Review on research of irrigation regime and its environmental effect in winter wheat field of North China Plain

The North China Plain known as "China granary"is the main winter wheat producing areas. However,it has been frequently and seriously affected by drought because of monsoon climate,especially winter drought and spring drought have been frequent and serious during recent decades. Making full use of the limited irrigation water resources to guarantee the safety of winter wheat production is a serious challenge for ensuring stable and high yield of winter wheat in the North China Plain. The key to solving this problem is how to make a scientific irrigation management based on the environmental effects. Although many studies have been done on drought and water-saving irrigation systems of winter wheat,there were less comprehensive commentary recently and still a lot of insufficiencies on interactive combinations of irrigation time,irrigation frequency and the environment effects,which have been based on overwintering water and the first springing water,especially for the adverse effects of current climate change and water shortage. This paper reviews the latest researches at home and abroad on the irrigation management systems( sufficient irrigation and deficit irrigation) and the environmental effects of irrigation in the key irrigation periods of winter wheat in the North China Plain. The responses of various developmental stages and physiological processes of winter wheat to water deficit are different. In particular developmental stages,the water deficit is not entirely negative effects,and it might have some adaptive effects on moderating water deficit to a certain extent. Deficit irrigation is through the artificial stage regulation to form state water budget at different developmental stages of winter wheat. Based on the theory of vulnerability and adaptability to drought,winter wheat will adjust its distribution pattern of assimilation to various organs. This process includes the impacts on many aspects: such as the development stages,weather conditions,the soil' s physical,chemical and biological properties,andwinter wheat yield. Eventually winter wheat will achieve the change of passive responses on water deficit. The purpose is to improve the conversion efficiency at each stages of irrigation water- soil water- plant water- photosynthesis- biomass- yield.The key to ensure stable and high yield of winter wheat in the North China Plain with deficit irrigation is to determine the critical water demand period under different environmental conditions. Ove