Optimum use of the limited growing period for maize (Zea mays L.) in short season areas is essential to maximize grain yield. The objective of this study was to evaluate the effects of vegetative phase duration (VPD), i.e., time from planting to silk emergence, and actual filling period duration (AFPD) on grain yield and its components in short season maize germplasm. Eleven random mating populations were subjected to divergent selection to form four subpopulations in each that varied in VPD and AFPD, both measured on an Ontario Corn Heat Units (CHU) basis. The material was evaluated in three environments in Ontario, viz., Innerkip 1981, Woodstock 1982, and Ridgetown 1982. Soil type at each location was a Burford silt loam (Typic Hapludalf). The direct effects of selection, and the correlated responses of other agronomic traits, including grain yield, were significant for most traits. For example, at Ridgetown 1982 average differences between the two extreme subpopulation groups were 200 CHU for VPD, 57 CHU for AFPD, 46 g kg−1for grain moisture at harvest, and 2.0 Mg ha−1for grain yield. The joint effect of varying VPD and AFPD on grain yield and components, i.e., kernel number per plant and 1000 kernel mass, was assessed by fitting quadratic response surface models. Increased VPD had positive, significant effects on grain yield; increased AFPD had slight positive effects but these were generally not significant. Differences in kernel number per plant contributed most to grain yield variation within any environment, whereas 1000 kernel mass contributed most to grain yield differences across environments. These results indicate a vegetative size limitation for grain yield of short season maize in the material studied. This should not be interpreted strictly as a source (supply of photoassimilate) limitation during the grain filling period, because preanthesis source size may partly determine kernel number per plant and thus affect sink size.
|Number of pages||6|
|State||Published - 1989|