Researches on contribution rate of rainfall to the yield of spring wheat

A computer model of relationship is established between spring wheat yield，and soil organic matter content，precipitation，air temperature using the data of state farm ，Heilongiiang Province in 40 remaining years，in the way of the plurality normal regression means．The analyzed results show that in the locality conditions，the largest contribution rate of the year rainfall to spring wheat yield is 24kg／hm²·mm；from jointing to florescence stage(brief 50 days)when the precipitation is below 80mm，the largest contribution rate is 45kg／hm²·mm to the spring wheat yield of precipitation；in the milk stage(brief 20 days)when the precipitation is below 10mm，the largest contribution rate of precipitation is 36kg/hm²·mm．