ADULT PLANT REACTION TO STEM RUST OF LINES OF MARQUIS WHEAT WITH SUBSTITUTED GENES FOR RESISTANCE

Abstract

The adult plant reactions to eight races of stem rust were determined for nine lines of Marquis wheat carrying identified genes for stem rust resistance, three lines of the variety Chinese into which single chromosomes of Red Egyptian had been substituted, and six parental varieties. The adult plant reactions of the Marquis lines carrying the genes Sr6, Sr7, and Sr8 resembled the seedling reactions. The Marquis line carrying Sr9a from Kenya 117A and Sr9b from Red Egyptian were similar in adult plant reaction although they differed in seedling reaction to a culture of race 29-1 (Can.). Two lines of Marquis carrying Sr10 were resistant in the adult stage to races 56 and 29-1 (Can.) which can attack them in the seedling stage. The reactions of the substitution lines and the Marquis lines carrying the same genes were similar, although the substitution lines were more susceptible to some races.