Abstract: The conclusions about the“midday rest”of winter wheat were drawn based on the greatamount of field investigations.1.The phenomenon of“midday rest”was not the physiologi-cal characteristic inherent in winter wheat.It was caused by stoma dosing at the middayunder water stress of soil.2.The degree of the stoma closing at the midday depended on thelevel of soil water stress and the intensity of solar radiation.3.The phenomenon of“middayrest”could be avoided through increasing the water content of soil.

Key words: cropping pattern, summer maize, canopy structure, photosynthesis characteristics, grain-filling.