The combining ability of recombinant S-lines developed from an F-2 maize population

Starting with the F-2 generation of the single-cross commercial hybrid Lore na (PR3183), recombinant lines were developed combining half-sib/S1 evaluat ion on widely spaced plants in the direction of high yielding pet sc. Combi ning ability tests consisted of crosses between: (a) recombinant lines of c ommon pedigree and (b) recombinant lines and freely available inbred lines. The highest-yielding crosses between recombinant lines reached 100% of the original F-1 hybrid in a percentage of 14.2, Low heterosis was estimated o wing to additive gene action of recombinant lines. Crosses between recombin ant lines and freely available inbred lines outyielded significantly the co mmercial F-1 hybrid in a percentage of 33.3. Heterosis was greater and the original F-1 hybrid was outyielded significantly because of non-additive ge ne action. When the applied breeding procedure on a source population with high yield adaptability is adopted and where effects of intergenotypic comp etition masking the inherent genotypic value are controlled, population imp rovement may be substituted by combined half-sib/S1 selection for productiv ity of lines per se in low stress conditions during the very early stages.