Methods to evaluate tbe genetic maize divergence and its relation with the diallelic crossings

Abstract

The utilization of the multivariate techniques to estimate the genetic divergence was evaluated to help maize (Zea mays L.) breeders to identify promising materials to obtain hybrids or populations with large genetic variability. With this purpose, twenty eight populations, with different origins were evaluated in a competition assay with the generations S₀ and S₁, and in hybrid combinations on a diallel crossing system. Beyond these populations, seven testers were used, that were evaluated in. a simple lattice 21 x 21 in Sete Lagoas, MG, Brazil. Measurements were made in the S₀ generation based in sixteen traits, and multivariate analysis was performed on this data. Later, divergence was evaluated with the multivariate distance (generalized Malialanobis). It should be noticed that: multivariate evaluation of genetic divergence before any crossing would avoid many crosses to be made, reducing the cost and increasing the precision of experiments; genetic divergence was small and due to the variety BAHI-TUSON and BR 136 related to the others. This fact was responsible to the small variation on the estimates of the: combining ability and heterosis.