Corn Production as Affected by Plant Population and Hybrids of Varying Maturity

Abstract

The environment of the western edge of the North American cornbelt is, on the average, less favorable and more variabIe for corn (Zea mays L. ) production than farther east. Consequently, in this <'fringe, of which northeast Kansas is representative, one year may resemble typical cornbelt conditions while the next may be characterized by drought, high temperatures, and resulting lower yields. Securing information on optimum plant population in this area is important because of high yield fluctuations ofter encountered among locations and years. Data on the response of different hybrids to stand density in such environments are limited. Numerous studies have been conducted to determine the optimum plant population and extent of plant population X hybrid interaction for most major corn-growing areas. Results of older trials, however, may not be applicable now in the western edge of the cornbelt because of increased nitrogen fertilizer use and development of hybrids with higher yield potential. Dungan et v1. (3) and Stringfield (9) have reviewed the literature on the subject. Optimum stands were related to soil productivity, with soil moisture availability and soil fertility probably the most important components. In the western edge of the cornbelt, moisture becomes relati?vely more important in limiting corn yields than farther east. Several researchers (1, 2, 6, 10) have shown that different hybrids may vary in response to stand density. Tolerance to high stand density is related to tolerance of low light intensity (6, 7). Other work has shown that the activity of the light-sensitive enzyme, nitrate reductase, decreases with decreased light intensity (4) and is lower in shadeintolerant hybrids (4, 5 ) . This study was to investigate 1) the optimum plant population for corn production on certain nonirrigated soils in the western fringe of the cornbelt, and 2) the extent of plan population X hybrid interaction, using hybrids of varying maturities.