Study On The Risk Assessment Technology Of Chilling Damage For Corn In Northeast China

This paper was based on 10km*10km data of meteorological factors and corn growth phases, via calculating critical heat indices on every grid, obtained the chilling damage indices on every grid. By experience orthogonal function analysis and wavelet analysis on chilling damage indices, it showed spatial-temporal variation in the regulation and multiple-time-scale characteristics. On the basis of the principle risk analysis, it established indicator system applicable to the Northeast chilling damage, analyzed the variation coefficient of the heat index, the probability of occurrence of chilling damage, production rate risk index, and the performance of disaster resistance respectively. On the basis of above risk analysis, it established Integrated Risk Index, obtained risk indices on every grid in Northeast of China. The primary conclusions were:Chilling damage for corn in Northeast of China has three distribution modes: wholly identical mode, the center of the largest absolute value located at Yanbian state of Jilin province and Mudanjiang of Heilongjiang province, as is the most sensitive area for chilling damage in Northeast of China. Southwest contrary to the northeast mode, the center of the largest absolute value located at Daxing'anling and Xiaoxing'anling , as is another important sensitive area for chilling damage in Northeast of China. Northwest contrary to the southeast mode, the center of the largest absolute value located at the northwest part of Heilongjiang province and Changbai mountain areas in the east part of Jilin province, the cold-warm trend of two areas are reverse, both are the sensitive areas for chilling damage in Northeast of China.Analysis of time coefficients of three spatial distribution modes of corn chilling damage shows: during 1971 and 1976 there was an 8-year period for the first mode passed the test line, during 1963 and 1974 there was a 2-year period for the third mode passed test line.The low-value area of the variation coefficient of the heat index had mainly distributed in the plains, and the middle-value and high-value areas had mainly distributed in the Daxing'anling, Xiaoxing'anling, Changbai Mountain area, Baicheng , Jilin Province sand, the sand and mountain areas, where the variation coefficient is higher than the plains'variation coefficient . The probability of the risk index of general chilling damage had distributed as the following characteristics: the low-value area had mainly distributed in the plains; the middle-value area had mainly distributed in the Changchun, Siping and Liaohe Plain;The high-value area had distributed in the central part of Heilongjiang Province, the Southwest and Eastern part of Jilin Province, where included the Daxin'anling, Xiaoxing'anling, Changbai Mountain area. The high-value area of severe chilling damage mainly located at mountain areas.Yield reduction rate probability of two grades of corn were calculated based on the method of probability and statistic and it demonstrated that high risk regions of slight output reduction mainly were situated in Changchun, Siping and Sanjiang Plain. High risk regions of moderate and severe output reduction were same located in the Changbai Mountain areas.The low risk regions of chilling damage in Northeast area of China for corn mainly included the places that were Jiamusi and Hegang in Sanjiang Plain, most of Songnen Plain and Liaodong Peninsula. Distribution of the moderate risk regions were respectively as follows, and there were Liaohe Plain and Chaoyang in the Liaoning Province, Jilin, Tonghua, Liaoyuan and Baicheng area in the Jilin Province, Heihe, Yicun and Mudanjiang in the Heilongjiang Province. The high risk regions mainly were situated in the Jlin Province including Yanbian State, Baishan, Tonghua and Daxinganling area belonging to Heilongjiang Province.