Yield sustainability of winter wheat under three limited-irrigation schemes based on a 28-year field experiment

Sustainable intensification is an agricultural development direction internationally. However, little is known about the yield sustainability of winter wheat(Triticum aestivum L.) under limited irrigation schemes on the North China Plain(NCP). A 28-year field experiment from 1991 to 2018 at Wuqiao Experimental Station was used to characterize long-term yield, evapotranspiration(ET), and water use efficiency(WUE) trends under three irrigation treatments(W1, irrigation just before sowing; W2, irrigation before sowing and at jointing stage; W3, irrigation before sowing, at jointing stage, and at anthesis).Yield gaps and the effects of genetic improvement, climate change, and climate variables on wheat yield and key phenological stages were estimated using the Agricultural Production Systems Simulator(APSIM) model. Grain yield and WUE of winter wheat increased during the 28 years under the three irrigation treatments, and the upward trend of WUE followed a saturation curve pattern. ET increased slightly. Simulation results showed that genetic improvement dramatically prolonged the phenological stages of vegetative growth period and contributed to yield increase by 0.03%–15.6%. The rapid increase in yield with lower water use was associated mainly with an increase in biomass with genetic improvement and partly with an increase in harvest index. A curvilinear relationship between WUE and yield emphasized the importance of obtaining high yields for high WUE. The yield gaps between potential yield and yield under W1 treatment increased from 1991 to 2018 but were relatively constant for the W2 and W3 treatments. Elevated atmospheric CO2concentration offset the negative effects of temperature increase on yield, leading to minor(-2.3% to 0.3%) changes in yield under climate change. Thus, genetic improvement played a dominant role in yield increase, and limited-irrigation schemes(W2 and W3) can increase wheat yield and promote sustainability of crop production on the NCP.