Abstract In plant breeding, the dialelic models univariate have aided the selection of parents for hybridization. Multivariate analyses allow combining and associating the multiple pieces of information of the genetic relationships between traits. Therefore, multivariate analyses might refine the discrimination and selection of the parents with greater potential to meet the goals of a plant breeding program. Here, we propose a method of multivariate analysis used for stablishing mega-traits (MTs) in diallel trials. The proposed model is applied in the evaluation of a multi-environment complete diallel trial with 90 F1’s of simple maize hybrids. From a set of 14 traits, we demonstrated how establishing and interpreting MTs with agronomic implication. The diallel analyzes based on mega-traits present an important evolution in statistical procedures since the selection is based on several traits. We believe that the proposed method fills an important gap of plant breeding. In our example, three MTs were established. The first, formed by plant stature-related traits, the second by tassel size-related traits, and the third by grain yield-related traits. Individual and joint diallel analysis using the established MTs allowed identifying the best hybrid combinations for achieving F1’s with lower plant stature, tassel size, and higher grain yield.

O objetivo deste trabalho foi caracterizar morfologicamente a dissimilaridade genética entre 25 genótipos de milho (Zea mays L.), visando a seleção dos mais divergentes e de maior potencial produtivo, por meio da análise multivariada, em cinco ambientes de cultivo do Sul do Brasil. As linhagens endogâmicas dos dois grupos heteróticos foram provenientes do banco de germoplasma da empresa KSP Sementes Ltda. Utilizaram-se 15 linhagens como genitores femininos e oito linhagens como genitores masculinos. Os ensaios foram conduzidos na safra agrícola 2011/2012 em cinco ambientes, com delineamento de blocos completos ao acaso com três repetições por local. Foram avaliados 15 caracteres de interesse agronômico. A divergência genética foi avaliada por meio do método de agrupamento de Tocher e UPGMA. As estimativas da D² indicam os pares de genótipos 6 e 22 como mais distantes geneticamente, e 1 e 14 os pares mais similares. Foram identificados nove grupos divergentes em ambos os métodos de agrupamento. Os caracteres profundidade de grãos, diâmetro do sabugo, massa de sabugo, diâmetro de espiga e peso de 100 grãos foram os principais determinantes na quantificação da divergência genética. Para o melhoramento de milho, os genótipos com maiores potenciais são 5, 15, 12, 20, 9, 25 e 10.

The aim of this study was to morphologically characterize the genetic dissimilarity among 25 maize (Zea mays L.) genotypes in order to select the most divergent and higher yield potential, by multivariate analysis, in five cultivation environments in southern Brazil. The inbred lines of the two heterotic groups were from the genebank company KSP Seeds Ltda. Fifteen inbred lines were used as female parents and eight inbred lines as male parents. The tests were conducted during the harvest 2011/2012 in five environments, in randomized complete block design with three replications per location. We evaluated 15 characters of agronomic interest. Genetic divergence was assessed by the clustering method of Tocher and UPGMA. Estimates of D² indicated genotype pairs 6 and 22 as genetically more distant, and 1 and 14 the most similar pairs. Nine different groups were identified in both clustering methods. The depth of grain, cob diameter, cob weight, ear diameter and weight of 100 grains characters were the main determinants in the quantification of genetic divergence. For breeding purposes, genotypes 5, 15, 12, 20, 9, 25 and 10 are those of higher potential.