Study of Water-demand Regulations and Water Use Efficiencies of Rice under Condition of Different Water-saving Irrigation Systems

Study of water-demand regulations and water use efficiencies under condition of different irrigation systems of rice were carried out by serial field-scale experiments.The results obtained showed that the third and fourth steps of rice life were the key periods of water-demand.Under Controlling Irrigation system,71% of the total amount of local flood irrigation water would be saved while irrigation water use efficiency was 4.2 times of that of local flood irrigation.It demonstrated that Controlling Irrigation of rice was one of the most productive irrigation systems with sound water-saving effect and high water use efficiency,and thus this irrigation system was suitable to be used in irrigation areas of semiarid zone,especially in those along the Yellow river.