Genetics of slow- rusting resistance to leaf rust in bread wheat

Genetic architecture of slow-rusting resistance to leaf rust was studied using generation mean analysis involving six basic generations (P₁, P₂, F₁, F₂, BC₁ and BC₂) of two bread wheat crosses viz., J 24 x HD 2189 and J 24 x HS 347. The individual and joint scaling tests revealed the presence of digenic epistasis for inheritance of slow-leaf rusting in both the crosses. The best fitting model revealed the significance of only additive (d) gene effect in cross J 24 x HD 2189 where simple selection could be effective for exploiting slow rusting phenomenon. In case of cross J 24 x HS 347, all the gene effects except (m) were significant indicating importance of additive and non-additive gene effects. Therefore, improvement through reciprocal recurrent selection, biparental mating or diallel selective mating could be employed for improvement of this trait. However, number of gene pairs controlling slow-leaf rusting was quite variable in both the crosses.