the choice of low temperature disaster to th maize of three provinces in Northeast China was the study aresa, the crop growth model WOFOST was improved appropriately, analysed and tested in regional scale, and achieves the quantitative analysis and dynamic evaluation of low temperature disaster to th maize. The yields simulated under the condition of average temperatur 1961-2006 is the usual standard, the yields simulated under the condition of actual temperature in relevant year, by contrasting those two yields to decide the yield reduce rate. the yield reduce rate and meteorological condition were divided to the standard of serious degree for low temperature disaster. By experiment for numerical simulation, to determine the main meteorological factor and its value for causing the yield reduce, furthermore to determine the evaluation indexes of low temperature disaster. Based on the evaluation indexes, the impact evaluation was carried out in study area, the impact evaluation for disaster including typical years and ages. From the simulation results, the spatial distribution of low temperature disaster is decreasing by degrees from Northeast to Southwest in each decade in recent 50a, but it is different in the areas and grades of low temperature disaster. The evaluation results could be response

Freezing injury is one of the most serious agro鄄meteorological disasters of winter wheat in North China, restricting yield and its suitability. Under the background of climate change, the warming trend in China is significant, especially in winter. However, freezing injury of winter wheat during winter still happened sometimes in Huang鄄Huai Winter Wheat Area (HHWWA) , therefore, identify the spatial and temporal patterns of freezing injury during winter under the background of climate change is very important to defense the freezing injury. In this study, based on the daily temperature data of 47 meteorological stations in HHWWA from 1960 to 2010, the trends of accumulated negative temperature and over鄄wintering durations were analyzed, and spatial and temporal variation of freezing injury during winter in HHWWA were identified, taking the accumulated negative temperature as freezing injury indices. Over the past 50 years, the average absolute values of accumulated negative temperature were ranged from 17.3 to 240.8 益 •d, increased from south to north. Moreover, the accumulated negative temperature decreased at a rate of 1. 8-38. 3益•d per decade from 1961 to 2010, and the higher

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Climate data from seventy鄄one meteorological stations in the soybean planting areas in three provinces of Northeast China (NEC) during 1961 to 2010 were used to calculate the reference crop evapotranspiration using the Penman鄄Monteith formula. Then combined with the revised crop coefficient, soybean water requirement can be obtained during each growth stage. Finally, we calculated the Crop Water Deficit Index (CWDI) by considering cumulative effects of moisture surplus condition during the soybean growing season. and obtained the degree of drought Based on this index and the degree of drought, the characteristics of spatio鄄temporal variation for occurrence frequency and degree of soybean drought in NEC during the study period were analyzed. Result shows that there is a significant spatial variation in the occurrence frequency of soybean drought, which was increased from east to west. Light drought is the most frequent drought, followed by the middle drought and heavy drought during the whole soybean growing season. There could be relatively higher frequency of light drought in the western regions of Heilongjiang Province and the western and southern regions of Liaoning Province. In the western regions of Jilin Province, there is relatively less frequency of light drought, but the frequencies of middle drought and heavy drought are higher. We also found the basic vegetative phase (sowing to branching) experienced

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