[Dynamic identification of double-early rice heat and its spatiotemporal characteristics in Jiangxi Province, China]. / 江西早稻高温热害等级动态判识及时空变化特征.

Constructing evaluation indicator for rice heat damage based on hot weather process (occurring time of hot weather and its duration) can realize the dynamic identification of rice high-temperature heat damage level, which is of great importance to the precisely monitoring, warning and assessment of rice heat. Meteorological, historical disaster and phenological data on double-early rice in Jiangxi Province were integrated to retrieve the historical heat of double-early rice. The dynamic index of high temperature heat injury on early rice based on high temperature weather process was constructed based on K-S distribution fitting test and confidence interval method. The results were verified with reserved independent samples. A rice heat index (M) was calculated, with which rice heat risk was analyzed. The results showed that the starting time and duration of hot weather were key factors affecting the occurrence of rice heat damage, with the effect of starting time greater than the duration. Light, moderate, and severe rice heat for 3-5 d was identified at 10-12, 5-9 and 2-4 d after heading respectively. Similarly, light, moderate and severe rice heat lasting for 6-8 d and >8 d started at 11-18, 8-10, 1-7 d after heading and 12-18, 8-11, 0-7 d after heading respectively. The coincident rate of rice heat damage indicator was 73.7%, and that verified to be identical or one grade different was 89.5%. The linear tendency rate of M from 1981 to 2015 was 0.04·a-1, with abrupt change from low to high around 1999. A high M (>0.18) was mainly found in the middle and the northeast part of the study area. Increasing trends of a high M occurred in the middle, northeast and south of Jiangxi, with tendency rates > 0.04·a-1. In general, the indicators constructed in this study realized the dynamic identification of process-based rice heat. The middle and northeast parts of Jiangxi Province were identified as high risk areas for double-early rice heat.