Optimizing Planting Density and Irrigation Depth of Hybrid Maize Seed Production Under Limited Water Availability

Improvement in seed vigor and yield of hybrid maize is required to ensure food security. Optimal planting density and irrigation depth under limited water availability are critical for hybrid maize seed production in arid areas. Based on field experimental data during 2012 to 2017, an integrated model was established to optimize planting density and border irrigation depth for achieving high yield and seed vigor of hybrid maize under limited water availability. For different field experiments, a planting density of 9.75 plants m -2 under full irrigation was control treatment. The experimental results showed that water deficit decreased yield, evapotranspiration, and aboveground biomass per plant. The highest yield obtained by the planting density of 12.75 plants m -2 under full irrigation. The single crop coefficient and crop water production function models were modified to simulate evapotranspiration and yield, respectively. Using kernel number per plant and plant growth rate during the flowering stage, a kernel weight model was established. In the optimized model, the maximum yield and minimum irrigation depth were weighted as an objective function, and kernel weight was constrained. Three minimum relative kernel weight options were considered, included consistent with control (option 1), unconstrained (option 2), and ranged from 0.60 to 0.90 (option 3). In option 1, the optimal irrigation depth during the whole stage under control planting density decreased by 24.3%–39.4% compared to the conventional practices. In option 2, the yield increased but the average kernel weight decreased by 25% than control. In the option 3, average planting density decreased by 10.2%, yield reduced by 2.0%, but kernel weight increased by 9% compared to option 2. Thus option 3 can be recommended for hybrid maize seed production with limited water availability in arid regions of Northwest China. Our research provided a new theoretical method to improve yield, and ensure seed vigor of hybrid maize in arid regions