AbstractTwelve corn (Zea mays L.) hybrids and selections were evaluated for yield and other plant characters at densities of 45,000 and 90,000 plants/ ha. The study showed no yield advantage when densities were increased to 90,000 plants/ha. Significant differences among entries were observed in time to midsilk, ear height, plant height, test weight, weight of 1000 kernels, rust severity, and yield. No population-density x entry interaction for these characters was observed. Significant differences between population densities and among entries were observed in diameter of the third internode and number of ears per plot. Hybrid Pioneer 304C had the highest yield; Mayorbela, the highest test weight; Diente de Caballo and Pioneer 3068, the highest 1 000-kernel weight; and PR-Mp4 and Pioneer 3068, the lowest rust rating. The yields of Pioneer 304C, Pioneer 105A, Pioneer 3068, and PR-3 were very similar at both plant densities, while those of Pioneer 3048 and PR-Mo2 were higher by 27 and 20%, respectively, at the higher plant density. In six entries (PR-Mp4, DeKalb B-666, PR-Mo2 x Pr-3, Diente de Caballo, Mayorbela, and DeKalb B-660) yield was from 33 to 14% lower at the higher plant density.
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