Abstract:

To provide a scientific basis for rice protection against low temperature and continuous rain in Sichuan during different fertility periods, this paper divided Sichuan into six sub-regions based on topographic and climatic characteristics. The study took records of 91 meteorological stations from 1961 to 2020 as the analysis data, and used the linear propensity estimation method and low temperature and continuous rain disaster indicators, to calculate the frequency of disasters, disaster index, and climate propensity rate, and analyze the spatial and temporal distribution characteristics of low temperature and continuous rain disasters. The results are as follows. (1) The frequency of mild, moderate and severe low temperature disasters during the transplanting and tillering stage of rice in Sichuan was 0.38%-27.5%, 0%-57.6% and 0%-75.3%, respectively. Although the frequency of mild low temperature disaster was small, it covered the widest area, followed by moderate low temperature disaster, mainly in the mountainous area of southwest Sichuan, and the high frequency of severe low temperature disaster was only observed in Guang’an and Longchang. (2) The frequency of light, medium and heavy continuous rain disaster was 8.8%-25.5%, 1.4%-8.0% and 0%-11.2% respectively, the frequency of light, medium and heavy continuous rain disaster had a decreasing trend, and the frequency of medium and heavy disasters were the highest in the northern part of the mountainous area in southwest Sichuan. (3) The frequency of low temperature and continuous rain disaster was 0%-26.1%. Low temperature and continuous rain disaster was in the northern part of the mountainous area of southwest Sichuan, the hilly area of southern Sichuan basin, and the mountainous area of Sichuan basin edge. (4) There were 23 stations recorded significantly interannual variations in the number of days of low-temperature and continuous rain disaster from 1961 to 2020. The number of disaster days per decade decreased in the southern part of mountainous area of southwest Sichuan, the mountainous area of Sichuan basin edge, and the shallow hills of central Sichuan basin, while the number of disaster days increased in the remaining areas. The low-temperature and continuous rain disaster in Sichuan decreased in most areas of the province in recent years in rice transplanting to tillering stage, except some stations in the hilly areas in the south of Sichuan basin and the parallel ridge and valley areas of the east of the basin.

Key words: rice planting in Sichuan, transplanting to tillering stage, low temperature and continuous rain, disaster distribution