Improving Wheat Yield and Water-Use Efficiency by Optimizing Irrigations in Northern China

Achieving the goal of increasing both crop yield and water-use efficiency with a better irrigation regime is a major challenge in semi-arid areas. In this study, we presented a two-season field experiment (October 2018–June 2019 and October 2019–June 2020) that considered drought stresses, i.e., no irrigation (W0), irrigated in jointing (W1), both in jointing and flowering (W2) after re-greening, and wheat varieties (S086; J22). The results showed that a 45.5% excess of irrigation water input did not promote wheat yield (W1 vs. W2). S086 was beneficial for the usage of soil water consumption under a low amount of irrigation water in both seasons. In addition, irrigation positively affected the activities of superoxide dismutase and catalase in flag leaves (p < 0.05). A decrease in irrigation helped to increase the concentrations of soluble sugar and proline and decrease the amount of malondialdehyde content for S086. For the water- and irrigation-water-use efficiency, W1 was significantly increased by 20.6–21.7% and 38.3–39.3% in 2018–2019 and 23.4–24.4% and 43.8–44.7% in 2019–2020, respectively, as compared to W2. Additionally, a higher yield for S086 than J22 was found under deficit irrigation. Consequently, our study suggested that the S086 variety combined with a total amount of irrigation water of 165 mm might be recommended to meet the win–win goal of high crop yields and water-use efficiency for reducing ground water depletion in the future.