesis by the lettuce crop wilKl be inhibited only during the transient periods of NOx accumulation in the glasshouse./lettuce/Lactuca sativa0leaf photosynthesis/canopy photosynthesis/growth/nitrogen oxides/greenhouse/air pollution/conductance\Rx  Lh v  Carlson, T.N.//Bunce, J.A.The Effect of Atmospheric Carbon Dioxide Doubling on Transpiration Preprint Volume Tenth Conference on Biometeorology and Aerobiology and the Special Session on Hydrometeorology1991 Sept. 10-13Salt Lake CitNy, UtahBoston, MassachusettsAmerican Meteorological Society1991196-1990transpiration/photosynthesis/transpiration model/conductance/crops\Challa, H.//Schapendonk, A.H.C.M.Dynamic Optimization of CO2 Concentration in Relation to Climate Control in Greenhouses Enoch, H.Z.//Kimball, B.A. eds. Physiology, Yield, and EconomicsBoca Raton, FloridaCRC Press, Inc.1986Vol.PII147-160#Carbon Dioxide Enrichment of Greenhouse Crops0commercial use of CO2/greenhouse/modeling/CO2 measurement and control\Chaudhuri, U.N.//Kirkham, M.B.//Kanemasu, E.T.Carbon Dioxide and Water Level Effects on Yield and Water Use of Winter Wheat Agronomy Journal199082637-641-Agron. J.. Increasing levels of atmospheric CO2 may have major effects on Ryield and water use of winter wheat (Triticum aestivum L.). The objective was to determine the effect of elevated levels of CO2 on grain yield and water use from planting to harvest under two water levels. 'Newton' winter wheat was grown in the fielSd under ambient (340 uL/L) and elevated levels (485, 660, and 825 uL/L) of CO2, during three growing seasons, in 16 underground boxes (77 cm long, 37 cm wide, and 180 cm deep) containing a Muir silt loam (fine-silty, mixed, mesic Cumulic Haplustoll). T Water in half of the boxes was maintained 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 weighed in the fall and spring to determine the amount of water use by transpiration. Plastic Uchambers (121 by 92 by 168 cm) covered the boxes to maintain different CO2 levels. Grain yield of the high-water-level wheat grown under ambient CO2 was about the same as the grain yield of low-water-level wheat grown at the highest level of CO2 (825V uL/L) (3-yr means: 725 and 707 g/m2, respectively). Similar results were obtained for yield components (spike number, spike weight, kernels/spike, and kernel weight). High-water-level wheat grown with 825 uL/L CO2 transpired more water than low-watWer-level wheat grown under ambient levels of CO2 (3-yr means: 453 and 370 L/m2, respectively). Under high and low water levels, 29 and 31% less water was required, respectively, to produce a gram of grain when the CO2 concentration was raised from amXbient 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./wheat/Triticum aestivum0rhizotron/yield/reproduction/water stress/transpiration/outdoor growth chambers\*Y ! Chaudhuri, U.N.//Kirkham, M.B.//Kanemasu, E.T.Root Growth of Winter Wheat under Elevated Carbon Dioxide and Drought Crop Science199030853-857-Crop Sci.. With the atmospheric concentration of CO2 increasing, it is important to kn[ow 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 1\6 plastic chambers (121 by 92 by 168 cm) in the field under ambient CO2 (340 uL/L) and elevated levels of CO2 (485, 660, and 825 uL/L). Each chamber was placed over an underground box (77 by 37 cm at the top; 180 cm deep) containing a Muir silt loam ](fine-silty, mixed, mesic Cumulic Haplustoll). The boxes could be pulled out of the ground for observation of the roots. Half of the boxes were maintained at field capacity (0.38 m3/m3) (well-watered or not stressed plants) and half between 0.14 to ^0.25 m3/m3 (drought-stressed plants). At harvest, root dry weights at different depths and stem dry weight were determined. Roots of plants grown under the three elevated levels of CO2 penetrated to the maximum depth of observation (176 cm) before r_oots of plants grown under the ambient level. At harvest, the difference in root growth between elevated and ambient levels of CO2 was most pronounced at the top level (0- to 10-cm depth). Roots of drought-stressed plants grown with 825 uL/L CO2 had` a greater dry weight than roots of well-watered plants grown with ambient CO2. The ratio of root to stem weight usually showed no trend (neither increase or decrease) with increasing CO2 concentration. Total dry weight at harvest of well-watered roaots grown 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-yr mean: 123 g/m2). The results indicated that high CO2 (825 uL/L) can compensate for restrictions in root growth by drobught./wheat/Triticum aestivum0rhizotron/root:shoot ratio/roots/water stress/growth/outdoor growth chambers\*y  Chaudhuri, U.N.//Burnett, R.B.//Kirkham, M.B.//Kanemasu, E.T.Effect of Carbon Dioxide on Sorghum Yield, Root Growth, and Water Use Agricultural and Forest Meteorology198637109-122-Agric. For. Meteorol.. The concentration of atmdospheric carbon dioxide (CO2) is rising. The effect of higher than ambient levels of CO2 on plants grown in the sub-humid central Great Plains of the U.S.A. has not been investigated. Therefore, an experiment was conducted at Manhattan, Kansas, to setudy the effect of elevated levels of CO2 on grain sorghum [Sorghum bicolor (L.) Moench]. During the summer of 1984, the sorghum was grown in rhizotrons in which root and shoot growth could be monitored throughout the growth cycle. The tops of the pflants were enclosed in plastic chambers, which contained one of four concentrations of CO2: 330 (ambient), 485, 660, and 795 uL/L. Enriched CO2 delayed the boot, half bloom, and soft dough stages. Sorghum grown at elevated concentrations of CO2 yigelded more roots and shoots than plants grown with 330 uL/L. At all soil-profile depths, root numbers and weights were higher at elevated CO2 than at ambient CO2. However, water use per unit dry matter of leaf, stem, root, and grain was decreased 13h, 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 increase in leaf area indices resulted in a lower canopy resisitance./sorghum/Sorghum bicolor0rhizotron/roots/growth//WUE/growth stages/yield/transpiration/conductance/outdoor growth chambers\*" 1 Chaves, M.M.//Pereira, J.S.Water Stress, CO2 and Climate Change Journal of Experimental Botany1992431131-1139-J. Exp. Bot.. Climate change may bring about increased aridity of large areas of Europe. Higher temperatures, largerk water deficits and high light stress are likely to occur in conjunction with elevated atmospheric CO2. This raises the question whether a high CO2 concentration in the atmosphere can compensate for the decrease in carbon gain in water-stressed plantsl. The processes which determine dry matter production and the ways they are affected by soil water deficits are discussed. It is now well established that in most species and under most circumstances stomata are the main limiting factor to carbon upmtake under water deficit, the photosynthetic machinery being highly resistant to dehydration. However, when other stresses are superimposed, a decline in photosynthetic capacity may be observed. In the short term, under drought conditions, the increnase in CO2 in the atmosphere may diminish the importance of stomatal limitation for carbon assimilation, inhibit photorespiration, stimulate carbon partitioning to soluble sugars and increase water-use efficiency. Some recent evidence seems to indicaote that under conditions of high irradiance, plants growing at elevated CO2 may develop protection towards photoinhibition, which might otherwise result in significant losses in plant production under stress conditions. In the longer term though, a npegative acclimation of photosynthesis appears to occur in many species, an explanation for which still needs to be clearly identified. Similarly, the effects of extended exposure to elevated CO2 under arid conditions are not known. Plant production qis 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, experimental as well as simulatory ervidence suggests that doubling CO2 concentration in the air may improve carbon assimilation and compensate partially for the negative effects of water stress even if we assume a down-regulation of the photosynthetic process as a result of acclimation sto elevated CO2.0water stress/review/photosynthesis/fluorescence/light/simulation/conductance/photosynthetic acclimation/climate change\Chen, J.J.//Sung, J.M.Gas Exchange Rate and Yield Responses of Virginia-type Peanut to Carbon Dioxide Enrichment Crop Science1990301085-1089-Crop Sci.. Poor seed fill and resultant seed-coat shriveling occur commonly on Virginiua-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 CO2v 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 throughwout 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 carboxxylase/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 prodyuction 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./peanut/Arachis hypogaea0lzeaf photosynthesis/yield/source-sink balance/ribulose bisphosphate carboxylase/seed production/proteins/outdoor growth chambers\*   Chu, C.C.//Coleman, J.S.//Mooney, H.A.Controls of Biomass Partitioning between Roots and Shoots: Atmospheric CO2 Enrichment and the Acquisition and Allocation of Carbon and Nitrogen in Wild Radish Oecologia199289580-587-Oecologia|. 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 concentrations (200 ppm, 330 ppm and 600 ppm) with stable hydroponic 150 umol/L nitrate supply. Radish biomass accumulation, photosynthetic ra~te, water use efficiency, nitrogen per unit leaf area, and starch and soluble sugar levels in leaves increased with increasing atmospheric CO2 concentration, whereas specific leaf area and nitrogen concentration of leaves significantly 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 shoots 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./radish/Raphanus sativus/Raphanus raphanistrum0allocation/root:shoot ratio/nitrogen/carbohydrates/growth analysis/controlled environment chambers\*  Coleman, J.S.//Rochefort, L.//Bazzaz, F.A.//Woodward, F.I.Atmospheric CO2, Plant Nitrogen Status and the Susceptibility of Plants to an Acute Increase in Temperature Plant, Cell and Environment199114667-674-Plant Cell Environ..  Elevated levels of CO2 in the atmosphere are expected to affect plant performance and may alter global temperature patterns. 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 differently 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 either 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 in 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 responded 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 could 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 tolerate an acute increase in temperature./Abutilon theophrasti/Amaranthus retroflexus/Sinapis alba/white mustard0temperature/heat shock/nitrogen/growth stages/growth/reproduction//sunlit controlled environment chambers\. B W c v  - 4 Coleman, J.S.//Bazzaz, F.A.Effects of CO2 and Temperature on Growth and Resource Use of Co-occurring C3 and C4 Annuals Ecology1992731244-1259-Ecology. We examined how CO2 concentrations and temperature interacted to affect growth, resource acquisition, and resource allocation 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 treatments had significant independent and interactive effects on plant growth, resource allocation, and resource acquisition (i.e., photosynthesis and nitrogen uptake), and the strength and direction of these effects were often dependent on plant species. For example, final biomass of Amaranthus was enhanced by elevated CO2 at 28 but was depressed at 38. For 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 temperature 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 while that of Amaranthus decreased. Furthermore, high CO2 apparently enhanced the ability of Amaranthus to retain nitrogen at this temperature, which may have helped to enhance photosynthesis, whereas nitrogen retention was unaffected in Abutilon. 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 CO2 grown plants, but increased rates of photosynthesis per unit leaf area early in the experiment apparently compensated for 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 nitrogen content and leaf photosynthesis This may have led to the reduced biomass accumulation of high CO2 grown plants that 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 allocation of biomass to roots, irrespective of temperature. Plants of both species grown under an elevated temperature regime had 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 treatments. For example, significant effects of CO2 treatment on the growth of Abutilon were evident early, prior to the initiation 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 detectable until the final 30 d of the experiment. Elevated CO2 interacted with temperature to affect plant productivity in different 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 the rates of net leaf area production and loss, nitrogen retention, and, to a lesser degree, photosynthesis and resource partitioning./Amaranthus retroflexus/Abutilon theophrasti0controlled environment chambers/temperature/nitrogen/growth analysis/conductance/photosynthesis/allocation/root:shoot ratio/C3/C4/leaf area development/senescence/old field communities\2        < D ] g   > F g o               Conroy, J.//Barlow, E.W.//Bevege, D.I.Response of Pinus radiata Seedlings to Carbon Dioxide Enrichment at Different Levels of Water and Phosphorus: Growth, Morphology and Anatomy Annals of Botany198657165-177-Ann. Bot.. Eight week old seedlings of Pinus radiata D. Don, grown at three levels of phosphorus, were subjected to three watering 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 under water stress it was 38 per cent. The NAR responded similarly to CO2. The number, length, diameter and specific weight of 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 increases in the yield of field grown P. radiata will occur even at sites where water limits growth. However, there is little possibility of improving growth where phosphorus deficiency is chronic./Pinus radiata0trees/phosphorus/water stress/anatomy/morphology/growth/controlled environment chambers\z3 @      Conroy, J.P.//Milham, P.J.//Barlow, E.W.R.Effect of Nitrogen and Phosphorus Availability on the Growth Response of Eucalyptus grandis to High CO2 Plant, Cell and Environment199215843-847-Plant Cell Environ.. The response of Eucalyptus grandis seedlings to elevated atmospheric CO2 concentrations was examined by growing seedlings 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 affected by CO2 concentration. At 660 umol CO2/mol, seedling dry weight was up to five times greater than at 340 umol CO2/mol. The 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 stimulated 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 phosphorus availability, increasing nitrogen from 40 to 160 mg/kg soil had little effect on plant growth. At high CO2, growth reached a maximum at between 80 and 160 mg nitrogen/kg soil. Total uptake of phosphorus was greater at high CO2 concentration 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 specific leaf weight was greater. The nitrogen and phosphorus concentration in the foliage was lower at elevated CO2 concentration partly because of the higher specific leaf weight. These results indicate that critical foliar concentrations currently used to define nutritional status and fertilizer management may need to be reassessed as the atmospheric CO2 concentration rises./Eucalyptus grandis0trees/nutrition/nitrogen/phosphorus/growth/controlled environment chambers\Rt    Conroy, J.P.//Milham, P.J.//Bevege, D.I.//Barlow, E.W.R.Influence of Phosphorus Deficiency on the Growth Response of Four Families of Pinus radiata Seedlings to CO2-Enriched Atmospheres Forest Ecology and Management199030175-188-For. Ecol. Manage.. Four half-sib families of Pinus radiata (D. Don) (20080, 20010, 20022 and 20062) were grown in pots under conditions where P was either deficient or adequate and water was supplied daily. Seedlings of all four families were exposed to 340 (ambient levels) or 660 uL CO2/L in controlled environment chambers for 16 weeks. Families 20010 and 20062 were grown at the same CO2 concentrations for 22 weeks. A subset of plants grown in the chambers were subject to drought and their water potentials and relative water contents measured. In the glasshouse experiment, photosynthesis, conductance and elongation of needles were measured. The fresh and dry-weights of the tops of the plants were measured in both experiments. Elevated CO2 concentrations increased shoot growth in all families, apparently through increases in photosynthesis. At 340 uL CO2/L, family 20062 accumulated the most dry-weight and 20010 the least. However, family 20010 responded so strongly to 660 uL CO2/L that it produced as much dry-matter as 20062. Phosphorus deficiency generally diminished the response to high CO2. Again, 20010 was outstanding in that its CO2 response was least reduced by P deficiency. Carbon dioxide enrichment did not increase the drought-tolerance of any of the four families, either by reducing conductance or by facilitating osmotic adjustment. These results provide strong indications that the higher levels of atmospheric CO2 expected in the next century will increase the growth of P. radiata where P availability is adequate, but may reduce growth in areas where rainfall is low. Finally, the capacity to respond to CO2 enrichment appears to be widely distributed among superior P. radiata genotypes selected by the Forestry Commission of New South Wales. However the magnitude of response varies considerably, particularly where P is deficient./Pinus radiata0trees/family responses/nutrition/phosphorus/water stress/growth/photosynthesis/conductance/carbohydrates/controlled environment chambers\   (     Conroy, J.P.//Milham, P.J.//Mazur, M.//Barlow, E.W.R.Growth, Dry Weight Partitioning and Wood Properties of Pinus radiata D. Don after 2 Years of CO2 Enrichment Plant, Cell and Environment199013329-337-Plant Cell Environ.. Advanced selections (families 20010 and 20062) of P. radiata D. Don were exposed to either 340 or 660 umol CO2/mol for 2 years to establish if growth responses to high CO2 would persist during the development of woody tissues. The experiment was carried out in glasshouses and some of the trees at each CO2 concentration were subjected to phosphorus deficiency and to periodic drought. CO2 enrichment increased whole-plant dry matter production irrespective of water availability, 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 in whole-plant dry matter production was similar for both families; however, family 20010 partitioned larger amounts of dry weight to the trunks than family 20062, which favoured the roots and branches. Wood density was generally increased by elevated CO2 and for family 20010 this increase was due to thickening of the tracheid walls. Tracheid length was similar at both CO2 levels but differed between families. These results suggest that, as the atmospheric CO2 concentration rises, field-grown P. radiata should produce more dry weight at sites where phosphorus is not acutely deficient, even where drought 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./Pinus radiata0family responses/trees/nutrition/phosphorus/water stress/anatomy/allocation/wood properties/greenhouse\zm z  #   Conroy, J.P.//Milham, P.J.//Reed, M.L.//Barlow, E.W.Increases in Phosphorus Requirements for CO2-Enriched Pine Species Plant Physiology199092977-982-Plant Physiol.. Pinus radiata D. Don (half-sib families 20010 and 20062) and Pinus caribaea var hondurensis (an open-pollinated family) were grown for 49 weeks at seven levels of phosphorus and at CO2 concentrations of either 340 or 660 microliters per liter, to establish if the phosphorus requirements differed between the CO2 concentrations and if mycorrhizal associations were affected. When soil phosphorus availability was low, phosphorus uptake was increased by elevated CO2. This may have been related to changes in mycorrhizal competition. When the phosphorus concentration in the youngest fully expanded needles was above 600 milligrams per kilogram the shoot weight of all pine families was greater at high CO2 due to increases in rates of photosynthesis. More dry weight was partitioned to the stems of P. radiata family 20010 and P. caribaea. At foliar phosphorus concentrations above 1000 milligrams per kilogram (P. radiata) and 700 milligrams per kilogram (P. caribaea), growth did not increase at 340 microliters of CO2 per liter. Soluble sugar levels in the same needles mirrored the growth response, but the starch concentration declined with increasing phosphorus. At 660 microliters of CO2 per liter, shoot weight and soluble sugar concentrations were still increasing up to a foliar P concentration of 1800 milligrams per kilogram for P. radiata and 1600 milligrams per kilogram for P. caribaea. The starch concentration did not decline. These results indicate that higher foliar phosphorus concentrations are required to realize the maximum growth potential of pines at elevated CO2./Pinus radiata/Pinus caribaea0trees/nutrition/phosphorus/mycorrhizae/growth/carbohydrates/allocation/fluorescence/controlled environment chambers/leaf photosynthesis\B        B L o z   ! , Conroy, J.P.//Smillie, R.M.//Kuppers, M.//Bevege, D.I.//Barlow, E.W.Chlorophyll a Fluorescence and Photosynthetic and Growth Responses of Pinus radiata to Phosphorus Deficiency, Drought Stress, and High CO2 Plant Physiology198681423-429-Plant Physiol.. Needles from phosphorus deficient seedlings of Pinus radiata D. Don grown for 8 weeks at either 330 or 660 uL CO2/L displayed chlorophyll a fluorescence induction kinetics characteristic of structural changes within the thylakoid chloroplast membrane, i.e., constant yield fluorescence (Fo) was increased and induced fluorescence ([Fp-Fi]/Fo) was reduced. 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 deficiency had occurred as shown by the similarity in the fluorescence characteristics and maximum rates of photosynthesis of the needles from the two P treatments. However, acclimation did not occur in the plants grown at 660 uL CO2/L. The light saturated rate of photosynthesis of needles with adequate P was higher at 660 uL CO2/L than at 330 uL CO2/L, whereas photosynthesis of P deficient plants showed no increase when grown at the higher CO2 concentration. The average growth increase due to CO2 enrichment was 14% in P deficient plants and 32% when P was adequate. In drought stressed plants grown at 330 uL CO2/L, there was a reduction in the maximal rate of quenching of fluorescence (Rq) after the major peak. Constant yield fluorescence was unaffected but induced fluorescence was lower. These results indicate that electron flow subsequent to photosystem II was affected by drought stress. At 660 uL CO2/L this response was eliminated showing that CO2 enrichment improved 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./Pinus radiata0trees/nutrition/water stress/leaf photosynthesis/fluorescence/growth/controlled environment chambers\ Q R   4 A     Conroy, J.P.//Virgona, J.M.//Smillie, R.M.//Barlow, E.W.Influence of Drought Acclimation and CO2 Enrichment on Osmotic Adjustment and Chlorophyll a Fluorescence of Sunflower during Drought Plant Physiology1988861108-1115-Plant Physiol.. 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 for 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 fell from 5.8 millimeters per second on the first day of drought to 1.3 millimeters per second on the fourth day and was approximately 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 which time the relative water content was 36%. By the sixth day of drought, areas near the margins of the leaves were desiccating 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./sunflower/Helianthus annuus0water stress/osmotic adjustment/fluorescence/conductance/water status/controlled environment chambers\  B S ' ( 6 = Cooper, C.F.Carbon Dioxide Enhancement of Tree Growth at High Elevations Science1986231859-Science. Technical comment./bristlecone pine/limber pine0trees/tree-ring analysis/altitude/photosynthesis\Coudret, A.//Ferron, F.//Laffray, D.High CO2 Partial Pressure Effects on Dark and Light CO2 Fixation and Metabolism is Vicia faba Leaves Photosynthesis Research19857115-126-Photosynth. Res.. Stomatal opening on Vicia faba can be induced by high CO2 partial pressures (10.2%) in dark as well as in light. Stomatal aperture was measured in both cases with a hydrogen porometer. The distribution of 14C among early products of photosynthesis was studied. Comparisons are made with carboxylations occurring when stomata were open in the dark with CO2-free air and in light with 0.034% CO2. Results showed that in high CO2 partial pressures in light, less radioactivity was incorporated in Calvin cycle intermediates and more in sucrose. carboxylations and photorespiration seemed to be inhibited. In the dark in both CO2 conditions, 14C incorporation was found in malate and aspartate but also in serine and glycerate in high CO2 conditions. In light these changes in metabolic pathways may be related with the deleterious effects recorded on leaves after long-term expositions to high partial pressure of CO2./Vicia faba0stomata/14C/metabolites/photorespiration/controlled environment chambers\Rx    Couteaux, M.M.//Bottner, P.//Rouhier, H.//Billes, G.Atmospheric CO2 Increase and Plant Material Quality: Production, Nitrogen Allocation and Litter Decomposition of Sweet Chestnut Teller, A.//Mathy, P.