Effects of Different Water and Nitrogen Supply Modes on Peanut Growth and Water and Nitrogen Use Efficiency under Mulched Drip Irrigation in Xinjiang

The optimization of irrigation and fertilization indexes for peanuts with drip irrigation is urgently needed in Xinjiang. A field experiment was conducted during the 2021 peanut growing season at Urumqi, Xinjiang, in Northwestern China, to evaluate the effects of different water and nitrogen treatments on the growth, yield, and water and nitrogen utilization of peanuts. In field experiments, we set up three irrigation levels (irrigation water quotas of 22.5, 30, and 37.5 mm, respectively, for W₁, W₂, and W₃), two nitrogen application levels (77.5 and 110 kg·ha^-1, recorded as N₁ and N₂), and a control treatment (W₂N₀) that did not include the application of nitrogen. The results showed that nitrogen application enhanced the growth, physiological indexes, yield, and water use efficiency of the W₁, W₂, and W₃ treatments when the irrigation volume remained the same. In comparison with no nitrogen application (W₂N₀), the peanut growth, physiological indexes, yield, and water use efficiency improved with increasing irrigation amounts in the N₁ and N₂ treatments. With an increase in the irrigation volume, the water use efficiency grew; the W₃N₂ treatment had the highest water use efficiency, which was 1.32 kg·m^-3. The total water consumption and reproductive-stage water consumption of the peanuts in all treatments increased with the irrigation volume, and a high yield was achieved at 402.57 mm, which was 5.2974 Mg·ha^-1. In the W₁, W₂, and W₃ treatments, the nitrogen partial factor productivity significantly decreased as the nitrogen application increased, with the nitrogen partial factor productivity in the W₃N₁ treatment being the highest, at 60.61 kg·kg^-1. A comprehensive evaluation based on principal component analysis assigned W₃N₂ the higher score. These findings suggest that irrigation water quotas of 37.5 mm should be coupled with 110 kg·ha^-1 nitrogen applications for peanuts using drip irrigation in mulch film in Xinjiang.