Variation in spatial and temporal distribution of chilling injury of rice under climate change in Northeast China

Rice production in Northeast China is critical especially for ensuring long-term food safety in our country. Thus strengthening research on agricultural meteorological disasters under climate change background is needed to avert the disadvantage of future climate change. This study analyzed the trend of change in heat resources based on three meteorological indicators during the May-September rice growth season under climate change. The indicators used included monthly mean temperature, total monthly mean temperature of May to September during 1961?2010 and anomaly of total mean temperature of May to September during 1981 2010 in Northeast China. By using 0.5⁰E × 0.5⁰N lattice data for ground temperature during 1961-2010, 359 grid points of temperature were extracted in the three provinces of Northeastern China. Based on meteorology industry standards of delayed chilling injury of rice in Northeast China (QX/T182-2013), ArcGIS platform and statistical methods were used to regionalize temporal and spatial distributions of rice chilling injury and probability of occurrence of rice chilling injury during 1981?2010 in Northeast China. Comparative analysis was also conducted on the results of chilling injury of rice with records from China Meteorological Disaster Authority (Heilongjiang, Jilin and Liaoning Volume) during 1981-2000 and on news report from the internet period after 2000. The results showed monthly mena temperature (T_5-9) and total monthly mean temperature (∑T_5-9) of May to September from 1960s to 2000s increased markedly, and the areas with T_5-9≥15 ℃ and≥20 ℃, ∑T_5-9≥83 ℃ enlarged too. The anomaly of total mean temperature of May to September (ΔT_5-9) changed to positive gradually from negative. Climate change had significantly improved the quality of heat needed for crop growth, creating favorable conditions for rice production in Northeast China. The analyses showed that under the influence of climate warming, the regional distribution and occurrence frequency of mild, moderate and severe rice chilling injury exhibited significant decreasing trend during 1981-2000. In the 2000s, the mainly areas of rice chilling injury were concentrated in north and southeast Heilongjiang Province and southeast Jilin Province, with occurrence frequency range of 0.1-0.2. The occurrence years and regions of rice chilling injury in Northeast China during 1981-2010 were broadly in line with historical records. Significantly reduction in rice chilling injury induced very favorable conditions for abundant rice harvest in Northeast China in the recent decade. Irrespectively, there was need to pay further attention to rice chilling injury occurrence in localized areas of Northeast China in order to improve local defense measures.