Integrated Moderate Stay-Green Hybrids and Optimal Nitrogen Management Improving Maize Productivity and Grain Nitrogen Uptake

Investigating the interaction effect of nitrogen (N) management strategies and stay-green types of maize hybrids is essential for enhancing N use efficiency and developing N-efficient hybrids. A field experiment was conducted with five N management treatments (Control, Opt.N*70%, Opt.N, Opt.N*130%, and Con.N) and two stay-green types of maize hybrids (stay-green hybrids: DH605 and ZD958; moderate-green hybrids: XY335 and XY1266) to examine their interaction effects on maize yield, aboveground biomass, and N uptake and allocation. The highest grain yields for moderate stay-green and over stay-green maize hybrids were 12.8 Mg ha−1 and 10.8 Mg ha−1, respectively. Compared to over stay-green hybrids, moderate stay-green hybrids exhibited a significantly higher aboveground biomass and N uptake. Under an optimal N (Opt.N) treatment, moderate stay-green hybrids achieved a 15.8% higher grain yield than over stay-green hybrids. Under the Opt.N*130% treatment, moderate stay-green hybrids had the highest grain N concentration, averaging 13.1 g kg−1. Nitrogen application enhanced N allocation to grains, resulting in a 3.1–7.7% increase in grain N content. Moderate stay-green hybrids with optimal N management exhibited a 1.9% higher grain N content compared to over stay-green hybrids, whereas their vegetative organs had a relatively lower N content except for the Opt.N*130% treatment. Selecting a suitable maize hybrid (e.g., moderate stay-green maturity hybrid, XY335) and optimizing N fertilizer management can enhance grain yield, grain N content, and enhance N absorption and utilization efficiency.