Mean components for choosing maize populations to extract inbred lines

The choice of germplasm is one of the most important phases of a genetic improvement program to the fact that it is the initial development stage of superior hybrids. Hence, the objectives of this study were to obtain the estimates of m+o and d, and inbreeding depression for grain yield and plant height traits, for cultivars lacking this information, and thus to predict the potential of maize hybrids for the extraction of lines. The F-1 and F-2 generations of 12 maize hybrids were tested at two sites, during the crop years of 2017-18 and 2018-19, accounting for four environments. Both the generations were evaluated in contiguous experiments in randomized blocks design with three and two repetitions during the years 2017-18 and 2018-19, respectively. The data on plant height and grain yield were collected, per plot, from both the generations, utilizing which, the m+a and d mean components were estimated. The effects of dominance had greater importance for the character grain yield. The most promising hybrids for extraction of lines were AG1051, AG8025, BG7046, DKB455, and OMEGA due to their greater estimates of m+o. The hybrids AG8025 and BG7046 were associated with high values of m+a and grain yield. For the plant height trait, there was a greater contribution of additive effects. Therefore, greater inbreeding depression was observed for the grain yield trait when compared to the height of the plant.