AS  Vol.5 No.5 , April 2014
Interaction of Carbon Dioxide Enrichment and Soil Moisture on Photosynthesis, Transpiration, and Water Use Efficiency of Soybean

Soybean (Glycine max (L.) Merrill) is one of the most important oil and protein sources in the world. Interactive effect of elevated carbon dioxide (CO2) and soil water availability potentially impact future food security of the world under climate change. A rhizotron growth chamber experiment was conducted to study soil moisture interactions with elevated CO2 on gaseous exchange parameters of soybean under two CO2 concentrations (380 and 800 μmol·mol-1) with three soil moisture levels. Elevated CO2 decreased photosynthetic rate (11.1% and 10.8%), stomatal conductance (40.5% and 36.0%), intercellular CO2 concentration (16.68% and 12.28%), relative intercellular CO2 concentration (17.4% and 11.2%), and transpiration rate (43.6% and 39%) at 42 and 47 DAP. This down-regulation of photosynthesis was probably caused by low leaf nitrogen content and decrease in uptake of nutrients due to decrease in stomatal conductance and transpiration rate. Water use efficiency (WUE) increased under elevated CO2 because increase in total dry weight of plant was greater than that of water use under high CO2 conditions. Plants under normal and high soil moisture levels had significantly higher photosynthetic rate (7% to 16%) favored by optimum soil moisture content and high specific water content of soybean plants. Total dry matter production was significantly high when plants grown under elevated CO2 with normal (74.3% to 137.3%) soil moisture level. Photosynthetic rate was significantly and positively correlated with leaf conductance and intercellular CO2 concentration but WUE was significantly negatively correlated with leaf conductance, intercellular CO2 concentration and transpiration rate. However, the effect of high CO2 on plants depends on availability of nutrients and soil moisture for positive feedback from CO2 enrichment.

Cite this paper: Madhu, M. and Hatfield, J. (2014) Interaction of Carbon Dioxide Enrichment and Soil Moisture on Photosynthesis, Transpiration, and Water Use Efficiency of Soybean. Agricultural Sciences, 5, 410-429. doi: 10.4236/as.2014.55043.

[1]   Singh, G. and Shivakumar, B.G. (2010) The Role of Soybean in Agriculture. In: Singh, B., Ed., The Soybean: Botany, Production and Uses, CAB International, UK, 24-47.

[2]   Mutei, H. (2011) Papel do Brasil no combate a fome no mundo. In: Siqueira, F., Caju, J. and Moreira, M., Eds., Boletim de Pesquisa da Soja, Fundacao MT, Mato Grosso, 45-48.

[3]   Lisar, S.Y.S., Motafakkerazad, R., Hossain, M.M. and Rahman, I.M.M. (2012) Water Stress in Plants: Causes, Effects and Responses. In: Rahman, I.M.M. and Hasegawa, H., Eds., Water Stress, In Tech, Croatia, 1-14.

[4]   Sionit, N., Hellmers, H. and Strain, B.R. (1982) Interaction of Atmospheric CO2 Enrichment and Irradiance on Plant Growth. Agronomy Journal, 74, 721-725.

[5]   Kimball, B.A. (1983) Carbon Dioxide and Agricultural Yield: An Assemblage and Analysis of 430 Prior Observations. Agronomy Journal, 75, 779-788.

[6]   Morison, J.I.L. (1985) Sensitivity of Stomata and Water Use Efficiency to High CO2. Plant, Cell and Environment, 8, 467-474.

[7]   Morison, J.I.L. (1998) Stomatal Response to Increased CO2 Concentration. Journal of Experimental Botany, 49, 443452.

[8]   Cure, J.D. and Acock, B. (1986) Crop Responses to Carbon Dioxide Doubling: A Literature Survey. Agriculture and Forest Meteorology, 38, 127-145.

[9]   Sharma, A. and Sengupta, U.K. (1990) Carbon Dioxide Enrichment Effect on Photosynthesis and Related Enzymes in Vigna Radiate Wilczek. Indian Journal of Plant Physiology, 33, 340-346.

[10]   Eamus, D. (1991) The Interaction of Rising CO2 and Temperatures with Water Use Efficiency. Plant, Cell and the Environment, 14, 843-852.

[11]   Drake, B.G. and Leadley, P.W. (1991) Canopy Photosynthesis of Crops and Native Plant Communities Exposed to Long-Term Elevated CO2. Plant, Cell and the Environment, 14, 853-860.

