COMBINED, FAMILY AND INDIVIDUAL SELECTION SYSTEMS IN THE BREEDING OF MAIZE (Zea mays L.)

Abstract

Nine methods of combined selection in maize derived from three types of families and three types of pollination are described. Fami­lies are of half sibs (MH), full sibs (HC) and S₁ lines or self sibs (AH), while pollination procedures are crosses of the appropiate kind among selected plants in order to generate the same type of family, pollination with a balanced composite of the families under test, and self pollination of selected plants. Expected responses to selection of the methods are obtained through the general response to selection formula and are compared with those of the individual and family selec­tion systems. The maize population to which selection is applied is suposed to have heredability of 0.20, degree of dominance of 1.3 and gene frequency of 0.5. Some theoretical and practical considerations on gain per cycle and gain per year are made in relation to the choice of the most adequate system and method of selection.