Resistance to Bird Cherry-Oat Aphid, Rhopalosiphum padi (L.), in Spring Barley, Hordeum vulgare L.

Abstract. Progeny from 17 spring barley, Hordeum vulgare L., lines identified with potential resistance to bird cherry-oat aphid, rhopalosiphum padi (L.) (Hemiptera: Aphididae), from previous evaluation in a greenhouse were evaluated as seedlings in a greenhouse in 2014. Flats were rated on a scale of 1 to 4 when susceptible check Morex was dead. Even though some lines had many seedlings that survived, none were true breeding. Survivors from three sources, CI 1969, CI 1128, and STARS 9301B, and their non-infested checks were grown in the greenhouse in a randomized complete-block design with nine replications. Grain yield and yield components were measured to determine the accuracy of evaluation to identify meaningful resistance in terms of grain yield. Although all three lines had significantly less seedling height and leaf number compared to non-infested checks at the time of rating, their grain yield at maturity was not significantly different than that of their respective checks. CI 1969 responded to infestation with a 9% increase in spikelets per spike while CI 1128 suffered a 15% loss in 100-kernel weight. Resistance to bird cherry-oat aphid, identified by evaluation of seedlings in a greenhouse, protected against loss of grain yield. The three lines can be used in breeding programs for resistance to bird cherry-oat aphid.