//Jeffers, J.N.R. eds. Responses of Forest Ecosystems to Environmental ChangesLondonElsevier Applied Science1992429-436. Two-year-old sweet chestnut trees were grown for two other years in a doubled CO2 atmosphere. The result was an increase by 20% of the net production and, as an effect of dilution, a decrease of the nitrogen concentration in the storage organs and in the leaf litter compared to a control grown in ambient air in the same conditions. The produced litter - with a C:N twice higher than the control - was used for a decomposition experiment conducted over 10 months in experimental units that can be leached. After sterilization, the litter was inoculated with a mixed microflora and animal groups in order to induce a food web of increasing complexity (microflora + Protozoa; + nematodes; + Collembola; + Isopoda). In the units inoculated with the most diversified fauna, the respiration increased as the trophic complexity increased to a maximum of 30% higher than in the control units while in the units inoculated only with microflora and protozoa, the decomposition was reduced by 60%. This stimulating effect in the complex units was due to a change in the composition (white-rot fungi invasion) and activity of the microflora induced by the presence of the fauna./sweet chestnut/Castanea sativa0trees/roots/litter decomposition/nitrogen/carbon:nitrogen ratio/allocation/microflora/protozoa/nematodes/Collembola/Isopoda/fungi/respiration/outdoor growth chambers\Couteaux, M.M.//Mousseau, M.//Celerier, M.L.//Bottner, P.Increased Atmospheric CO2 and Litter Quality: Decomposition of Sweet Chestnut Leaf Litter with Animal Food Webs of Different Complexities Oikos19916154-64-Oikos. Two-year-old chestnut trees were grown for two yr under ambient (350 ppm) and enriched (700 ppm) CO2 concentrations, in two naturally lit growth chambers. The doubling of CO2 resulted in a dilution of the nitrogen concentration in the leaf litter, with C:N ratios of 40 and 75 for the ambient and enriched CO2 concentrations, respectively. The litter was sterilized and inoculated with microflora and animal groups of increasing complexity (microflora + Protozoa + nematodes + Collembola + Isopoda) and incubated over 24 wk. Every two wk, the CO2 release was measured and the litter was leached with demineralized H2O. The following analyses were performed on the leachates: pH, total nitrogen, dissolved and particulate (Protozoa, nematodes and Rotifera). The initial decomposition stages (the first 12 wk) were dominated by the litter quality factor: CO2 release and nitrogen losses in leachates were higher and carbon losses lower in water leaching from the litter with low C:N ratio. Towards the late stages, when carbon mineralization decreased in the control litter, the animal effect emerged in litter with a high C:N ratio. Two groups appeared: (1) In the microflora + Protozoa units, carbon mineralization was reduced by 60% compared with the control litter. (2) In the diversified food web combinations, it became progressively higher with increasing complexity of the animal community and was enhanced by 30% compared with the control litter. This unexpected fundamental difference was explained by a change in the composition and activity of the microflora. Litter bleaching, respiration, C and N leaching and acidification rose with increasing animal complexity of the systems. Biological and chemical reasons explaining the invasion by white-rot fungi and its activity only in the material with a high C:N ratio are discussed. During the 24 wk, nitrogen and phosphorus mineralization was very low, indicating a high incorporation of the nutrient in the soil biomass./sweet chestnut/Castanea sativa0litter decomposition/microflora/Protozoa/nematodes/Collembola/Isopoda/Rotifera/fungi/carbon:nitrogen ratio/outdoor growth chambers\Cure, J.D. In Strain, B.R.//Cure, J.D. eds. Carbon Dioxide Doubling Responses: A Crop SurveyWashington, D.C.Dept. of Energy Carbon Dioxide Research Division1985DOE/ER-1238#Direct Effects of Increasing Carbon Dioxide on Vegetation0review//agriculture/C3/C4/environmental interactions/light/nutrition/temperature/water stress/photosynthetic acclimation/NAR/conductance/allocation/root:shoot ratio/transpiration/yield/harvest index\Cure, J.D.//Acock, B.Crop Responses to Carbon Dioxide Doubling: A Literature Survey Agricultural and Forest Meteorology198638127-145-Agric. For. Meteorol.. Atmospheric carbon dioxide (CO2) concentration will probably double by the middle of the next century. Since this is widely expected to increase crop yields, the Department of Energy has established a research program to gather data on the effects of CO2 on plants and to develop models that can be used to predict how plants will behave in a future high-CO2 world. This paper identifies strengths and weaknesses in the knowledge base for modelling plant responses to CO2. It is based on an extensive tabulation of published information on responses of ten leading crop species to elevated CO2. The response variables selected for examination were: (a) net carbon exchange rate, (b) net assimilation rate, (c) biomass accumulation, (d) root:shoot ratio, (e) harvest index, (f) conductance, (g) transpiration rate and (h) yield. The results were expressed as a predicted percentage change of the variable in response to a doubled CO2 concentration. In most instances, a linear model was used to fit the response data. Overall, the net CO2 exchange rate of crops increased 52% on first exposure to a doubled CO2 concentration. For net assimilation rate, the increases were smaller, but fell with time in a similar way. The C4 crops responded very much less than C3 crops. The responses of biomass accumulation and yield were similar to that for carbon fixation rate. Yield increased on average 41% for a doubling of CO2 concentration. The variation in harvest index was small and erratic except for soybeans, where it decreased with a doubling of CO2 concentration. Conductance and transpiration were both inversely related to CO2 concentration. Transpiration decreased 23% on average for a doubling of CO2. Crop responses to CO2 during water stress were variable probably because high CO2 both increased leaf area (which increases water use) and reduced stomatal conductance (which decreases water use). However, low nutrient concentrations limited the responses of most crops to CO2. The absolute increase in photosynthetic rate in response to high CO2 concentration was always greater in high light than in low light, but this was not necessarily true of the relative increase. In all except one study, responses to CO2 were larger at high temperature than at low. Most of these studies were done in high light intensity. In low light intensity, the effect of temperature on the CO2 response was smaller.0review/C3/C4/agriculture/environmental interactions/nutrition/light/water stress/photosynthetic acclimation/conductance/transpiration/NAR/growth/allocation/root:shoot ratio/yield/harvest index\Cure, J.D.//Israel, D.W.//Jr, T.W. RuftyNitrogen Stress Effects on Growth and Seed Yield of Nonnodulated Soybean Exposed to Elevated Carbon Dioxide Crop Science198828671-677-Crop Sci..Limitations in nutrient availability apparently can restrict plant response to CO2 enrichment; however, the alterations in physiological processes associated with such restrictions have not been defined. This experiment was conducted to investigate certain physiological responses of N-limited soybean (Glycine max [L.] Merr. cv. Lee) plants growing in a CO2 enriched environment and to examine their role in determining growth and yield. The nonnodulating soybean plants were grown to maturity in controlled environment chambers at 350 or 700 uL/L CO2 and at 0.05, 1.0, 2.5, 5.0 or 10.0 mM KNO3 supplied in nutrient solution. Substantial increases in whole-plant growth and seed yield occurred in both CO2 treatments with increasing nitrate levels; the increases were greater, however, at high CO2. At all NO3 levels except the lowest, exposure to high CO2 resulted in increased total leaf area, mean net assimilation rate, NO3 uptake, and N utilization efficiency. Increased NO3 uptake was associated with larger root systems, as uptake per u nit of root mass was lower than controls. Carbon dioxide enrichment had little effect on dry matter partitioning among plant parts or harvest index. Alterations in partitioning were related to differences in NO3 supply. The results suggest that atm ospheric CO2 enrichment can stimulate seed yield of soybean even when the availability of N in the rhizosphere is limited./Glycine max/soybean0nitrogen/nutrition/allocation/growth/yield/seed production/controlled environment chambers\*  Cure, J.D.//Jr., T.W. Rufty,//Israel, D.W.Assimilate Utilization in the Leaf Canopy and Whole-Plant Growth of Soybean during Acclimation to Elevated CO2 Botanical Gazette198714867-72-Bot. Gaz.. Young vegetative soybeans (Glycine max 'Ransom') were exposed to control (350 uL/L CO2) or CO2 enriched (700 uL/L CO2) environments continuously for 22 days. Alterations in carbon acquisition, assimilate utilization by the leaf canopy and whole-plant growth were followed to characterize plant acclimation at high CO2. Whole-plant dry weight (DW) progressively increased at high CO2 relative to the control throughout the experiment. The initial DW increases were associated with the accumulation of nonstructural assimilates in leaves and increased specific leaf weight (SLW). After 3 days, however, DW began to accumulate rapidly in stems and roots under high CO2, and SLW no longer increased relative to controls. Total leaf area did not increase significantly at high CO2 until 13 days after the start of treatments. Net assimilation rates declined under both CO2 conditions but remained higher at 700 uL/L CO2 throughout the experiment. The increases in stem and root DW during week 1 at high CO2 were accompanied by (1) an early increase in the estimated rate of assimilate utilization in the canopy during the dark phase of the diurnal cycle and (2) a later increase in the estimated rate of assimilate utilization during the light phase. The results indicate that dark mobilization of assimilates from source leaves responded 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./soybean/Glycine max0acclimation/growth/source-sink balance/assimilate partitioning/controlled environment chambers/remobilization\*  Cure, J.D.//Jr., T.W. Rufty,//Israel, D.W.Phosphorus Stress Effects on Growth and Seed Yield Responses of Nonnodulated Soybean to Elevated Carbon Dioxide Agronomy Journal198880897-902-Agron. J. 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 plant response to enriched atmospheric CO2. Nonnodulating soybean (Glycine max [L.] Merr., 'Lee') plants were grown from germination to maturity in controlled environment chambers at 350 or 700 uL/L CO2 and supplied with a complete nutrient solution 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 mM 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 over 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 size 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./soybean/Glycine max0phosphorus/nutrition/growth/allocation/yield/seed production/controlled environment chambers\*  Cure, J.D.//Jr., T.W. Rufty,//Israel, D.W.Alterations of Soybean Leaf Development and Photosynthesis in a CO2-Enriched Atmosphere Botanical Gazette1989150337-345-Bot. Gaz.. This study was conducted to characterize changes in the canopy photosynthetic leaf area of developing soybean (Glycine max [L.] Merr. cv. Lee) exposed to a CO2-enriched atmosphere. Young, vegetative plants were exposed to 350 or 700 uL/L CO2 for 15 d. Plant dry mass and total leaf area were greater in the CO2-enriched environment. Emergence and expansion rates of main stem leaves increased at high CO2, but the areas of individual leaves at full expansion were affected very little (5-10% greater than controls). More rapid leaf expansion rates occu rred in the light and dark. Under CO2-enriched conditions, the net CO2 exchange rates of all leaves on the main stem were higher before and after full expansion. Stomatal conductance was lower in high CO2 only after leaves approached full expansion.! Leaf development on the lateral branches also was increased at high CO2, accounting for 40% of the total increase in leaf area by the end of the experiment. We conclude 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./soybean/Glycine max0acclimation/leaf area development/growth analysis/conductance/leaf photosynthesis/controlled environment chambers\*$ #/ Cure, J.D.//Jr., T.W. Rufty,//Israel, D.W.Assimilate Relations in Source and Sink Leaves during Acclimation to a CO2-Enriched Atmosphere Physiologia Plantarum199183687-695-Physiol. Plant.. Evidence from previous studies suggest%ed that adjustments in assimilate formation and partitioning in leaves might occur over time when plants are exposed to enriched atmospheric CO2. We examined assimilate relations of source (primary unifoliate) and developing sink (second mainstem tri&foliate) leaves of soybean (Glycine max [L.] Merr. cv. Lee) plants for 12 days after transfer from a control (350 uL/L) to a high (700 uL/L) CO2 environment. Similar responses were evident in the two leaf types. Net CO2 exchange rate (CER) immediate'ly increased and remained elevated in high CO2. Initially, the additional assimilate at high CO2 levels in the light was utilized in the subsequent dark period. After approximately 7 days, assimilate export in the light began to increase and by 12 d(ays reached rates 3 to 5 times that of the control. In the developing sink leaf, high rates of export in the light occurred as the leaf approached full expansion. The results indicate 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./soybean/Glycine max0acclimation/source-sink balance/photosynthesis/assimilate partitioning/controlle*d environment chambers/remobilization\*   Curry, R.B.//Peart, R.M.//Jones, J.W.//Boote, K.J.//Jr., L.H. Allen,Response of Crop Yield to Predicted Changes in Climate and Atmospheric CO2 Using Simulation Transactions of the ASAE1990331383-1390-Trans. ASAE. Soybean growth, and yield for 19 locations in southeastern U.S.A. were simulated for 30 years (1951-80) of climate data. Three different climate change scenarios, with and without supplemental irrigation, were used with the SOYGRO crop model. The three climate sce-narios were standard historic data and two scenarios based on changes predicted by two general circulation models (GCM) for a doubling of atmospheric carbon dioxide. Results were analyzed for four different conditions: normal weather, doubled CO2 alo.ne, climate change alone, and the combined effect of climate change and doubled CO2. Results 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./soybean/Glycine max0crop model/agriculture/simulation/yield/climate\Curtis, P.S.//Balduman, L.M.//Drake, B.G.//Whigham, D.F.Elevated Atmospheric CO2 Effects on Belowground Processes in C3 and C4 Estuarine Marsh Communities Ecology1990712001-2006-Ecology. Belowground carbon allocation is a major1 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 for2 two full growing seasons using open top chambers. One community was dominated 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. Root3 and rhizome growth were studied in the 2nd yr of exposure 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 th4e Scirpus community. Those roots were also significantly lower in percentage of nitrogen than roots from ambient-grown plants. There was no effect of elevated CO2 on root growth or nitrogen content in the Spartina community or in the C4 component of5 the mixed community./Scirpus olneyi/Spartina patens/Distichlis spicata0roots/C3/C4/salt marsh/allocation/aquatic plants/growth/nitrogen/open-top chambers/halophytes\F T x  6          Curtis, P.S.//Drake, B.G.//Leadley, P.W.//Arp, W.J.//Whigham, D.F.Growth and Senescence in Plant Communities Exposed to Elevated CO2 Concentrations on an Estuarine Marsh Oecologia19897820-26-Oecologia. Three high marsh communit8ies 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 communities of Scirpus olneyi (C3) and Spart9ina patens (C4), and a mixed community of S. olneyi, S. patens, and Distichlis 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. These results demonstrate that elevated atmospheric CO2 can ca;use increased aboveground production in a mature, unmanaged ecosystem./Scirpus olneyi/Spartina patens/Distichlis spicata0salt marsh/C3/C4/growth/net primary productivity/senescence/growth analysis/community level CO2 responses/open-top chambers/halo<phytes\        $ * < * 3 =Curtis, P.S.//Drake, B.G.//Whigham, D.F.Nitrogen and Carbon Dynamics in C3 and C4 Estuarine Marsh Plants Grown under Elevated CO2 in situ Oecologia198978297-301-Oecologia. Carbon dioxide concentrations were elevated in three es?tuarine communities for an entire growing season. Open top chambers 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. pa@tens 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%-A40% 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 wBas 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. ContinCued growth responses to elevated CO2 could, however, be limited by the ability of S. olneyi to increase the total aboveground N pool./Scirpus olneyi/Spartina patens/Distichlis spicata0aquatic plants/salt marsh/C3/C4/carbon:nitrogen ratio/nutrition/aDllocation/litter decomposition/litter quality/mineralization/open-top chambers/halophytes/nitrogen\       E       d m    ) 2 FCurtis, P.S.//Teeri, J.A.Seasonal Responses of Leaf Gas Exchange to Elevated Carbon Dioxide in Populus grandidentata Canadian Journal of Forest Research1992221320-1325-Can. J. For. Res.. Rising atmospheric carbon dioxide concenHtrations 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 seaIson. 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 Jshoot 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 incKreased 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 initial slope of the net CO2 assimilation versus intercellular CO2 partial pressLure 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 content and leaf weight (mg/cm2) both increased. In ambient grown plants stomatalM conductance also declined at day 68. In contrast, plants grown at elevated CO2 showed no late-season decline in photosynthetic capacity or changes in leaf weight, suggesting a delay in senescence with long-term exposure to high CO2. High CO2 grown Nplants also maintained photosynthetic sensitivity to increasing Ci throughout the exposure period, while ambient CO2 grown plants were insensitive to Ci above 400 ubar on day 68. These results indicate the potential for direct CO2 fertilization of P.O grandidentata in the field and provide evidence for a new mechanism by which elevated atmospheric CO2 could influence seasonal carbon gain./Populus grandidentata0trees/leaf photosynthesis/senescence/acclimation/open-top chambers\ ` Pu y     U \   Dahlman, R.C.CO2 and Plants: Revisited Vegetatio1993104/105339-355-Vegetatio. The decade-long USA research program on the direct effects of CO2 enrichment on vegetation has achieved important milestones and has produced a numbeRr of interesting and exciting findings. Research beginning in 1980 focused on field experiments to determine whether phenomena observed in the laboratory indeed occurred in natural environments. The answer is yes. Data obtained from numerous field Sstudies show mixed response of crop and native species to CO2 enrichment however. Nearly all experiments demonstrate that plants exhibit positive gain when grown at elevated CO2; although the magnitude varies greatly. Most crop responses range from T30 to 50% increase in yield. Results from long-term experiments with woody species and ecosystems are even more variable. Huge growth responses (100 to nearly 300% increase relative to controls) are reported from several tree experiments and the salUt-marsh ecosystem experiment. Other results from experiments with woody species and the tundra ecosystem suggest little or no effect of CO2 on physiology, growth or productivity. Numerous studies of the physiology of the CO2 effect are continuing inV attempts to understand controlling mechanisms and to explain the variable growth responses. Particular emphasis needs to be given to physiological measures of interactions involving the CO2 effect and other environmental influences, and to the wide-Wranging observations of photosynthesis acclimation to CO2. Prospects for future research are identified.0review/crops/trees/ecosystem level CO2 responses/environmental interactions/photosynthetic acclimation/growth/CO2 enrichment studies\Dahlman, R.C.//Strain, B.R.//Rogers, H.H.Research on the Response of Vegetation to Elevated Atmospheric Carbon Dioxide Journal of Environmental Quality1985141-8-J. Environ. Qual.. The global rise in atmospheric CO2 is an establYished phenomenon. Irrespective of whether a CO2-induced climate change occurs, it is abundantly clear that the earth's mantle of vegetation will be directly affected by increased CO2 levels. Carbon dioxide is essential for plant growth (plants obtaiZn C from CO2 in the atmosphere); a higher level of CO2 will increase the rate of photosynthesis. Quantitative information on the CO2-induced growth response for field situations is needed for assessments of (i) possible benefits to agriculture, (ii) [the amount of fossil C that can be sequestered by CO2-accelerated growth of the biosphere, and (iii) unknown or unidentified effects of CO2 on the physiology, structure, and function of plants and ecosystems. Along with knowledge of CO2 effects on cl\imate and other factors, information on direct plant effects will be used in comprehensive evaluations of policy options related to increasing atmospheric CO2. Herein, a discussion 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.0review/agriculture/ecosystem level CO2 responses\Davis, T.D.//Potter, J.R.Relations between Carbohydrate, Water Status and Adventitious Root Formation in Leafy Pea Cuttings Rooted under Various Levels of Atmospheric CO2 and Relative Humidity Physiologia Plantarum198977185-190-Ph_ysiol. Plant.. Three levels of atmospheric CO2 and 2 levels of relative humidity (RH) during the rooting period were tested for their effect on several factors presumed to influence adventitious root formation in leafy pea (Pisum sativum L. cv. Ala`ska) cuttings. Compared to normal CO2 levels (350 uL/L), neither 1800 nor 675 uL/L CO2 affected the rooting percentage or the number of roots per cutting. However, 1800 uL/L CO2 increased root and shoot dry weight, root length, carbohydrate levels ian the base of the cuttings and water potential (w) of cuttings compared to normal levels of CO2. Compared to 87% RH, 55% RH decreased all of the above parameters, including the number of roots per cutting. A polyvinyl chloride antitranspirant (whicbh partially blocks stomata and slows photosynthesis) applied simultaneously with 87% RH increased w and root length but lowered all of the other above parameters, compared to 87% RH without antitranspirant. Increasing current photosynthate (productsc of photosynthetic activity after excision), carbohydrate, or w either alone or together was associated with increased root system size but not necessarily with increased rooting percentage or root number. The data are consistent with a hypothesis tdhat the number of roots per cutting increased with increasing current photosynthate and carbohydrate until some other factor became limiting. Also, the effect of w on rooting percentage and root number was mediated through its effect on current photeosynthate and carbohydrate./Pisum sativum0rooting/carbohydrates/relative humidity/antitranspirant/water status/controlled environment chambers/VPD\*  de Cortzar, V.G.//Nobel, P.S.Worldwide Environmental Productivity Indices and Yield Predictions for a CAM Plant, Opuntia ficus-indica, Including Effects of Doubled CO2 Levels Agricultural and Forest Meteorology199049261-279-Agricg. For. Meteorol.. The productivity of Opuntia ficus-indica was predicted for 253 regions on a worldwide basis using data from 1464 weather stations within 60 of the equator. First, the climatic data were used to calculate daily values of a PAR inhdex, a temperature index and a water index. These indices, each of which has a maximum value of unity when that environmental factor is not limiting net CO2 uptake by O. ficus-indica over a 24-h period, were multiplied together to give an environmential productivity index, which indicates how the three environmental factors limit net CO2 uptake and hence productivity. The photosynthetically active radiation (PAR) index for a canopy of closely spaced plants that have a high productivity per unit gjround area was >/= 0.20 for 25% of the earth's land surface. The temperature index annually was >/= 0.50 for 81% of the earth's land surface, indicating that local temperatures do not greatly limit net CO2 uptake by this species. The water index wask >/= 0.50 for 79% of the earth's surfaces for O. ficus-indica which exhibits Crassulacean acid metabolism with its accompanying high water-use efficiency. Predicted productivities for O. ficus-indica without irrigation were at least 10 metric tons/hal/y, the value for many important annual agronomic crops, for 41% of the earth's land area. Irrigation increased such high productivity regions to 77% of the earth's land surface area within 60 of the equator. For simulations that included the worldmwide changes in PAR, temperature and rainfall patterns that will most likely accompany a doubling in the ambient CO2 level, the high productivity of 10 tons/ha/y was predicted to occur for 54% of the earth's land surface area. Under elevated CO2, then 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./Opuntia ficus-indica0CAM/climate/simulation/net primary productivity/light/temperature/water streoss/environmental interactions\ s   (        p Del Castillo, D.