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Crown Rust Tolerance of Avena sativa-type Oats Derived from Wild Avena sterilis. M. D. Simons, Research Plant Pathologist, Plant Science Research Division, ARS, USDA, Ames, Iowa 50010; Phytopathology 62:1444-1446. Accepted for publication 29 June 1972. DOI: 10.1094/Phyto-62-1444.

To test the hypothesis that Avena sterilis indigenous to Israel has tolerance to crown rust (Puccinia coronata var. avenae) potentially valuable in commercial production, three strains rated susceptible in reaction type were crossed with the highly susceptible A. sativa cultivars Richland and Clinton. Cultivated-type rust-susceptible segregates selected from the resulting populations were evaluated for field tolerance in epiphytotics artificially initiated with a mixture of common crown rust races. Relative tolerance of segregates to infection was estimated by comparison of the average weight of kernels from infected plants with that from rust-free controls. The amount of tolerance transmitted by the different A. sterilis parents varied significantly as estimated by the mean tolerance values of the lines derived from each parent. All 23 lines derived from Richland were significantly more tolerant than Richland; 19 of the 23 lines derived from Clinton were significantly more tolerant than Clinton. Heritability of tolerance was estimated to be 76%. Almost all derived lines were lower in yield, under rust-free conditions, than were their respective cultivated parents.

Additional keywords: responses to infection.