THE METHODS OF SELECTION OF RED-CLOVER MA TERIALS RESISTANT TO BEAN YELLOW MOSAIC-VIRUS

The study was aimed at testing the effect of preselection in view of r esistance to bean yellow mosaic virus (BYMV) in two populations of red clover originating from new selections HZ-III. The field experiments were conducted in the glasshouse to breed the plants in field conditio ns. Lower percentage of plants with symptoms of virus infection and pl ant mortality (Figs 1, 2) was found in both evaluated populations in p reselected treatments. Two methods were used for selection of red clov er genotypes resistant to BYMV. In the first one the red clover plants were mechanically inoculated by BYMV in the glasshouse, healthy plant s were transferred into field conditions and studied in individual pla nting for two years. The evaluation in the glasshouse served as a test of resistance of different populations to BYMV in glasshouse conditio ns (Tab. I). Seven sets of different red clover materials (varieties, ecotypes, strains, gene plasmas) were evaluated in this way during sol ution. The trial included 6 889 plants in total (Tab. II). The second method consisted in evaluation of red clover plants in field condition s and symptomless plants were transferred in clone segments into the g lasshouse. Two sets of red clover materials of the total number of 2 2 60 plants (Tabs III, IV) were evaluated. The plants resistant to BYMV in both procedures could be used in breeding for resistance to this vi rus.