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United States Department of Agriculture

Agricultural Research Service

Title: Rice Growth, Yield and Photosynthetic Responses to Elevated Atmospheric Carbon Dioxide Concentration and Drought

Authors
item Baker, Jeff
item Allen, Leon

Submitted to: Journal of Crop Improvements
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 17, 2003
Publication Date: January 1, 2005
Citation: Baker, J.T., Allen Jr, L.H., 2005. Rice growth, yield and photosynthetic responses to elevated atmospheric carbon dioxide concentration and drought. Journal of Crop Improvements. 13:7-30.

Interpretive Summary: Global climate change involves rising levels of carbon dioxide in the earth's atmosphere and may also result in more drought conditions in some areas of the world. Rice is a major food crop and plays an important role in the global budgets of methane and carbon dioxide. Drought is common in some rainfed rice production systems. In this paper, we summarize results of experiments conducted by the University of Florida and USDA-ARS at Gainesville, FL, USA where the effects and interactions of elevated atmospheric carbon dioxide concentration and periodic drought were examined in relation to grain yield and canopy-scale gas exchanges, specifically photosynthesis, respiration, evapotranspiration and methane emissions. We conclude that in the absence of air temperature increases, future global increases in CO2 should promote rice growth and yield while providing a modest reduction of near 10% in water use and so increase drought avoidance. Photosynthetic rate saturated with respect to CO2 near 500 ppm. Carbon dioxide enrichment significantly increased both canopy net photosynthetic rate (21 to 27%) and water-use efficiency while reducing evapotranspiration by about 10%. This water saving under CO2 enrichment allowed photosynthesis to continue for about one to two days longer during drought in the enriched compared with the ambient CO2 control treatments.

Technical Abstract: In this paper, we summarize results of experiments conducted by the University of Florida and USDA-ARS at Gainesville, FL, USA where the effects of elevated atmospheric carbon dioxide concentration and periodic drought were examined in relation to grain yield and canopy-scale gas exchanges, specifically photosynthesis, respiration, evapotranspiration and methane emissions. We conclude that in the absence of air temperature increases, future global increases in CO2 should promote rice growth and yield while providing a modest reduction of near 10% in water use and so increase drought avoidance. Photosynthetic rate saturated with respect to CO2 near 500 ppm. Carbon dioxide enrichment significantly increased both canopy net photosynthetic rate (21 to 27%) and water-use efficiency while reducing evapotranspiration by about 10%. Reductions in rice respiration following drought and re-watering appeared to be related to reductions in above-ground biomass due to accelerated leaf senescence. When compared at common, near ambient CO2, daytime CO2 enrichment resulted in higher Rd compared with the ambient grown controls. We also detected a rapid and reversible, direct inhibition of Rd with rising chamber CO2 at an air temperature of 28°C. Our results indicate that CO2 can increase methane emissions while paddy water drainage and soil aeration may be a viable mitigation strategy for reducing methane emissions.

Last Modified: 8/27/2014
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