Resistance evaluation of oat genotypes to stem rust (Puccinia graminis f. sp. avenae)

The resistance in seedling and adult plant of 13 varieties and 37 lines of oats against stem rust caused by Puccinia graminis f. sp. avenae was evaluated. TNQ and TFQ races and isolates AMEX18.21.1.1 and AMEX18.18.1.1 for seedling evaluation; and AMEX18.18.1.1 isolate in adult plants were used. The Diamante, Menonita, Karma and Turquesa varieties were resistant in seedling to the TFQ race, but susceptible to TNQ and the isolates AMEX18.21.1.1 and AMEX18.18.1.1, the other varieties were susceptible to the two races and isolates. All varieties were susceptible to isolate AMEX18.18.1.1, in seedling, but in adult plants these were classified as susceptible, intermediate and only Teporaca was resistant. The 37 lines were classified into 17 groups by final severity and sister lines. Genotypes 25, 28, 34, 39 and 48 were seedling resistant to AMEX18.18.1.1, and the rest were susceptible. In the field all the lines were resistant and only genotype 19 of group 14, reached a 20% infection. From its response in seedlings and in adult plants of the advanced lines, it is inferred that resistance is conditioned by adult plant genes.