Plant Population And Row Spacing Effects On Corn: Plant Growth, Phenology, And Grain Yield

The average U.S. plant population continues to increase as U.S. growers continue to push corn (Zea mays L.) grain yields higher. However, this increased plant population typically causes more intra-row stress to the plants, potentially reducing yields. Narrower row spacings may be used to reduce the stress by increasing the plant-to-plant spacing within a row. The objective of this study was to evaluate the influence of plant spatial arrangement (population and/or row spacing) on corn plant growth, phenology, and grain yield. In 2017 and 2018, six contemporary commercial hybrids were planted at 94,000, 109,000, 124,000, or 139,000 plants ha(-1) in 76- and 51-cm row spacings at two locations in Illinois. Plant spatial arrangement affected corn growth, phenology, and grain yield. The greatest grain yield of 18.5 Mg ha(-1) resulted from planting 109,000 plants ha(-1) in a 51-cm row spacing. In a 76-cm row spacing, the minimum plant population maximized yield at 17.5 Mg ha(-1). On average across plant populations, plants in a 51-cm row spacing yielded 0.8 Mg ha(-1) more than when planted in a 76-cm row spacing. With increased plant populations, plants produced more shoot biomass, whereas root biomass was unchanged. Narrower row spacings helped mitigate crowding stress at greater plant populations by promoting phenotypic changes that consequently led to greater yield.