General and specific combining ability and reciprocal effects of several economic characters in different white leghorn lines

Abstract

Four genetic ally different populations of White Leghorn were studied. Griffing's model was applied on diallelic crosses composed of paternal lines, a group of F₁ generations and their reciprocals. The crosses were tested within a year, in four repetitions and where conducted at the Poultry Section of the Instituto de Pesquisas e Experimentação Agropecuárias do Centro-Sul (IPEACS). Two of the populations, tabelled A and B, were the results of long progeny selections and the other two, labelled C and D, were hybrids of North American origin to be used in a double cross for commercial purposes. This choice permitted a comparison between these two groups of germplasm, with the aim of evaluating the desirability of producing our own hybrids in our own environment. The analysis covered the effects of the general and specific combining abilities and the effects of reciprocal crosses of the four lines in relation to ten economic characters. In general, the local lines A and B were better or, at least, not inferior to C and D lines, concerning the general combining ability (additive effects). In relation to the specific combining ability (dominance effects), hybrid AB was not significantly different from CD, concerning seven of the eight characters studied. In relation to the reciprocals, there was no significant difference between crosses AB and CD. The conclusion was in favor of the local production of hybrids, since genotype - environment interactions may be the cause of the grest decline in the phenotypic value of imported lines.