[12]   Lawlor, D.W. and Mitchell, R.A.C. (1991) The Effect of Increasing CO2 on Crop Photosynthesis and Productivity: A Review of Field Studies. Plant, Cell and Environment, 14, 807-918.

[13]   Stitt, M. (1991) Raising CO2 Level and Their Potential Significance for Carbon Flow in Photosynthetic Cell. Plant, Cell and the Environment, 14, 741-762.

[14]   Sasek, T.W. and Strain, B.R. (1991) Effect of CO2 Enrichment on the Growth and Morphology of a Native and Introduced Honey Suckle Vine. American Journal of Botany, 78, 69-75.

[15]   Bowes, G. (1993) Facing the Inevitable: Plants and Increasing Atmospheric CO2. Annual Review of Plant Physiology, 44, 309-332.

[16]   Idso, K.E. and Idso, S.B. (1994) Plant Responses to Atomspheric CO2 Enrichment in the Face of Environmental Constraint: A Review of the Past 10 Year’s Research. Agriculture and Forest Meteorology, 69, 153-203.

[17]   Sage, R.F. (1994) Acclimation of Photosynthesis to Increasing Atmospheric CO2: The Gas Exchange Perspective. Photosynthesis Research, 39, 351-368.

[18]   Jiang, G.M. (1995) The Impact of Global Increasing CO2 on Plants. Chinese Bulletin of Botany, 12, 1-7.

[19]   Allen, L.H., Kirkham, M.B., Olszyk, D.M. and Whitman, C.E. (1997) Advances in Carbon Dioxide Effects Research. ASA Special Publication N. 61, Madison, 228 p.

[20]   Drake, B.G., Gonzalez-Meler, M.A. and Long, S.P. (1997) More Efficient Plants: A Consequence of Rising Atmospheric CO2? Annual Review of Plant Physiology and Plant Molecular Biology, 48, 609-639.

[21]   Wang, X.L., Xu, S.H. and Liang, H. (1998) The Experimental Study of the Effects of CO2 Concentration Enrichment on Growth, Development and Yield of C3 and C4 Crops. Agricultural Sciences in China, 31, 55-61.

[22]   Das, M., Pal, M., Zaidi, P.H., Raj, A. and Sengupta, U.K. (2000) Growth Response of Mung Bean to Elevated CO2. Indian Journal of Plant Physiology, 5, 137-140.

[23]   Ulman, P., Catsky, J. and Pospisilova, J. (2000) Photosynthetic Traits in Wheat Grown under Decreased and Increased CO2 Concentration, and after Transfer to Natural CO2 Concentration. Biologia Plantarum, 43, 227-237.

[24]   Wu, D.X. and Wang, G.X. (2000) Interaction of CO2 Enrichment and Drought on Growth, Water Use, and Yield of Broad Bean (Vicia faba). Environmental Experimental Botany, 43, 131-139.

[25]   Hui, D F., Luo, Y.Q., Cheng, W.X., Coleman, J.S., Johnson, D.W. and Sims, D.A. (2001) Canopy Radiationand Water-Use Efficiencies as Affected by Elevated CO2. Global Change Biology, 7, 75-91.

[26]   Wu, D.X., Wang, G.X., Bai, Y.F., Liao, J.X. and Ren, H.X. (2002) Responses of Growth and Water Use Efficiency of Spring Wheat to Whole Season CO2 Enrichment and Drought. Acta Botany Sinica, 44, 1477-1483.

[27]   Kimball, B.A., Kobayahi, K. and Bindi, M. (2002) Responses of Agricultural Crops to Free-Air CO2 Enrichment. Advances in Agronomy, 77, 293-368.

[28]   Srivastava, A.C., Khanna, Y.P., Meena, R.C., Pal, M. and Sengupta, U.K. (2002) Diurnal Changes in Photosynthesis, Sugars, and Nitrogen of Wheat and Mungbean Grown under Elevated CO2 Concentration. Photosynthetica, 40, 221225.

[29]   IPCC (2007) Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge University Press, Cambridge.

[30]   Prior, S.A., Runion, G.B., Rogers, H.H. and Arriaga, F.J. (2010) Elevated Atmospheric Carbon Dioxide Effects on Soybean and Sorghum Gas Exchange in Conventional and No Tillage Systems. Journal of Environmental Quality, 39, 596-608.

