Variabilidade genética em famílias s1 de diferentes populações de milho

Abstract

The objectives of the present work were directed towards the study of genetic variability in seven maize populations with a broad genetic base, as a guide for population improvement. The field evaluation was conducted in completely randomized blocks, at one location (Anhembi, São Paulo state) with different groups of S1 families obtained from seven populations (GO-D: dent type, GO-F: flint type, GO-L: long ear, GO-G: thick ear; and composites G3, G4 and GO-S). Estimates were obtained for genetic variance (progeny mean basis), phenotypic variance of families means, and coefficient of heritability (broad sense) for progeny means. Estimates of heritability were high for ear weight (0.89 to 0.94), ear length (0.77 to 0.88) and ear diameter (0.77 to 0.92); and lower for plant height (0.58 to 0.80) and ear height (0.54 to 0.84), thus showing the high potential of the populations for recurrent selection based on S1 families. Ear yield in the base populations used as controls varied from 11,200 kg ha-1 (GO-D) to 12,800 kg ha-1 (G3). The means of S1 families varied from 6,070 kg ha-1 (GO-F) to 7,380 kg ha-1 (G4); the inbreeding depression in S1 families varied from 37.5% (G4) to 48.0% (G3) relative to the non-inbred population.