//Acock, B.//Reddy, V.R.//Acock, M.C.Elongation and Branching of Roots on Soybean Plants in a Carbon Dioxide-Enriched Aerial Environment Agronomy Journal198981692-695-Agron. J.. Plants grown in high CO2 concentrrations ([CO2]) often have a higher root weight than those grown in low [CO2]. It is usually assumed that the plants with this extra root weight can explore a greater volume of soil and will, therefore, have more water available to them. To test thiss 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 containers in the growth chambers had a glass side antd new root growth appearing at the glass was measured and marked two or three times each week. Root weight at the end of the season (93 d after emergence) was 26 to 31% higher in [CO2]-enriched chambers compared with the 330 uL/L treatment, and cumuluative 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 v[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./swoybean/Glycine max0roots/growth/SPAR units\*  Dons, C.Effects of Long-Term CO2 Enrichment under Different Irradiance Regimes on Growth and Photosynthesis in Lemna gibba Photosynthetica198822328-334-Photosynthetica. Cultivation in CO2-enriched air increased the growth rate yof 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 levzels. Changes in leaf area ratio and dry mass content were associated with increased starch content. Also morphological changes occurred in high-CO2-grown plants./Lemna gibba/duckweed0aquatic plants/light/photosynthesis/growth/carbohydrates/photosyn{thetic feedback inhibition/morphology/controlled environment chambers\p {   d e   Downton, W.J.S.//Grant, W.J.R.//Chacko, E.K.Effect of Elevated Carbon Dioxide on the Photosynthesis and Early growth of Mangosteen (Garcinia mangostana L.) Scientia Horticulturae199044215-225-Scientia Hortic.. Mangosteen is a p}otentially 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 ex~amined 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 weight increased by 77%. The stimulatory effect of CO2 was greatest on root and stem dry weight, which doubled. Although a smaller proportion of dry weight was partitioned into leaves compared with control plants, CO2 enrichment increased average leaf size by about 10%, specific leaf dry weight by 17% and total leaf area by 28%. By comparison, plants from the same apomictic seedling population grown under shadehouse conditions in Darwin, Australia, developed more slowly, consistent with descriptions in the literature, and were substantially smaller and lower in dry weight compared to the plants grown under controlled conditions, even in the absence of CO2 enrichment, and had not developed lateral branches by harvest time. Reasons for this difference are suggested which may enable improvement of the early growth of mangosteen plants under field nursery conditions./mangosteen/Garcinia mangostana0trees/light/growth/leaf photosynthesis/controlled environment chambers\*  Downton, W.J.S.//Grant, W.J.R.//Loveys, B.R.Carbon Dioxide Enrichment Increases Yield of Valencia Orange Australian Journal of Plant Physiology198714493-501-Austr. J. Plant Physiol.. The response to elevated CO2 of 3-year-old fruiting Valencia orange scions (Citrus sinensis (L.) Osbeck) on citrange rootstock (C. sinensis x Poncirus trifoliata (L.) Raf.) was studied over a 12-month period under controlled environmental conditions. CO2 enrichment to approx. 800 ubar CO2 which commenced just prior to anthesis shortened the period of fruitlet abscission. Trees enriched to 800 ubar CO2 retained 70% more fruit, which at harvest were not significantly smaller in diameter or lower in fresh weight than fruit from control trees grown at approx. 400 ubar CO2. Fruit from the CO2 enriched trees also did not differ from the controls in soluble solids content, dry weight, seed number or rind thickness. The progression of fruit coloration was more rapid for the CO2-enriched trees. Dry weight of leaves and branches from the scion portion of the trees and the roots and stem of the rootstock portion did not differ between treatments at time of harvest. Leaf areas were also similar. However, specific leaf dry weight was 25% greater for the CO2 enriched treatment. Changes in dry matter partitioning resulted from the greater fruit yield (58% increase in dry weight) with CO2 enrichment. Photosynthetic rates observed at intervals over the experimental period were always lower in the CO2 enriched treatment compared to controls when measured at the same partial pressure of CO2. However photosynthetic rates in the CO2 enriched cabinet were always higher because of the increased level of CO2. The extent of this difference between the treatments varied with fruit development and increased from 23% higher photosynthetic rates in the CO2 enriched chamber at the end of flowering to 77% higher rates when fruits were 5 cm in diameter and decreased to 18% higher rates when fruit coloration was well advanced. Flushes of leaves that developed during the experiment also showed similar photosynthetic responses to CO2 enrichment and their photosynthetic rates declined as fruit matured. These results indicate that crop yield by fruit trees will increase as global levels of CO2 continue to rise, at least in those species that experience source limitation during fruit development./Valencia orange/Citrus sinensis0crops/trees/yield/source-sink balance/photosynthetic acclimation/reproduction/greenhouse/leaf photosynthesis/rates\z   ? J M `  Doyle, T.W.Seedling Response to CO2 Enrichment under Stressed and Non-stressed Conditions Jacoby, G.C.//Hornbeck, J.W. eds. Proceedings of the International Symposium on Ecological Aspects of Tree Ring AnalysisSpringfield, VirginiaNTIS1987494-500. Loblolly pine and sweetgum seedlings were obtained from a Duke University phytotron study, where three groups were grown in different atmospheres of CO2 (i.e., 350, 500, 650 ppmv). Seedlings were grown over three growing seasons, and included a set of water-stressed and non-stressed individuals. X-ray densitometry was used to evaluate growth and density characteristics of the wood samples. Cross-sectional discs of these samples were radiographed and scanned with a microdensitometer to determine ring width, area, density and mass for each growth year. Results indicated significant differences in wood 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, almost 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. These 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 and need to determine growth responses at preindustrial era CO2 concentrations in order to more accurately identify the postulated "fertilizer" effect on modern forests./loblolly pine/sweetgum/Liquidambar styraciflua/Pinus taeda0trees/tree-ring analysis/wood properties/water stress/growth/greenhouse\Drake, B.G.//Leadley, P.W.Canopy Photosynthesis of Crops and Native Plant Communities Exposed to Long-term Elevated CO2 Plant, Cell and Environment199114853-860-Plant Cell Environ.. There have been seven studies of canopy photosynthesis of plants grown in elevated atmospheric CO2: three of seed crops, two of forage crops and two of native plant ecosystems. Growth in elevated CO2 increased canopy photosynthesis in all cases. The relative effect of CO2 was correlated with increasing temperature: the least stimulation occurred in tundra vegetation grown at an average temperature near 10C and the greatest in rice grown at 43C. In soybean, effects of CO2 were greater during leaf expansion and pod fill than at other stages of crop maturation. In the longest running experiment with elevated CO2 treatment to date, monospecific stands of a C3 sedge, Scirpus olneyi (Grey), and a C4 grass, Spartina patens (Ait.) Muhl., have been exposed to twice normal ambient CO2 concentrations for four growing seasons, in open top chambers on a Chesapeake Bay salt marsh. Net ecosystem CO2 exchange per unit green biomass (NCEb) increased by an average of 48% 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./Scirpus olneyi/Spartina patens0review/community level CO2 responses/canopy photosynthesis/temperature/photosynthetic acclimation/C3/C4/aquatic plants/open-top chambers/halophytes\c q    ( B Q Drake, B.G.//Leadley, P.W.//Arp, W.J.//Nassiry, D.//Curtis, P.S.An Open Top Chamber for Field Studies of Elevated Atmospheric CO2 Concentration on Saltmarsh Vegetation Functional Ecology19893363-371-Funct. Ecol.. Small open top chamber (0.8 m x 1.0 m) were developed to maintain elevated CO2 concentrations in three plant communities in a brackish marsh ecosystem. Mean annual CO2 concentrations were 340 +/- 22 uL/L in chambers which received no added CO2 and 686 +/- 30 uL/L in chambers with elevated CO2 concentrations. Light quality was not effected in the photosynthetically active wavelengths but the chamber reduced light quantity by 10%. Night-time air temperatures inside the chamber (Ti) averaged 2C above air temperature outside the chamber (To) due to heating from the air blowers. Air temperature profiles through the plant canopy and boundary layer showed that daytime temperature differences (Ti -To) were greater than night-time differences and this day/night difference also depended on the plant community. Effects of the chamber on the 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./Scirpus olneyi/Spartina patens/Distichlis spicata0open-top chambers/C3/C4/salt marsh/community level CO2 responses/aquatic plants/halophytes/exposure methods\        Drake, B.G.//Rogers, H.H.//Jr, L.H. Allen, In Strain, B.R.//Cure, J.D. eds. Methods of Exposing Plants to Elevated Carbon DioxideWashington, D.C.Dept. of Energy Carbon Dioxide Research Division1985DOE/ER-0238#Direct Effects of Increasing Carbon Dioxide on Vegetation0review/exposure methods\du Cloux, H.//Andre, M.//Gerbaud, A.//Daguenet, A.Wheat Response to CO2 Enrichment: Effect on Photosynthetic and Photorespiratory Characteristics Photosynthetica198923145-153-Photosynthetica. The effects of doubling atmospheric CO2 concentration on photosynthesis and photorespiration were studied on wheat cultivated for 37 or 72 d in growth chambers at a density of planting of 200 and 40 plants per m2. Net photosynthetic rate (Pn) was measured continuously during the experiments and response curves to CO2 were made at intervals. Differences observed between the CO2 curves of the plants grown in normal and CO2 enriched atmosphere could be explained by the greater leaf area of the second group of plants. Photorespiration was tested by the Warburg effect or measured directly on isolated plants by the uptake of 18-O2. Oxygen uptake was reduced by 40% by the high CO2 treatment, but high CO2 plants were identical to the control group when returned to the same conditions. The enhancement of dry matter production was due to the kinetic response of Pn to CO2, as there was no appreciable long-term adaptation of the kinetic characteristics of photosynthesis./wheat/Triticum aestivum0canopy photosynthesis/photorespiration//oxygen/photosynthetic acclimation/plant density/controlled environment chambers\R  - / du Cloux, H.C.//Andre, M.//Daguenet, A.//Massimino, J.Wheat Response to CO2 Enrichment: Growth and CO2 Exchanges at Two Plant Densities Journal of Experimental Botany1987381421-1431-J. Exp. Bot.. The vegetative growth of wheat (Triticum aestivum L., var. Capitole) was followed for almost 40 d after germination 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 the experiment the CO2 gas exchanges of each canopy were measured 24 h/d. These provided a continuous growth curve for each treatment, which were compared with dry weights.  After a small stimulation at the start (first 13 d), no further effect of CO2 enrichment was observed on relative growth rate (RGR). However, RGR was stimulated throughout the experiment when plotted as a function of biomass. The final stimulation of dry weight at 660 mm3/dm3 CO2 was a factor of 1.45 at high density and 1.50 at low density; contrary to other studies, no diminution of this CO2 effect on dry weight was observed over time. Nevertheless, at low density, a transient additional enhancement of biomass (up to 1.70) was obtained at a leaf area index (LAI) below 1. This effect was attributed to a different build up of the gain of carbon in the case of an isolated plant or a closed canopy. In the former, the stimulation of leaf area and the net assimilation rate are both involved; in the 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./wheat/Triticum aestivum0canopy photosynthesis/growth analysis/plant density/leaf area development/controlled environment chambers\*  Dugal, A.//Yelle, S.//Gosselin, A.Influence of CO2 Enrichment and its Method of Distribution on the Evolution of Gas Exchanges in Greenhouse Tomatoes Canadian Journal of Plant Science199070345-356-Can. J. Plant Sci.. Net photosynthesis, stomatal conductance, internal CO2 concentration and transpiration were measured on the fifth well-developed and excised leaf of tomato seedlings (Lycopersicon esculentum Mill. 'Vedettos') 48-83 d old. These measurements were taken in order to monitor the evolution of the gas exchanges of seedlings exposed to concentrations of 330 or 1000 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 substantially increased the net photosynthesis rate of the seedlings, particularly at the beginning of the experiment. The long-term effects of CO2 enrichment subsided after a few weeks of treatment. Intermittent CO2 enrichment was partially helpful in remedying the loss of effectiveness of the CO2 after a long period of enrichment. High CO2 concentrations reduced the opening of the stomata. Our work shows that maintaining a high internal CO2 content in the leaves would indirectly reduce the stomatal conductance of the seedlings. However, our results show that the long-term loss of photosynthetic efficiency in the enriched seedlings cannot be attributed solely to an increase in the resistance of the stomata, since the internal 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./tomato/Lycopersicon esculentum0leaf photosynthesis/intermittent enrichment/conductance/greenhouse/photosynthetic acclimation/WUE/horticultural crops\*  Eamus, D.//Duff, G.Increased Atmospheric Carbon Dioxide Levels and Vegetation Responses in the Tropics Moffatt, I.//Webb, A. eds. Conservation and Development Issues in North AustraliaCasuarina (Darwin), Northern Territory, AustraliaNorth Australia Research Unit, Australian National University1992145-1540review/carbohydrates/conductance/respiration/community level CO2 responses/modeling/climate\Eamus, D.Carbon Dioxide and Plant Physiological Processes Cannell, M.G.R.//Hooper, M.D. eds. The Greenhouse Effect and Terrestrial Ecosystems of the UKEdinburgh Research Station, Bush Estate, PenicuikInstitute of Terrestrial Ecology, Natural Environment Research Council19900review/physiological CO2 responses/photosynthesis/conductance/growth/respiration/environmental interactions/photosynthetic acclimation\Eamus, D.Atmospheric CO2 and Trees, from Cellular to Regional ResponsesNew YorkAcademic Press, Inc.1992Vol. 1157-169#Encyclopedia of Earth System Science0review/trees/photosynthesis/respiration/allocation/growth/WUE/conductance/environmental interactions/community level CO2 responses/modeling/climate\Eamus, D.//Jarvis, P.G.The Direct Effects of Increase in the Global Atmospheric CO2 Concentration on Natural and Commercial Temperate Trees and Forests Begon, M.//Fitter, A.H.//Ford, E.D.//Macfadyen, A. eds. Advances in Ecological Research, Vol. 19New YorkAcademic Press Ltd.19891-550review/trees/forest/photosynthesis/conductance/respiration/growth/allocation/WUE/nutrition/nitrogen fixation/stress\Ehret, D.L.//Jolliffe, P.A.Leaf Injury to Bean Plants Grown in Carbon Dioxide Enriched Atmospheres Canadian Journal of Botany1985632015-2020-Can. J. Bot.. Bush bean (Phaseolus vulgaris L.) plants grown in atmospheres enriched with CO2 (1400 uL/L) showed marked reductions in photosynthetic capacity and accelerated chlorosis of primary leaves. Leaf injury was observed only in CO2 enriched plants, but the degree of injury was regulated by secondary factors, light and temperature. Conditions of relatively high light intensity (340-370 umol/m2/s photosynthetic photon flux density) or cool temperature (20C) promoted leaf injury of CO2-enriched plants. Leaf starch accumulation was highest under conditions that caused injury. The enhanced chlorosis and corresponding decline in photosynthetic activity, however, were not related to changes in stomatal diffusive resistance or leaf water status. Contaminant gases, such as ethylene, were not detectable in the CO2-enrichment chambers./bean/Phaseolus vulgaris0light/temperature/leaf photosynthesis/leaf injury/photosynthetic feedback inhibition/controlled environment chambers\*  Eamus, D.The Interaction of Rising CO2 and Temperatures with Water Use Efficiency Plant, Cell and Environment199214843-852-Plant Cell Environ.. Recent data concerning the impact of elevated atmospheric CO2 upon water use efficiency (WUE) and the related measure, instantaneous transpiration efficiency (ITE), are reviewed. It is concluded from both short and long-term studies that, at the scale of the individual leaf or plant, an increase in WUE or ITE is generally observed in response to increased atmospheric CO2 levels. However, the magnitude of this increase may decline with time. The opinion that elevated CO2 may substantially decrease transpiration at the regional scale is discussed. The mechanisms by which elevated CO2 may cause a change in these measures are discussed in terms of stomatal conductance, assimilation and respiration responses to elevated CO2. Finally, recent experimental data and model outputs concerning the impact of the interaction of increased temperature with elevated CO2 on WUE, ITE and yield are reviewed. It is concluded that substantially more data is required before reliable predictions about the regional scale response of WUE and catchment hydrology can be made.0review/WUE/temperature/stomata/transpiration/modeling\El Kohen, A.//Mousseau, M.Effet d'un Doublement de la Teneur en CO2 Atmospherique sur le Bilan Carbone de Jeunes Chataigniers Bulletin de la Societe Ecophysiologique199015135-147-Bull. Soc. Ecophysiol.. In French./chestnut/Castanea sativa0trees/carbon budget/canopy photosynthesis/respiration/outdoor growth chambers\El Kohen, A.//Pontailler, J.-Y.//Mousseau, M.Effect of Doubling of Atmospheric CO2 Concentration on Dark Respiration in Aerial Parts of Young Chestnut Trees (Castanea sativa Mill.) Comptes Rendus des Sciences (Paris)1991t. 312, Serie III477-481-C.R. Acad. Sci. Paris. Two-year-old sweet chestnut seedlings were grown in constantly ventilated tunnels at ambient (350 vpm) or double (700 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 compared 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 control plant respiration and when decreased, it enhanced CO2 enriched plant respiration. The explanation of these findings remains 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./Castanea sativa/sweet chestnut0trees/respiration/carbon budget/outdoor growth chambers\*  El Kohen, A.//Rouhier, H.//Mousseau, M.Changes in Dry Weight and Nitrogen Partitioning Induced by Elevated CO2 Depend on Soil Nutrient Availability in Sweet Chestnut (Castanea sativa Mill.) Annales des Sciences Forestieres19924983-90-Ann. Sci. For.. The effect of 2 levels of atmospheric carbon dioxide (ambient, i.e. 350 ppm, and double, i.e. 700 ppm) and 2 contrasting levels of mineral nutrition on dry weight, nitrogen accumulation and partitioning were examined in 2-year-old chestnut seedlings (Castanea sativa Mill.), grown in pots outdoors throughout the vegetative season. Fertilization had a pronounced effect on dry weight accumulation, tree height, leaf area, and plant nitrogen content. Carbon dioxide enrichment significantly 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 diameter but not height were increased. Carbon dioxide enrichment significantly reduced the nitrogen concentration in all organs, 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./Castanea sativa/sweet chestnut0trees/nutrition/nitrogen/growth/allocation/root:shoot ratio/litter quality/outdoor growth chambers\R     El Kohen, A.//Venet, L.//Mousseau, M.Growth and Photosynthesis of Two Deciduous Forest Species at Elevated Carbon Dioxide Functional Ecology19937480-486-Funct. Ecol.. 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 temperate 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 weeks in sweet chestnut and then an acclimation process took place. No effect of an increased CO2 could be found on sweet chestnut leaf area or leaf number, while a significant effect was found with beech, in which total leaf area per plant increased, owing to a greater number of growth flushes, each with larger leaves. The partitioning of the biomass increase due to elevated CO2 was very different in the two species. All additional dry matter was allocated to the roots in sweet chestnut, 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./sweet chestnut/Castanea sativa/Fagus sylvatica/beech0trees/growth/allocation/photosynthesis/photosynthetic acclimation/outdoor growth chambers\R    Eng, R.Y.N.//Tsujita, M.J.//Grodzinski, B.The Effects of Supplementary HPS Lighting and Carbon Dioxide Enrichment on the Vegetative Growth, Nutritional Status and Flowering Characteristics of Chrysanthemum morifolium Ramat Journal of Horticultural Science198560389-395-J. Hort. Sci.. Supplementary high pressure sodium (HPS) lighting (140 umol/m2/s) and CO2 enrichment (1375 uL/L) improved the vegetative growth of Chrysanthemum morifolium cv Dramatic by increases in stem length, stem diameter, root weight ratio, dry weight, relative growth and net assimilation rates. Three-week-old chrysanthemums grown under CO2 enrichment and HPS lighting had lower leaf weight and stem weight ratios as well as lower foliar nutrient content than those grown under ambient CO2 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 superior to either factor used alone. With 24 h HPS supplementary lighting CO2 enrichment was most effective in improving vegetative growth and flower quality when applied during the daytime. Night CO2 enrichment was not commercially beneficial at the light levels employed in this study./Chrysanthemum morifolium/chrysanthemum0commercial use of CO2/flower production/light/allocation/greenhouse\R    Enoch, H.Z.//Zieslin, N.Growth and Development of Plants in Response to Carbon Dioxide Concentrations Applied Agricultural Research19883248-256-Appl. Agric. Res.. Quality of protected crops can be improved by controlling the aerial carbon dioxide (CO2) in the greenhouse. The influence of atmosphere CO2 concentration on partitioning of dry matter, leaf growth and development, stem growth, root formation, branching and tillering, growth of the whole plant and on flowering is described in this review. At elevated CO2 concentrations apical dominance in C3 and C4 plants is weakened resulting in higher root-to-shoot ratios and increased side shoot development (branching, tillering, etc.). Most effects of elevated CO2 concentration appear to be secondary effects of photosynthesis enhancement leading to higher leaf weight per unit area, greater stem weight per unit length, and an increase in absolute growth rate--but not always an increase in relative growth rate. The influence of elevated CO2 concentration 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.0review/commercial use of CO2/flower production/allocation/root:shoot ratio\Condon, M.A.//Sasek, T.W.//Strain, B.R.Allocation Patterns in Two Tropical Vines in Response to Increased Atmospheric CO2 Functional Ecology19926680-685-Funct. Ecol.. 1. Our study addresses two questions. (a) When net primary productivity increases in tropical vines, is there an 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 inmposed 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./Psiguria racemosa/Psiguria umbrosa0controlled environment chambers/vines/tropical forest/tubers/allocation\  D T  " c s   v   " Fajer, E.D.//Bowers, M.D.//Bazzaz, F.A.The Effects of Enriched Carbon Dioxide Atmospheres on Plant-Insect Herbivore Interactions Science19892431198-1200-Science. Little is known about the effects of enriched CO2 atmospheres, which may exist in the next century, on natural plant-insect herbivore interactions. Larvae of a specialist insect herbivore, Junonia coenia (Lepidoptera: Nymphalidae), were reared on one of its host plants, Plantago lanceolata (Plantaginaceae), grown in either current low (350 parts per million) or high (700 ppm) CO2-environments. Those larvae raised on high-CO2 foliage grew more slowly and experienced greater mortality, especially in early instars, than those raised on low-CO2 foliage. Poor larval performance on high-CO2 foliage was probably due to the reduced foliar water and nitrogen concentrations of those plants and not to changes in the concentration of the defensive compounds, iridoid glycosides. Adult pupal weight and female fecundity were not affected by the CO2 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./Plantago lanceolata0Junonia coenia/insects/herbivory/nitrogen/allelochemicals/controlled environment chambers\Rh v   Fajer, E.D.//Bowers, M.D.//Bazzaz, F.A.The Effects of Enriched CO2 Atmospheres on the Buckeye Butterfly, Junonia coenia Ecology199172751-754-Ecology/Plantago lanceolata0Junonia coenia/allelochemicals/herbivory/insects/nitrogen/controlled environment chambers\*j x Fajer, E.D.//Bowers, M.D.