Impact of Extreme Heat on Corn Yield in Main Summer Corn Cultivating Area of China at Present and Under Future Climate Change

Extreme high temperatures may drastically reduce crop yield, especially when occurring during critical growth stages. The risk of future high temperatures may increase under global warming, this raises concerns regarding crop production. China is one of the most important corn production and consumer countries. The main summer corn cultivation region in China was taken as a sample to study the effects of extreme temperature on corn yield at present and in the near future (2021–2050). The determination of extreme high temperature threshold for corn is critical for assessment result. Based on historical observation data, we built a nonlinear regression model between temperature and corn yield, the extreme high temperature threshold of corn was determined as 36.06 °C in the study area. Multi-year average extreme high temperature days of the entire region during 1986–2015 were  5.2 days, the highest values appearing in the Midwestern area. The multi-year average extreme high temperature days increased every additional day could resulted in a 226.62 kg/ha multi-year average corn yield reducing. And over half of the stations, corn yield fluctuations had significant correlations with the number of extreme high temperature days (Nehtd). Nehtd displayed an increasing trend and reached 7.4 days and 11.6 days during 2021–2050 under RCP4.5 and RCP8.5, which could result in corn yield decreased by 9.2% and 27.3%, respectively.