SIMULATION EXPERIMENT OF POSSIBLE EFFECTS OF VARIOUS ARID PERIODS IN SPRING ON WINTER WHEAT IN NORTH CHINA
华北春旱年型对冬小麦影响的模拟试验

The arid periods of 3,5,7,10 and 14 years of winter wheat in spring are simulated by controlled quantitative sprinking irrigation by large moving waterproof canopy to keep out of precipitation.The possible effects of various arid periods in spring on different growing stages and yield of winter wheat are studied.The field experimental results show that with the increase in arid periods,growing rates of root,stem and leaf of winter wheat reduce distinctly;biomass tiller number in spring,total spike number per unit area,grains per spike and weight of thousand grains of winter wheat decrease;spike length of winter wheat becomes shorter,and numbers of unfertilized spike increase.The winter wheat yields in arid periods of 3,5,7,10 and 14 years in spring are cut down by 2\^6,14\^6,22\^1,42 and 47% than the contrast respectively.There are exponential function curve relations between arid degrees in spring and yield of winter wheat.