Evaluation of Narrow-Row Corn (Zea mays L.) Production in the Mid-South.

Mid-South corn producers are continuously searching for ways to increase grain yields and ultimately net returns. In this region, growers typically plant on 96-cm beds to facilitate drainage of excess rainfall and irrigation but are concerned about wide row spacings causing issues as plant populations steadily increase. The objective of this research was to evaluate a narrow-row corn production system on 48-cm rows at multiple plant populations. The experiment assessed two row spacings (48 and 96 cm) and sub-plots that contained five plant populations (61,775; 86,485; 111,195; 135,905; and 160,615 plants ha^-1). This study took place across eight site-years; in 2017, Mississippi State, Stoneville, and Verona, MS, 2018, (2) Mississippi State, and Verona, MS, and in 2019, Mississippi State and Tchula, MS. Across all locations and years, row spacing affected stalk diameter (P < 0.01), ear length (P = 0.03) and ear width (P = 0.04). Pooled over plant population, narrow-rows increased stalk diameter, ear length, and ear width by 4%, 7%, and 3%, respectively. Grain yield (P = 0.31) did not significantly increase but numerically increased by 0.49 Mg ha^-1. Population affected leaf area index (P < 0.01), SPAD (P < 0.01), stalk diameter (P < 0.01), ear length (P < 0.01), ear width (P < 0.01), grain yield (P < 0.01), and net returns (P < 0.01). Pooled over row spacing, SPAD, stalk diameter, ear length and ear width all decreased as plant population increased but leaf area index increased as plant population increased. Grain yield was maximized at plant populations of 111,195 and 135,905 plants ha^-1, while net returns above seed cost were optimized at 86,485 and 111,195 plants ha^-1. In conclusion, although narrow-row spacing did not significantly increase grain yield, other desirable variables such as stalk diameter, ear length, and ear width increased.