//Bazzaz, F.A.Performance and Allocation Patterns of the Perennial Herb, Plantago lanceolata, in Response to Simulated Herbivory and Elevated CO2 Environments Oecologia19908737-42. We tested the prediction that plants grown in elevated CO2 environments are better able to compensate for biomass lost to herbivory than plants grown in ambient CO2 environments. The herbaceous perennial Plantago lanceolata (Plantaginaceae) was grown in either near ambient (380 ppm) or enriched (700 ppm) CO2 atmospheres, and then after 4 weeks, plants experienced either 1) no defoliation; 2) every fourth leaf removed by cutting; or 3) every other leaf removed by cutting. Plants were harvested at week 13 (9 weeks after simulated herbivory treatments). Vegetative and reproductive weights were compared, and seeds were counted, weighed, and germinated to assess viability. Plants grown in enriched CO2 environments had significantly greater shoot weights, leaf areas , and root weights, yet had significantly lower reproductive weights (i.e. stalks + spikes + seeds) and produced fewer seeds, than plants grown in ambient CO2 environments. Relative biomass allocation patterns further illustrated differences in plant  responses to enriched CO2 atmospheres: enriched CO2-grown plants only allocated 10% of their carbon resources to reproduction whereas ambient CO2-grown plants allocated over 20%. Effects of simulated herbivory on plant performance were much less dra matic 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 reduction s in root weights with leaf area removal, indicating that plants compensated for lost above-ground tissues, and maintained comparable levels of reproductive output and seed viability, at the expense of root growth./Plantago lanceolata0herbivory/surv ivorship/allocation/reproduction/controlled environment chambers\Rc v   Fajer, E.D.//Bowers, M.D.//Bazzaz, F.A.The Effect of Nutrients and Enriched CO2 Environments on Production of Carbon-based Allelochemicals in Plantago: A Test of the Carbon/Nutrient Balance Hypothesis The American Naturalist1992140707-723-Am. Nat.. In a test of the carbon/nutrient (C/N) balance hypothesis, we grew the perennial herb Plantago lanceolata in different CO2 and nutrient environments and then (1) measured the total allocation to shoots, roots, and reproductive parts and (2) quantified aucobin, catalpol, and verbascoside contents of replicate plants of six genotypes. Plants grown under low-nutrient conditions do have higher concentrations of carbon-based allelochemicals than plants grown under high nutrient conditions. However, in contrast to the C/N balance hypothesis, plants grown in elevated (700 uL/L) CO2 conditions had similar, or lower, concentrations of carbon-based allelochemicals than plants grown in ambient (350 uL/L) CO2 conditions. We suggest that augmented substrate concentrations (i.e., excess carbohydrates) are a necessary but insufficient trigger for increased 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, reproduction, 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./Plantago lanceolata0nutrition/carbon/carbohydrates/carbon:nitrogen ratio/allocation/allelochemicals/herbivory/controlled environment chambers\R  W j Farrar, J.F.//Williams, M.L.The Effects of Increased Atmospheric Carbon Dioxide and Temperature on Carbon Partitioning, Source-sink Relations and Respiration Plant, Cell and Environment199114819-830-Plant Cell Environ.. Herbaceous C3 plants grown in elevated CO2 show increases in carbon assimilation and carbohydrate accumulation (particularly starch) within source leaves. Although changes in the partitioning of biomass between root and shoot occur, the proportion of this extra assimilate made available for sink growth is not known. Root:shoot ratios tend to increase for CO2 enriched herbaceous plants and decrease for CO2-enriched trees. Root:shoot ratios for cereals tend to remain constant. In contrast, elevated temperatures decrease carbohydrate accumulation within source and sink regions of a plant and decrease root:shoot ratios. Allometric analysis of at least two species showing changes in root:shoot ratios due to elevated CO2 show no alteration in the whole-plant partitioning of biomass. Little information is available for interactions between temperature and CO2. Cold-adapted plants show little response to elevated levels of CO2, with some species showing a decline in biomass accumulation. In general though, increasing temperature will increase sucrose synthesis, transport and utilization for CO2-enriched plants and decrease carbohydrate accumulation within the leaf. Literature reports are discussed in relation to the hypothesis that sucrose is a major factor in the control of plant carbon partitioning. A model is presented in support.0review/allocation/source-sink balance/temperature/carbohydrates/modeling/respiration\Ferguson, J.J.//Avigne, W.T.//Allen, L.H.//Koch, K.E.Growth of CO2-enriched Sour Orange Seedlings Treated with Gibberellins/Cytokinins Proceedings of the Florida State Horticultural Society19869937-39-Proc. Fla. State Hort. Soc.. Enriched CO2 atmospheres and specific plant growth regulators are known to stimulate plant growth, but their combined effects on citrus seedlings have not been studied. Sour orange (Citrus aurantium L.) seedlings were treated with plant growth regulators (6-benzyladenine [250 ul/l]; 6 benzyladenine and gibberellic acid [250 ul/l]; gibberellin 3 [450 ul/l] and gibberellin 4+7 [250 ul/l]) and grown at either ambient or elevated CO2 levels (330 or 660 ul/l). Seedli ngs treated with GA4+7 and grown at elevated CO2 levels were taller and had greater leaf weight than plants given all other treatments. Leaf number increased under elevated CO2 levels when BA or GA4+7 were applied. Stem weight was unaffected by grow!th 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./sour orange/Citrus aurantium0trees/growth regulators/growth/SPAR units\*"  Fetcher, N.//Jaeger, C.H.//Strain, B.R.//Sionit, N.Long-term Elevation of Atmospheric CO2 Concentration and the Carbon Exchange Rates of Saplings of Pinus taeda L. and Liquidambar styraciflua L. Tree Physiology19884255-262-Tree Ph$ysiol.. The relationship between carbon exchange rate (CER) and internal CO2 concentration was measured in leaves of saplings of Liquidambar styraciflua L. (sweetgum) and Pinus taeda L. (loblolly pine) grown from seed for more than 14 months at atm%ospheric 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 response to con&centration of CO2 during measurement, but was higher in both species when grown at 500 than at 350 uL/L CO2. The net effect of a long-term increase in CO2 concentration from 350 to 500 uL/L was an increase in CER of loblolly pine, but a slight decrea'se 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./sweetgum/Liquidambar styraciflua/loblolly pine/Pinus taeda0conductance/leaf (photosynthesis/ribulose bisphosphate carboxylase/photosynthetic acclimation/greenhouse\    o    )Ehret, D.L.//Jolliffe, P.A.Photosynthetic Carbon Dioxide Exchange of Bean Plants Grown at Elevated Carbon Dioxide Concentrations Canadian Journal of Botany1985632026-2030-Can. J. Bot.. Leaves of bean plants (Phaseolus vulgaris +L. cv. Pure Gold Wax) grown in atmospheres enriched in CO2 (1400 uL/L) showed a decrease in CO2 exchange capacity when compared with unenriched plants (340 uL/L) measured at the same CO2 concentration. The decrease was not associated with changes in ,chlorophyll concentration or photorespiratory activity. The decrease was less evident in older leaves, in leaves maintained at low light intensity, and in those with reduced chlorophyll contents. Respiration rates in leaves of CO2-enriched plants in-creased only under conditions that caused a concurrent decrease in photosynthetic capacity. Enriched leaves had higher starch contents than unenriched leaves. The results were consistent with the idea that CO2 enrichment decreases photosynthetic capa.city when photoassimilate supply exceeds sink demand./Phaseolus vulgaris/bean0leaf photosynthesis/respiration/carbohydrates/photosynthetic feedback inhibition/controlled environment chambers\*   Fried, J.S.//Surano, K.A.//Daley, P.F.//Shinn, J.H.//Anderson, P.Biomass Production and Nutrient Responses of Ponderosa Pine to Long-term Elevated CO2 Concentrations Tauer, C.G.//Hennessey, T.C. eds. Proceedings of the Ninth North Amer0ican Forest Biology Workshop1986 June 15-18Stillwater, OklahomaDepartment of Forestry, Oklahoma State University, Stillwater, OklahomaSociety of American Foresters198611-18. Ponderosa pine saplings and seedlings were continuously expose1d to elevated CO2 concentrations of ambient, and ambient +75, +150, and +300 ppm in open-top chambers for 27 months. Saplings responded by reducing above ground biomass production. Although potassium concentration in both saplings and seedlings dimi2nished as CO2 concentration increased, no nutrients appeared to become limiting to growth as a result of elevated CO2. Concentrations of Ca, Mg and Zn in the saplings at different concentrations of CO2 mirrored root densities, indicating that an incr3ease in root density at +150 ppm may account for greater nutrient concentrations observed in that tree./Pinus ponderosa/ponderosa pine0open-top chambers/trees/X-ray densitometry/nutrition/roots/nitrogen/phosphorus/potassium/sulfur/calcium/magnesium/4manganese/iron/zinc\Fung, I.Y.//Tucker, C.J.//Prentice, K.C.Application of Advanced Very High Resolution Radiometer Vegetation Index to Study Atmosphere-Biosphere Exchange of CO2 Journal of Geophysical Research1987922999-3015-J. Geophys. Res.. Nor6malized difference vegetation indices derived from radiances measured by the Advanced Very High Resolution Radiometer aboard the NOAA 7 polar-orbiting satellite were used to prescribe the phasing of terrestrial photosynthesis. The satellite data were7 combined with field data on soil respiration and a global map of net primary productivity to obtain the seasonal exchange of CO2 between the atmosphere and the terrestrial biosphere. The monthly fluxes of CO2 thus obtained were employed as source/si8nk 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 loca9tions of the remote monitoring stations. The results demonstrate that satellite data of high spatial and temporal resolution can be used to provide quantitative information about seasonal and longer-term variations of photosynthetic activity on a glo:bal scale. Atmospheric CO2 observations and a three-dimensional atmospheric model have been 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.0modeling/photosynthesis, global/advanced very high resolution radiometer/normalized difference vegetation index/net primary productivity/reflectance/radiation/remote sensing\Furbank, R.T.//Walker, D.A.Chlorophyll A Fluorescence as a Quantitative Probe of Photosynthesis: Effects of CO2 Concentration during Gas Transients on Chlorophyll Fluorescence in Spinach Leaves New Phytologist1986104207-213-New Ph=ytol.. 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, result>s in a hyperbola. When these data are replotted on an inverse-reciprocal plot, an apparent Km(CO2) for the fluorescence transient can be obtained which closely approximates the Km(CO2) for carbon assimilation under similar conditions. Transitions 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 compon@ents 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./spinach/Spinacia oleracea0leaf photosynthesis/fluorescence\RA( ) % & +Hendrey, G.R.The DOE/USDA FACE Program: Goal, Objectives, and Results Through 1989 Critical Reviews in Plant Sciences19921175-83-Crit. Rev. Plant Sci.. The FACE system is a tool for studying the effects of CO2 enrichment on vegCetation and natural ecosystems and the exchange 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 bDecause the plant and field conditions are relatively uniform, thus permitting an evaluation of FACE performance. Cotton is a woody perennial with well-known physiological characteristics and a high level of response to CO2 enrichment. It is thereforEe a convenient subject for experimentation. 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 ambiFent air. The system operates effectively over plant canopies ranging in stature from bare ground to 200 cm with both open and closed canopies. Control of CO2 concentrations over large plots is within the criterion range +/- 20% of set point for 1-minG averages at least 80% of the time in all of these situations over both vertical and horizontal profiles. The area under effective control is described, approximately, by the diameter of the FACE array minus 4 m and is as large as 380 m2 in the largeHst configuration tested to date (Hendrey 1992). In 1989 a 12-m diameter "sweet spot" in the center of the FACE array had season-long average CO2 concentrations throughout the volume from ground level to the top of the canopy that were within the rangIe 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 accJumulation, both above ground and below ground. Soil respiration also increased in CO2 enriched plots. Enriched plants matured earlier and, in general, had greater agronomic yields. Water use efficiency increased with CO2 enrichment. The FACE sysKtem as reported here has had two years of successful biological experimentation. Results from these experiments are intended for use in evaluating both the effects of CO2 on plants and ecosystems, and on the feedback processes operating between the bLiosphere and atmosphere that are the primary, short-term regulators of atmospheric CO2 concentration.0FACE/exposure methods\,Hendrey, G. R.ed.FACE: Free Air CO2 Enrichment for Plant Research in the Field Conger, B.V. series ed. Critical Reviews in Plant SciencesBoca Raton, FloridaCRC Press, Inc.1992Vol. 110FACE/review/exposure methods\-Hendrey, G.R.Global Greenhouse Studies: Need for a New Approach to Ecosystem Manipulation Critical Reviews in Plant Sciences19921161-74-Crit. Rev. Plant Sci.0review/CO2 enrichment studies/carbon cycle/ecosystem level CO2 responseOs/community level CO2 responses/scaling/exposure methods\Allen, L.H., Jr.//Drake, B.G.//Rogers, H.H.//Shinn, J.H.Field Techniques for Exposure of Plants and Ecosystems to Elevated CO2 and Other Trace Gases Critical Reviews in Plant Sciences19921185-119-Crit. Rev. Plant Sci.0review/expoQsure methods/scaling\Allen, L.H., Jr.Free-Air CO2 Enrichment Field Experiments: An Historical Overview Critical Reviews in Plant Sciences199211121-134-Crit. Rev. Plant Sci.0FACE/exposure methods\Lewin, K.F.//Hendrey, G.R.//Kolber, Z.Brookhaven National Laboratory Free-Air Carbon Dioxide Enrichment Facility Critical Reviews in Plant Sciences199211135-141-Crit. Rev. Plant Sci.0FACE/exposure methods\Lipfert, F.W.//Alexander, Y.//Hendrey, G.R.//Lewin, K.F.//Nagy, J.Performance Analysis of the BNL FACE Gas Injection System Critical Reviews in Plant Sciences199211143-163-Crit. Rev. Plant Sci.0FACE/exposure methods\Nagy, J.//Lewin, K.F.//Hendrey, G.R.//Lipfert, F.W.//Daum, M.L.FACE Facility Engineering Performance in 1989 Critical Reviews in Plant Sciences199211165-185-Crit. Rev. Plant Sci.. Following prototype development of the first BNVL FACE system on Long Island in 1986, the first full-scale (22-m diameter) FACE array was built at Yazoo City, MS, in 1987. Three additional arrays were built (with some modification of the configuration of all four arrays) in 1988 in Yazoo City. InW 1989 the four arrays were moved to Maricopa, AZ. The FACE system has proven to be very reliable with 3 to 7% of available experimental time lost to system failures in 1989 in the various arrays. Analysis of modes of failure and component failures aXre 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 control deviations as a function of these variables are presented. AY statistical model relating CO2 use to wind speed and solar 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 chaZnges 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 concentrations measured at the center of the arrays were within 1 umol/mol of the[ 550 umol/mol target concentration. Averaging over all four arrays and all periods of operation, the 1-s observations measured at the center of the FACE arrays remained within +/- 20% of 550 umol/mol for 88% of the time. The corresponding 1-min aver\age was within +/- 10% for 88% of the time and within +/- 20% for 98% of the time. Studies of spatial control within one of the arrays demonstrated the general acceptability of control of CO2 concentrations in a central plot of 12-m diameter. Expe]riments using tracers and multi-port monitoring of the spatial distribution of CO2 showed that this area constituted a "sweet spot" within which CO2 concentrations were +/- 20% of the target CO2 concentration at least 80% of the time. A 63-port selec^table sequencing sampler was set up as a three-dimensional sampling system. Over 16,000 observations of 1-s grab samples were taken with this multiport sampler. Average values at each sampling node showed that spatial variability of CO2 concentratio_ns throughout the volume of the "sweet spot" in 1989 varied by less that +/- 5%. Of these 1-s grab samples 0.44% exceeded twice the target concentration of 550 umol/mol but 110 umol at the top of the canopy. Grab-samples taken in "bucket tests" aver`aging over 5-min found a wind-dependent gradient across the "sweet spot" that was as high as 160 umol. However, those ranges are still within the design criteria.0FACE/exposure methods\7Hileman, D.R.//Bhattacharya, N.C.//Ghosh, P.P.//Biswas, P.K.//Jr., L.H. Allen,//Lewin, K.F.//Hendrey, G.R.Distribution of Carbon Dioxide within and above a Cotton Canopy Growing in the FACE System Critical Reviews in Plant Sciences1992b11187-194-Crit. Rev. Plant Sci.0FACE/exposure methods\9Hileman, D.R.//Ghosh, P.P.//Bhattacharya, N.C.//Biswas, P.K.//Jr., L.H. Allen//Peresta, G.//Kimball, B.A.A Comparison of the Uniformity of an Elevated CO2 Environment in Three Different Types of Open-top Chambers Critical Reviews in Plandt Sciences199211195-202-Crit. Rev. Plant Sci.. 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 COe2 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 enrichmfent 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, gexcept 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 rouhnd 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.0open-top chambers/exposurie methods\Evans, L.S.//Hendrey, G.R.Responses of Cotton Foliage to Short-term Fluctuations in CO2 Partial Pressures Critical Reviews in Plant Sciences199211203-212-Crit. Rev. Plant Sci./cotton/Gossypium hirsutum0leaf photosynthesis/controklled environment chambers/14C/CO2 pulses\Mauney, J.R.//Lewin, K.F.//Hendrey, G.R.//Kimball, B.A.Growth and Yield of Cotton Exposed to Free-Air CO2 Enrichment Critical Reviews in Plant Sciences199211213-222-Crit. Rev. Plant Sci.. This experiment successfully grew a cotmton 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 statistically significant results. On Day Of Year (nDOY) 220, 112 days after planting, the FACE plots had 45% greater dry weight than controls. Thereafter, the FACE plots added weight at a slower rate than the controls, so that at the final harvest the difference was only 20%. The crop allocated a groeater proportion of its dry weight to roots in the FACE plots than in the controls. On DOY235 when the total dry weight increase was 39%, the root dry weight increase in the FACE plots was 85%. The uniformity of the crop response within the plots apnd between replications will allow a greater area to be used in future 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 canq be used for sampling crop response./cotton/Gossypium hirsutum0FACE/growth/allocation/yield\1Hendrix, D.L.Influence of Elevated CO2 on Leaf Starch of Field-Grown Cotton Critical Reviews in Plant Sciences199211223-226-Crit. Rev. Plant Sci./cotton/Gossypium hirsutum0FACE/carbohydrates\8Hileman, D.R.//Bhattacharya, N.C.//Ghosh, P.P.//Biswas, P.K.//Lewin, K.F.//Hendrey, G.R.Responses of Photosynthesis and Stomatal Conductance to Elevated Carbon Dioxide in Field-Grown Cotton Critical Reviews in Plant Sciences1992112t27-231-Crit. Rev. Plant Sci./cotton/Gossypium hirsutum0FACE/leaf photosynthesis/conductance\Kimball, B.A.//Jr., P.J. Pinter,//Mauney, J.R.Cotton Leaf and Boll Temperatures in the 1989 FACE Experiment Critical Reviews in Plant Sciences199211233-240-Crit. Rev. Plant Sci./cotton/Gossypium hirsutum0FACE/temperature/exposurve methods\NPinter, P.J., Jr.//Anderson, R.J.//Kimball, B.A.Evaluating Cotton Response to Free-Air Carbon Dioxide Enrichment with Canopy Reflectance Observations Critical Reviews in Plant Sciences199211241-249-Crit. Rev. Plant Sci./cotton/Goxssypium hirsutum0FACE/reflectance/normalized difference vegetation index/agriculture/radiation/remote sensing\Rogers, H.H.//Prior, S.A.//O'Neill, E.G.Cotton Root and Rhizosphere Responses to Free-Air CO2 Enrichment Critical Reviews in Plant Sciences199211251-263-Crit. Rev. Plant Sci.. The increase in atmospheric CO2 concentration is knzown to enhance the growth and yield of many crops. However, there is a paucity of data on belowground responses to CO2 enrichment. New information is needed in the related areas of: root systems, rhizosphere populations and dynamics, and the edaphic{ factors with which they interact. Free-air CO2 enrichment (FACE) studies initiated at Yazoo City, MS (1988), and Maricopa, AZ (1989) provided the first opportunity to examine belowground processes of an agro-ecosystem at elevated levels of CO2 under| realistic environmental conditions. Cotton (Gossypium hirsutum L.) was grown under ambient CO2 conditions (360 ppm) and CO2 enriched conditions (550 ppm). Carbon dioxide exposure times were just over 6 weeks, ending August 31, in 1988 and 14 weeks,} ending September 22, in 1989. In 1988, the number of lateral roots was 20% higher for the elevated CO2 treatment. Strong increasing trends were observed for taproot length, top diameter, dry weight, and volume. Root length and dry weight densities~ were either significant or showed a tendency to increase at depth increments between 0-45 cm and 15-30 cm soil depth, respectively, due to CO2 enrichment. Whole profile root length density appeared to be higher at the 550 ppm level; root dry weight density went up by 33%. Consistent indications of increased bacterial populations and microbial activity were observed. Although mycorrhizal infection was not enhanced, the greater root length densities suggested greater total plant mycorrhization.  In 1989, CO2 enrichment increased taproot volume and dry weight by 73 and 83%, respectively. Lateral root length, dry weight, and total number were up 100, 157, and 35%. At the 550 ppm treatment level root length density was increased by 21-32% in the upper layers of the soil profile (0-45 cm), with an average increase of 18% for the whole profile. Root dry weight density showed a 100% increase due to added CO2. Elevated CO2 increased dry weight densities by 71-147% at the top three depths (0-45 cm) and clear patterns of increase were observed from 45-75 cm. Field data presented here indicate that elevated CO2 stimulates cotton root proliferation. These new data provide a valuable first time insight into belowground responses of an agro-ecosystem exposed to elevated atmospheric CO2./cotton/Gossypium hirsutum0FACE/roots/rhizosphere/soil microorganisms/growth/allocation\* ! |Kimball, B.A.Cost Comparisons among Free-Air CO2 Enrichment, Open-Top Chamber, and Sunlit Controlled-Environment Chamber Methods of CO2 Exposure Critical Reviews in Plant Sciences199211265-270-Crit. Rev. Plant Sci.. The costs associated with producing high-CO2-grown plants were compared for three experimental techniques--free-air CO2 enrichment (FACE), open-top chambers (OTC), and sunlit controlled environment chambers (Soil, Plant, Atmosphere Research units, SPAR). The operating costs for treated plant production were estimated to be about $149,000/year and $128,000/year for SPAR and OTC, respectively. For FACE they were about $438,000/year, with the CO2 cost amounting to about $288,000/year for continuous enrichment by 300 umol/mol above ambient for a 6 month growing season. Substantial savings in FACE CO2 expense can be realized where lower concentrations or shorter enrichment duration can be used. Nevertheless, the FACE plots are much larger so there is a huge economy of scale. The cost per enriched area for plant growth was about $500/m/year for FACE compared to about $9,300 and $1,800/m/year for SPAR and OTC, respectively. When the additional costs of making scientific measurements was addressed, the cost of scientific labor was seen to be the largest expense of conducting research, 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.0FACE/controlled environment chambers/SPAR units/exposure methods\Kimball, B.A.//La Morte, R.L.//Peresta, G.J.//Mauney, J.R.//Lewin, K.F.//Hendrey, G.R.Weather, Soils, Cultural Practices, and Cotton Growth Data from the 1989 FACE Experiment in IBSNAT Format Critical Reviews in Plant Sciences199211271-308-Crit. Rev. Plant Sci./cotton/Gossypium hirsutum0FACE/modeling\|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. 001 in Green Report Series Field Studies of Plant Responses to Elevated Carbon Dioxide LevelsWashington, D.CU.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture, Agric. Res. Serv.1980#Response of Vegetation to Carbon Dioxide/soybean/Glycine max/loblolly pine/Pinus taeda/sweetgum/Liquidambar styraciflua/corn/Zea mays0open-top chambers/growth/yield/nitrogen/nitrogen fixation/leaf photosynthesis/conductance/WUE/anatomy/exposure methods\ Acock, B.//Reddy, V.R.//Whisler, F.D.//Baker, D.N.//McKinion, J.M.//Hodges, H.F.//Boote, K.J. 002 in Green Report Series The Soybean Crop Simulator GLYCIM: Model DocumentationWashington, D.C.U.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture, Agric. Res. Serv.1983#Response of Vegetation to Carbon Dioxide/soybean/Glycine max0modeling/crop model\Allen, L.H., Jr.//Boote, K.J.//Jones, J.W.//Mishoe, J.W.//Jones, P.H.//Vu, C.V.//Valle, R.