Study of water-demand regulations and water use efficiencies for water-saving rice cultivation patterns

The study of water-demand regulations and water use efficiencies(WUE) under conditions of different water-saving rice cultivation patterns were carried out through the field-scale experiments.The results show that the evapotranspiration of rice or rape reduced by a wide margin,and the water requirement and requirement intensity and coefficient at every stage change greatly with the growth regulation function and the compensation effect on crop of water-saving rice cultivation patterns.Thus,the new water requirement rules of water-saving rice cultivation patterns are formed.Compared with the conventional double cropping rice puttern,the water requirement intensities of the watersaving irrigation pattern of the double cropping rice(WSIPDCR),the flood-drought cultivation pattern of double cropping rice(FDCPDCR),and the water-saving rice cultivation pattern of rice and rape rotation(WSRCPRRR) decrease by 0.76 mm/d,1.15 mm/d and 0.71 mm/d,respectively; The leakage intensities of WSIPDCE,FDCPDCR,and WSRCPRRR decrease by 0.12 mm/d,0.16 mm/d and 0.19 mm/d,respecitively.The WUE of WSIPDC,FDCPDCR,and WSRCPRRR increase by 30.14%,47.95% and 17.81% respectively.