Variability in ratio between ear and plant height among maize top cross hybrids ear and plant height of maize top cross hybrids

In a large number of plant species, including maize, different phenotypic traits have undergone major changes through the breeding process, resulting in the creation of varieties and hybrids of good agronomic performance. This study aimed to examine the variability of the plant height (PH) and plant height to the uppermost ear (EH) of maize top cross hybrids obtained from crossing 31 local landraces with three genetically divergent testers (L217, L73B013 and L255/75-5). Top cross hybrids were tested in a two-year experiment, at four locations, in two replicates. The grand mean of top cross hybrids for PH and EH were 255.8 cm and 101.8 cm. Analysis of variance showed that all sources of variation (environment - year × location (E), landrace (B), tester effect (A), as well as their interactions) were highly significant (p≤0.01), except for triple interaction (A × B × E). The coefficients of variation for the PH and EH were 4.76% and 8.87%. A highly significant correlation was found between the examined traits (r=0.785; p <0.01). Linear regression of PH and EH shows that the increase of EH by 0.5 cm is followed by the 1 cm of PH increase. Based on the results, the general combining ability (GCA) of landraces for the examined traits, is under the influence of the additive effect of genes, i.e. tall landraces per se in crosses with all three testers give tall hybrids and inversely. In maize production, a trait of interest is the small EH/PH ratio. Landraces MB1960, MB642 and MB1890 showed the best GCA for a given trait, so they can serve as sources of a given trait in pre-breeding programmes.