我国东北地区玉米冷害风险评估

根据年平均寒积温水平，将东北地区的玉米冷害分成4个区域。在分析各冷害区域年寒积温距平与年减产率关系的基础上，确定东北地区各地无冷害影响年、一般冷害年、严重冷害年的年寒积温距平指标。将危险度、脆弱度和暴露度作为冷害风险的评估因子，建立了冷害风险评估指标体系，并应用层次分析法对各指标赋予权重。建立了冷害危险度与年平均寒积温的回归方程，利用地理因子构建了年平均寒积温空间格点化模型，应用地理信息系统推算东北地区玉米冷害危险度，由危险度、脆弱度和暴露度得到我国东北地区玉米冷害风险指数，并开展风险评估。结果表明:东北地区的玉米冷害风险空间分布呈北侧和南部低、东部中等、西部高，松嫩平原东北部和西北部以及吉林省中北部主要为较高或高风险区，三江平原主要为中等风险区，黑龙江省北部、吉林省东南部和辽宁省主要为较低或低风险区。

Risk Assessment of Maize Chilling Injury in Northeast China

The northeast region is an important maize production area in China. Chilling injury is a main meteorological disaster for maize, and yields of maize decrease over 15% in several serious chilling injury years. A new index of maize chilling injury is established, and the risk of the chilling injury is assessed. Based on previous research, the damage inflicted temperatures in each growing period of maize (including seedling stage, jointing stage, flowering stage and filling stage) are determined. A new chilling injury index of cold accumulated temperature (T_CA for short) is defined, which can quantitatively describe strength of chilling injury, and its value is the difference between damage inflicted temperature and environment temperature. Calculation formulas of daily T_CA, periodical T_CA and annual T_CA are given.According to decadal mean T_CA, four regions of maize chilling injury in Northeast China are divided. Based on the analysis of relationship between annual T_CA anomaly and annual yield reduction rates of the above regions, index of annual T_CA anomaly in Northeast China is classified into 3 types: Chilling injury year but no damage, common damage year and serious damage year. Risks of chilling injury are calculated and regression equations are built. Finally, a model of space grid annual average T_CA is constructed by geographical factors, including the latitude, longitude and altitude, and the probabilities of chilling injury are calculated by application of GIS. The risk index of maize chilling injury is a multiplication of disaster probability, vulnerability and exposure. Therefore, risks of maize chilling injury in Northeast China are assessed. The assessment shows that risks are low in the northern and the southern parts, while high in the western, middle and eastern areas. High risk regions include the northeast and northwest of Songnen Plain and the north center of Jilin Province, middle risk regions include the Sanjiang Plain, and risks are low in the north of Heilongjiang Province, the southeast of Jilin Province and the whole of Liaoning Province. These results may provide guidance for maize chilling injury prevention, loss reduction and planting structure adjustment in Northeast China.