Grain yields and evapotranspiration dynamics of drip-irrigated maize under high plant density across arid to semi-humid climates

Global water shortage has been a non-negligible issue threatening the sustainable development of agriculture and food security. To alleviate the contradiction between food desire and water limit, a synergistic improvement in grain yields (GY, kg ha−1) and water use efficiency (WUE, kg m−3) should be achieved. In this study, a combination of mulched drip irrigation and a high-yield maize cultivation system with high plant density (12 × 104 plants ha−1) was introduced to achieve the dual goal of high yields and water-saving. The study aims at identifying optimal irrigation quotas for three climatic conditions, i.e., Changji, an arid region (annual precipitation 141 mm), Qitai, a semi-arid region (269 mm), and Xinyuan, a semi-humid region (476 mm). Field experiments were carried out to explore dynamics of crop evapotranspiration (ETc, mm) of maize across arid to semi-humid climate, in 2018 and 2019. Six experimental treatments were designed according to local precipitation, including five irrigation levels under a high plant density of 12 × 104 plants ha−1, and a conventional irrigation level under a common planting density of 9 × 104 plants ha−1 taken as the control. There existed a quadratic relationship between GY and irrigation amounts, and between GY and ETc. A negative linear relationship was observed between WUE and irrigation amounts, and between WUE and ETc. Daily water consumption intensity (DWCI, mm d−1) of maize increased from VE to VT stage, reached maximum values of 9.3 mm d−1 (Changji), 6.4 mm d−1 (Qitai), and 5.0 mm d−1 (Xinyuan), respectively, during VT to R3 stage, and then declined until maturity, indicating that VT to R3 stage is a high water consumption period (water sensitive period) of maize. Generally, the occurrence of maximum DWCI and its sensitive period were delayed with increase of precipitation from arid to semi-humid climate. The optimum irrigation quota recommended was 720 mm for Changji, 540 mm for Qitai, and 180 mm for Xinyuan, respectively. Compared to the control, the recommended irrigation quota saved 11–60% irrigation water, and improved average WUE by 11–65%, without sacrificing maize yields (>15 Mg ha−1). We conclude that dual goal of high yields and high WUE of maize can be achieved with high plant density using optimal irrigation quotas and regimes, especially under semi-arid climate.