Abstract:

Based on daily maximum temperature data from 96 meteorological stations in Hunan Province during 1961−2025, this study analyzed the spatiotemporal characteristics of high temperature heat damage and evaluated its risk during the heading stage of early rice and middle rice. The results showed that during 1961−2025, the harmful heat accumulation temperature during the heading stage of early rice in Hunan exhibited an insignificant increasing trend, with a climate tendency rate of 55.1℃·d·10y⁻¹. In contrast, both the the number of occurrences and the number of occurrence days of high temperature heat damage showed a significant upward trend, with climate tendency rates of 6.7times·10y⁻¹ and 39.3d·10y⁻¹, respectively. For middle rice, the harmful heat accumulation temperature, the number of occurrences and the number of occurrence days of high temperature heat damage during the heading stage all increased significantly during the study period, with climate tendency rates of 222.8℃·d·10y⁻¹, 10.7times·10y⁻¹, and 88.5d·10y⁻¹, respectively. Spatially, the climatic risk of high temperature heat damage during the heading stage of early and middle rice in Hunan was characterized by higher risk in the east and lower risk in the west, with high−risk areas mainly distributed in Hengyang, Zhuzhou and other regions, and low−risk areas located in southwestern Hunan. These findings clarify the evolution pattern, spatiotemporal distribution characteristics, and climatic risk of high−temperature heat damage during the heading stage of early and middle rice in Hunan, providing important guidance for regional rice meteorological disaster risk management and planting structure adjustment.

Key words: Rice, Heading period, High temperature heat damage, Harmful heat accumulation temperature, Risk assessment