Kernel Growth Rate and Duration in Maize as Affected by Plant Density and Genotype1

Abstract

The rate of kernel dry weight accumulation and filling period duration of corn (Zea mays L.) have been suggested as significant factors that influence yield potential. To determine the importance and usefulness of these kernel characteristics, environmental and genetic variations should be investigated. The objectives of this study were to measure the effects of plant density on the kernel growth components and observe the inheritance of these characteristics in the F1 hybrids. Kernel dry weight accumulation rate and effective filling period duration (EFPD) were examined in three corn inbreds and their three F1 hybrids at two plant densities. Kernel dry weight accumulation rate was not affected by plant density; however, EFPD was 2.5 days less at the high plant density. The resultant, smaller kernels along with a reduced number of kernels resulted in a 20% yield reduction per plant at the higher plant density. Yield per plant and per unit area in response to changes in plant density were altered more by kernel number per plant than by kernel size.A significant increase in kernel size contributed to the greater F1 yields although the major advantage of the hybrids was due to more kernels per plant. In two of the three F1 hybrids, the larger kernel size was due solely to longer EFPD's since the rate of dry weight accumulation of one of the parental inbreds was the same as that of the F1's. In the other F2 hybrid, both rate and EFPD were greater in the F1 genotype than for either parental inbred.These data show that EFPD but not the rate of kernel growth is influenced to a limited extent by plant density and both are under genetic control. Thus genetic modification of these kernel growth components should be feasible.