Relationship of seedling and adult plant resistance and evaluation of wheat germplasm against tan spot (Pyrenophora tritici-repentis)

Genetic resistance is the most effective, economical and environment friendly method of managing tan spot of wheat caused by the ascomycete Pyrenophora tritici-repentis (Died.) Drechs. (anamorph Drechslera tritici-repentis, Died.). This study was carried out to determine the association between seedling and adult plant resistance in winter wheat cultivars, study the inheritance of tan spot resistance and evaluate wheat germplasm for resistance. A significant positive correlation was noted between seedling resistance evaluated in greenhouse and adult plant resistance estimated in field conditions. The absence of segregation into resistant plants in the F(1) disomic crosses of the resistant spring and winter wheat cultivars with the susceptible cultivars, and the segregation of the corresponding F(2) crosses into 1 resistant: 3 susceptible ratio indicated that tan spot resistance is controlled by a single recessive gene which inherits qualitatively. The winter wheat cultivars: Ibis, Heines VII, Albrecht, Solitar, Ohio, Toronto, Yindos, Zenith and Kronjuwel, and the spelt wheat cultivars: Ceralion, Hercule, and Schwabenkorn showed highly resistant response to both race 1 and race 5 isolates. We recommend these genotypes to be used for gene deployment in wheat breeding programs.