GENERATION MEANS ANALYSIS OF RESISTANCE TO HEAD SMUT IN MAIZE

Head smut, caused by Sphacelotheca reilana (Kuhn) Clint, is a disease affecting maize (Zea mays L) in southwest France. Generation means analysis was used to determine the relative importance of additive, dominance, and epistatic effects controlling resistance of maize to head smut. The parental inbred lines, Fl, F2, and first backcross generations of A632 x Al88 and LH74 x LMZ66 were tested for head smut resistance at La Reole, France in 1990 and 1991. Additive effects accounted for 97% of the variation among A632 x A188 generations and 88% of the variation among LH74 x LMZ66 generations. Dominance and epistatic effects were minor compared with additive effects. The absence of entries x years interaction indicated that multiple-year screening of germplasm is not necessary. This result, as well as the preponderance of additive genetic effects, should enhance progress in selection for head smut resistance.