[31]   IPCC (2001) Climate Change 2001: Impact, Adaptation, and Vulnerability. A Report of Working Group II of the Intergovernmental Panel on Climate Change, 18 p.

[32]   Rosenzweig, C., Iglesias, A., Yang, X.B., Epstein, P.R. and Chivian, E. (2001) Climate Change and Extreme Weather Events; Implications for Food Production, Plant Diseases, and Pests. Global Change and Human Health, 2, 90-104.

[33]   Schneider, S.H. (2001) What is “Dangerous” Climate Change. Nature, 411, 17-19.

[34]   Long, S.P., Ainsworth, E.A., Rogers, A. and Ort, D.R. (2004) Rising Atmospheric Carbon Dioxide: Plants Face the Future. Annual Review of Plant Biology, 55, 591-628.

[35]   Bates, B.C., Kundzewicz, Z.W., Wu, S. and Palutikof, J.P. (2008) Climate Change and Water. Technical Paper of the Intergovernmental Panel on Climate Change, IPCC Secretariat, Geneva.

[36]   Kruijt, B., Witte, J.P.M., Jacos, C.M.J. and Kroon, T. (2008) Effects of Rising Atmospheric CO2 on Evapotranspiration and Soil Moisture: A Practical Approach for the Netherlands. Journal of Hydrology, 349, 257-267.

[37]   Lotze-Campen, H. and Schellnuber, H.J. (2009) Climate Impacts and Adaptation Options in Agriculture: What We Know and What We Don’t Know. Journal für Verbraucherschutz und Lebensmittelsicherheit, 4, 145-150.

[38]   Poorter, H., Berkel, Y.V. and Baxter, R. (1997) The Effects of Elevated CO2 on the Chemical Composition and Construction Costs of Leaves of 27 C3 Species. Plant, Cell and the Environment, 20, 472-482.

[39]   Allen Jr., L.H. and Boote, K.J. (2000) Crop Ecosystem Responses to Climate Change: Soybean. In: Reddy, K.R. and Hodges, H.F., Eds., Climate Change and Global Crop Productivity, CABI Publishing, UK, 133-160.

[40]   Ainsworth, E.A., Davey, P.A., Bernacchi, C.J., Dermody, O.C., Heaton, E.A., Moore, D.J., Morgan, P.B., Naidu, S.L., RA, H.S.Y., Zhu, X.G., Curtis, P.S. and Long, S.P. (2002) A Meta-Analysis of Elevated CO2 Effects on Soybean (Glycine max) Physiology, Growth and Yield. Global Change Biology, 8, 695-709.

[41]   Pickering, N.B., Allen Jr., L.H., Albrecht, S.L., Jones, P., Jones, J.W. and Baker, J.T. (1994) Environmental Plant Chambers: Controls and Measurements Using CR-10T Data Loggers. In: Watson, D.G., Zuzueta, F.S. and Harrison, T.V., Computers in Agriculture: Proceedings of the 5th International Conference, American Society of Agricultural Engineers, St. Joseph, 29-35.

[42]   Reddy, K.R., Kakani, V.G., Zhao, D., Koti, S. and Gao, W. (2004) Interactive Effects of Ultraviolet-B Radiation and Temperature on Cotton Physiology, Growth, Development and Hyperspectral Reflectance. Photochemistry and Photobiology, 79, 416-427.

[43]   Ewert, F., Rodriguez, D., Jamieson, P., Semenov, M.A., Mitchell, R.A.C., Goudriaan, J., Porter, J.R., Kimball, B.A., Pinter, Jr., P.J., Manderscheid, R., Weigel, H.J., Fangmeier, A., Fereres, E. and Villalobos, F. (2002) Effects of Elevated CO2 and Drought on Wheat: Testing Crop Simulation Models for Different Experimental and Climatic Conditions. Agriculture, Ecosystems and Environment, 93, 249-266.

[44]   Amthor, J.S. (2001) Effects of Atmospheric CO2 Concentration on Wheat Yield: Review of Results from Experiments Using Various Approaches to Control CO2 Concentration. Field and Crop Research, 73, 1-34.

[45]   Gifford, R.M. (1979) Growth and Yield of CO2-Enriched Wheat under Water-Limited Conditions. Australian Journal of Plant Physiology, 6, 367-378.

[46]   Kramer, P.J. (1981) Carbon Dioxide Concentration, Photosynthesis, and Dry Matter Production. BioScience, 31, 29-33.

