Study On The Monitoring And Evaluation Of Sterile-type Chilling Damage Of Rice In Northeast China

Rice is one of the most important food crops in China.Northeast China is the main production area of rice and Chilling damage often occurs in there.In order to explore the comprehensive monitoring and evaluation method of sterile-type chilling damage and disaster monitoring,the daily mean air temperature data and rice growth stage record date and rice yield data and remote sensing date are used to analyzed the effects of sterile-type chilling damage in 2004-2012 in Northeast China.The main conclusions are as follows:(1)In 2004-2012,the number of counties with the largest rice yield reduction in Northeast China was in 2009,with 50.9% of the counties having different degrees of rice yield reduction,and 100 counties have seen rice yield reduction in 2009;In 2008,23 counties(cities)reduced production,accounting for the lowest proportion(13.3%).In that year,there was no county with severe yield reduction in the whole northeast region.In terms of the spatial distribution of the production reduction counties,the counties with severe production reduction are mainly located in Heilongjiang Province,the number of counties with severe production reduction in Jilin Province is much smaller than that in Heilongjiang Province,The counties in Liaoning Province are mainly moderate and mild production reduction.(2)In the years where the yield reduction degree of rice is more serious than that of counties where the yield reduction degree is more serious,the consistency and judgment rate of the evaluation results based on the industry standard(QX / t182-2013)is higher than that based on the national standard(GB / t34967-2017);In the years when rice yield reduction is relatively low,the evaluation of chilling injury based on national standard(GB / t34967-2017)will be underestimated.Compared with national standard(GB / t34967-2017),industry standard(QX / t182-2013)is more suitable for the monitoring and evaluation of sterile-type chilling damage in Northeast China.(3)The area unsuitable for rice growth decreased gradually and the rice growth-suited area with different maturity showed an expanding trend towards north and east.Among them,the late-maturating rice area showed the most significant increase.The ratio of the stations with sterile-type chilling damage was the largest in the early-maturating rice area,followed by the midseason-maturating rice area and latematurating rice area.The occurrence frequency of sterile-type chilling damage varied greatly among stations and rice growth-suited areas with different maturity.During 1986-1995,1996-2005 and 2006-2015,obvious sterile-type chilling damage mainly occurred in the midseason-maturating,late-maturating and early-maturating rice area,respectively.During 2006-2015,the frequency of sterile-type chilling damage reduced in the midseason-maturating rice area and Slight grade in the late-maturating rice area.It should be noted that sterile-type chilling damage in Northeast China was still uncertain despite the overall decline in frequency,and probably occurred in any area and any year.The fluctuation of steriletype chilling damage led to the increase of its uncertainty.In the context of climate change,the planting system,disaster prevention and relief measures should be reasonably arranged in combination with the characteristics of sterile-type chilling damage occurrences,so as to reduce its impact on rice yield.(4)Base on the maximum drop of NDVI to evaluate the sterile-type chilling damage in 2006,2009 and 2012,the results show that the spatial distribution of the sterile-type chilling damage assessment results is basically consistent with the remote sensing assessment results.It shows that NDVI index is reasonable to evaluate the rice cold disaster in Northeast China.Using the method of natural breakpoint classification to classify the maximum reduction of NDVI,the real damage situation of sterile-type chilling damage in the study area can be presented.