Comparative evalution of di- and tetraploid accessions of red clover (Trifolium pretense L.) for resistance to powdery mildew (Erysiphe polygoni DC)

The aim of this study was to evaluate the tolerance of twelve genetic accessions of red clover to Powdery mildew (Erysiphe polygoni DC). The trial was carried out during 2014-2015 at the Experimental station of soya-bean Pavlikeni at a natural infection. The plant type of reaction was evaluated by a fourgrade scale depending on the % of leaves with typical symptoms. A significant effect (P<0.001) of the genotype, and hence the level of ploidy, on the type of reaction to the disease of powdery mildew was established. Average for the period of study, the tetraploid accessions of red clover were rated as moderately susceptible (score 3.1), and the diploid ones – as moderately resistant (score 2.7). In the selection (breeding) of red clover the diploid accessions P-3 and Sofia-52 variety can be used as genetic sources of tolerance to powdery mildew.