[47]   Pooter, H. (1993) Interspecific Variation in the Growth Response of Plants to an Elevated Ambient CO2 Concentration. Vegetatio, 104-105, 77-97.

[48]   Thompson, G.B. and Woodward, F.J. (1994) Some Influences of CO2 Enrichment, Nitrogen Nutrition and Competition on Grain Yield and Quality in Spring Wheat and Barley. Journal of Experimental Botany, 45, 937-942.

[49]   Ziska, L.H., Weerakoon, W., Namuco, O.S. and Pamplona, R. (1996) The Influence of Nitrogen on the Elevated CO2 Response in Field Grown Rice. Australian Journal of Plant Physiology, 23, 45-52.

[50]   Bunce, J.A. (1998) The Temperature Dependence of the Stimulation of Photosynthesis by Elevated Carbon Dioxide in Wheat and Barley. Journal of Experimental Botany, 49, 1555-1561.

[51]   Pooter, H. (1998) Do Slow-Growing Species and Nutrient-Stressed Plants Respond Relatively Strongly to Elevated CO2? Global Change Biology, 4, 693-697.

[52]   Mo, X.G., Lin, Z.H. and Liu, S.X. (2007) Climate Change Impacts on the Ecohydrological Processes in the Wuding River Basin. Acta Ecologica Sinica, 27, 4999-5007.

[53]   Thomas, A. (2008) Agriculture Irrigation Demand under Present and Future Climate Scenarios in China. Global and Planetary Change, 60, 306-326.

[54]   Cox, P.M., Betts, R.A., Jones, C.D., Spall, S.A. and Totterdell, I.J. (2000) Acceleration of Global Warming Due to Carbon-Cycle Feedbacks in a Coupled Climate Model. Nature, 408, 184-187.

[55]   Hansen, W.J., Sato, M., Ruedy, R., Lacis, A. and Oinas, V. (2000) Global Warming in the Twenty-First Century: An Alternative Scenario. Proceedings of the National Academy of Sciences of the United States of America, 97, 9875-9880.

[56]   Kaspar, T.C., Moorman, T.B. and Logsdon, S.D. (1992) The National Soil Tilth Laboratory and Rhizotron. In: Reetz, H.F., Ed., Roots of Plant Nutrition, Potash and Phosphate Institute, Atlanta, 52-60.

[57]   Klepper, B. and Kaspar, T.C. (1994) Rhizotrons: Their Development and Use in Agricultural Research. Agronomy Journal, 86, 745-753.

[58]   Makino, A. (1994) Biochemistry of C3-Photosynthesis in High CO2. Journal of Plant Research, 107, 79-84.

[59]   Peet, M.M. (1984) CO2 Enrichment of Soybeans. Effects of Leaf/Pod Ratio. Physiologia Plantarum, 60, 38-42.

[60]   Idso, S.B. and Kimball, B.A. (1991). Downward Regulation of Photosynthesis and Growth at High CO2 Levels. No Evidence for Either Phenomenon in Three-Year Study of Sour Orange Trees. Plant Physiology, 96, 990-992.

[61]   Rogers, G.S., Milham, P.J., Thibaud, M.C. and Conroy, J.P. (1996) Interaction between Rising CO2 Concentration and Nitrogen Supply in Cotton. I. Growth and Leaf Nitrogen Concentration. Australian Journal of Plant Physiology, 23, 119-125.

[62]   Moore, B.D., Cheng, S.H., Sims, D. and Seeman, J.R. (1999) The Biochemical and Molecular Basis for Photosynthetic Acclimation to Elevated Atmospheric CO2. Plant, Cell and Environment, 22, 567-582.

[63]   Ainsworth, A.E., Rogers, A., Nelson, R. and Long, S.P. (2004) Testing the “Source-Sink” Hypothesis of Down Regulation of Photosynthesis in Elevated CO2 in the Field with Single Gene Substitution in Glycine max. Agriculture and Forest Meteorology, 122, 85-94.

[64]   Kanemoto, K., Yamashita, Y., Ozawa, T., Imanishi, N., Nguyen, N.T., Suwa, R., Mohapatra, P.K., Kanai, S., Moghaieb, R.E., Ito, J., El-Shemy, H. and Fujita, K. (2009) Photosynthetic Acclimation to Elevated CO2 Is Dependent on N Partitioning and Transpiration in Soybean. Plant Science, 177, 398-403.

