BIOLOGICAL FEATURES OF GROUNDNUT MICROSYMBIONTS WIDESPREAD IN THE SOILS OF UKRAINE

Objective. Study the presence of nodule bacteria in the soils of Ukraine, capable of nodulatinggroundnut, isolate new strains of rhizobia from peanut nodules, study their morphological, culturaland serological properties and the ability to form symbiosis with different legumes. Methods. Microbiological (isolation of nodule bacteria from nodules and cultivation of microorganisms, studying biological properties of strains), serological (producing antisera to Bradyrhizobium lupini367a, studying rhizobia diversity in groundnut nodule populations, studying serological identity ofnew strains), vegetation experiment (studying formation and functioning of groundnut symbioticsystems with nodule bacteria, studying host specificity of new strains of groundnut rhizobia), gaschromatography (determining nitrogen-fixing activity of rhizobia in symbiosis with groundnut),mathematical and statistical. Results. Representatives of two species, B. lupini and B. japonicum,were found in nodule populations of rhizobia during the cultivation of groundnut plants on sodpodzolic soil and leached chernozem. The dominant microsymbionts of groundnut were lupine nodule bacteria of serogroup 367a (54.2 % and 45.8 % according to soils). Fewer nodules wereformed by intensive growing soybean rhizobia of serogroup КВ11 (16.7 % and 12.5 %). The shareof nodule bacteria not classified in the studied serogroups was 21.9 % and 41.7 %. Fifteen newstrains of nodule bacteria were isolated from groundnut nodules, which were morphologically, culturally and serologically identified as B. lupini serogroup 367a (7 of them), B. japonicumserogroup KB11 (4 of them) and Bradyrhizobium sp. (4 of them). New strains of B. lupini fromgroundnut nodules are able to infect white and yellow lupine but do not nodulate soybeans. Strainsidentified as B. japonicum form nodules on soybean roots but do not infect lupine. Serologically unidentified strain Bradyrhizobium sp. AR3, which is able to form a symbiosis with both lupine andsoybean (phenotypes Nod+Fix+) was obtained. Conclusion. For the first time it was established thatgroups of nodule bacteria capable of nodulating groundnut are present in the agrocenoses ofUkraine. Fifteen new strains of groundnut rhizobia were obtained, which were identified as B. lupini, B. japonicum and Bradyrhizobium sp.