Varietal traits limiting the grain yield of tropical maize

Abstract

Abstract Tropical maize varieties were grown at a tropical lowland location in various -seasons and at a highland location in Mexico to study the general growth pattern of tropical maize. The following results were obtained. 1. The tropical maize variety grown at the lowland location in summer was characterized by (a) a high growth rate and a short growth duration, (b) a small leaf area duration during maturing, (c) a sizable loss of dry weight at late maturity, (d) a low harvest index, and (e) a small number of kernels formed per unit field area. Although these characters may be interrelated, the predominant cause of the former two appear to be environmental and that of the latter three, genetic. 2. The grain yield of tropical maize grown at the lowland location in summer was low mostly because of a small number of kernels and maybe also because of short leaf area duration. The senescence of leaves after silking was rapid and the growth duration was short under high temperatures. 3. Although the number o...