[65]   Farage, P.K., McKee, I.F. and Long, S.P. (1998) Does a Low Nitrogen Supply Necessarily Lead to Acclimation of Photosynthesis to Elevated CO2? Plant Physiology, 118, 573-580.

[66]   Conroy, J. and Hocking, P. (1993) Nitrogen Nutrition of C3 Plants at Elevated Atmospheric CO2 Concentrations. Physiologia Plantarum, 89, 570-576.

[67]   Pettersson, R. and McDonald, A.J.S. (1994) Effects of Nitrogen Supply on the Acclimation of Photosynthesis to Elevated CO2. Photosynthesis Research, 39, 389-400.

[68]   Nakano, H., Makino, A. and Mae, T. (1997) The Effect of Elevated Partial Pressures of CO2 on the Relationship between Photosynthetic Capacity and N Content in Rice Leaves. Plant Physiology, 115, 191-198.

[69]   Hocking, P.J. and Meyer, C.P. (1991) CO2 Enrichment Decreases Critical Nitrate and Nitrogen Concentration in Wheat. Journal of Plant Nutrition, 14, 571-584.

[70]   Conroy, J.P. (1992) Influence of Elevated Atmosphere CO2 Concentration on Plant Nutrition. Australian Journal of Botany, 40, 445-456.

[71]   Gifford, R.M., Barrett, D.J. and Lutze, J.L. (2000) The Effect of Elevated CO2 on C:N and C:P Mass Ratio of Plant Tissues. Plant and Soil, 224, 1-14.

[72]   Manderscheid, R., Bender, H.J., Jager, H.J. and Weigel, H.J. (1995) Effect of Season Long CO2 Enrichment on Cereals. II. Nutrient Concentrations and Grain Quality. Agriculture, Ecosystems and Environment, 54, 175-185.

[73]   Cotrufo, M.F., Ineson, P. and Scott, A. (1998) Elevated CO2 Reduces the Nitrogen Concentration of Plant Tissues. Global Change Biology, 4, 43-54.

[74]   Vara Prasad, P.V., Allen Jr., L.H. and Boote, K.J. (2005) Crop Responses to Elevated Carbon Dioxide and Interaction with Temperature—Grain Legumes. Journal of Crop Improvement, 13, 113-155.

[75]   Huber, S.C., Rogers, H.H. and Mowry, F.L. (1984) Effects of Water Stress on Photosynthesis and Carbon Partitioning in Soybean (Glycine max [L.] Merr.) Plants Grown in the Field at Different CO2 Levels. Plant Physiology, 76, 244-249.

[76]   Hesketh, J.D., Woolley, J.T. and Peters, D.B. (1984) Leaf Photosynthetic CO2 Exchange-Rates in Light and CO2 Enriched Environments. Photosynthetica, 18, 536-540.

[77]   Sionit, N., Rogers, H.H., Bingham, G.E. and Strain, B.R. (1984) Photosynthesis and Stomatal Conductance with CO2Enrichment of Container and Field-Grown Soybeans. Agronomy Journal, 76, 447-451

[78]   Chen, X.M., Begonia, G.B., Alm, D.M. and Hesketh, J.D. (1995) Soybean Stomatal Acclimation to Long-Term Exposure to CO2-Enriched Atmospheres. Photosynthetica, 31, 51-57.

[79]   Ferris, R., Wheeler, T.R., Hadley, P. and Ellis, R.H. (1998) Recovery of Photosynthesis after Environmental Stress in Soybean Grown under Elevated CO2. Crop Science, 38, 948-955.

[80]   Ziska, L.H, Bunce, J.A. and Caulfield, F.A. (2001) Rising Atmospheric Carbon Dioxide and Seed Yield of Soybean Genotypes. Crop Science, 41, 385-391.

[81]   Acock, B., Reddy, V.R., Hodges, H.F., Baker, D.N. and McKinion, J.M. (1985) Photosynthetic Response of Soybean Canopies to Full-Season Carbon Dioxide Enrichment. Agronomy Journal, 77, 942-947.

[82]   Allen Jr., L.H., Baker, J.T., and Boote, K.J. (1996) The CO2 Fertilization Effect: Higher Carbohydrate Production and Retention as Biomass and Seed Yield. In: Bazzaz, F. and Sombroek, W., Eds., Global Climate Change and Agricultural Production, FAO, Rome, 65-100.

