Grain and Forage Yields of Irrigated Second-Crop Corn Seeded on Five Planting Dates
1984
Widstrom, N. W. | Young, J. R. | Martin, W. K. | Shaver, D. L.
Corn (Zea mays L.) is a widely-grown summer crop in the United States. Where the growing season is of sufficient length, a second crop can be accommodated. This study identifies the optimum planting date and best of seven experimental hybrids for second crop grain and forage yields. The experimental hybrids with subtropical germplasm and/or heat tolerance were evaluated for five planting dates on a Typic Paleudult in seven to eight replications for 2 years. Previous studies considered fewer hybrids over a narrow range of planting dates. Among our plantings ranging from 1 June to 1 August, the 1 June planting achieved the maximum forage yield of 42.0 Mg ha⁻¹ while a mid-June planting gave an optimum grain yield of 4.40 Mg ha⁻¹ when averaged over both years. The heat-tolerant hybrids, C6862 and C7867, produced about two-thirds the yields of other hybrids during 1981 with below normal growing conditions but in 1980 were fully competitive with the five hybrids having tropical germplasm when excessive heat, moisture much below normal, and insect pressure prevailed during the summer growing season. Significant interactions between hybrids and planting dates occurred for grain yields in 1980 and for grain and forage yields in 1981. The best average grain and forage yields of 4.43 and 38.5 Mg ha⁻¹, respectively, were produced by X5802. Forage yields were much more consistent than grain yields when viewed over years or hybrids. To maximize the probability of success, summer plantings of corn should be made as early as possible, and an option to harvest as forage should always be maintained to prevent losses when adverse weather conditions suppress grain yields.
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