Nodulation and N2 fixation effectiveness of Bradyrhizobium strains in symbiosis with adzuki bean, Vigna angularis

Abstract

In pot experiment, one isolate Knj from a Serbian soil, four strains of Bradyrhizobium japonicum and three strains of Bradyrhizobium spp. were examined for the effect on adzuki bean nodulation and effectiveness in symbiotic N2 fixation. All the tested strains produced root nodules in adzuki bean. Strains of B. japonicum showed high potential of N2 fixation, particularly 525 and 542. B. japonicum strains resulted 65-71% shoot dry weight and 99-138% total N content of uninoculated control with full N content (100%). No significant difference was found between the plants inoculated with Bradyrhizobium spp. strains and uninoculated control plants without N (40-42 and 42% shoot dry weight, respectively), which indicated symbiotic N2 fixation inactivity of the Bradyrhizobium spp. strains. Knj strain had the middle position (56% shoot dry weight). These data showed that B. japonicum 525 and 542 strains could be used in further investigations in order to apply them as inoculants in microbiological N fertilizers.