Factors which modify the resistance of wheat to bunt,Tilletia tritici

Abstract

does not appear. First page follows. In an earlier publication(2)4 the author presented data which indicated that Martin wheat differs from such susceptible varieties of wheat as White Federation and Hard Federation in one main dominant factor for resistance to bunt, Tilletia tritici, and that Hussar wheat differs from these susceptible varieties in two main factors for resistance, one of which was shown to be identical with the Martin factor. Because some susceptible plants nearly always escape infection it was necessary to classify F2 on the basis of percentages of bunt in F3 rows which were grown from the seed of individual F2 plants. Although Martin and Hussar were completely free from bunted plants, there were not enough bunt-free F3 rows to make up the resistant classes. A few rows with a low percentage of bunt had to be included in the resistant groups. At that time it was pointed out that the presence of a few diseased plants in resistant rows might be due to modifying factors. Also it was suggested that genetically resistant plants occasionally might become infected.