Predictive and actual gains in two maize populations after intra- and inter-population recurrent selection / Ganhos preditivos e realizados em duas populações de milho após seleção recorrente intra e interpopulacional

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

The intra-(SRIA) and inter-population (SRIE) recurrent selections are breeding methods used to improve plant population means without drastically reducing the genetic variability after repeated selection cycles. However, SRIE has not been efficient in increasing the means of the two populations simultaneously. An alternative method can be the combination of SRIA and SRIE selections. Thus, the objective of this work was to evaluate the genetic gains of the populations Sinduro and Sindente, applying the breeding method intra-and inter-population recurrent selection. For this purpose, two corn synthetic populations, Sinduro and Sindente, originated from Embrapa Corn and Sorghum (CNPMS) were used. The Sinduro population was used as tester of the Sindente population (inter-population method) and of its own Sinduro population (intra-population method). Two recombination cycles were carried out, with 144 S1 progenies per cycle. These progenies were test crossed with Sinduro, generating Sinduro x Sindente inter-population and Sinduro x Sinduro intra-population. The progenies were evaluated in five environments in the first cycle and in three in the second, in a 12 x 12 lattice design with one row per plot and two repetitions. The traits evaluated were plant and ear height, ear weight and prolificacy. Analyses of variance and co-variance were carried out and the genetic, additive, environmental variance and genetic covariance components were estimated for the intra-and inter-population progenies. Based on the proposed method, the new variance components were defined as being the genetic variance of the deviations of the inter- for the intra-population additive effects and genetic co-variance of the intra-population additive effects as being the deviations of the inter-for the intra-population additive effects. The existence of genetic variability was observed for all traits in the first cycle and only for plant and ear height in the second cycle. The selection intensity practiced in the first cycle exhausted the genetic variability for ear weight and prolificacy, making continued improvement difficult. Thus, the continuity of the breeding program depends on the increase of the genetic variability in the progeny populations.

ASSUNTO(S)

maize breeding melhoramento milho seleção selection melhoramento vegetal

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