Effect of High Plant Density on Silage and Grain Yields of Six Corn Hybrids¹

Six hybrids, ranging in maturity from early to late, were evaluated at 2 locations for 3 years in densities of 40, 50, 60, 70, and 80 thousand plants per hectare. The diverse nature of the six hybrids resulted in significant hybrid differences for all traits measured. Hybrids differed in response to density only for grain yield and ears per 100 stalks. The hybrid most responsive to high planting rates had more ears per 100 stalks at high populations than the other hybrids. At high populations, ear height (but not plant height) was increased and stalk diameter decreased. Highest silage yields were obtained from 80,000 plants but were not significantly higher than yields from 70,000 plants per hectare. Highest grain yields were obtained at 70,000 plants per hectare. Ear weight at this population was 127 g. Because greater mechanical harvesting losses tend to occur at higher populations, near‐maximum grain yields probably would be obtained at 60,000 plants per hectare. Significant population ✕ location interactions were observed for both silage and grain yields.