//Campbell, W.J. 003 in Green Report Series Effects of Increased Carbon Dioxide on Photosynthesis and Agricultural Productivity of Soybeans. 1981 Progress ReportWashington, D.C.U.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture, Agric. Res. Serv.1982#Response of Vegetation to Carbon Dioxide/soybean/Glycine max0SPAR units/growth/yield/growth stages/nitrogen/carbohydrates/ribulose bisphosphate carboxylase/canopy photosynthesis/conductance\Acock, B.//Baker, D.N.//Reddy, V.R.//McKinion, J.M.//Whisler, F.D.//Del Castillo, D.//Hodges, H.F. 004 in Green Report Series Soybean Responses to Carbon Dioxide: Measurement and Simulation 1981Washington, D.C.U.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture, Agric. Res. Serv.1982#Response of Vegetation to Carbon Dioxide/soybean/Glycine max0SPAR units/respiration/allocation/roots/modeling/canopy photosynthesis\{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. 005 in Green Report Series Field Studies of Plant Responses to Elevated Carbon Dioxide LevelsWashington, D.C.U.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture, Agric. Res. Serv.1981#Response of Vegetation to Carbon Dioxide/soybean/Glycine max0open-top chambers/water stress/carbohydrates/anatomy/yield/growth/exposure methods\ Acock, B.//Reddy, V.R.//Del Castillo, D.//Hodges, H.F.//Baker, D.N.//McKinion, J.M.//Whisler, F.D. 008 in Green Report Series Soybean Responses to Carbon Dioxide: Measurement and Simulation 1982Washington, D.CU.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture, Agric. Res. Serv.1983#Response of Vegetation to Carbon Dioxide/soybean/Glycine max0simulation/SPAR units/water stress/yield/modeling/photosynthesis model/canopy photosynthesis/respiration\}Rogers, H.H.//Bingham, G.E.//Brownie, C.//Cure, J.D.//Drake, B.G.//Heck, W.W.//Huber, S.C.//Israel, D.W. 009 in Green Report Series Field Studies of Plant Responses to Elevated Carbon Dioxide LevelsWashington, D.C.U.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture, Agric. Res. Serv.1982Response of Vegetation to Carbon Dioxide/soybean/Glycine max0open-top chambers/Rhizobium/anatomy/leaf photosynthesis/conductance/carbohydrates/nitrogen fixation/growth/yield/modeling/exposure methods\DeWitt, C.A.//Waldron, R.E.//Lambert, J.R. 010 in Green Report Series Effects of Carbon Dioxide Enrichment on Nitrogen Fixation in Soybeans 1982Washington, D.C.U.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture, Agric. Res. Serv.1983#Response of Vegetation to Carbon Dioxide/soybean/Glycine max0SPAR units/nitrogen fixation/growth/WUE/canopy photosynthesis\~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. 012 in Green Report Series Field Studies of Plant Responses to Elevated Carbon Dioxide LevelsWashington, D.C.U.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture, Agric. Res. Serv.1983#Response of Vegetation to Carbon Dioxide/soybean/Glycine max/sweet potato/Ipomoea batatas0open-top chambers/anatomy/water stress/nitrogen/leaf area development/cultivar responses/seed production/yield/exposure methods\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. 014 in Green Report Series Effects of Increased Carbon Dioxide and Water Stress Interactions on Photosynthesis, Transpiration, and Productivity of Soybeans. 1983 Progress ReportWashington, D.C.U.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture, Agric. Res. Serv.1984#Response of Vegetation to Carbon Dioxide/soybean/Glycine max0SPAR units/leaf photosynthesis/photosynthetic acclimation/transpiration/WUE/water stress/growth/yield/Ci/Ca\iReardon, J.C.//Lambert, J.R.//Acock, B. 016 in Green Report Series The Influence of Carbon Dioxide Enrichment on the Seasonal Patterns of Nitrogen Fixation in SoybeansWashington, D.C.U.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture, Agric. Res. Serv.1990#Response of Vegetation to Carbon Dioxide/soybean/Glycine max0SPAR units/nitrogen fixation/canopy photosynthesis\)Oechel, W.C.//Hastings, S.//Hilbert, D.//Lawrence, W.//Prudhomme, T.//Riechers, G.//Tissue, D. 019 in Green Report Series The Response of Arctic Ecosystems to Elevated Carbon Dioxide RegimesWashington, D.C.U.S. Dept. of Energy, Carbon Dioxide Research Division1984#Response of Vegetation to Carbon Dioxide/Carex bigelowii/Eriophorum vaginatum/Ledum palustre/Vaccinium vitis-idaea/Vaccinium uliginosum/Betula nana/Salix pulchra0carbon sequestering/community level CO2 responses/respiration/modeling/species competition/canopy photosynthesis/tundra/tracking chambers/exposure methods\@Parker, M.L.//Taylor, F.G.//Doyle, T.W.//Foster, B.E.//Cooper, C.//West, D.C. 020 in Green Report Series Radiation Densitometry in Tree-Ring Analysis: A Review and Procedure ManualWashington, D.C. and Oak Ridge, TennesseeU.S. Dept. of Energy, Carbon Dioxide Research Division, and Environmental Sciences Division, Oak Ridge National Laboratory1985#Response of Vegetation to Carbon Dioxide0review/wood properties/X-ray densitometry/dendrochronology/tree-ring analysis\Kimball, B.A.//Mauney, J.R.//Guinn, G.//Nakayama, F.S.//Jr., P.J. Pinter,//Clawson, K.L.//Reginato, R.J.//Idso, S.B. 021 in Green Report Series Effects of Increasing Atmospheric CO2 on the Yield and Water Use of CropsWashington, D.C.U.S. Dept. of Agriculture, Agric. Res. Serv.1983#Response of Vegetation to Carbon Dioxide/cotton/Gossypium hirsutum0open-top chambers/growth/yield/evapotranspiration/crops/exposure methods\Kimball, B.A.//Mauney, J.R.//Guinn, G.//Nakayama, F.S.//Jr., P.J. Pinter,//Clawson, K.L.//Idso, S.B.//Butler, G.D.//Radin, J.R. 023 in Green Report Series Effects of Increasing Atmospheric CO2 on the Yield and Water Use of CropsWashington, D.C.U.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture, Agric. Res. Serv.1984#Response of Vegetation to Carbon Dioxide/cotton/Gossypium hirsutum0open-top chambers/water stress/yield/leaf photosynthesis/conductance/water/WUE/crops\Drake, B.G.//Curtis, P.S.//Arp, W.J.//Leadley, P.W.//Johnson, J.//Whigham, D. 044 in Green Report Series Effects of Elevated CO2 on Chesapeake Bay Wetlands. III. Ecosystem and Whole Plant Responses in the First Year of Exposure, April-November 1987Washington, D.C.U.S. Dept. of Energy, Carbon Dioxide Research Division1988#Response of Vegetation to Carbon Dioxide/Spartina patens/Distichlis spicata/Scirpus olneyi0open-top chambers/nitrogen/canopy photosynthesis/leaf photosynthesis/senescence/net primary productivity/photosynthesis model/water status/halophytes/exposure methods\;Owensby, C.E.//Coyne, P.I.//Auen, L.M. 054 in Green Report Series Rangeland-Plant Responses to Elevated CO2. Part II: Large-Chamber SystemsWashington, D.C.U.S. Dept. of Energy, Atmospheric and Climate Research Division1989#Response of Vegetation to Carbon Dioxide/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 tenuiflora0open-top chambers/growth/tallgrass prairie/leaf area development/ruminants/grazing/exposure methods/grasses\<Owensby, C.E.//Coyne, P.I.//Auen, L.M.//Sionit, N. 059 in Green Report Series Rangeland-Plant Response to Elevated CO2: Large-Chamber SystemWashington,D.C.U.S. Dept. of Energy, Atmospheric and Climate Research Division1990#Response of Vegetation to Carbon Dioxide/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 scurfpea0open-top chambers/nitrogen/ruminants/roots/litter quality/forage quality/acid detergent fiber/tallgrass prairie/exposure methods/grasses\RBazzaz, F.A.//Garbutt, K.//Williams, W.E. For The Effect of Elevated Atmospheric CO2 on Plant Communities. TR023 in Yellow Report SeriesSpringfield, VirginiaNTIS, U.S. Dept. of Commerce1985DOE/EV/04329-5#Dept. of Energy, Carbon Dioxide Research Division0review/controlled environment chambers/air pollution/sulfur dioxide/growth/leaf photosynthesis/conductance/WUE/C3/C4/water stress/species competition/light/nutrition/reproduction/phenology/growth analysis\Allen, S.G.//Idso, S.B.//Kimball, B.A.//Baker, J.T.//Jr., L.H. Allen,//Mauney, J.R.//Radin, J.W.//Anderson, M.G. For Effects of Air Temperature on Atmospheric CO2-Plant Growth RelationshipsSpringfield, VirginiaNTIS, U.S. Dept. of Commerce1990TR048, DOE/ER-0450T#Dept. of Energy, Carbon Dioxide Research Division and U.S. Dept. of Agriculture, Agricultural Research Service0review/temperature/photosynthesis/conductance/phenology/carbohydrates/yield\1Arp, W.J.//Drake, B.G.//Pockman, W.T.//Curtis, P.S.//Whigham, D.F.Interactions between C3 and C4 Salt Marsh Plant Species during Four Years of Exposure to Elevated Atmospheric CO2 Vegetatio1993104/105133-143-Vegetatio. Elevated atmospheric CO2 is known to stimulate photosynthesis and growth of plants with the C3 pathway but less of plants 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 CO2/mol) on a salt marsh vegetation with both C3 and C4 species was investigated. Elevated CO2 increased the biomass of the C3 sedge Scirpus olneyi growing in a pure stand, while the biomass of the C4 grass Spartina patens in a monospecific community 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 the salt marsh, while the C3 sedge Scirpus olneyi was most abundant at the lower elevations, and the mixed community occupied 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 affect the species distribution in the salt marsh if it allows Scirpus to grow at higher elevations where it in turn may affect the growth of Spartina./Spartina patens/Scirpus olneyi/Distichlis spicata0open-top chambers/salt marsh/aquatic plants/species competition/C3/C4/growth/community level CO2 responses/water stress/salt stress/halophytes\B   +   U c   - 5   * 2 / Arp, W.J. Vegetation of a North American Salt Marsh and Elevated Atmospheric Carbon Dioxide.AmsterdamDoctoral Thesis, Centrale Huisdrukkerij Vrije Universiteit1991/Distichlis spicata/Spartina patens/Scirpus olneyi0open-top chambers/salt marsh/leaf photosynthesis/evapotranspiration/C3/C4/growth/species competition/source-sink balance/photosynthetic acclimation/water status/halophytes\Gale, J.Carbon Dioxide Enhancement of Tree Growth at High Elevation Science1986231859-860. Technical comment.0trees/tree-ring analysis/altitude/photosynthesis\Garbutt, K.//Williams, W.E.//Bazzaz, F.A.Analysis of the Differential Response of Five Annuals to Elevated CO2 during Growth Ecology1990711185-1194-Ecology. 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 species of old field annual plants -- Abutilon theophrasti (C3), Amaranthus retroflexus (C4), Ambrosia artemisiifolia (C3), Chenopodium album (C3) and Setaria faberii (C4) -- were grown for their entire life cycle as individuals at CO2 concentration of 350 uL/L, 500 uL/L, and 700 uL/L. Emergence time, growth rate, shoot water status, photosynthesis, conductance, 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 potential significantly increased (became less negative) with increasing CO2 in Amaranthus and Setaria. Similar but statistically nonsignificant trends were found in Chenopodium and Abutilon. Overall rate of photosynthesis increased with CO2 but 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 species, 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 characters measured at the final harvest only specific leaf area (SLA) showed a consistent response to CO2, decreasing with increasing CO2. Significant CO2 x species interactions were also found for leaf area, leaf biomass, biomass of reproductive parts, 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 proportion 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 increasing 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./Abutilon theophrasti/Amaranthus retroflexus/Ambrosia artemisiifolia/Chenopodium album/Setaria faberii0sunlit controlled environment chambers/competition/growth analysis/leaf photosynthesis/C3/C4/reproduction/nitrogen/light/old field communities\J*         ' 6      % - * 4 9 @       H O        %  2  =  B  J  p  w     Gardestrom, P.Adenylate Ratios in the Cytosol, Chloroplasts and Mitochondria of Barley Leaf Protoplasts during Photosynthesis at Different Carbon Dioxide Concentrations FEBS Letters1987212114-118-FEBS Lett.. Barley (Hordeum vulgare) protoplasts were incubated in darkness and in the light at saturating and limiting CO2 concentrations. The protoplasts were fractioned by a membrane filtration technique which allows quenching ot 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./barley/Hordeum vulgare0metabolites/leaf photosynthesis/adenylates\*  Gates, D.M. In Strain, B.R.//Cure, J.D eds. Global Biospheric Response to Increasing Atmospheric Carbon Dioxide ConcentrationWashington, D.C.Dept. of Energy, Carbon Dioxide Research Division1985DOE/ER-0238#Direct Effects of Increasing Carbon Dioxide on Vegetation0ecosystem level CO2 responses/net primary productivity/tree-ring analysis/carbon budget/biotic growth factor/review\Gaudillere, J.-P.//Mousseau, M.Short Term Effect of CO2 Enrichment on Leaf Development and Gas Exchange of Young Poplars (Populus euramericana cv I 214) Acta Oecologica/Oecologia Plantarum19891095-105-Acta Oecologica/Oecol. Plant.. 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 area and specific weight and contained more stomata, epidermal cells and chlorophyll per unit area. Leaf developmental characteristics (Relative Leaf Expansion, Leaf Plastochron Index, Leaf Expansion Duration) were modified by the treatment. Leaves 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. On 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)./poplar/Populus euroamericana0controlled environment chambers/leaf area development/growth analysis/trees/stomatal density/stomatal index/canopy photosynthesis/leaf photosynthesis/conductance/WUE/respiration\R{  B C  Gifford, R.M.The Effects of the Build-up of Carbon Dioxide in the Atmosphere on Crop Productivity Australian Society of Agronomy Proceedings of the 5th Australian Agronomy Conference1989 Sept. 24-29University of Western Australia, Perth, Western AustraliaAustralian Society of Agronomy19890review/crops/agriculture/temperature/photosynthesis/climate change\Gifford, R.M.Interaction of Carbon Dioxide with Growth-Limiting Environmental Factors in Vegetation Productivity: Implications for the Global Carbon Cycle Desjardins, R.L.//Gifford, R.M.//Nilson, T.//Greenwood, E.A.N. eds.BerlinSpringer Verlag1992Vol. I24-58#Advances in Bioclimatology0review/carbon cycle/net primary productivity/environmental interactions/photosynthetic acclimation/respiration/source-sink balance/nutrition//scaling\Gifford, R.M.Interactions with Vegetation Pearman, G.I. ed. Greenhouse: Planning for Climate ChangeNew YorkE.J. Brill198883-89. 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 significant part in determining climate by affecting the partitioning of incoming solar energy over land. This partitioning may change as a result of CO2 effects on vegetation. In one way or another vegetation contributes to and/or is affected by the other major changing components of the global atmosphere -- O3, CH4, CFCs, N2O. Current best estimates of the scale of net deforestation of the world indicate that it is releasing about a quarter as much CO2 to atmosphere as fossil fuel burning is. However, the increasing CO2 concentration in the atmosphere is probably increasing the growth of vegetation. It is estimated that the net annual storage of extra carbon in the form of more standing biomass and soil organic matter than hitherto, may approximately equal the carbon released by net deforestation. Quantitative appraisal of the global carbon cycle reveals that to attempt to permanently remove the fossil fuel-derived CO2 from the atmosphere by massive re-afforestation or 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 CO2.0deforestation/carbon cycle/reforestation\ Gifford, R.M.Photosynthesis and the Greenhouse Effect Chemistry and the Environment, Proceedings of Regional Symposium1989BrisbaneLondonCommonwealth Science Council199059-71!Noller, B.N.//Chadha, M.S."eds.. The greenhouse effect, whereby atmospheric CO2 and water vapour prevent the Earth's surface from being totally frozen is likely to be amplified by the anthropogenic emissions of fossil fuel CO2. The global carbon cycle links photosynthesis to the greenhouse effect on all timescales up to millions of years. Major characteristics of the Earth's atmospheric composition, notably the low CO2 and the high oxygen concentrations were created by the evolution of plant photosynthesis. The low CO2 concentration in the atmosphere probably came about by the substantial acceleration of rock weathering that plants, especially angiosperms, cause. Calcium released by weathering moves to the oceans where it paces the formation of calcium carbonate rocks which are a massive carbon pool that dwarfs all others combined. On a timescale of millions of years the carbon from calcium carbonate is cycled back to the atmosphere via volcanoes. On shorter timescales of sociopolitical concern photosynthesis is involved with the current global change in atmospheric CO2 increase. From what we known about plant photosynthetic and growth responses to increasing CO2 concentration interacting with other limiting environmental factors, it seems very likely that the biosphere is absorbing, into standing biomass and soil organic matter, some of the CO2 emitted from fossil fuel burning and net deforestation thereby contributing to the "missing carbon" that does not appear as an increase in atmospheric CO2 concentration. However, the scope for accelerating this CO2 sequestering process by planting 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.0carbon cycle/carbon sequestering/climate change/photosynthesis/review/deforestation/reforestation\ Gifford, R.M.Exploiting the Fertilizer Effect of Increasing Atmospheric Carbon Dioxide Climate and Food Security, International Symposium on Climate Variability and Food Security in Developing Countries1987 Feb. 5-9New Delhi, Indiaand American Association for the Advancement of Science, Washington, D.C.International Rice Research Institute, Manila1989477-487. High CO2 concentrations fertilize plants by stimulating photosynthesis, suppressing photorespiration, and reducing transpiration per unit leaf area. CO2 enhancement of growth occurs at both optimal and nonoptimal levels of other environmental variables (light, water, temperature, nitrogen nutrients, salinity). Severely phosphate-deficient plants may not respond 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 agricultural environments (e.g., adverse climatic change, soil loss and deterioration, acid precipitation). Because yield increase 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 the 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 atmospheres. Cropping boundaries may move onto more saline and drought-prone soils, although this would probably be bad policy 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.0review/agriculture/environmental interactions/yield/climate change/cultivar responses\Gifford, R.M.Direct Effects of Higher Carbon Dioxide Concentrations on Vegetation Pearman, G.I. ed. Greenhouse: Planning for Climate ChangeNew YorkE.J. Brill1988506-519. 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 concentration 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 effect" involve several physiological phenomena, some that are certainly p rimary (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 (greater leaf area development and branching, reduced stomatal frequency, redu ced dark respiration, changes to reproductive development). It is often assumed that the reduction in stomatal conductance at high CO2 concentration will lead to reduced evapotranspiration from vegetated regions, all else being equal. There are both  physiological and boundary-layer meteorological 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. However, the size of the CO2-fertilizing effect on yield for a currently adapted variety is similar to that of the associated temperature-dependent reduction of yield. So the net effect on cereal yield in a region will depend on the success at introducing 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.0review/crops/yield/photosynthesis/transpiration/conductance/climate change\ Gifford, R.M.//Lambers, H.//Morison, J.I.L.Respiration of Crop Species under CO2 Enrichment Physiologia Plantarum198563351-356-Physiol. Plant.. Respiratory characteristics of wheat (Triticum aestivum L. cvs Gabo and WW15), mung bean (Vigna radiata L. Wilczek cv. Celera) and sunflower (Helianthus annuus L. cv. Sunfola) were studied in plants grown under a normal CO2 concentration and in air containing an additional 340 or 250 uL/L CO2. Such an increase in global atmospheric CO2 concentration has been forecast for about the middle of the next century. The aim was to measure the effect of high CO2 on respiration and its components. Polarographic and, with wheat, CO2 exchange techniques were used. The capacity of the alternative pathway of respiration in roots was determined polarographically in the presence of 0.1 mM KCN. The actual rate of alternative pathway respiration was assessed by reduction in oxygen consumption caused by 10 mM salicylhydroxamic acid. Each species responded differently. In wheat, growth in high atmospheric CO2 was associated with up to 45% reduction in respiration by both roots and whole plants. Use of respiratory inhibitors in polarographic measurements on wheat roots implicated reduction in the degree of engagement of the alternative pathway as a major contributor to this reduced respiratory activity of high-CO2 plants. No change was found in the total sugar content per unit wheat root dry weight as a result of high CO2. In none of the species was there an increase in the absolute, or relative, contribution by the alternative pathway to total respiration of the root system. Thus the improved photosynthetic assimilate supply of plants grown in high CO2 did not lead to increased diversion of carbon through the non-phosphorylating alternative pathway of respiration in the root. On the contrary, in wheat grown in high CO2, the reduced loss of carbon through that route must have contributed to their larger dry weight./wheat/Triticum aestivum/mung bean/Vigna radiata/sunflower/Helianthus annuus0crops/greenhouse/canopy photosynthesis/respiration/carbohydrates/alternative respiratory pathway\z    & 7  Gifford, R.M.//Morison, J.I.L.Photosynthesis, Water Use and Growth of a C4 Grass Stand at High CO2 Concentration Photosynthesis Research1985777-90-Photosynth. Res.. Leaf photosynthesis rate of the C4 species Paspalum plicatulum Michx was virtually CO2-saturated at normal atmospheric CO2 concentration but transpiration decreased as CO2 was increased above normal concentrations, thereby increasing transpiration efficiency. To test whether this leaf response led growth to be CO2-sensitive when water supply was restricted, plants were grown in sealed pots of soil as miniature swards. Water was supplied either daily to maintain a constant water table, or at three growth restricting levels on a 5-day drying cycle. Plants were either in a cabinet with normal air (340 umol (CO2)/mol (air)) or with 250 umol/mol enrichment. Harvesting was by several cycles of defoliation. With abundant water supply high CO2 concentration did not cause increased growth, but it did not cause an increase in growth over a wide range of growth-limiting water supplies either. Only when water supply was less than 30-50% of the amount used by the stand with a water-table was there evidence that dry weight growth was enhanced by high CO2.  In addition, with successive regrowth, the enhancing effect under a regime of minimal water allocations, became attenuated. Examination of leaf gas exchange, growth and water use data showed that in the long term stomatal conductance responses were !of little significance in matching plant water use to low water allocation; regulation of leaf area was the mechanism through which consumption matched supply. Since high CO2 effects operate principally via stomatal conductance in C4 species, we post"ulate that for this species higher CO2 concentrations expected globally in future will not have much effect on long term growth./Paspalum plicatulum0grasses/C4/controlled environment chambers/WUE/growth/conductance/leaf photosynthesis/water stress\#*   Goudriaan, J.Simulation of Ecosystem Response to Rising CO2, with Special Attention to Interfacing with the Atmosphere Rosenzweig, C//Dickinson, R. eds. Climate Vegetation Interactions, a NASA Workshop1986 January 27-29Greenbelt, M%arylandGreenbelt, MarylandNASA Goddard Space Flight Center198668-750modeling/simulation/net primary productivity/ecosystem level CO2 responses\Goudriaan, J.//Bijlsma, R.J.Effect of CO2 Enrichment on Growth of Faba Beans at Two Levels of Water Supply Netherlands Journal of Agricultural Science198735189-191-Nether. J. Agric. Sci.. The occurrence of growth enhancement by' increased CO2 levels is well established under optimal conditions. A growth analysis study of faba beans, grown under two CO2 levels (350 and 700 cm3/m3) in combination with two levels of water supply, showed that the beneficial CO2 effect is mainta(ined 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.))/Vicia faba/broad bean0greenhouse/growth analysis/water stress/WUE/senescence\Goyal, A.//Tolbert, N.E.Variations in the Alternative Oxidase in Chlamydomonas Grown in Air or High CO2 Plant Physiology198989958-962-Plant Physiol.. Chlamydomonas in the resting phase of growth has an equal capacity of about 1+5 micromole O2 uptake per hour per milligram of chlorophyll for both the cytochrome c, CN-sensitive respiration, and for the alternative, salicylhydroxamic acid-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 salicylhydroxamic acid. Measured total respiration was considerably less than the combined capacities for respirat-ion. During the log phase of growth on high (2-5%) CO2, the alternative respiraiton capacity decreased about 90% but returned as the culture entered the lag phase. When the alternative oxidase capacity was low, addition of salicylic acid or cyanide .induced its reappearance. When cells were grown on low (air-level) CO2, which induced a CO2 concentrating mechanism, the alternative oxidase capacity did not decrease during the growth phase. Attempts to measure in vivo distribution of respiration b/etween the two pathways with either CN or salicylhydroxamic acid alone were inconclusive./Chlamydomonas reinhardtii0cell culture/agae/alternative respiratory pathway\ B O   0? @ & '   Graham, R.L.