Qualitative approach to study karnal bunt inheritance in bread wheat (Triticum aestivum L.)

For fitting qualitative genetic models to the available data, the whole range of Karnal bunt infection was divided into four categories viz. 0–5, 5–10, 10–15 and >15 per cent as resistant, moderately resistant, susceptible and highly susceptible classes, respectively. Results based on plants falling into different infection groups in P₁, P₂, F₁ and F₂ for the crosses viz. (R x R), (R x S) and (S x S) revealed that the resistance was partially dominant. In the present study, two dominant genes/gene groups were speculated in the resistant lines and it was concluded that HD29, W485, H567.71, HP1531 and CMH77.308 constituted the resistant group and WH542, UP2382 and PBW343 constituted the susceptible group. Variety ALDAN possessed some minor susceptibility genes whereas WL6975 and CPAN3045 expressed differently in different genetic backgrounds and showed a variable segregation behaviour.