Plant Density Effect on Grain Yield of Corn Hybrids Diverse in Leaf Orientation1

Abstract Corn (Zea mays L.) yields have increased when corn plant leaves are more vertically oriented compared to normal corn leaf habit, but there is little information on yield effect of plant density changes in corn genotypes that have erect leaf orientation. This work was conducted to evaluate the grain yield response to plant density of corn hybrids diverse in leaf orientation. Eighteen corn hybrids differing in leaf orientation were grown at five densities in 1969 and 1970. Data recorded were grain yield; ear moisture; and angle, width, and length of the leaf above the ear. In both years hybrids differed significantly for yield, leaf angle, leaf width, leaf length, and length to the breakpoint of the leaf above the ear and densities differed for yield, leaf angle, leaf width, and leaf length (1969 only). Yield and leaf angle (small angle characterizes uprightness) were negatively correlated at low populations; the correlation approached 0 as plant density increased. Hybrids were grouped on the basis of leaf angles and yield response to population in 1970. When groups differed in leaf angle, the linear regression coefficients of yield on density did not differ statistically. However, there was a statistical difference between linear regression coefficients, with no difference in mean leaf angles, when hybrids were grouped by yield response to population.