VISUAL MASS SELECTION AND HALF SIBS SELECTION ON A F2 INTERVARIETAL CROSS OF MAIZE

Abstract

The response to selection of two cycles from stratified visual mass selection (SVMS) and two cycles of half-sibs selection (HSS), obtained from the F2 of the intervarietal cross between Zacatecas 58 SM₂₀ and Tuxpeño Crema 1 SM₁₂ maize (Zea mays L.) varieties, was evaluated in two experiments conducted at Chapingo and Tecamac, México, under a completely randomized blocks design with four replications. Treatments arrangement was split plots, where densities 62 625 and 83 375 plants/ha were assigned to whole plots and varieties were assigned to subplots. The varieties included were the original varieties, the F₁ and F₂ generations of the intervarietal cross, composite cycles 1 and 2 of SVMS and HSS, and the hybrids H-139, H-135 and H-38E, as checks. The average genetic gain for grain yield per cycle of selection for HSS was 10 %, and 5.7 % for SVMS. Although for SVMS there was no difference between population densities, selection response in HSS was 13.4 % for low density and 7.1 % for high density, respectively.