Association between Genetic Factors for Crown Rust Resistance and Yield in Oats¹

Abstract

Summary Through a backcrossing program two series of oat ( Avena sativa L.) lines were created, one early and one midseason, that were isogenetic except for genes that conditioned crown‐rust reaction. The lines were tested under crown rust epiphytotic and rust‐free environments, and three of the resistance genes were found associated with sizable deviations in grain yield under the rust‐free conditions. In both early and midseason genetic backgrounds the crown rust reaction gene from C.I. 8079, an Avena sterilis line, was associated with an increase in grain yield. The crown‐rust reaction gene from C.I. 7171 was associated with an increase in yield in the early genotype, but not in the midseason. The crown rust reaction gene from C.I. 7232, a derived tetraploid, was tested only in the midseason genotype in which it was associated with a 9.6% reduction in grain yield.