Impact of elevated CO2 and temperature on rice yield and methods of adaptation as evaluated by crop simulation studies

Impact of elevated CO2 and temperature on rice yield in eastern India was simulated by using the ORYZA1 and the INFOCROP rice models. The crop and weather data from 10 different sites, viz., Bhubaneswar, Chinsurah, Cuttack, Faizabad, Jabalpur, Jorhat, Kalyani, Pusa, Raipur and Ranchi, which differed significantly in their geographical and climatological factors, were used in these two models. For every 1 degrees C increase in temperature, ORYZA1 and INFOCROP rice models predicted average yield changes of -7.20 and -6.66%, respectively, at the current level of CO2 (380 ppm). But increases in the CO2 concentration up to 700 ppm led to the average yield increases of about 30.73% by ORYZA1 and 56.37% by INFOCROP rice. When temperature was increased by about +4 degrees C above the ambient level, the differences in the responses by the two models became remarkably small. For the GDFL, GISS and UKMO scenarios, ORYZA1 predicted the yield changes of -7.63, -9.38 and -15.86%, respectively, while INFOCROP predicted changes of -9.02, -11.30 and -21.35%. There were considerable differences in the yield predictions for individual sites, with declining trend for Cuttack and Bhubaneswar but an increasing trend for Jorhat. These differences in yield predictions were mainly attributed to the sterility of rice spikelets at higher temperatures. Results suggest that the limitations on rice yield imposed by high CO2 and temperature can be mitigated, at least in part, by altering the sowing time and the selection of genotypes that possess higher fertility of spikelets at high temperatures. (C) 2007 Elsevier B.V. All rights reserved.