Diallel analysis of scald and net blotch resistance in barley (Hordeum vulgare L.)

Scald and net blotch are major foliar diseases of barley causing high yield losses worldwide including Ethiopia. Development of varieties with double resistance is an effective approach of managing both diseases. However, the genetic background of the barley parents was not studied for future resistance breeding. Thus, the objective of the study was to assess genotype performances against scald and net blotch, investigate gene effects involved in controlling the diseases for future breeding and suggest better breeding system. Therefore, twenty eight barley genotypes were evaluated in a randomized complete block design with three replications at Holetta in 2015. Combining ability analysis showed general combining ability (GCA) and specific combining ability (SCA) was highly significant (P0.01) for initial disease severity, final percent severity and Area under disease pressure curve (AUDPC) for both scald and net blotch except for SCA in initial and AUDPC  of net blotch. This revealed the importance of additive and non-additive gene actions in controlling resistance for both diseases. HB1307 and HB42 parents were general combiner for scald and net blotch resistance. The result suggests the possibility of developing diverse populations from superior GCA parents to scald and net blotch through diallel intermating of selected segregants followed by selection at late generations. And final disease rating can be useful for evaluating a large number of barley genotypes to both diseases. Key words: Barley (Hordeum vulgare L.), additive and non additive gene effects, combining ability.