High‐Temperature Episodes with Spatial‐Temporal Variation Impacted Middle‐Season Rice Yield in China

Abstract

Core Ideas Quantified high‐temperature intensity, frequency, and duration as HDH index.High‐temperature episodes between booting and flowering increased significantly.High‐temperature episodes had a significant negative effect on rice yield. Booting and flowering stages of rice are most sensitive to high‐temperature episodes. However, the effect of spatial‐temporal characteristics of high‐temperature episodes on booting and flowering stages in the middle‐season rice cropping region of China were less commonly found in the literature. A data analysis of historical climate and rice yield was conducted to characterize the spatial and temporal variability of high‐temperature episodes between booting and flowering stages and their impact on middle‐season rice grain yield in China. Three high‐temperature indices, including high‐temperature hours (HH), high‐temperature intensity (HI), and high‐temperature degree hours (HDH), were developed to quantify the high‐temperature intensity, frequency, and duration based on maximum temperature records of the last 30 yr from 219 stations in the main middle‐season rice cropping area of China. The HH and HI indices between booting and flowering stages increased significantly in all subregions. Especially in the Central China (CC) subregion, high‐temperature episodes were more severe than those in the East China (EC) subregion and Southwest (SW) subregion. The HDH index, considering the duration and intensity of high‐temperature episodes, was required to describe the correlation between high‐temperature episodes and yield variability. Significant negative (p < 0.05) impacts of the variability of high‐temperature episodes on the observed grain yield were found in all subregions. Rice yield would decrease by 113.9 kg ha−1, 19.1 kg ha−1, and 22.2 kg ha−1 with an HDH increase of 1.0°C·d in the EC, CC, and SW subregions, respectively. High‐temperature episodes were detrimental to middle‐season rice production of China.