//Turner, M.G.//Dale, V.H.How Increasing CO2 and Climate Change Affect Forests BioScience199040575-587-BioSci.0review/ecosystem level CO2 responses/biome level CO2 responses/biosphere level CO2 responses/modeling/clim2ate change/species range/forest\Grant, W.J.R.//Fan, H.M.//Downton, W.J.S.//Loveys, B.R.Effects of CO2 Enrichment on the Physiology and Propagation of Two Australian Ornamental Plants, Chamelaucium uncinatum (Schauer) x Chamelaucium floriferum (MS) and Correa schlechtend4alii (Behr) Scientia Horticulturae199252337-342-Scientia Hortic.. Root formation on both Chamelaucium and Correa cuttings maintained at high humidity in an enclosed fog tunnel was significantly enhanced when ambient CO2 was increased from 3550 to 800 ubar. CO2 enrichment resulted in decreased transpiration 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 rai6sing the intercellular partial pressure of CO2. Increased 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 th7e stimulation of rooting associated with CO2 enrichment probably derives from the improved water relations of the cuttings rather than from increased carbohydrate levels./Chamelaucium uncinatum/Chamelaucium floriferum/Correa schlechtendalii0sunlit c8ontrolled environment chambers/commercial use of CO2/horticultural crops/rooting/carbohydrates/water status/transpiration\      9O [ ` f |    Graumlich, L.J.Subalpine Tree Growth, Climate, and Increasing CO2: An Assessment of Recent Growth Trends Ecology1991721-11-Ecology. LaMarche et al. (Science 225: 1019-1021, 1984) hypothesized that recent trends of increasing ri;ng widths in subalpine conifers may be due to the fertilizing effects of increased atmospheric CO2. Five tree-ring series from foxtail pine (Pinus balfouriana), lodgepole pine (P. murrayana), and western juniper (Juniperus occidentalis) collected in <the Sierra Nevada, California, were analyzed to determine if the temporal and spatial patterns of recent growth were consistent with the hypothesized CO2-induced growth enhancement. Specifically, I address the following questions: (1) Can growth tren=ds 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 var>iation. For the remaining two sites, trends in the residuals from the growth/climate models indicate systematic underestimation of growth during the past decade that could be interpreted as either CO2 fertilization or as a response to extreme climati?c 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 among subalpine @conifers in the Sierra Nevada. While the results presented here offer no support for the hypothesized CO2 fertilization effect, they do provide insights into the response of subalpine conifers to climatic variation. Response surfaces demonstrate tAhat 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 precipitation and warm summeBrs for all three species, substantial species-to-species variation occurs in the response to these two variables./Juniperus occidentalis/western juniper/Pinus balfouriana/foxtail pine/Pinus murrayana/lodgepole pine0trees/tree-ring analysis/climate/dCendrochronology/altitude\zy       Graybill, D.A.A Network of High Elevation Conifers in the Western U.S. for Detection of Tree-Ring Growth Response to Increasing Atmospheric Carbon Dioxide Jacoby, G.C.//Hornbeck, J.W. eds. Proceedings of the International Symposium on EEcological Aspects of Tree-Ring Analysis. U.S. Dept. of Energy Conference ReportDOE/CONF-8608144Springfield, VirginiaNTIS1987463-474. Tree-ring width growth at high elevation upper treeline sites in the western U.S.A. evidences unparalleFled increase during the past century in comparison to growth records of the preceding 500 or more years. Causes for this do not yet appear to be solely climatic in origin because it remains unclear that crucial variables affecting growth such as tempGerature or precipitation, have changed correspondingly during their length of record. Given the recent exponential rise of CO2, and its potential for affecting tree growth at high elevations, it cannot yet be ruled out as an agent of change. The rHates of ring-width growth increase in some cases appear to exceed the levels of known or estimated changes in climatic parameters and also in CO2. This may in part be due to changes in the growth potential of the organisms themselves, providing an amIplifying effect to environmental inputs. This could include changes such as increasing needle mass that provides increased photosynthetic capacity, increased root growth that provides greater nutrient availability and increased water use efficiency tJhat 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./Pinus aristataK/Pinus longaeva0trees/tree-ring analysis/altitude\Gulyaev, B.I.Influence of CO2 Concentration on Photosynthesis, Growth and Productivity of Plants Physiology and Biochemistry of Cultured Plants198618574-591-Physiol. Biochem. of Cultured Plants (Fiziologi i aibiokhimi i akultumykhM Rasteni). 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 atmospheNre is, mainly, a result of the photosynthesis intensification and leaf area growth. The assimilates' pool level in plants depends on the determination degree of vegetative growth, ability of the root system to utilize an excess of assimilates and on Othe environmental conditions, which explains why deep inhibition of photosynthesis under these conditions is not always observed. Relative effect of CO2 enrichment on the productivity is higher with lower illuminations, as the assimilates' deficiencyP is compensated by the photosynthesis intensification. The rate of plant development slightly depends on Ca while the total plants' resistance increased with Ca. Efficiency of water utilization grows almost twice with Ca duplication. CO2 enrichmentQ makes efficiency of symbiotic nitrogen-fixation in leguminous plants higher. In Russian.0review/CO2 enrichment studies\Guy, R.D.//Reid, D.M.Photosynthesis and the Influence of CO2-Enrichment on Delta-13 C Values in a C3 Halophyte Plant, Cell and Environment1986965-72-Plant Cell Environ.. Shifts in [delta]-13C of the graminaceous C3 halophyte PuSccinellia 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 carboxyTlase activity decreased with salinity, phosphoenolpyruvate 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-eUnrichment 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 indVicated that intercellular CO2 concentrations 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 efficiencyW was enhanced./Puccinellia nuttalliana0salt stress/grasses/isotope discrimination/ribulose bisphosphate carboxylase/phosphoenolpyruvate carboxylase/WUE/halophytes/conductance/C3/Ci:Ca\*  Guy, M.//Granoth, G.//Gale, J.Cultivation of Lemna gibba under Desert Conditions. II: The Effect of Raised Winter Temperature, CO2 Enrichment and Shading on Productivity Biomass1990231-11-Biomass. The aim of this work was to inYcrease 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 theZ ambient, about 340 umol/mol, or to higher concentrations. The plastic covers attenuated photosynthetically active light by about 30%. Winter-season yields in the covered ponds, maintained at ambient CO2 concentration, were 39% higher than in the un[covered ponds. This could be ascribed to raised temperatures. Enrichment of the atmosphere with CO2 further increased yields by as much as 28%. The different treatments did not affect protein content expressed as a percentage of dry weight. Labora\tory 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 reduced pond temperatures at midday by about 5-6C and resulte]d in a 30-80% increase in growth. It was concluded that under desert conditions similar to those prevailing in this trial, high yields of Lemna gibba can be achieved throughout a growing season of 12 months per year by covering the ponds and raisin^g 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 economics/Lemna gibba/duckweed0outdoor growth _chambers/growth/temperature/light/growth analysis/environmental interactions\. 9   = H d o Grulke, N.E.//Riechers, G.H.//Oechel, W.C.//Hjelm, U.//Jaeger, C.Carbon Balance in Tussock Tundra under Ambient and Elevated Atmospheric CO2 Oecologia199083485-494-Oecologia. Whole ecosystem CO2 flux under ambient (340 uL/L) anad elevated (680 uL/L) CO2 was measured in situ in Eriophorum tussock tundra on the North Slope of Alaska. Elevated CO2 resulted in greater carbon acquisition than control treatments and there was a net loss of CO2 under ambient conditions at this uplband tundra site. These measurements indicate a current loss of carbon from upland tundra, possibly the result of recent climatic changes. Elevated CO2 for the duration of one growing season appeared to delay the onset of dormancy and resulted in appcroximately 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 higdher at elevated CO2 levels. Rapid homeostatic adjustment to elevated CO2 may limit carbon uptake in upland tundra. Abiotic factors were evaluated as predictors of ecosystem CO2 flux. For chambers exposed to ambient and elevated CO2 levels for the deuration 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 temperature, and air temperature were also predictive of seasonal ecosystem flux, but onlyf at elevated CO2 levels. At any combination of physical conditions, flux of the elevated CO2 treatment was greater than that at ambient. In short-term manipulations of CO2, tundra exposed to elevated CO2 had threefold greater carbon gain, and had onge half the ecosystem level, light compensation point when compared to ambient CO2 treatments. Elevated CO2-acclimated tundra had twofold greater carbon gain compared to ambient treatments, but there was no difference in ecosystem level, light compenshation point between elevated and ambient CO2 treatments. The predicted future increases in cloudiness could substantially decrease the effect of elevated atmospheric CO2 on net ecosystem carbon budget. These analyses suggest little if any long-term istimulation of ecosystem carbon acquisition by increases in atmospheric CO2./Eriophorum vaginatum L.0tracking chambers/ecosystem level CO2 responses/canopy photosynthesis/respiration/tundra/photosynthetic acclimation/carbon budget\* j' Hanan, J.J.CO2 Enrichment for Greenhouse Rose Production Enoch, H.Z.//Kimball, B.A. eds. Physiology, Yield, and EconomicsBoca Raton, FloridaCRC Press, Inc.1986Vol.II142-149#Carbon Dioxide Enrichment of Greenhouse Crops. Tlhe literature indicates that CO2 enrichment is a successful and important adjunct to commercial plant production, the actual practices being a function of climatic location and the particular technological surroundings. For roses, there has been a himatus 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, with actual use of COn2 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 photosynthetically active spectruom. 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 new investigative approachesp. Second, we need to emphasize the importance of plant water potential on rates if CO2 enrichment is to achieve maximum, efficient utilization. Any student of practical plant physiology learns that the major portion of radiation impinging upon a welql-watered plant is converted to latent heat. The importance of this major energy redistribution supplies the rationale for a large portion of research at agricultural research stations. Parenthetically, more than 90% of total water withdrawals in thre Southwestern U.S. is for irrigation. Based upon this review, and some 30 years of observation, it seems to me that manipulation of water potential to maximize CO2 uptake offers the greatest opportunity for significant technological advance in incresasing 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 weltl as plant temperature./rose0review/greenhouse/commercial use of CO2/flower production/environmental interactions/horticultural crops/water status\Hand, D.W.The 'Greenhouse Effect': Is It Best Studied in Greenhouses? Professional Horticulture1989376-82-Prof. Hort.0review/commercial use of CO2/greenhouse/horticultural crops\Hand, D.W.CO2 Sources and Problems in Burning Hydrocarbon Fuels for CO2 Enrichment Enoch, H.Z.//Kimball, B.A. eds. Status and CO2 SourcesBoca Raton, FloridaCRC Press, Inc.1986Vol.I99-121#Carbon Dioxide Enrichment of Greenhouwse Crops. CO2 enrichment of the greenhouse atmosphere is an invaluable technique for improving the performance of high-value salad and flower crops during the difficult winter period when poor light limits growth and development. According to govexrnment statistics there are approximately 500 ha of heated glasshouses and film-plastic covered structures (greenhouses) in England and Wales equipped specifically for CO2 enrichment. Additional areas of glasshouses receive incidental enrichment wheny growers either use direct-fired burners for warm-air heating or grow their crops in raised beds of decomposing straw. CO2 for enrichment purposes can be either supplied in liquid form or produced directly by burning hydrocarbon fuels with a low-suzlfur content in the atmosphere. Bulk storage of liquid CO2 is difficult to justify economically on small areas of glasshouses (i.e., less than 4000 m2) but handling liquid CO2 in cylinders is laborious, time-consuming and expensive. Natural gas, LPG{ propane, and low-sulfur grades of kerosene (paraffin) are therefore favored by many growers because the CO2 is produced comparatively cheaply and the heat of combustion can provide a significant proportion of the daytime heat requirement 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 potentially damaging for crop p}roduction. The risk to crops of injury from gaseous air pollutants has also increased as growers have endeavored to reduce heating costs by making their greenhouses more airtight. Gaseous air pollutants, two groups account for most of the injuries t~o crops growing in greenhouses enriched with CO2 produced from hydrocarbon fuels. These are the 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 the burner flame of a CO2 producer by the heat-promoted combination of atmospheric nitrogen and oxygen. The rate at which nitrogen oxides are generated depends essentially on flame temperature, i.e., the hotter the flame the greater the emission of nitrogen oxides. Modern CO2 producers have a high flame temperature to ensure efficient fuel combustion and the formation of nitrogen oxides is an inevitable consequence of burner design. When threefold CO2 enrichment is practiced the concentration of nitrogen oxides in the greenhouse atmosphere can be as high as 0.5 uL/L. Such a level may cause injury to crops by reducing photosynthesis, inhibiting leaf expansion, depressing growth, and decreasing yield. Ethylene emissions from CO2 producers are the result of complex reactions involved in the pyrolysis and oxidation of hydrocarbon fuels. Burner design and operating variables such as the air-fuel ratio are crucial in determining the amount of ethylene released into the greenhouse atmosphere. In a well sealed greenhouse equipped for three-fold CO2 enrichment the ethylene concentration can easily rise to a level at which the pollutant has discernible effects on crops, (i.e., between 0.01 and 0.1 uL/L). Ethylene differs from the nitrogen oxides in that it is a naturally occurring plant growth regulator and can affect many growth, developmental, and aging processes. Escape of unburnt propylene gas (a major constituent of LPG propane) from loose-fitting connections to fuel-supply lines and faulty switching of gas-solenoid valves can cause injuries to crops similar to those induced by ethylene. Propylene concentrations of between 5 and 100 uL/L are commonly found in greenhouse atmospheres polluted 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.0review/greenhouse/commercial use of CO2/CO2 sources/air pollution/nitrogen oxides/exposure methods\!Hari, P.//Arovaara, H.Detecting CO2 Induced Enhancement in the Radial Increment of Trees. Evidence from Northern Timber Line Scandinavian Journal of Forest Research1988367-74-Scand. J. For. Res.. Annual Ring data from northern Finland was analysed in order to reveal possible trends in ring width development due to changes in environmental factors. The data was analysed using a four component multiplicative model. The components are: tree age, climatic conditions, tree position and changes in environmental conditions. Since the effect of tree age and position in the stand could be easily eliminated the main problem was thus to eliminate the effect of climatic conditions on ring width. This was based on the dependence of the daily radial increment and daily maximum temperature. The component associated with changing environmental factors, especially to CO2 enrichment, was determined using the model. The basal area development of the trees was calculated from measured and estimated ring widths. Depending on the value of the autocorrelation 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./Pinus sylvestris/Scots pine0trees/tree-ring analysis/modeling\"Harley, P.C.//Sharkey, T.D.An Improved Model of C3 Photosynthesis at High CO2: Reversed O2 Sensitivity Explained by Lack of Glycerate Reentry into the Chloroplast Photosynthesis Research199127169-178-Photosynth. Res.. Current models of C3 photosynthesis incorporate a phosphate limitation to carboxylation which arises when the capacity for starch and sucrose synthesis fails to match the capacity for the production of triose phosphates in the Calvin cycle. As a result, the release of inorganic phosphate in the chloroplast stroma fails to keep pace with its rate of sequestration into triose phosphate, and phosphate becomes limiting to photosynthesis. Such a model predicts that when phosphate is limiting, assimilation becomes insensitive to both CO2 and O2, and is thus incapable of explaining the experimental observation 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 reversed sensitivity to CO2 and O2 by invoking the net release of phosphate in the photorespiratory oxidation cycle. In order for this to occur, some fraction of the glycollate carbon which leaves the stroma and which is recycled to the chloroplast by the photorespiratory pathway as glycerate must remain in the cytosol, perhaps in the form of amino acids. In that case, 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./soybean/Glycine max/cotton/Gossypium hirsutum0leaf photosynthesis/respiration//oxygen/photosynthesis model/photosynthetic feedback inhibition/simulation/modeling\#Harley, P.C.//Thomas, R.B.//Reynolds, J.F.//Strain, B.R.Modelling Photosynthesis of Cotton Grown in Elevated CO2 Plant, Cell and Environment199215271-282-Plant Cell Environ.. Cotton plants were grown in CO2-controlled growth chambers in atmospheres of either 35 or 65 Pa CO2. A widely accepted model of C3 leaf photosynthesis was parameterized for leaves from both CO2 treatments using non-linear least squares regression 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 Rubisco activity (Vcmax), estimated from A versus Ci response curves measured at 29C, was about 10% lower in leaves from plants grown in high CO2. The relationship between key model parameters and total leaf N was linear, the only difference between 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 approximately 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./cotton/Gossypium hirsutum0controlled environment chambers/leaf photosynthesis/modeling/photosynthesis model/nitrogen/ribulose bisphosphate carboxylase\$Harley, P.C.//Weber, J.A.//Gates, D.M.Interactive Effects of Light, Leaf Temperature, CO2 and O2 on Photosynthesis in Soybean Planta1985165249-263-Planta. 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 parameters may be estimated from whole-leaf gas-exchange measurements. Carbon-dioxide response curves of net photosynthesis obtained using soybean plants (Glycine max (L.) Merr.) at four partial pressures of oxygen and five leaf temperatures are presented, and a method for estimating the kinetic parameters of RuBP carboxylase-oxygenase, as manifested in vivo, is discussed. 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 rates are applied to data collected on soybean. Combining these equations with those describing the kinetics of RuBP carboxylase-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./soybean/Glycine max0modeling/photosynthesis model/leaf photosynthesis/respiration/ribulose bisphosphate carboxylase/temperature/oxygen/light/environmental interactions\R     )Havir, E.A.//McHale, N.A.Regulation of Catalase Activity in Leaves of Nicotiana sylvestris by High CO2 Plant Physiology198989952-957-Plant Physiol.. The effect of high CO2 (1% CO2/21% O2) on the activity of specific forms of catalase (CAT-1, -2, and -3) (EA Havir, NA McHale [987] Plant Physiol 84: 450-455) in seedling leaves of tobacco (Nicotiana sylvestris, Nicotiana tabacum) was examined. In high CO2, total catalase activity decreased by 50% in the first 2 days, followed by a more gradual decline in the next 4 days. The loss of total activity resulted primarily from a decrease in CAT-1 catalase. In contrast, the activity of CAT-3 catalase, a form with enhanced peroxidatic activity, increased 3-fold in high CO2 relative to air controls after 4 days. Short-term exposure to high CO2 indicated that the 50% loss of total activity occurs in the first 12 hours. Catalase levels increased to normal within 23 hours after seedlings were returned to air. When seedlings were transferred to air after prolonged exposure to high CO2 (13 days), the levels of CAT-1 catalase were partially restored while CAT-3 remained at its elevated level. Levels of superoxide dismutase activity and those of several peroxisomal enzymes were not affected by high CO2. Total catalase levels did not decline when seedlings were exposed to atmospheres of 0.04% CO2/5% O2 or 0.04% CO2/1% O2, indicating that regulation of catalase in high CO2 is not related directly to suppression of photorespiration. Antibodies prepared against CAT-1 catalase from N. tabacum reacted strongly against CAT-1 catalase from both N. sylvestris and N. tabacum but not against CAT-3 catalase from either species. This observation, along with the rapid changes in CAT-1 and the much slower changes in CAT-3 suggest that one form is not directly derived from the other./Nicotiana sylvestris/Nicotiana tabacum/tobacco0enzymes/catalase/proteins/superoxide dismutase/peroxidase\ G [ [    L Y ^ h *He, H.//Kirkham, M.B.//Lawlor, D.J.//Kanemasu, E.T.Photosynthesis and Water Relations of Big Bluestem (C4) and Kentucky Bluegrass (C3) under High Concentration of Carbon Dioxide Transactions of the Kansas Academy of Science199295139-152-Trans. Kansas Acad. Sci.. As the carbon dioxide (CO2) concentration in the atmosphere increases, comparing how C3 and C4 plants will respond is important. The objective of this study was to determine the photosynthetic rate, intercellular CO2 concentration, transpiration rate, stomatal resistance, leaf temperature, water potential, and water requirement of a C3 grass (Kentucky bluegrass, Poa pratensis L.) and a C4 grass (big bluestem, Andropogon gerardii Vitman) growing in a fall in a tallgrass prairie in Kansas under two levels of CO2 (ambient and two-times ambient). Elevated CO2 increased the photosynthetic rate of Kentucky 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 concentration. Doubled CO2 reduced the transpiration rates and increased stomatal resistance of both grasses, but big bluestem was affected more than Kentucky bluegrass. The twice-ambient level of CO2 increased (between 0.2 and 0.3 MPa) the water potential of both grasses. Doubled CO2 decreased the water requirements of big bluestem and Kentucky bluegrass by 41.6% and 158%, respectively./Kentucky bluegrass/Poa pratensis/big bluestem/Andropogon gerardii0outdoor growth chambers/leaf photosynthesis/transpiration/Ci:Ca/conductance/C3/C4/water status/WUE/tallgrass prairie/WUE\R}    2Higginbotham, K.O.//Mayo, J.M.//L'Hirondelle, S.//Krystofiak, D.K.Physiological Ecology of Lodgepole Pine (Pinus contorta) in an Enriched CO2 Environment Canadian Journal of Forest Research198515417-421-Can. J. For. Res.. 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 Engelm.) 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. Significant 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 treatments. The same relationship was found in production of total leaf surface area. Increased leaf surface area yields a productive advantage to seedlings grown at concentrations of CO2 up to 2000 uL/L even if no increase in net photosynthesis is assumed. Biomass of stems, roots, and secondary leaves was increased in both elevated CO2 conditions, with root biomass approximately 15 times greater in seedlings grown at 1000 uL/L than in those grown at 330 uL CO2/L. Stomatal resistances were essentially the same for all treatments, indicating no CO2-induced stomatal closure to at least 2000 uL/L. Photosynthetic Vmax (milligrams per square decimetre per hour) for light response curves varied with CO2 concentration. If results are extrapolated 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./lodgepole pine/Pinus contorta0controlled environment chambers/trees/growth/conductance/allocation/roots/photosynthesis/light/water stress\zl z     4Hilbert, D.W.//Larigauderie, A.