[Effectiveness of strains of clover nodule bacteria adapted to the acid reaction of the soil].

The effectiveness and virulence of clover nodule bacterial strains of different origin was studied as they were adapted to acid pH (4.8) of soil in the course of seven years. In spite of their ecological adaptation (strains from acid and neutral soils), the majority of strains (10 among 20) grew well enough upon numerous transfers onto acid media under new conditions. However, only some adapted strains were more effective, than non-adapted ones on acid soil Storage of the strains on acid media for a prolonged time had a positive effect on their virulence, when clover was inoculated on calcareous soil.