The heat deficit index depicts the responses of rice yield to climate change in the northeastern three provinces of China

The northeastern three provinces of China (NTPC) is one of the main marketable rice bases in the country, and more than 60 % of marketable Japonica rice is produced in this region. Predicting the potential effects of climate change on rice yields in these provinces is critical because of the high amounts of rice consumption in China. In this study, we conducted correlation and regression analyses of the climate records of 79 meteorological stations and records of rice yields from the years 1960 to 2009 in NTPC. Several variables, which include the monthly mean, anomalies in the minimum and maximum temperatures during the rice-growing season (i.e., May-September) and the accumulated deficit temperature unit (ADU(n-)), which we introduced, were used to fit the rice yield anomalies. The results indicated that the rice yield in the NTPC was more significantly affected by monthly anomalies in ADU(n-) during the growing season than by those in the monthly averages of climatic factors. The ability of ADU(n-) models to explain variability amounted to 59.2, 40.3, 39.8 and 54.1 % of the rice yield in the Heilongjiang, Jilin, and Liaoning provinces, and of the average of the three provinces, respectively. Furthermore, the rice yield response to climate change was simulated, using future climate-change scenarios of the daily mean and minimum temperatures from regional climate models during the years of 2020-2040, and it was shown that the future warming scenario favored rice production in Northeast China that was increased by approximately 1.7 % above the present yield