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Uma avaliação do potencial de diferentes locais para a discriminação genotípica entre cultivares de milho (Zea mays L) (An Evaluation of the Potential of Different Locations for Genotypic Discrimination Among Corn Cultivars (Zea mays L))

R. Vencovsky^I; C.D. Cruz^II; A.C. Silva^III

^I Departamento de Genética, Escola Superior de Agricultura "Luiz de Queiróz"/USP,13400 Piracicaba, SP, Brasil
^IIDepartamento de Biologia Geral, Universidade Federal de Viçosa, 36570 Viçosa, MG, Brasil. Send correspondence to C.D.C.
^IIIAgroceres S/A, Caixa Postal 81, 38360 Capinópolis, MG, Brasil

ABSTRACT

Ear weight data from yield trials, conducted over a period of five years in eleven locations, were examined in order to evaluate the potential of these sites to discriminate among cultivars. Considering the yield response of the cultivars, a pattern of similarity among the locations was investigated. The main goal was to evaluate the degree of representativeness of the sites and to search for sites which, on the basis of their similarity in relation to others, could be excluded, when cost restrictions or other problems made this necessary.
The degree of similarity between pairs of locations was measured using two biometrical approaches. No general consistency was found in the clustering results of each method for each year and also over the years. It could be concluded that the investigated set of eleven sites is adequate, in the sense that they are essentially not repetitive.
Considering both methods jointly over time, not a single pair of locations remained consistently present in the same group of sites. However, a homogeneity of results was observed for locations Inhumas, Santa Helena and Ubá, which were consistently grouped in the same cluster, when the degree of similarity of response was measured by the coefficient of correlation. Hence, among these three, one or two, could be omitted, if necessary, with minimum loss in the amount of information for discriminating among cultivars.

Keywords: Genotypic discrimination; Zea mays.

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