Due to increase in SRD during GPw from 1981 to 2009, yield increased for spring wheat in Zone IV and Zone VI of northwestern China by 1.6% and 1.3%, respectively (Fig. 9). By contrast, yield deceased for winter wheat in Zone I by 1.4%. Due to decrease in SRD,yield increased for winter wheat in Zone V and for spring wheat in Zone VII of western China by 1.0% and 6.2%, respectively; however,deceased for winter wheat in Zone II and Zone III by 3.9% and 7.9%,respectively.