[83]   Allen Jr., L.H. (1994) Carbon Dioxide Increase: Direct Impacts on Crops and Indirect Effects Mediated through Anticipated Climate Changes. In: Boote, K.J., Bennett, J.M., Sinclair, T.R. and Paulsen, G.M., Eds., Physiology and Determination of Crop Yield, ASA, CSSA and SSSA, Madison, 425-459.

[84]   Van Oosten, J.J. and Besford, R.T. (1995) Some Relationship between the Gas Exchange, Biochemistry and Molecular Biology of Photosynthesis during Leaf Development of Tomato Plants after Transfer to Different Carbon Dioxide Concentrations. Plant, Cell and the Environment, 18, 1253-1266.

[85]   Stitt, M. and Krapp, A. (1999) The Interaction between Elevated Carbon Dioxide and Nitrogen Nutrition: The Physiological and Molecular Background. Plant, Cell and the Environment, 22,583-621.

[86]   Socias, F.X., Medrano, H. and Sharkey, T.D. (1993) Feedback Limitation of Photosynthesis of Phaseolus vulgaris L Grown in Elevated CO2. Plant, Cell and the Environment, 16, 81-86.

[87]   Prasad, P.V.V., Boote, K.J., Vu, J.C.V. and Allen Jr., L.H. (2004) The Carbohydrate Metabolism Enzymes Sucrose-P Synthase and ADG-Pyrophosphorylase in Phaseolus Bean Leaves Are Up-Regulated at Elevated Growth Carbon Dioxide and Temperature. Plant Science, 166, 1565-1573.

[88]   Rodoglou, K.M., Aphalo, P. and Jarvis, P.G. (1992) Response of Photosynthesis, Stomata1 Conductance and Water Use Efficiency to Elevated CO2, and Nutrient Supply in Acclimated Seedlings of Phaseolus valgaris L. Annals of Botany, 70, 257-264.

[89]   Law, B.E., Falge, E., Gu, L., Baldocchi, D.D., Bakwin, P., Berbigier, P., Davis, K., Dolman, A.J., Falk, M., Fuentes, J.D., Goldstein, A., Graanier, A., Grelle, A., Hollinger, D., Janssens, I.A., Jarvis, P., Jensen, N.O., Katul, G., Mahl, Y., Metteucci, G., Meyers, T., Monson, R., Munger, W., Oechel, W., Olson, R., Pilegaard, K., Paw, K.T., Thorgeirsson, H., Valentini, R., Verma, S., Vesala, T., Wilson, K. and Wofsy, S. (2002) Environmental Controls over Carbon Dioxide and Water Vapor Exchange of Terrestrial Vegetation. Agriculture and Forest Meteorology, 113, 97-120.

[90]   Park, Y.-I., Chowa, W.S., Anderson, J.M. and Hurry, V.M. (1996) Differential Acclimated Susceptibility of Photosystem II to Light Stress in Light Assimilated Pea Leaves Depends on the Capacity for Photochemical and Non-Radiactive Dissipation of Light. Plant Science, 115, 137-149.

[91]   Cure, J.D. (1985) Carbon Dioxide Doubling Response: A Crop Survey. In: Strain, B.R. and Cure, J.D., Eds., Direct Effects of Increasing Carbon Dioxide on Vegetation, US Department of Energy, Carbon Dioxide Research Division, Washington DC, 99-116.

[92]   Allen Jr., L.H. (1999) Evapotranspiration Responses of Plant and Crops to Carbon Dioxide and Temperature. Journal of Crop Production, 2, 37-70.

[93]   Clifford, S.C., Stronach, I.M., Black, C.R., Singleton-Jones, P.R., Azam-Ali, S.N. and Crout, N.M.J. (2000) Effects of Elevated CO2, Drought and Temperature on the Water Relations and Gas Exchange of Groundnut (Arachis hypogaea) Stands Grown in Controlled Environment Glasshouses. Physiologia Plantarum, 110, 78-88.

[94]   Wallace, J.S. (2000) Increasing Agricultural Water Use Efficiency to Meet Future Food Production. Agriculture, Ecosystem and Environment, 82,105-119.

[95]   Jones, P., Jones, J.W. and Allen Jr., L.H. (1985) Response of Soybean Canopy Growth, Photosynthesis, and Transpiration to Whole-Day Temperature Changes in Different CO2 Environment. Agronomy Journal, 77, 119-126.

