Genetic analysis of resistance to spot blotch (Bipolaris sorokiniana) in wheat

Abstract

Diallel analysis of spot blotch resistance was laid out involving six resistant and two susceptible genotypes of spring wheat of diverse origin in order to evaluate their general combining ability (GCA) and specific combining ability (SCA). The parents chosen showed wide variation for area under disease progress curve (AUDPC) of spot blotch. GCA and SCA effects were statistically significant for AUDPC score suggesting that additive as well as nonadditive genetic mechanisms were involved in the expression of resistance in these parents. Wheat genotypes Chirya-3, Shanghai-4, Suzhoe 128-OY, Suzhoe 1-58, Longmai and Cuanmai#18 had significantly negative GCA effects for AUDPC in F1 generations, suggesting their prime suitability for use in wheat breeding programs to improve resistance to spot blotch. The estimate of narrowsense heritability was 0.69 whereas broad-sense heritability was 0.92 in F1s. The results indicated predominance of additive gene action in the inheritance of spot blotch resistance in spring wheat.