Impact of hybrids, plant population density, and nitrogen strategies on corn grain yield and quality

Abstract

Corn (Zea mays L.) is a staple food and feed worldwide, and it is imperative to fill the existing corn yield gap. Agronomic optimum plant population (AOPP) and nitrogen rate (AONR) are key factors to consider for improving and maintaining corn production. However, the relationship between corn hybrids at variable planting densities across different N rates on plant morphology, grain yield, and grain quality is not yet fully understood. Therefore, a 2-year multi-site study aimed to assess how corn hybrids with and without Bt traits (DKC 70-27 and DKC 70-25, respectively), plant population (75,000, 87,500, 100,000, and 112,500 plants ha⁻¹), and N rates (0, 112, 224, and 336 kg N ha⁻¹) interact and impact plant characteristics and corn yield. Pooled over four site-years, the AONR ranged from 170 to 200 kg N ha⁻¹. This rate maximized the grain yield to 10–15 Mg ha⁻¹ with no differences noted due to hybrids or plant population. Although a three-way interaction between site-year, hybrid, and plant population was noted, an AOPP was immeasurable, and yield seldom increased when plant population exceeded 87,500 plants ha⁻¹. In conclusion, these findings suggest that both plant population and N rates can be optimized to close yield gaps, increase corn grain yield, and improve corn quality, offering sustainable agricultural solutions for corn production in the mid-southern United States.