Heat Stress In Irrigated Maize

Abstract

It is of critical importance to global food security and development that maize cropping systems maintain current levels of productivity under climate change, but our ability to develop targeted adaptation strategies is limited by uncertainty in predictions of crop response to high air temperatures. In this study, a statistical approach was used to identify crop responses to high temperature by controlling for management, location, soil moisture, and crop growth stage in nearly 2,000 yield values from the warmest region of the US Corn Belt. Results suggest that radiation, not temperature, is the most yield-limiting climate variable in irrigated maize production under optimal management. High temperatures during grain-fill impact yield gains from radiation, but yield response to high temperature during grain-fill is modified by prior temperature regime, suggesting mechanisms for thermo-acclimation in maize. Overall, climate explained only a small amount of yield variance relative to management, and slightly optimizing from within the range of current management practices was sufficient to offset any yield losses observed from high temperature. These results support the conclusions of Shaw et al. (2014) that multiple climate variables must be accounted for to accurately describe crop response to high temperatures. Limits to the applicability of econometric/statistical yield projections are discussed. iii