Abstract: We investigated the temporal and spatial variations of climate suitable areas of ratoon rice in Sichuan Basin during 1971 to 2020, aiming to provide a theoretical reference for rice production and coping with climate change in Sichuan. According to the cropping system, the Sichuan Basin could be divided into five rice-planting areas. Based on the daily meteorological data of 106 weather stations from 1971 to 2020, the active accumulated temperature and the duration of safe growing season for ratoon rice were calculated. Subsequently, the Sichuan Basin was divided into climate unsuitable area, climate sub-suitable area, and climate suitable area. Finally, we analyzed the climatic resources and change trend of the five rice-planting areas, as well as the distribution characteristics and evolution trends of the ratoon rice climate suitable areas. The results showed that the safe growing season of ratoon rice in the Sichuan Basin displayed a prolonged trend over the recent 50 years. The active accumulated temperature of safe growing season also increased, with the extension of growing season and the increase of active accumulated temperature being the largest in the agricultural area of the western basin plain. If the latitude shifts northward by 1°, the duration of safe growing season will shorten by 2-7 d and the active accumulated temperature of safe growing season will decrease by 73-170 ℃·d. With an increase of 100 m in altitude, the duration of safe growing season will shorten by 2-6 d and the active accumulated temperature of safe growing season will decrease by 105-187 ℃·d. In summary, the ranges of climate suitable and sub-suitable areas of ratoon rice showed expansion trends in Sichuan Basin, which are manifested in the expansion from south to north and from east to west. Reasonable adjustment of planting system and selection of suitable cultivars are the main measures to improve the utilization rate of climatic resources in rice growing season and enhance the yield and quality of rice in the five rice-planting areas.

Key words: ratoon rice, safe growing season, climate suitability, climate tendency rate, Sichuan Basin