//Reynolds, J.F.The Influence of Carbon Dioxide and Daily Photon-flux Density on Optimal Leaf Nitrogen Concentration and Root:Shoot Ratio Annals of Botany199168365-376-Ann. Bot.. Using a cost-benefit model, the leaf nitrogen concentration and root:shoot ratio that maximize whole-plant relative growth rate are determined as a function of the above-ground environment (integrated daily photon flux density and the concentration of carbon dioxide at the site of fixation within the leaf). The major advantage of this approach is that it determines the adaptive significance of leaf physiology by considering the functional integration of leaves and roots. The predicted response to increasing daily photon flux densities is an increase in optimal leaf N concentration (Nopt) and a concomitant increase in root:shoot ratio. Increased carbon dioxide concentration, on the other hand, reduce Nopt and only slightly change root:shoot ratio. The observed increase in leaf nitrogen concentration found in plants growing at high altitudes (low CO2 partial pressure) is also predicted. Since these responses to light and CO2 maximize the whole-plant relative growth rate, the observed adjustments that plants make to light and carbon dioxide concentration appear to be adaptive. We show that the relationship between photosynthesis and leaf nitrogen concentration is complex and depends on the light and CO2 levels at which photosynthesis is measured.  The shape of this function is important in determining Nopt and the opposite 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.0modeling/growth model/nitrogen/allocation/root:shoot ratio\5Hilbert, D.W.//Prudhomme, T.I.//Oechel, W.C.Response of Tussock Tundra to Elevated Carbon Dioxide Regimes: Analysis of Ecosystem CO2 Flux through Nonlinear Modeling Oecologia198772466-472-Oecologia. The response of tussock tundra to elevated atmospheric concentrations of CO2 was measured at Toolik Lake, Alaska in the summer of 1983. Computer-controlled greenhouses were used to determine diurnal ecosystem flux of CO2 under four treatments: 340 ppm, 500 ppm, and 680 ppm CO2, as well as 680 ppm CO2 with a four degree centigrade increase in temperature. For the seven days of data analyzed, net daily CO2 flux was significantly different between treatments. Net uptake was positively correlated with CO2 concentration in the chamber and negatively correlated with temperature. A nonlinear model was used to analyze this data set and to determine some of the reasons for different net CO2 flux. This model allowed an estimation of light utilization efficiency, total conductance of CO2, and a comparable measure of total respiration. From this analysis we conclude that nutrient limitations in the arctic decrease the capacity of tundra plants to make use of elevated CO2 concentrations. The plants respond by decreasing conductance in the presence of elevated CO2, which results in approximately equal gross uptake rates for the three CO2 treatments. Apparent changes in system respiration result in higher net uptake under elevated CO2 but this may be due to biases in the data. The treatment with increased temperature exhibited higher conductances and, consequently, higher gross uptake of CO2 than the other treatments. Higher temperatures, however, also increase respiration with the result being lower net uptake than would be expected in the absence of temperature increases.0tracking chambers/tundra/ecosystem level CO2 responses/photosynthesis model/respiration/temperature\;Hocking, P.J.//Meyer, C.P.Effects of CO2 Enrichment and Nitrogen Stress on Growth, and Partitioning of Dry Matter and Nitrogen in Wheat and Maize Australian Journal of Plant Physiology199118339-356-Austr. J. Plant Physiol.. Atmospheric CO2 levels are increasing, but little is known about how this will affect tissue concentrations and the partitioning of agriculturally important nutrients such as nitrogen (N) within crop plants. To investigate this, a glasshouse experiment was conducted in which wheat, a C3 species, and maize, a C4 species, were grown for 8 weeks at high CO2 (1500 cm3/m3) on N supplies ranging from deficient (0.5 mol/m3) to more than adequate for maximum growth (25 mol/m3). Wheat responded to both CO2 enrichment and N supply; maize responded only to N supply. CO2-enriched wheat produced about twice the dry matter of control plants at all levels of N supply. Tiller and ear numbers were increased by CO2 enrichment irrespective of N supply. Enriched wheat plants had lower Leaf Area Ratio but higher Net Assimilation Rate and Relative Growth Rate than control plants. There was no effect of CO2 enrichment on specific leaf weight. The enriched plants had lower shoot to root dry matter ratios than the controls at 6 mol/m3 N and higher. Shoot to root dry matter ratios of both wheat and maize increased with increasing N supply. CO2-enriched wheat plants accumulated more N than the controls but the proportional increase in N content was not as great as that in dry matter, with the result that concentrations of total-N and nitrate-N were lower in all organs of enriched plants, including ears. Nitrate reductase activity was lower in enriched than in control wheat plants. N-use efficiency by wheat was increased by CO2 enrichment. From a practical point of view, the study indicates that critical total-N and NO3-N concentrations used to diagnose the N status of wheat will need to be reassessed as global CO2 levels increase. Elevated CO2 may also reduce the protein content of grain and thus the baking quality of hard wheats./wheat/Triticum aestivum/maize/Zea mays0crops/greenhouse/allocation/nutrition/nitrogen/growth analysis/root:shoot ratio/nitrate reductase/C3/C\:Hocking, P.J.//Meyer, C.P.Carbon Dioxide Enrichment Decreases Critical Nitrate and Nitrogen Concentrations in Wheat Journal of Plant Nutrition199114571-584-J. Plant Nut.. Atmospheric carbon dioxide (CO2) levels are increasing,  In a glasshouse experiment with wheat grown at 5 levels of nitrate (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, respectively, for control plants grown at the ambient level of CO2. However, concentrations of NO3-N in the rooting medium required to produce maximum dry matter accumulation by CO2-enriched plants were similar to those of control plants at the three growth stages. Critical concentrations of NO3-N and total-N declined with time in stem bases and leaves of plants grown at both 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./wheat/Triticum aestivum0greenhouse/growth/nitrogen/nutrition/growth stages\<Hocking, P.J.//Meyer, C.P.Responses of Noogoora Burr (Xanthium occidentale Bertol.) to Nitrogen Supply and Carbon Dioxide Enrichment Annals of Botany198555835-844-Ann. Bot.. We studied the responses of Xanthium occidentale (Bertol.) (cocklebur or Noogoora burr), a noxious weed, to atmospheric 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 increment in dry matter was distributed equally between leaves and roots so that there was little effect on shoot-to-root dry-weight ratios. Growth was stimulated greatly by N and plateaued at 12 mM supplied N. Shoot-to-root dry-weight and total N ratios increased with increasing N supply. CO2 enrichment had no effect on the total amount of N accumulated by plants, but increased 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 plants. NO3 was a major form of N in xylem sap from detopped plants at low supplied NO3-N, but amino N was equal in importance at high supplied NO3-N in control and enriched plants. Concentrations of NO3 were lower in the xylem sap of CO2 enriched 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./Xanthium occidentale/cocklebur0greenhouse/nitrogen/nutrition/growth/allocation/root:shoot ratio\z7 K     =Hoddinott, J.//Jolliffe, P.The Influence of Elevated Carbon Dioxide Concentrations on the Partitioning of Carbon in Source Leaves of Phaseolus vulgaris Canadian Journal of Botany1988662396-2401-Can. J. Bot.. Plants may alter their growth pattern in response to being grown in elevated CO2 concentrations. The nature of the change 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 concentration on plant height, leaf area, or dry weight, but the specific leaf weight increased significantly with the CO2 concentration, indicating a denser leaf structure. The starch content of the leaves also increased significantly as the CO2 level increased. A primary leaf was pulse labelled with 14-CO2 and the depletion of label from that source leaf was monitored with a GM tube. The depletion of the count rate with time was described by a nonlinear curve fitting procedure that allowed the 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 export and storage were reduced in the dark at all CO2 levels, with an increase in the residence time of carbon in the export pool. Reducing the CO2 concentration around the source leaf just after labelling did not change carbon partitioning compared 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./Phaseolus vulgaris/bean014C/carbohydrates/assimilate partitioning/remobilization/carbon budget\R    >Hogan, K.P.//Smith, A.P.//Ziska, L.H.Potential Effects of Elevated CO2 and Changes in Temperature on Tropical Plants Plant, Cell and Environment199114763-778-Plant Cell Environ.. Very little attention has been directed at the responses of tropical plants to increases in global atmospheric CO2 concentrations and the potential climatic changes. The available data, from greenhouse and laboratory studies, indicate that the photosynthesis, growth and water use efficiency of tropical plants can increase at higher CO2 concentrations. However, under field conditions abiotic (light, water or nutrients) or biotic (competition or herbivory) factors might limit these responses. In general, elevated atmospheric CO2 concentrations seem to increase plant tolerance to stress, including low 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 than are temperate plants, so expected changes in temperature might be relatively more important in the tropics. Reduced transpiration due to decreased stomatal conductance could modify the effects of water stress as a cue for vegetative or reproductive 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.0review/tropical plants/environmental interactions/temperature/species range/phenology/allocation/herbivory/soil microorganisms/population level CO2 responses/community level CO2 responses\?Hollinger, D.Y.Gas Exchange and Dry Matter Allocation Responses to Elevation of Atmospheric CO2 Concentration in Seedlings of Three Tree Species Tree Physiology19873193-202-Tree Physiol.. Photosynthetic rates of 13-month-old Pinus radiata D. Don, Nothofagus fusca (Hook f.) Orst. and Pseudotsuga menziesii (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 grown in ambient and elevated concentrations of CO2 had similar rates of photosynthesis when measured at 620 uL/L CO2, but when 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./Pinus radiata/Nothofagus fusca/Pseudotsuga menziesii/Monterey pine/New Zealand red beech/Douglas-fir0trees/controlled environment chambers/allocation/leaf photosynthesis/photosynthetic acclimation/VPD/conductance\     $ 9     @Houghton, R.A.Biotic Changes Consistent with the Increased Seasonal Amplitude of Atmospheric CO2 Concentrations Journal of Geophysical Research1987924223-4230-J. Geophys. Res.. Monthly estimates of gross primary production (gross uptake of CO2 by plants) and ecosystem respiration (gross release of CO2 from the ecosystem) in an oak-pine forest in the northeastern United States were used in this study to examine the types of metabolic changes in terrestrial systems that might yield the increased seasonal amplitude of CO2 concentrations observed at several monitoring stations in recent years. In this study, increases in either photosynthesis or respiration increased the amplitude of the seasonal oscillation of CO2 concentrations if the increases were predominantly in the northern hemispheric summer and winter, respectively. The quantitative changes in metabolism required to produce the observed 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.0ecosystem level CO2 responses/respiration/modeling/forest/net primary productivity/CO2 seasonal flux/terrestrial metabolism/biosphere level CO2 responses\AHoughton, R.A.Terrestrial Metabolism and Atmospheric CO2 Concentrations BioScience198737672-678-BioSci.0review/terrestrial metabolism/CO2 seasonal flux/ecosystem level CO2 responses/net primary production/respiration/modeling/biosphere level CO2 responses\BHoupis, J.L.J.//Surano, K.A.//Cowles, S.//Shinn, J.H.Chlorophyll and Carotenoid Concentrations in Two Varieties of Pinus ponderosa Seedlings Subjected to Long-term Elevated Carbon Dioxide Tree Physiology19884187-193-Tree Physiol.. 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 both varieties showed  symptoms of stress including mottling, mid-needle abscission and early senescence. In both varieties, exposure to CO2 concentrations greater than ambient + 75 uL/L resulted in lower chlorophyll a, chlorophyll b and carotenoid concentrations. At ele vated 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. ponde rosa varieties were lower than those in current-season needles./Pinus ponderosa/ponderosa pine0open top chambers/trees/senescence/pigments\ t    T  `        CHoupis, J.L.J.//Surano, K.A.//Daley, P.F.//Shinn, J.H.Growth and Morphology of Pinus ponderosa Seedlings Exposed to Long-term Elevated Atmospheric Carbon Dioxide Concentration Proceedings of the Ninth North American Forest Biology Workshop1986 June 15-18Stillwater, OklahomaSociety of American Foresters, and Department of Forestry, Oklahoma State University198619-26!Tauer, C.G./Hennessey, T.C."eds.. The growth and morphology of two varieties of Pinus ponderosa were measured after two years of continuous fumigation with carbon dioxide. After two years of treatment, the seedlings of the Rocky Mountain variety showed no significant difference 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 quite different, with those at +150 ppm and +300 ppm significantly greater in height than those at +75 ppm and those at +150 ppm 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 significantly 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./ponderosa pine/Pinus ponderosa0open top chambers/trees/growth/morphology/leaf area development\RR a   EHrubec, T.C.//Robinson, J.M.//Donaldson, R.P.Effects of CO2 Enrichment and Carbohydrate Content on the Dark Respiration of Soybeans Plant Physiology198579684-689-Plant Physiol.. During the period of most active leaf expansion, the foliar dark respiration rate of soybeans (Glycine max cv Williams), grown for 2 weeks in 1000 microliters CO2 per liter air, was 1.45 milligrams CO2 evolved per hour leaf density thickness, 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 plants. For example, leaves of enriched plants displayed levels of nonstructural carbohydrate equivalent to 174 milligrams glucose 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 strong positive correlation between respiration rate and carbohydrate content was seen in high CO2 adapted plants, but not in 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 activities 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 adaptations 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./Glycine max/soybean0controlled environment chambers/respiration/enzymes/carbohydrates/leaf area development/growth\z $ Q U / 0 FHuerta, A.J.//Ting, I.P.Effects of Various Levels of CO2 on the Induction of Crassulacean Acid Metabolism in Portulacaria afra (L.) Jacq. Plant Physiology198888183-188-Plant Physiol.. In response to water stress, Portulacaria afra (L.) Jacq. (Portulacaceae) shifts its photosynthetic carbon metabolism from the Calvin-Benson cycle for CO2 fixation (C3) photosynthesis or Crassulacean acid metabolism (CAM)-cycling, during which organic acids fluctuate with a C3-type of gas exchange, to CAM. During the CAM induction, various attributes of CAM appear, such as stomatal closure during the day, increase in diurnal fluctuation of organic acids, and an increase in phosphoenolpyruvate carboxylase activity. It was hypothesized th at stomatal closure due to water stress may induce changes in 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 experiment were subjected to low (40 ppm), normal (ca. 330 ppm), and high (950 ppm) CO2 during the day with normal concentrations of CO2 during the night for 16 days. In water-stressed and in well-w"atered plants, CAM induction as ascertained by fluctuation of total titratable acidity, fluctuation of malic acid, stomatal conductance, CO2 uptake, and phosphoenolpyruvate carboxylase activity, remained unaffected by low, normal or high CO2 treatment#s. In well-watered plants, however, both low and high ambient concentrations of CO2 tended to reduce organic acid concentrations, low concentrations of CO2 reducing the organic acids more than high CO2. It was concluded that exposing the plants to t$he 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./Portulacaria afra0sunli%t controlled environment chambers/CAM/water stress/phosphoenolpyruvate carboxylase/metabolites/leaf photosynthesis/conductance\zn    C F &GHunt, R.//Hand, D.W.//Hannah, M.A.//Neal, A.M.Response to CO2 Enrichment in 27 Herbaceous Species Functional Ecology19915410-421-Funct. Ecol.. CO2-enrichment experiments were performed on 25 British native species of widely dif(fering ecology. Two crops, one C3 (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 q*uotient of present yield 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./Agrostis capillaris/Arrhenatherum elatius/Brachypodium pinnatum/Bromus erectus/Bromus sterilis/Cerastium fontanum/Chamerion angustifolium/Ch.enopodium album/Dactylis glomerata/Deschampsia flexuosa /Desmazeria rigida/Digitalis purpurea/Epilobium hirsutum/Festuca ovina/Festuca rubra/Helianthemum nummularium/Holcus lanatus/Koeleria macrantha/Plantago lanceolata/Poa annua/Poa trivialis/Rumex a/cetosella /Urtica dioica/Zea mays/Lolium perenne/Helianthus annuus/Eriophorum vaginatum0sunlit controlled environment chambers/plant strategies/growth/species competition/modeling\*  HIdso, S.B.The Aerial Fertilization Effect of CO2 and Its Implications for Global Carbon Cycling and Maximum Greenhouse Warming Bulletin of the American Meteorological Society199172962-965-Bull. Amer. Meteorol. Soc./Citrus auranti1um0open-top chambers/trees/growth/CO2 seasonal flux/biosphere level CO2 responses/temperature/carbon cycle\LIdso, S.B.Industrial Age Leading to the Greening of the Earth? Nature198632022-Nature0CO2 seasonal flux/temperature/biosphere level CO2 responses\OIdso, S.B.Three Phases of Plant Response to Atmospheric CO2 Enrichment Plant Physiology1988875-7-Plant Physiol.. Several years of research on seven different plants (five terrestrial and two aquatic species) suggest that the be4neficial effects of atmospheric CO2 enrichment may be divided into three distinct growth response phases. First is a well-watered optimum-growth-rate phase where a 300 parts per million increase in the CO2 content of the air generally increases plant5 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 normally indic6ative of impending death, where atmospheric CO2 enrichment may actually prevent plants from succumbing to the rigors of the environment and enable them to maintain essential life processes, as life ebbs from corresponding ambient-treatment plants./Ag7ave vilmoriniana/Daucus carota/carrot/cotton/Gossypium hirsutum/radish/Raphanus sativus/soybean/Glycine max/water fern/Azolla pinnata/water hyacinth/Eichhornia crassipes0open-top chambers/growth/aquatic plants/water stress\PIdso, S.B.Three Stages of Plant Response to Atmospheric CO2 Enrichment Plant Physiology and Biochemistry198927131-134-Plant Physiol. Biochem.. Weekly assessments of biomass production in water hyacinths (Eichhornia crassipes) a9nd daily assessments of new-leaf production in water lilies (Nymphaea marliac carnea) demonstrate that the positive effects of atmospheric CO2 enrichment on the growth rates of these plants are considerably greater both before (I) and after (III) the :primary maximum-growth-rate stage (II) characteristic of the middle portion of a plants' life cycle. For these two particular aquatic macrophytes, 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./Eichhornia crassipes/water hyacinth/water lily/Nymphaea marliac0open-top chambers/aquatic plants/growth\R  ( <? IIdso, S.B.Carbon Dioxide, Soil Moisture, and Future Crop Production Soil Science1989147305-307-Soil Sci.. Model simulations of the effects of increases in atmospheric carbon dioxide on air temperature, precipitation, and soil m>oisture suggest that the resultant "greenhouse effect" will be bad for agriculture. Experimental evidence, however, indicates otherwise, demonstrating that plants can more than compensate for the predicted adverse climatic changes. Indeed, recent ev?idence from around the globe suggests that a carbon-dioxide-induced stimulation of the biosphere is already in progress.0review/climate change/modeling/simulation/WUE/agriculture\MIdso, S.B. In Interactive Effects of Carbon Dioxide and Climate Variables on Plant GrowthMadison, WisconsinAmerican Society of Agronomy1990ASA Special Publication No. 53#Impact of Carbon Dioxide, Trace Gases, and Climate Change oAn Global Agriculture. The climate variables predicted to experience major modification as a result of future increases in atmospheric CO2 and other radiatively active trace gases are temperature and precipitation. Predicted changes in these two paBrameters should intensify the hydrologic cycle over the globe, but could produce opposite trends in certain regions. A "worst-case" scenario of consequent local reductions in summer soil moisture is evaluated in terms of the beneficial effects of atmCospheric CO2 enrichment on plant water use efficiency and the interactive effect of air temperature increase on the growth-enhancing effects of atmospheric CO2 enrichment. It is demonstrated that the direct biological impacts of concomitant increasesD in CO2 and air temperature are probably sufficient to offset the adverse effects of summer soil moisture reductions predicted by state-of-the-art climate/water balance models. It is also noted that the worst-case climate scenario is unrealistic. CoEnsequently, plant growth the world over should be significantly stimulated by atmospheric CO2 enrichment, a phenomenon that many people feel is already evident in a number of ecological indicators.0WUE/temperature/water stress/leaf photosynthesis/envFironmental interactions/hydrologic model/growth/climate change\KIdso, S.B.A General Relationship between CO2-induced Increases in Net Photosynthesis and Concomitant Reductions in Stomatal Conductance Environmental and Experimental Botany199131381-383-Environ. Exp. Bot.. Simultaneous measureHments of net photosynthesis and stomatal conductance of leaves of sour orange trees growing in normal and CO2-enriched air, together with similar data for cotton, soybeans and water hyacinth, suggest that a plant's photosynthetic response to atmospherIic CO2 enrichment is inversely proportional to its degree of CO2-induced stomatal closure./Citrus aurantium/sour orange0open-top chambers/trees/leaf photosynthesis/conductance\JIdso, S.B.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. Tellus199143B338-K341-Tellus0CO2 seasonal flux/biotic growth factor/rhizosphere\QIdso, S.B.//Allen, S.G.//Anderson, M.G.//Kimball, B.A.Atmospheric CO2 Enrichment Enhances Survival of Azolla at High Temperatures Environmental and Experimental Botany198929337-341-Environ. Exp. Bot.. In 2 years of experimentatMion with Azolla pinnata var. pinnata at Phoenix, Arizona, growth rates of this floating aquatic fern first decreased, then stagnated, and finally became negative when the mean air temperature rose above 30C. When the atmospheric CO2 content above thNe plants was increased from the mean ambient concentration of 340 umol CO2/mol air to 640 umol CO2/mol air, however, the debilitating effects of high temperatures were reduced: in one case to a much less severe negative growth rate, in another case toO merely a short period of zero growth rate, and in a third case to no discernible ill effects whatsoever -- in spite of the fact that the ambient treatment plants in this instance all died. With the double verification of this phenomenon provided by Pboth weekly biomass and periodic net photosynthesis determinations, it would appear that atmospheric CO2 enrichment may be capable of preventing the deaths of some plant species in situations where their demise is normally brought about by either the Qdirect effects of unduly high temperatures or by associated debilitating diseases./Azolla pinnata/water fern0open-top chambers/aquatic plants/temperature/canopy photosynthesis\zg m  R   SIdso, S.B.//Clawson, K.L.//Anderson, M.G.Foliage Temperature: Effects of Environmental Factors with Implications for Plant Water Stress Assessment and the CO2/Climate Connection Water Resources Research1986221702-1706-Water ResourTces Res.. Throughout the summer and fall of 1985, several day-long sets of foliage temperature measurements were obtained for healthy and potentially transpiring water hyacinth, cotton, and alfalfa plants growing in a sealed and unventilated greenhUouse 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 obtained out Vof doors under natural conditions, while dead, nontranspiring stands of alfalfa and water hyacinth were also monitored, both out of doors and within the greenhouse. Analyses of the data revealed that plant nonwater-stressed baselines, i.e., plots of Wfoliage-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 setXs, and (2) that these baselines are accurately described by basic theory, utilizing independently measured values of plant foliage and aerodynamic resistances to water vapor transport. These findings lead to some slight adjustments in the procedure fYor calculating the Idso-Jackson plant water stress index and they suggest that plants can adequately respond to much greater atmospheric demands for evaporation than what has been believed possible in the past. In addition, they demonstrate that the Zlikely net radiation enhancement due to a doubling of the atmospheric carbon dioxide concentration will have little direct effect on vegetation temperatures, but that the antitranspirant effect of atmospheric CO2 enrichment on foliage temperature may [be substantial./water hyacinth/Eichhornia crassipes/cotton/Gossypium hirsutum/alfalfa/Medicago sativa0crops/aquatic plants/temperature/transpiration/conductance/VPD\[Idso, S.B.