Resistance to oxalic acid (OA) of 37 lucerne and 3 red clover accessions was evaluated. The seeds of test entries were germinated in Petri dishes on filter paper moistened with 7 OA water solution concentrations: 0, 5, 7.5, 10, 15, 20, 30 mM. The test lucerne accessions did not differ by resistance to OA in regard to the origin of accessions or their development status. Accessions considerably differed by resistance at a concentration of 10 mM of OA solution. More than a third (42%) of lucerne accessions were totally susceptible to OA at conc. 30 mM. However, 0.0–23.8% of resistant seedlings of these accessions were found at OA conc. 20 mM. Lucerne accessions showing resistance (0.7–3.8%) at OA conc. 30 mM expressed a similar resistance level (3.1–26.7%) to OA conc. 20 mM as well as accessions totally susceptible to OA conc. 30 mM. The OA conc. 20 mM was adequate for selection of resistant seedlings in breeding material with a lower resistance, and conc. 30 mM was suitable for screening more resistant accessions. This method showed an efficient possibility to select seedlings resistant to OA and in turn to Sclerotinia spp. pathogens using simple materials and less work inputs as compared with methods described in the literature.

Keywords: lucerne, resistance, oxalic acid, Sclerotinia