Response of an Early‐maturing Corn Hybrid to Planting Date and Population in the Northern Plains1

Abstract

AbstractWith the development of extremely early‐maturing corn (Zea mays L.) cultivars, producers question how late planting can be delayed in semiarid regions without adversely affecting yields and what adjustments in plant populations are necessary. The present study was planned to acquire further information on yield potential of a short season hybrid corn at various planting dates and plant populations. At Mandan, N.D., a 68‐day maturing hybrid was grown at 20,000, 30,000, 40,000 and 60,000 plants/ha in 100‐cm row spacing for 2 years. Average planting dates were May 17 and June 7 and 28. In 1971 and 1972 (years of below normal rainfall), both planting date and plant population significantly affected grain yields. Delaying corn planting to June 7 and 28 reduced grain yield by 10 and 30%, respectively, compared to the May 17 planting. Optimum plant population was 30,000 plants/ha for both dry matter (forage) and grain yields regardless of planting date. Dry matter and grain yields averaged 5,180, 5,120, and 5,280 kg/ha, and 2,120, 1,930, and 1,500 kg/ha for May 17 and June 7 and 28 plantings, respectively. Ear water content increased at both the later dates of planting and at higher populations. Soil water withdrawal by corn was generally confined to the upper 90‐cm depth of soil for all planting dates. Water use efficiency for dry matter production was highest for the June 28 and least for the May 17 plantings. Wateruse efficiency for grain was usually similar for a given population at all planting dates.Results from this study indicate that an early maturing corn may be planted before mid‐June without greatly reducing dry matter and grain yields in the northern Great Plains.