Hot weather event-based characteristics of double-early rice heat risk: A study of Jiangxi province, South China

• Published in: Ecological indicators 2020-06, Vol.113, p.106148, Article 106148
• Main Authors: Yang, Jianying, Huo, Zhiguo, Li, Xiangxiang, Wang, Peijuan, Wu, Dingrong
• Format: Article
• Language: English
• Subjects: Extreme weather process/event; Flowering; Rice heat; Tmax
• ISSN: 1470-160X; 1872-7034
• DOI: 10.1016/j.ecolind.2020.106148

•Rice heat – lead characteristics of hot weather processes/events has been explored.•Particular phenological period severely hit by rice heat was investigated.•Hot weather event-based evaluation of rice heat was constructed.•Spatial-temporal characteristics of rice heat risk was identified in Jiangxi province. Frequent occurrences of extreme hot weather create severe rice heat disasters. Precisely assess rice heat risk based on the identification of the particular period severely hit by hot weather events is of great merit to improve public planning to minimize the deleterious impact of rice heat. In this study, maximum temperature, disaster and phenophase data on rice in Jiangxi province (typical planting area for double early rice in South China) were integrated to represent the historical heat of early double-cropping rice, facilitating the identification of particular period severely hit by historical rice heat and construction of hot weather event-based evaluation level of rice heat. Afterwards, a rice heat index (RHI) were constructed and calculated based on hot weather events and the exact rice growth stage (days before/after flowering, DF). The results showed that (1) Heat disasters occur approximately 15 d before flowering and the DF −5 to 0 was determined to have the highest possibility of rice heat, followed by the DF −10 to −5, with 29.41 and 22.06% of heat disasters starting in each period, respectively. (2) The probability of moderate and light heat damage was more than 80% when 3–5 d of hot weather occurred in the DF −5 to 5, while the probability of moderate and severe heat damage increased to 100% when >5 d of hot weather occurred in this period. More than 80% of >8 d rice heat started in DF −15 to 0, with severe rice heat accounting for approximately 90% in such a period. (3) Severe, moderate and light rice heat for 3–5 d was identified at DF −6 to 3, 4–5 and 6–9, respectively. Similarly, severe, moderate and light rice heat lasting for 6–8 d and >8 d started at DF −6 to 1, 2–5, 6–18 and −7 to −5, −4 to 4, 5–14, respectively. (4) A high RHI was mainly found in the middle and northeastern part of the study area from 1981 to 2015, with the RHI in most stations being greater than 0.25. Increasing trends of a high RHI occurred in the same areas of the RHI belt. Most stations in such areas exhibited slopes >0.15/10a. The results can provide technical and theoretical support for targeted rice heat assessment, and it can also universally applied