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ARS Home » Southeast Area » Mississippi State, Mississippi » Crop Science Research Laboratory » Genetics and Sustainable Agriculture Research » Research » Publications at this Location » Publication #81694
Title: WATER AND NUTRIENT DEFICITS, CROP YIELDS, AND CLIMATE CHANGE

Author
item REDDY, K - MISSISSIPPI STATE UNIV
item HODGES, H - MISSISSIPPI STATE UNIV
item McKinion, James

Submitted to: World Resources Review
Publication Type: Proceedings
Publication Acceptance Date: 6/30/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: Crops in the latter part of 21st century are expected to grow in a different environment than today. Climate change due to human activity is expected to bring changes in precipitation patterns and temperature, and thus aridity in certain areas. Crop responses to rising carbon dioxide environments have been largely determined in nearly optimum conditions for growth. Here, we report the results from cotton plants grown in naturally-lit chambers in which temperature, carbon dioxide, water, and nutrients were controlled and varied systematically. Photosynthesis and transpiration increased as solar radiation increased. Photosynthesis increased more in high carbon dioxide environments at all radiation levels. In high carbon dioxide environments, the predicted global increase in temperature should result in more photosynthatae production in well watered and fertilized crops. That translated into more growth, but not in all cases. Plants grown in high carbon dioxide environments produced more photosynthates even when water and minerals were less than optimum for growth. Plants grown in high carbon dioxide never completely compensated for lower photosynthesis caused by other environmental factors limiting that process. Similarly, low or lack of reproductive potential of many crops in high temperature environments was also not compensated by additional carbon dioxide.

Technical Abstract: Plant responses to rising CO2 environments have been largely determined in nearly optimum conditions for growth. In many studies, the nature of the experiment allowed only limited or no control of environmental factors other than [CO2]. Here, we report the results from cotton plants grown in naturally lit chambers in which temperature, [CO2], water, and nutrients were controlled and varied systematically. Photosynthesis and transpiration of crop canopies were measured continuously. Both vital processes increased as solar radiation increased. Photosynthesis increased more in high CO2 environments at all radiation levels. Transpiration, on a leaf area basis, was less in a high CO2 environment, but when transpiration of whole canopies was compared, there was no, or only a small effect of high [CO2]. High [CO2] caused more and larger leaves to be produced, compensating for the greater stomatal resistance found in individual leaves. In high CO2 environments, the predicted global increase in temperature should result in more photosynthate production in well watered and fertilized crops. Since reproductive processes are sometime damaged at high temperatures, crops produced primarily for grain or fruit may not benefit from additional growth in high CO2 environment. Crops produced largely for foliage or wood are expected to benefit from high [CO2], even in seasons in which temperatures are above optimum for growth. Plants grown in high CO2 environments produced more photosynthates even when water and nutrients are less than optimum for growth. Plants grown in high [CO2] never completely compensated for lower photosynthesis caused by other environmental factors limiting that process.