| By comparative analysis between the accumulated temperature above 0℃ and the yield of winter wheat and spring wheat,and between the accumulated temperature above 10℃ and the yield of corn,it has been shown that there are positive correlations between the accumulated temperature above 0℃ or 10℃ and the yields of winter wheat,spring wheat and corn in both dry farmlands and irrigation farmlands at 95% and 99% significant level,respectively.There is also a positive correlation between the autumn and spring precipitation and the yield of winter wheat in dry farmlands at 90% significant level.The climate warming causes the increase of thermal resource during the growing period of crops,and is propitious to the rise of yield.However,because of the reducing of precipitation,the effect of thermal resource increasing is limited,and the negative influence of climate warming on yield of crops has been displayed in Hedong region. |