//Kimball, B.A.Effects of Two and a Half Years of Atmospheric CO2 Enrichment on the Root Density Distribution of Three-year-old Sour Orange Trees Agricultural and Forest Meteorology199155345-349-Agric. For. Meteorol.. ] 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 enhan_cement 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./Citrus aurantium/sour orange0trees/open-top `chambers/roots/growth\_Idso, S.B.//Kimball, B.A.Growth Response of Carrot and Radish to Atmospheric CO2 Enrichment Environmental and Experimental Botany198929135-139-Environ. Exp. Bot.. Seven crops of carrots and 11 crops of radishes were grown from bseed in open-top, clear-plastic-wall, CO2-enrichment chambers throughout the entire year at Phoenix, AZ. Cumulative dry matter production at weekly intervals was significantly increased by a 300 ppm increase in the CO2 content of the air at all tempecratures encountered, but with progressively greater effects being registered at higher and higher temperatures. At 25C, the productivity enhancement factor for radish was about 1.5, while for carrot it was approximately 2.0. When regressed upon aird temperature, the productivity enhancement factors of both species decreased to a null value of 1.0 in the vicinity of 12C. The slope of the carrot relationship was nearly 250% greater than that of the radish relationship./carrot/Daucus carota/radiesh/Raphanus sativus0open-top chambers/growth/temperature/crops\RIdso, S.B.//Allen, S.G.//Kimball, B.A.Growth Response of Water Lily to Atmospheric CO2 Enrichment Aquatic Botany19903787-92-Aquat. Bot.. Hardy water lilies (Nymphaea cultivar 'Marliacea carnea') were grown out-of-doors at Phoengix, Arizona in sunken metal stock tanks located within open-top, clear plastic-wall, CO2-enrichment chambers; two were maintained at a CO2 concentration of 650 ppm and two were maintained at the ambient CO2 concentration of about 350 ppm. Over a 5-mohnth period, 25 different plant properties were evaluated, each one of which showed some degree of stimulation or enhancement under CO2-enriched conditions. In particular, net photosynthesis was increased by about 49%, leaf size by 18%, and integrated ileaf number x life span by 16%, which resulted in a whole-plant biomass enhancement of 270%. After 21 months, differences between treatments were not quite as dramatic; but at the conclusion of the experiment, the rhizomes in the CO2-enriched treatmejnt were still more than two-and-a-half times greater in total biomass than their ambient-grown counterparts./water lily/Nymphaea0open-top chambers/aquatic plants/growth/allocation/leaf area development\*  XIdso, S.B.//Kimball, B.A.Downward Regulation of Photosynthesis and Growth at High CO2 Levels Plant Physiology199196990-992-Plant Physiol.. Numerous photosynthesis and growth measurements of sour orange (Citrus aurantium L.) treles 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 ymears. 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./sour orange/Citrus aurantiunm0open-top chambers/trees/growth\*  `Idso, S.B.//Kimball, B.A.//Allen, S.G.Net Photosynthesis of Sour Orange Trees Maintained in Atmospheres of Ambient and Elevated CO2 Concentration Agricultural and Forest Meteorology19915495-101-Agric. For. Meteorol.. Eight sour porange 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 the trees have been continuously supplied with a qCO2-enriched atmosphere consisting of an extra 300 cm3 of CO2 per m3 of air. Data from a comprehensive inventory of all above-ground plant parts at the conclusion of two full years of growth under these conditions have revealed that the net effect ofr the CO2-enriched air was to more than double the normal production of biomass over the time interval. Here we report net photosynthesis measurements made throughout the last summer of the period, which suggest that the primary impetus for this larges growth response was an equivalent enhancement of the net photosynthetic rates of the CO2-enriched trees./sour orange/Citrus aurantium0open-top chambers/trees/photosynthesis/growth\WIdso, S.B.//Kimball, B.A.//Allen, S.G.CO2 Enrichment of Sour Orange Trees: 2.5 Years into a Long-term Experiment Plant, Cell and Environment199114351-353-Plant Cell Environ.. Eight sour orange trees have been grown from seedlinug 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 havlf 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 wambient-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 volxume. 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 ambiyent-treatment trees after 2 full years of growth./sour orange/Citrus aurantium0open-top chambers/trees/growth\TIdso, S.B.//Kimball, B.A.//Anderson, M.G.Atmospheric CO2 Enrichment of Water Hyacinths: Effects on Transpiration and Water Use Efficiency Water Resources Research1985211787-1790-Water Resources Res.. Open-top clear plastic wall{ chambers enclosing pairs of sunken metal stock tanks, one of each pair of which contained a full cover of water hyacinths, were maintained out-of-doors at Phoenix, Arizona for several weeks during the summer of 1984. One of these chambers represente|d ambient conditions, while the other three were continuously enriched with carbon dioxide to approximate target concentrations of 500, 650, and 900 ppm. During a 4-week period when plant growth was at its maximum, water hyacinth biomass production i}ncreased by 36% for a 300-600 ppm doubling of the atmospheric CO2 content, while water use efficiency, or the biomass produced per unit of water transpired, actually doubled. These results are similar to hat has been observed in several terrestrial p~lants and they indicate the general trend which may be expected to occur as atmospheric CO2 continues to rise in the years ahead./water hyacinth/Eichhornia crassipes0open-top chambers/aquatic plants/transpiration/WUE/growth\]Idso, S.B.//Kimball, B.A.//Anderson, M.G.Foliage Temperature Increases in Water Hyacinth Caused by Atmospheric CO2 Enrichment Archives for Meteorology, Geophysics and Bioclimatology1986Ser. B 36365-370-Arch. Met. Geoph. Biocl..  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./water hyacinth/Eichhornia crassipes0open-top chambers/aquatic plants/temperature/transpiration\YIdso, S.B.//Kimball, B.A.//Anderson, M.G.//Mauney, J.R.Effects of Atmospheric CO2 Enrichment on Plant Growth: the Interactive Role of Air Temperature Agriculture, Ecosystems and Environment1987201-10-Agric. Ecosystems Environ..  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./carrot/Daucus carota/radish/Raphanus sativus/water hyacinth/Eichhornia crassipes/water fern/Azolla pinnata0open-top chambers/aquatic plants/crops/temperature/growth\*  UIdso, S.B.//Kimball, B.A.//Mauney, J.R.Atmospheric Carbon Dioxide Enrichment Effects on Cotton Midday Foliage Temperature: Implications for Plant Water Use and Crop Yield Agronomy Journal198779667-672-Agron. J.. In an experiment designed to determine the likely consequences of the steadily rising carbon dioxide (CO2) concentration of Earth's atmosphere for the foliage temperature, water use, and yield of cotton (Gossypium hirsutum L. var. Deltapine-61) plants, cotton was grown out-of-doors at Phoenix, AZ, in open-top, clear-polyethylene-wall, CO2-enrichment chambers for three summers under mean daylight CO2 concentrations of 340, 500 and 640 umol CO2/mol air on an Avondale clay loam soil [fine-loamy, mixed (calcareous), hyperthermic Anthropic Torrifluvent]. Infrared thermometer measurements of the cotton 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 to produce a 9% reduction in per-unit-leaf-area plant transpiration rate and an 85% increase in crop biomass production, which 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 [Eichornia crassipes (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./cotton/Gossypium hirsutum0open-top chambers/temperature/VPD/crops/WUE/transpiration\R  x  ZIdso, S.B.//Kimball, B.A.//Mauney, J.R.Effects of Atmospheric CO2 Enrichment on Root:Shoot Ratios of Carrots, Radish, Cotton and Soybean Agriculture, Ecosystems and Environment198822293-299-Agric. Ecosystems Environ.. 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./soybean/Glycine max/cotton/Gossypium hirsutum/radish/Raphanus sativus/carrot/Daucus carota0open-top chambers/root:shoot ratio/allocation/crops/growth\VIdso, S.B.//Kimball, B.A.//Mauney, J.R.Atmospheric CO2 Enrichment and Plant Dry Matter Content Agricultural and Forest Meteorology198843171-181-Agric. For. Meteorol.. Fresh and dry plant weights were measured throughout a number of different CO2 enrichment experiments with six terrestrial 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./carrot/Daucus carota/cotton/Gossypium hirsutum/radish/Raphanus sativus/soybean/Glycine max/water fern/Azolla pinnata/water hyacinth/Eichhornia crassipes/Agave vilmoriniana/tomato/Lycopersicon esculentum0review/open-top chambers/dry matter content\^Idso, S.B.//Kimball, B.A.//Anderson, M.G.//Szarek, S.R.Growth Response of a Succulent Plant, Agave vilmoriniana, to Elevated CO2 Plant Physiology198680796-797-Plant Physiol.. Large (about 200 grams dry weight) and small (about 5 grams dry weight) specimens of the leaf succulent Agave vilmoriniana Berger were grown outdoors at Phoenix, Arizona. Potted plants were maintained in open-top chambers constructed with clear, plastic wall material. Four CO2 concentrations of 350, 560, 675, and 885 microliters per liter were used during two growth periods and two water treatments. Small and large plants were grown for 6 months, while a few large plants were grown for 1 year. Wet-treatment plants received water twice weekly, whereas dry-treatment plants received slightly more water than they would under natural conditions. Plant growth rates in all treatments were significantly different between small and large specimens, but not between 6 month and 1 year large plants. Only the dry-treatment plants exhibited statistically different growth rates between the CO2 treatments. This productivity response was equivalent to a 28% and 3-fold increase when mathematically interpolated between CO2 concentrations of 300 and 600 microliters per liter for large and small plants, respectively./Agave vilmoriniana0open-top chambers/growth/growth analysis/water stress/CAM\R^ p  1 bIsrael, D.W.//Jr., T.W. Rufty,//Cure, J.D.Nitrogen and Phosphorus Nutritional Interactions in a CO2 Enriched Environment Journal of Plant Nutrition1990131419-1433-J. Plant Nut.. Nonnodulated soybean plants (Glycine max [L.] Merr. 'Lee') were supplied with nutrient solutions containing growth 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 environments 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 efficiencies 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./soybean/Glycine max0controlled environment chambers/nutrition/growth/nitrogen/phosphorus/allocation/yield\*  dJansen, C.M.//Pot, S.//Lambers, H.The Influence of CO2 Enrichment of the Atmosphere and NaCl on Growth and Metabolism of Urtica dioica L Marcelle, R.//Clijsters, H.//Van Poucke, M. eds. Biological Control of PhotosynthesisDordrecht, The NetherlandsMartinus Nijhoff Publishers1986143-146. Urtica dioica plants were grown at 0 and 25 mM NaCl at two concentrations to determine the effect of CO2 enrichment on their response to NaCl. Their relative growth rate was stimulated by CO2 enrichment, which can be explained by their enhanced photosynthetic rate. The relative growth rate was reduced by NaCl at both CO2 concentrations. This reduction was associated with a reduction of their photosynthetic rate. The leaf area ratio was negatively correlated with the photosynthetic rate and counteracted both the response to CO2 enrichment and to NaCl./Urtica dioica0controlled environment chambers/salt stress/growth analysis/canopy photosynthesis/respiration\R{  8 E eJarvis, P.G.Atmospheric Carbon Dioxide and Forests Philosophical Transactions of the Royal Society, London (Series B)1989324369-392-Phil. Trans. R. Soc. Lond. B.. Knowledge about the effects of the rise in atmospheric CO2 concentration on trees and forest is assessed and, the converse, the possible impact of forests on the atmospheric CO2 concentration is discussed. At the cellular scale, much is known about the role of CO2 as a substrate in photosynthesis, but only little about its role as an activator and regulator. At the leaf scale, the response of CO2 assimilation to CO2 concentration has been described often and is well represented by biochemically based models, but there is inadequate information to parameterize the models of CO2-acclimated leaves. Growth and partitioning to the roots of seedlings and young trees generally increases in response to a doubling in atmospheric CO2 concentration. Experimental results are very variable, because of the differing length of the experiments, the artificial conditions and the artefactual constraints. At larger scales, direct measurements of responses to increase in atmospheric CO2 are impractical but models of canopy processes suggest that significant increases in CO2 assimilation will result from the rise in atmospheric concentration. Inferences from the increase in amplitude of the seasonal oscillation in the global atmospheric CO2 concentration at different latitudes suggest that forest is having a significant impact on the global atmospheric concentration, but it seems unlikely that expansion of the forest resource could effectively reduce the increase in atmospheric CO2.0review/trees/forest/leaf photosynthesis/photosynthetic acclimation/CO2 seasonal flux/carbon sequestering/modeling\fJiao, J.Predicting the Growth Response of Greenhouse Roses to Aerial Environments Based on Carbon Dioxide Exchange StudiesPh.D. DissertationUniversity of Guelph, Canada1989(Dissertation Abstracts Vol. 50:04-B, p.1187. The influence of aerial environment (i.e. irradiance, CO2 concentration, and temperature) on net CO2 exchange of single-stemmed 'Samantha' roses at different stages of flowering shoot development was studied. Photosynthesis and photorespiration in leaves of different ages were similar, except in the young expanding leaves, which had lower net assimilation rates due to their lower leaf conductance and carboxylation efficiency. Long-term CO2 enrichment did not reduce photosynthetic efficiency. Leaf photosynthesis was saturated at 500 umol/m2/s photosynthetically active radiation (PAR). At saturation irradiance and ambient CO2 concentration, photosynthesis and photorespiration of mature leaves were insensitive to temperature change from 15 to 30C. Whole plant net photosynthetic rates were similar on a leaf area basis at different stages of shoot development. Whole plants had higher saturation irradiance (1000 umol/m2/s) but lower net photosynthetic rates than those of single leaves due to mutual shading and respiration of sink organs. Second-order polynomial functions were used to predict whole plant net photosynthesis at various aerial environments. Irradiance, CO2 concentration, and temperature attributed 70%, 20%, and 5%, respectively, to the total variance explained by the model (R2=0.86). The predicted optimal temperatures for whole plant net photosynthesis increased from 19 to 25C with increasing irradiance and CO2 concentration. The Arrhenius equation described dark respiration temperature response well. Although night respiration increased with day-time carbon (C) gain, plant daily growth was still proportional to day-time CO2 assimilation. A whole plant daily growth model was developed by combining a dark respiration model with a day-time C gain model. The use of net CO2 exchange as a nondestructive estimation of biomass production under various irradiance, CO2 concentration, and temperature conditions provided physiological basis of environmental control of plant growth and productivity. The data and models presented can be served as a guideline for setting and controlling the greenhouse environment for rose production./rose/Rosa hybrida0greenhouse/temperature/light/flower production/horticultural crops/leaf photosynthesis/canopy photosynthesis/respiration/modeling/commercial use of CO2/carboxylation efficiency\gJiao, J.//Tsujita, M.J.//Grodzinski, B.Influence of Temperature on Net CO2 Exchange in Roses Canadian Journal of Plant Science199171235-243-Can. J. Plant Sci.. The effect of temperature on net CO2 exchange of source and sink tissues of the flowering shoots and of whole plants was examined using single-stemmed Samantha roses. At all stages of shoot development, the optimal temperature range for whole-plant carbon (C) gain at saturating irradiance and ambient CO2 level was between 20 and 25C, narrower than the temperature range for optimal leaf net photosynthesis. Dark respiration increased more dramatically than photosynthesis with temperatures between 15 and 35C. At 25C, C loss due to respiration from the flower bud at colour bud stage accounted for 45% of the C loss of the flowering shoot. At low irradiance levels (e.g., 200 umol/m2/s) whole-plant net photosynthesis was greater at 16 than at 22C because of a greater reduction in respiration. Lowering the night temperature from 27 to 17C also increased daily C gain due to a reduction in the C lost at night. Whole-plant net photosynthesis of plants grown and measured at enriched (1000 +/- 100 uL/L) CO2 was greater than that of plants grown and measured at ambient (350 +/- 50 uL/L) level at temperatures between 15 and 35C. Furthermore, the optimal temperatures for whole-plant net photosynthesis in CO2 enrichment was higher than at ambient CO2 level./rose/Rosa hybrida0greenhouse/temperature/light/canopy photosynthesis/source-sink balance/modeling/carbon budget/respiration\hJiao, J.//Tsujita, M.J.//Grodzinski, B.Influence of Radiation and CO2 Enrichment on Whole Plant Net CO2 Exchange in Roses Canadian Journal of Plant Science199171245-252-Can. J. Plant Sci.. At three stages of flowering shoot development, varying the irradiance and CO2 levels had a similar effect on the whole-plant net CO2 exchange rate (NCER) of Samantha rose plants. At 22C, the NCER was saturated at 1000 umol/m2/s photosynthetically active radiation (PAR). The duration of the light period was also important in determining daily carbon (C) gain. When roses were exposed to a constant daily radiant energy dose of 17.6 umol/m2 provided either as a 12-h irradiation interval 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 irradiation at the lower photon flux density retained 80% more C. Under saturating irradiance, the net photosynthetic rate at an enriched (1000 uL/L) CO2 level was almost double that at ambient (350 uL/L) CO2. However, plants grown at ambient and enriched CO2 levels had similar whole-plant NCERs when compared at the same assay CO2 level. Under CO2 enrichment the flower stem 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./rose/Rosa hybrida0greenhouse/carbon budget/light/canopy photosynthesis/temperature\iJiao, J.//Tsujita, M.J.//Grodzinski, B.Optimizing Aerial Environments for Greenhouse Rose Production Utilizing Whole-plant Net CO2 Exchange Canadian Journal of Plant Science199171253-261-Can. J. Plant Sci.. A daily growth model was developed for Samantha roses based on nondestructive measurements of whole-plant net CO2 exchange rate (NCER) under various aerial environmental conditions. Irradiance, CO2 concentration, and temperature accounted for 70, 20, and 5%, respectively, of the variance in whole-plant net photosynthesis explainable by a second-order polynomial model (R2=0.86). The predicted optimal temperatures for whole-plant net photosynthesis increased from 19 to 24C with increasing irradiance from 100 to 1200 umol/m2/s and CO2 concentration from 350 to 1500 uL/L. Dark respiration rate increased exponentially with temperature and could be predicted by the Arrhenius equation. Even though respiratory carbon (C) loss at night increased linearly with daytime C gain, daily C gain (delta C) was still proportional to daytime net photosynthesis. The relative contribution of irradiance (100-1200 umol/m2/s), day length (8-16 h), CO2 concentration (350-1500 uL/L), day temperature (15-30C), and night temperature (15-25C) to plant daily growth was 64, 31, 4, 0.3, and 0.7%, respectively./rose/Rosa hybrida0modeling/growth model/greenhouse/environmental interactions/temperature/light/daylength/flower production/horticultural crops/respiration/canopy photosynthesis/carbon budget\kJohnson, R.H.//Lincoln, D.E.Sagebrush and Grasshopper Responses to Atmospheric Carbon Dioxide Concentration Oecologia199084103-110-Oecologia. Seed- and clonally-propagated plants of Big Sagebrush (Artemisia tridentata var. tridentata) were grown under atmospheric carbon dioxide regimes of 270, 350 and 650 uL/L and fed to Melanoplus differentialis and M. sanguinipes grasshoppers. Total shrub biomass significantly increased as carbon dioxide levels increased, as did the weight and area of individual leaves. Plants grown from seed collected in a single population exhibited a 3-5 fold variation in the concentration of leaf volatile mono- and sesquiterpenes, guaianolide sesquiterpene lactones, coumarins and flavones within each CO2 treatment. The concentration of leaf allelochemicals did not differ significantly among CO2 treatments for these seed-propagated plants. Further, when genotypic variation was controlled by vegetative propagation, allelochemical concentrations also did not differ among carbon dioxide treatments. On the other hand, overall leaf nitrogen concentration declined significantly with elevated CO2. Carbon accumulation was seen to dilute leaf nitrogen as the balance of leaf carbon versus nitrogen progressively increased as CO2 growth concentration increased. Grasshopper feeding was highest on sagebrush leaves grown under 270 and 650 uL/L CO2, but varied widely within treatments. Leaf nitrogen concentration was an important positive factor in grasshopper relative growth but had no overall effect on consumption. Potential compensatory consumption by these generalist grasshoppers was apparently limited by the sagebrush allelochemicals. Insects with a greater ability to feed on chemically defended host plants under carbon dioxide enrichment may ultimately consume leaves with a lower nitrogen concentration but the same concentration of allelochemicals. Compensatory feeding may potentially increase the amount of dietary allelochemicals ingested for each unit of nitrogen consumed./Artemisia tridentata/sagebrush0controlled environment chambers/Melanoplus differentialis/Melanoplus sanguinipes/insects/herbivory/allelochemicals/nitrogen\    K d i w pKano, A.Growth Model of Greenhouse Tomatoes with Carbon Dioxide Enrichment: Development and Experimental Tests (Simulation, Modelling)Ph.D. DissertationTexas A&M University1985(Dissertation Abstracts Vol. 46:10-B, p.3272 (147 pp.). 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./tomato/Lycopersicon esculentum0modeling/growth model/greenhouse/light/temperature/growth rate/yield/horticultural crops\rKats, G.//Olszyk, D.M.//Thompson, C.R.Open Top Experimental Chambers for Trees Journal of the Air Pollution Control Association1985351298-1301-JAPCA0open-top chambers/trees/exposure methods\mJolliffe, P.A.//Ehret, D.L.Growth of Bean Plants at Elevated Carbon Dioxide Concentrations Canadian Journal of Botany1985632021-2025-Can. J. Bot.. 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./bean/Phaseolus vulgaris0controlled environment chambers/growth analysis/yield\*  sKaushal, P.//Guehl, J.M.//Aussenac, G.Differential Growth Response to Atmospheric Carbon Dioxide Enrichment in Seedlings of Cedrus atlantica and Pinus nigra ssp. Laricio var. Corsicana Canadian Journal of Forest Research1989191351-1358-Can. J. For. Res.. 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./Cedrus atlantica/Pinus nigra0greenhouse/trees/rhizotron/roots/root:shoot ratio/growth/carbohydrates/allocation/transpiration/WUE/leaf photosynthesis\2}        # 3 @ K V ] c l              tKe, D.//Jr., M.E. Saltveit,Carbon Dioxide-induced Brown Stain Development as Related to Phenolic Metabolism in Iceberg Lettuce Journal of the American Society of Horticultural Science1989114789-794-J. Amer. Soc. Hort. Sci.. 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 (browning of epidermal tissue) and sunken epidermal areas (pitting) a few millimeters in diameter. Pitting occurred in high-CO2 atmospheres at 5C with no increase in phenolic content, but browning did not develop until the tissue had been transferred to air at 25C. Browning developed within several hours of transfer to air and the degree of browning was correlated with the 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 tissue to elevated CO2 increased ionically bound indoleacetic acid (IAA) oxidase activity, but reduced soluble IAA oxidase activity. Application of an aqueous solution of 1.0 mM IAA to the tissue before treatment did not significantly reduce browning. 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