In order to seek the optimal irrigation scheme for high yield and high water use efficiency (WUE) of winter wheat

and provide theoretical and technical support for water-saving and high-yielding cultivation of winter wheat

supplemental irrigation (SI) experiments were conducted to explore the methods for determining the optimal supplemental irrigation amount at critical growth stages of winter wheat according to water consumption and natural water supply. The experiments were conducted from 2007 to 2015 on the basis of the same water and fertilizer management during the sowing period

and the rain-fed treatment during the growing season (without irrigation during emergence to maturity) was taken as the control. Two factors including time and amount of SI were set. Selected the annual rain-fed treatment and the optimal supplemental irrigation treatments with better grain yield and WUE

and the natural water supply

irrigation capacity and grain yield of these treatments during growth period were analyzed statistically. The results showed that the grain yield was significantly correlated with the main water supply (soil water storage in 0—100 cm soil layer +irrigation amount at sowing) at sowing period and the precipitation in different growth stages under rain-fed conditions

but there was no significant relation between them under the optimal SI conditions. The suitable cumulative water supply from sowing to each critical growth stages for achieving high yield and high WUE was basically stable. Appropriate SI could effectively compensate for the lack of natural water supply at different growth stages. Under suitable water supply conditions at sowing stage

there was a significant quadratic curve relationship between the optimal SI amount and the rain-fed grain yield from emergence to jointing

and there was a significant negative correlation between the above two parameters from emergence to flowering stage. In addition

the volumetric soil water content in 0—20

0—40

0—60

20—40

20—60 cm soil layers were all significantly linearly related to soil water storage in 0—100 cm soil layer at sowing period. It was feasible to predict soil water storage in 0—100 cm soil layer by using 0—40 cm soil water content. 8-year-experimental results showed that the optimum irrigation rate during the whole growth period of winter wheat in Huang-Huai plain was averagely 101.8 mm

ranged from 51.0 to 172.0 mm

and this kind of irrigation rate could achieve high yield (9 000～10 000 kg/hm2) and high WUE (20.3～26.8 kg/hm2/mm) . The data from two experimental sites during 2015—2016 showed that the soil water storage in 0—100 cm soil layer could be predicted by the volumetric soil water content in 0—40 cm soil layers

and the simulated values were consistent with the measured values. Compared with the quota irrigation treatment

on-demand SI treatment not only maintained high grain yield

but also reduced irrigation water by 36.2～57.6 mm

saved water by 20.1%～32.0%

and significantly improved WUE.