Yield response of supplementary irrigation at the anthesis stage of winter wheat

To explore the feasibility of water-saving irrigation measures based on long-term positioning experiments on winter wheat (Triticum aestivum L.) under different irrigation and nitrogen application treatments, the main factors influencing the effect of supplementary irrigation at the anthesis stage on yield increase were explored in Gaocheng and Qingyuan, China. The experiment was designed as a split-plot arrangement, with the irrigation type as the main plot and nitrogen application rate as the sub-plots. The irrigation treatments consisted of two levels based on the amount of irrigation: 60 mm at the jointing stage (W1) and 60 mm at the jointing and anthesis stages, respectively (W2). The nitrogen treatments consisted of three levels: 0 (N0), 120 (N120), and 240 kg ha−1 (N240). Over time, the soil organic matter and total nitrogen content of N0 decreased significantly, resulting in a gradual increase in the difference between the yield increase effect of N0 and that of the nitrogen application treatment. The effect of supplementary irrigation on winter wheat yield at the anthesis stage was significantly affected by soil water storage (SWS) before sowing. The smaller the soil water storage before sowing, the larger the yield increase ratio with supplementary irrigation at the anthesis stage. The yield increase due to supplementary irrigation at the anthesis stage was also affected by precipitation during the winter wheat growth period, particularly from the jointing stage to the anthesis stage. When the precipitation from the jointing stage to the anthesis stage was < 31.9 mm, the yield increase from supplementary irrigation at the anthesis stage was significant. The results indicated that in the case of sufficient SWS before sowing, 31.9 mm of precipitation from the jointing stage to the anthesis stage could be used as a reference value for irrigation at the anthesis stage.