Selecting Rhizobium tropici strains for use with beans (Phaseolus vulgaris L.) in India: Infectiveness and tolerance of salinity and sodicity

Six strains of Rhizobium tropici, isolated from Brazilian acidic soils, were screened on the basis of their growth in Yeast Extract Mannitol (YEM) broth containing varying levels of salinity, pH and temperature. Infectiveness of salt tolerant strains of Rhizobium tropici (BR- 885 and BR-865) for nodulation and nitrogen fixation of French bean (Phaseolus Vulgaris L.) under sodic soil condition were tested to select the suitable strain for agronomical purposes. Assessment of active N₂ - fixation in the soils treated with varying levels of nitrogen and phosphorus was worked out to find out the suitable doses of Chemical N and P for the highest nitrogen fixation. 40 kg N ha⁻¹, 120 kg P₂ O₅ ha⁻¹ and seed inoculation with BR-885 strain of Rhizobium tropici proved most suitable combination to fix the highest amount of nitrogen (78.6 kg ha⁻¹) under sodic soil condition.