[96]   Rogers, H.H., Cure, J.D., Thomas, J.F. and Smith, J.M. (1984) Influence of Elevated CO2 on Growth of Soybean Plants. Crop Science, 24, 361-366.

[97]   Kimball, B.A., Mauney, J.R., Guinn, G., Nakayama, F.S., Pinter Jr., P.J., Clawson, K.L., Idso, S.B., Butler, G.D. and Radin, J R. (1984) Response of Vegetation to Carbon Dioxide, Ser 023. Effect of Increasing Atmospheric CO2 on the Yield and Water of Crops. US Department of Energy and USDA, US Water Conservation Laboratory and US Western Cotton Research Laboratory, USDA-ARS, Phoenix.

[98]   Jones, P., Jones, J.W. and Allen Jr., L.H. (1985b) Seasonal Canopy CO2 Exchange, Water Use, and Yield Components in Soybean Grown under Different CO2 and Water Stress Conditions. Transactions in American Society of Agricultural Engineers, 28, 2021-2028.

[99]   He, J.X., Wang, J. and Liang, H.J. (1995) Effect of Water Stress on Photochemical Function and Protein Metabolism of Photosystem II in Wheat Leaves. Plant Physiology, 93, 771-777.

[100]   Flagella, Z., Campanile, R.G., Stoppeli, M.C., De Caro, A. and Di Fonzo, N. (1998) Drought Torlance of Photosynthetic Electron Transport under CO2-Enriched and Normal Air in Cereal Species. Plant Physiology, 104, 753-759.

[101]   Boyer, J.S. (1982) Plant Productivity and Environment. Science, 218, 443-448.

[102]   Farquhar, G.D., Wong, S.O., Evans, T.R. and Hubiok, K.T. (1989) Photosynthesis and Gas Exchange. In: Flowers, H.G. and Jones, M.B., Eds., Plant under Stress, Cambridge University Press, Cambridge, 47-67.

[103]   Kaiser, W.M. (1987) Effects of Water Deficit on Photosynthetic Capacity. Physiologia Plantarum, 71, 142-149.

[104]   Yu, G.R., Wang, Q.F. and Zhuang, J. (2004) Modeling the Water Use Efficiency of Soybean and Maize Plants under Environmental Stress: Application of a Synthetic Model of Photosynthesis-Transpiration Based on Stomatal Behavior. Journal of Plant Physiology, 161, 303-318.

[105]   Flexas, J., Barón, M., Bota, J., Ducruet, J., Gallé, A., Galmeés, J., Jiménez, M., Pou, A., Ribas-Carbó, M., Sajnani, C., Tomás, M. and Medrano, H. (2009) Photosynthesis Limitations during Water Stress Acclimation and Recovery in the Drought-Adapted Vitis Hybrid Richter-110 (V. berlandieri × V. rupestri). Journal of Experimental Botany, 60, 23622377.

[106]   Pinheiro, C. and Chaves, M.M. (2011) Photosynthesis and Drought: Can We Make Metabolic Connections from Available Data? Journal of Experimental Botany, 62, 869-882.

[107]   Flexas, J., Ribas-Carbó, M., Bota, J., Galmés, J., Henkle, M., Martínez-Canellas, S. and Medrano, H. (2006) Decrease Rubisco Activity during Water Stress Is Not Induced by Decreased Relative Water Content but Related to Conditions of Low Stomatal Conductance and Chloroplast CO2 Concentration. New Phytology, 172, 73-82.

[108]   Flexas, J., Bota, J., Galmés, J., Medrano, H. and Ribas-Carbó, M. (2006) Keeping a Positive Carbon Balance under Adverse Conditions: Responses of Photosynthesis and Respiration to Water Stress. Physiologia Plantarum, 127, 343352.

[109]   Chaves, M.M., Maroco, J.P. and Pereira, J. (2003) Understanding Plant Responses to Drought from Genes to the Whole Plant. Functional Plant Biology, 30, 239-264.

[110]   Chaves, M.M., Flexas, J. and Pinheiro, C. (2009) Photosynthesis under Drought and Salt Stress: Regulation Mechanisms from Whole Plant to Cell. Annals of Botany, 103, 551-560.

[111]   Grassi, G. and Magnani, F. (2005) Stomatal, Mesophyll Conductance and Biochemical Limitations to Photosynthesis as Affected by Drought and Leaf Ontogeny in Ash and Oak Trees. Plant, Cell and Environment, 28, 834-849.

