| Comparisons of heterosis were made for canopy development, light utilization, biomass accumulation, seed growth, and embryo size among maize hybrids and their parents' inbred lines. The field experiments were conducted at three plant population densities (PPD), hybrids at 27,500 and 55,000, inbreds at 55,000 and 110,000 plants ha;Embryo weight, embryo length, and embryo axis length of hybrids were greater than their parents even when compared for seed equal size.;Leaf area index (LAI) of inbreds at 110,000 (double PPD) was equal to or higher than their hybrids at 55,000 (normal PPD). This response was also true for inbreds at normal PPD compared with hybrids at 27,500 (half PPD). Light interception response followed the LAI pattern. However, grain and total dry matter (TDM) yields were greater for hybrids.;Actual and effective grain filling period duration (AGFPD and EGFPD), crop growth rate (CGR), kernel number m;These data suggest that the greater kernel number, kernel size, GFPD, and KGR of hybrids account, to large extent, for the higher grain yield.;Percentage leaf N and its remobilization to grain in hybrids were greater than that in inbreds. Percentage non-structural carbohydrates in hybrid stalk was lower, but their remobilization was faster than that in inbred. These data suggest greater sink capacity of hybrids as compared to inbreds.;Overall, hybrid progeny strongly exhibited heterosis for embryo size, kernel weight, yield components, LAI, yields of grain, and TDM. |
