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

Authors: SINHA, NAMITA - Mississippi State University; Jeffers, Daniel; WILLIAMS, DYLAN - Mississippi State University; BHEEMANAHALLI, RAJU - Mississippi State University; REED, VAUGHN - Mississippi State University; HENRY, W. BRIEN - Mississippi State University; Babiker, Ebrahiem; DHILLON, JAGMAN - Mississippi State University

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/21/2025
Publication Date: 9/6/2025
Citation: Sinha, N., Jeffers, D., Williams, D., Bheemanahalli, R., Reed, V., Henry, W., Babiker, E.M., Dhillon, J. 2025. Impact of hybrids, plant population density, and nitrogen strategies on corn grain yield and quality. Agronomy Journal. 17:5. https://doi.org/10.1002/agj2.70135.
DOI: https://doi.org/10.1002/agj2.70135

Interpretive Summary: Corn is a staple food and feed worldwide, and it is imperative to fill the existing corn yield gap. Agronomic optimum plant population density and nitrogen rates are key approaches to improve and maintain corn production. However, the relationship between hybrids at variable plant population density tested across distinct nitrogen rates on plant morphology, grain yield, and grain quality remains abstruse. Therefore, a two-year multi-site study aimed to assess how corn hybrids, plant density and nitrogen rates interact and impact plant characteristics and grain yield. The factors tested included four plant density (75,000, 87,500, 100,000, and 112,500 plants per hectares), nitrogen rates (0, 112, 224, and 336 kg per hectares) using two corn hybrids (DKC 70-27 and DKC 70-25) with and without genes inserted from Bacillus thuringiensis (Bt), which produce proteins with insecticidal properties against different insects. The findings suggest that both plant population density and nitrogen rates can be optimized to close yield gaps, increase grain yield and improve corn quality, offering sustainable agricultural solutions for corn production in mid southern U.S.

Technical 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 two-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 U.S.