ESTIMATES OF GENETIC-PARAMETERS AMONG AND WITHIN HALF-SIB FAMILIES IN2 SELECTION CYCLES ON THE EEL(2) MAIZE (ZEA-MAYS L) POPULATION

Two cycles of selection among and within half-sib families were evalua ted on the maize population EEL(2), from 1987 to 1989 in the north, so uth and highland of Espirito Santo State, Brazil, in order to estimate the efficiency of selection for the trait ear weight. Two hundred hal f-sib families, were evaluated in each cycle, using two latices 10 x 1 0, with two replications per location. For the cross over, the selecti on rates of 15% among progenies, and 12,5% within progenies was used. For the trait ear weight, the analysis of variance individual and comb ined, detected significant differences for progenies and for the inter action of progenies x locations. The additive genetic variance values varied for locations and cycles, ranging from 501.4 to 1002.7 (g/plant )(2). The values of those variances at combined analysis were smaller than the values of individual analysis: 58.0 (g/plant)(2) for the firs t cycle and 292.7 (g/plant)(2) for the second cycle. Mean expected gai ns were 1.5% and 8.2% at first and second cycles, respectively. The ma gnitude of those estimations, the high values of heritability and of g enetic variation coefficients, associated to the high means of progeni es productivity, indicate the high potential of this population in a b reeding program.