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Genetic variability in two maize (Zea mays L.) populations and its relationship with intra- and interpopulation recurrent selection

C.L. Souza Jr.; J.B. Miranda F°

Departamento de Genética, ESALQ/USP, Caixa Postal 83, 13400 Piracicaba, SP, Brasil

ABSTRACT

The objective of the present work was to evaluate the genetic potential of the maize (Zea mays L.) populations ESALQ-PB1 and BR-105 for intra- and interpopulation recurrent selection. Design b of Miranda F °. (Rev. Bras. Genet. 5: 745-760, 1982) was used to estimate genetic and phenotypic variances and covariances at the intra- and interpopulation levels. Genetic variance estimates were considered to be of intermediate values and indicated that population ESALQ-PB1 had greater genetic variability than BR-105 for yield (Y) and ear height (EH), but less for plant height (PH). The estimates of the ratio( (U   + A21)/(UA1A2+ Q_AZA1), taken as a measure of the genetic potential for heterosis expression and improvement, indicated that a significant change in heterosis through selection is expected only for yield. The expected gain in heterosis was 1.54 g/plant through reciprocal recurrent selection with half-sib families. On the basis of the expected gain through selection for yield and on the performance of the populations per se and of the interpopulation hybrid, it was concluded that the base populations have good potential for population improvement as well as for heterosis exploitation in crosses.

Keywords: genetic; variability; maize; Zea mays; interpopulation; selection.

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