Combining ability and gene action for Alternaria blight and powdery mildew resistance in linseed

A 10 x 10 diallel set excluding reciprocals was made to study the gene action for Alternaria blight and powdery mildew resistance in linseed. Combining ability analysis revealed the involvement of both additive and non-additive gene effects in both F1 and F2 generations with predominance of former. Close correspondence between mean performance of the parents and their gca effects was observed over generations for both diseases. GS 280 x NP29 and Neelum x Chambal were best specific combiners over generations for low incidence of Alternaria blight and powdery mildew, respectively. Therefore, crosses involving high x high general combiners in case of Alternaria blight may be utilized for obtaining transgressive segregants. For powdery mildew, population improvement followed by recurrent selection is suggested to accumulate desirable genes.