Change of heat resources and the effects on rice production in the Songliao River Basin

Based on daily temperature data of 177 stations in the Songliao River Basin Basin from 1961 to 2022, the obvious characteristics of climate warming and the effects on rice production were studied using multiple statistic methods and agricultural climate standards. The results show that the mean temperature from May to September increases significantly with the warming rate at 0.25 ℃/10 a in the Songliao River from 1961 to 2022, and an abrupt change occurred in 1995. During 1996-2022, The boundary of suitable rice planting area moves to Man zhouli, Xin baerhu Left Banner, Bo ketu, Elunchun Banner and Sunwu northwestward in the Songliao River Basin. The suitable rice planting area of late maturing variety expands obviously from Liaoning and western Jilin to central Jilin and south western Hei longjiang eastward and northward compared with that 1961-1995. The station occurrence ratio of sterile-type chilling injury at the rice heading and flowering stages showes a slight decreasing trend from 1961 to 2022. After climate warming, the number of stations affected by sterile-type chilling injury at the rice heading and flowering stages decreases by 9.8%, and the chilling injury occurrence frequency generally showes an increasing trend in the northwest and north, and a decreasing trend in the east and south. The occurrence of sterile-type chilling injury is correlated with maturity upgrade, heat change and temperature fluctuation at the rice heading and flowering stages. Maturity type upgrading leads to the increase of the chilling injury occurrence frequency by 7.1% on average. Due to climate warming, the chilling injury occurrence frequency mainly decreases (accounting for 71.5% of stations). In addition, the chilling injury occurrence frequency increases mainly due to the increased coefficient of temperature variation in a small number of stations.