Dry matter accumulation after silking and kernel weight are the key factors for increasing maize yield and water use efficiency

Abstract Reducing use of irrigation water and improving crop yield are important since water shortage and food security are the two main problems in developing sustainable agriculture. In this study, we aim to reduce the conventional irrigation amount and to determine the mechanisms for yield formation and water use efficiency (WUE) increasing, and to identify the optimal irrigation amount for high yield maize (> 15 Mg ha–1) under mulch drip irrigation in arid, semi-arid, and semi-humid areas. Experiments carried out in the arid area (Changji), semi-arid area (Qitai), and semi-humid area (Xinyuan) in 2018 and 2019 showed that the optimal irrigation amount was 720 mm, 540 mm, and 180 mm, respectively. As compared to the irrigation amount used by farmers irrigation amount (maximum irrigation amount), the optimal irrigation amount recorded in our study could save 11.1–60.0% of water. At the same time, the WUE and irrigation water use efficiency (IWUE) increased by 5.2–60.3% and 7.9–181.6% with maize yield > 15 Mg ha–1. Less than optimal irrigation, increasing yield and WUE by increasing both dry matter accumulation after silking (DMA) and thousand kernel weight (TKW). Over optimal irrigation, the yield further increased mainly by increasing dry matter at maturity, and increasing WUE by kernel number per ear. The most photosynthate was transferred from leaves and stems to grains in minimum irrigation, but the lowest that in maximum irrigation. Therefore, DMA and TKW are the key factors to increase yield and WUE under less than optimal irrigation. Optimize irrigation goal may be to improve the transport of photosynthate to grain in the future.