Proper Growth Stages and Deficit Degree of Crop Regulated Deficit Irrigation

Crop Regulated Deficit Irrigation (RDI)，based on the crop-water relations，is an irrigation technique with high yield and water use efficiency. The beneficial effect of moderate water deficit was analyzed using the data of field experiments in Shaanxi，Gansu and Xinjiang. It showed that RDI should be applied at the early growth stage. The degree of water deficit can reach 45%～50% of field capacity，which has no bad effect on crop yield and can increase crop water use efficiency obviously. And some problems of RDI were also disscussed.