Association between dwarfing genes 'Rht1' and 'Rht 2' and resistance toSeptoria tritici Blotch in winter wheat (Triticum aestivum L. em Thell).

Differences in levels of resistance toSeptoria tritici blotch were observed in plants with a specific height-reducing gene. When the gene 'Rht 2' was present either as an isoline or in the progeny, a higher degree of resistance was found. The most susceptible plants were observed in populations carrying the 'Rht 1' gene. Associations, as determined by phenotypic correlations, were detected betweenSeptoria tritici blotch and tall stature, late heading, and maturity. Plants having short stature, early heading, early maturity, and acceptable levels of resistance were identified in the F2 population whenRht 2 was present. Results of this study indicated that wheat breeders must select the appropriate dwarfing source that may confer resistance and grow large F2 populations, in order to increase the probability of obtaining desired genotypes.