Risk division on winter wheat suffering from spring wet damages in Jiangsu Province
江苏省冬小麦湿渍害的风险区划

Spring wet damage has brought a serious impact to the growth and yield of winter wheat in the southern China. Efficient risk divisions of wet damages shall play an important role on the safe production of winter wheat. In this paper, some meteorological factors such as ten-day precipitation, ten-day sunshine time, and ten-day rainfall days were selected to reflect the characteristic of wet damage occurrence in spring and the data of these factors in all springs of 49 years (from 1960 to 2008) were used to analyze the relationship between them and the climate yield of winter wheat in Jiangsu Province. The results were followed as: (1) In Jiangsu Province, the change of the above factors in the springs have been significantly associating with the fluctuation of the climatic yield. (2) The path analysis showed that the ten-day precipitation and ten-day sunshine time were the two direct factors influencing on the climatic yield of winter wheat but the ten-day rainfall days had indirect impact on it. (3) Q index was used to distinguish the wet years form the years of other types and establish an integrated risk exponential model about the wet damage of winter wheat combined with the occurrence frequency of wet damages and the drop percentage in winter wheat yield. (4)The established risk exponential model were applied to evaluate the risks of winter wheat suffering from wet damage in the different regions of Jiangsu Province and divide the regions of different risk grades. Consequently, some measures of prevention from the wet damage were put forward and it will provide a scientific basis for the prevention from wet disasters and mitigate the loss of the winter wheat production in Jiangsu Province.