Development of an irrigation regime for winter wheat to save water resources by avoiding irrigation at anthesis stage

Latest published information is limited on agronomic responses of winter wheat to irrigation quantity and the necessity of irrigation at the anthesis stage. This study was conducted to (1) evaluate winter wheat yield, water use, assimilate redistribution and economic benefit with respect to water input and (2) quantify relationship between water input and yield to develop a standard for withholding irrigation at anthesis. A 4-year long field experiment was conducted to evaluate winter wheat water use, yield formation pathway and farmers' income under three irrigation regimes: rainfed, irrigation at sowing and jointing (SJ-W) and irrigation at sowing, jointing and anthesis (SJA-W). The yield formation pathway was correlated with the water-induced variation in assimilate redistribution and accumulation. Throughout the experimental period, wheat yield was 19-38% lower in rainfed than that under other irrigation treatments. Moreover, SJ-W treatment substantially increased biomass accumulation at anthesis, accelerated assimilate redistribution in vegetative organs and eventually resulted in a similar wheat yield to that of SJA-W. Simultaneously, the SJ-W treatment had lower irrigation water, reduced additional irrigation cost, suppressed yield loss and obtained a similar farmer's net income to the SJA-W treatment. Water-induced variations in yield were determined by irrigation, rainfall and soil water storage. SJ-W plots receiving 204-331 mm water input (rainfall + irrigation) before anthesis and holding 549-587 mm soil water during anthesis stage achieved higher irrigation water use efficiency and yield relative to the rainfed and SJA-W plots. In contrast, water input under rainfed plots exceeded 200 mm before anthesis, limiting yield substantially even when seasonal soil water consumption exceeded 160 mm. Developing a standard for withholding irrigation at the anthesis stage should incorporate 204-331 mm of water input (rainfall + irrigation) before anthesis and 549-587 mm soil water storage at anthesis, which could achieve a high wheat yield and save water resources.