[112]   Lawlor, D.W. and Cornic, G. (2002) Photosynthetic Carbon Assimilation and Associated Metabolism in Relation to Water Deficits in Higher Plants. Plant, Cell and Environment, 25, 275-294.

[113]   Lawlor, D.W. and Tezara, W. (2009) Causes of Decreased Photosynthetic Rate and Metabolic Capacity in Water-Deficient Leaf Cells: A Critical Evaluation of Mechanisms and Integration of Processes. Annals of Botany, 103, 561-579.

[114]   Lockwood, J.G. (1999) Is Potential Evapotranspiration and Its Relationship with Actual Evapotranspiration Sensitive to Elevated Atmospheric CO2 Levels? Climatic Change, 41, 193-212.

[115]   Brumbelow, K. and Georgakakos, A. (2001) An Assessment of Irrigation Needs and Crop Yield for the United States under Potential Climate Changes. Journal of Geophysical Research: Atmospheres, 106, 27383-27405.

[116]   Ainsworth, E.A. and Long, S.P. (2005) What Have We Learned from 15 Years of Free-Air CO2 Enrichment (FACE)? A Meta-Analytic Review of the Responses of Photosynthesis, Canopy Properties and Plant Production to Rising CO2. New Phytology, 165, 351-372.

[117]   Ainsworth, E.A. and Rogers, A. (2007) The Response of Photosynthesis and Stomatal Conductance to Rising CO2: Mechanisms and Environmental Interactions. Plant, Cell and the Environment, 30, 258-270.

[118]   Long, S.P., Ainsworth, E.A., Leakey, A.D.B., Nosberger, J. and Ort, D.R. (2006) Food for Thought: Lower-Than-Expected Crop Yield Stimulation with Rising CO2 Concentrations. Science, 312, 1918-1921.

[119]   Ainsworth, E.A. (2008) Rice Production in a Changing Climate: A Meta-Analysis of Responses to Elevated Carbon Dioxide and Elevated Ozone Concentration. Global Change Biology, 14, 1642-1650.

[120]   Rogers, A., Fischer, B.U., Bryant, J., Frehner, M., Blum, H., Raines, C.A. and Long, S.P. (1998) Acclimation of Photosynthesis to Elevated CO2 under Low-Nitrogen Nutrition Is Affected by the Capacity for Assimilate Utilization. Perennial Ryegrass under Free Air CO2 Enrichment. Plant Physiology, 118, 683-689.

[121]   Taiz, L. and Zeiger, E. (1998) Plant Physiology. 2nd Edition, Sinauer Associates Publishers, Sunderland, Massachusetts.

[122]   Morison, J.I.L. and Gifford, R.M. (1984) Plant Growth and Water Use with Limited Water Supply in High CO2 Concentrations. I. Leaf Area, Water Use and Transpiration. Australian Journal of Plant Physiology, 11, 361-374.

[123]   Chen, J.J. and Sung, J.M. (1990) Gas Exchange Rate and Yield Responses of Virginia-Type Peanut to Carbon Dioxide Enrichment. Crop Science, 30, 1085-1089.

[124]   Stronach, I.M., Clifford, S.C., Mohamed, A.D., Singleton-Jones, P.R., Azamali, S.N. and Crout, N.M.J. (1994) The Effects of Elevated Carbon Dioxide, Temperature and Soil Moisture on the Water-Use of Stands of Groundnut (Arachis hypogaea L.). Journal of Experimental Botany, 45, 1633-1638.

[125]   Clifford, S.C., Black, C.R., Roberts, J.A., Stronach, I.M., Singleton-Jones, P.R., Mohamed, A.D. and Azamali, S.N. (1995) The Effect of Elevated Atmospheric CO2 and Drought Onstomatal Frequency in Groundnut (Arachis hypogaea L.). Journal of Experimental Botany, 46, 847-852.

[126]   Prasad, P.V.V., Boote, K.J., Allen Jr., L.H. and Thomas, J.M.G. (2002) Effects of Elevated Temperature and Carbon Dioxide on Seed-Set and Yield of Kidney Bean (Phaseolus vulgaris L.). Global Change Biology, 8, 710-721.

[127]   Acevedo, E., Fereres, E., Hsiao, T.C. and Henderson, D.W. (1979) Growth Trends, Water Potentials, and Osmotic Adjustment of Maize and Sorghum Leaves in the Field. Plant Physiology, 64, 476-480.