Inheritance of Leaf Rust Reaction and Other Characters in a Spring Wheat Cross 1

C. S. W u and E. R. Ausemus' w the exception of Thatcher, most of the hard red spring wheat varieties now being grown were derived from Hope or its sib selection, H-44. These Hope derivatives were resistant to leaf rust, Piiccinia mbigo-uern tritici (Erikss. and Henn. ) Carl., previous to 1944, but have been susceptible since then, due probably to the increase in prevalence of races 126 and 128, of the disease organism. The damage from leaf rust infection was estimated to be 20% in North Dakota in 1947 ( l o ) . New sources of leaf rust resistance are available now, but no available resistant variety is adapted for growing in the hard red spring wheat area. Some are highly resistant not only to a collection of races in the field, but also to a large number of individual races in the seedling stage in the greenhouse. It has been necessary, therefore, to combine these new sources of resistance with the desirable characters of standard varieties. The primary purpose of this study was to determine the mode of inheritance of leaf rust reaction to a collection of races in the field and to certain individual races in the seedling stage in the greenhouse. A summary of the mode of inheritance of various characters in wheat was given by Ausemus et al. (3). The genetics of wheat with particular attention to leaf rust and stem rust was given by Hayes and Immer (4).