Resistance of barley cultivars and accessions to pathotypes of the spot blotch causative agent

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Background. The spot blotch disease caused by the hemibiotrophic fungus Bipolaris sorokiniana has become a serious problem for barley. Utilization of resistant or tolerant barley cultivars ensures sustainable diversity conservation and environmentfriendly crop production. Thus, supplying barley breeders with sources of resistance to harmful diseases is an urgent task. Materials and methods. A set of 100 barley accessions, earlier selected for different levels of resistance to B. sorokiniana, served as the material for this study. Eleven isolates of B. sorokiniana of various geographic origin, belonging to 4 pathotypes, were used for testing. The resistance of barley seedlings was assessed under controlled laboratory conditions, and that of adult plants under artificial infection pressure in the field. Responses to B. sorokiniana were scored using the 0–9 rating scale.Results and conclusions. Barley genotypes with race-specific resistance to the spot blotch causative agent were identified. The percentage of barley genotypes resistant to five isolates of B. sorokiniana pathotype 1 averaged 24.2%; two isolates of pathotype 3, 29.5%; three isolates of pathotype 7, 18.3%; and one isolate of pathotype 0, 37%. Barley accessions manifesting resistance in their seedlings, but susceptible in the phase of milk-wax ripeness, and vice versa, with seedling susceptibility and adult resistance, were identified. Six (6) barley genotypes showed seedling and adult resistance to pathotype 1, nine (9) to pathotype 3, and two (2) to pathotype 7. No barley accessions resistant to all isolates of the pathogen were found.