Increased Temperatures Have Dramatic Effects on Growth and Grain Yield of Three Maize Hybrids

Rising temperatures under climate change are projected to have negative impacts on crop growth and production. These conclusions are not based on direct observations but on projected model results. A study conducted comparing normal seasonal temperatures (1980–2010) for Ames, IA, to a normal + 4°C environment with the same water vapor deficit evaluated the impacts of temperature on maize (Zea mays L.) development and production. The rate of phenological development increased at higher temperatures; however, the relationship of leaf collar and leaf tip appearance to growing degree days was the same between temperature regimes. There was no effect on total leaf area or vegetative dry matter production, but grain yields decreased from 84 to 100% because of exposure to high nighttime temperatures and disruption of the pollination process as evidenced by the large reduction in kernels per ear. Projected increases in temperature will negatively affect grain production and threaten food security. National Laboratory for Agriculture and the Environment, 2110 University Blvd., Ames, Iowa 50011. Mention of a specific tradename or product does not imply endorsement or preferential treatment by USDA. USDA is an equal opportunity employer. Core Ideas • Projected Corn Belt temps by the end of the 21st century increase the rate of phenological