Resistance of Barley toPuccinia graminisf. sp.triticiandPuccinia graminisf. sp.secalis

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Abstract
Seedlings of barley cultivars possessing the T-gene developed low weighted infection types that indicated the plants were resistant when infected with races 113-RTQ,151-QSH, and 29-HJC of Puccinia graminis f. sp. tritici. However, four cultivars that lack the T-gene had low weighted infection types that were not significantly different from those displayed by the T-gene cultivars to either or both race 113-RTQ and 151-QSH. This suggests that these cultivars possess resistance gene(s) that are different from the T-gene. Race 29-HJC most clearly distinguished the cultivars with the T-gene from those without it. When barleys were infected with race HQ of P. graminis f. sp. secalis, seedlings of most cultivars developed relatively low weighted infection types; Heitpas-5 and Steptoe had the highest weighted infection types. Barleys possessing the T-gene could not be distinguished from those cultivars without the gene to this race of the rye stem rust pathogen. In the field, cultivars with and without the T-gene were tested with a composite of races 113-RTQ, 151-QSH, 29-HJC, 151-QFB, and 15-TNM of P. graminis f. sp. tritici. Terminal rust severities and the type of uredia present on plants indicated that barleys with the T-gene were moderately resistant to moderately susceptible to this composite of races. In the group of cultivars lacking the T-gene, Heitpas-5, and Black Hull-less were moderately susceptible, whereas the other cultivars were susceptible. In field tests with race HQ of P. graminis f. sp. secalis, Black Hull-less was resistant and Valkie, Hispont, and Heitpas-5 were moderately resistant. The cultivars with the T-gene were susceptible to moderately susceptible and could not be distinguished from some barleys that lack the T-gene.