Corn response to row spacing and plant population in the Mid‐South United States

Abstract

AbstractMid‐South corn (Zea mays L.) producers continuously search for ways to increase grain yield. In this region, growers typically plant on 96‐cm beds to facilitate drainage of excess rainfall and irrigation but are concerned about wide row spacing causing intra‐row stress as plant populations steadily increase. The objective of this research was to determine the effect of row spacing and plant population on morphology and grain yield. The experiment assessed two row spacing (48 and 96 cm) and subplots that contained five plant populations (61,775, 86,485, 111,195, 135,905, and 160,615 plants ha–1). This study took place across six site‐years; in 2017, Starkville and Verona, MS, 2018, two in Starkville, MS, and in 2019, Starkville and Tchula, MS. Pooled over site‐years and plant populations, narrow rows increased grain yield by 5% (p < .01), stalk diameter by 4% (p < .01), and kernels per row by 6% (p < .01), compared to wide rows. Pooled over site‐years and row spacing, plant height, soil plant analysis development (SPAD) value, stalk diameter, kernel rows, kernels per row, and hundred‐kernel weight decreased as plant population increased except for ear height and leaf area index (LAI), which increased. Agronomic optimum plant populations ranged from 104 to 119 thousand ha–1 and were dependent upon site‐year. In conclusion, decreases in inter‐row spacing and increases in intra‐row spacing increased grain yield.