Drought tolerant Rhizobium sp. VRE1 induced osmotic stress tolerance, seed germination and seedling vigor in blackgram (Vigna mungo L.)
Brundha Annadurai, Z John Kennedy, Sivakumar Uthandi
In the present study, we evaluated the mechanism of osmotic stress-resilient nodule endophytic Rhizobium sp. VRE1 grown in simulated osmotic stress conditions. The results showed that Rhizobium sp. VRE1 tolerated up to -0.73 MPa and produced a detectable amount of IAA (2.0µg mL-1). A significant increase in the concentration of total free amino acids, proline, and total soluble sugar content due to inoculation of Rhizobium sp. VRE1 was observed moisture stressed conditions. However, the protein content had reportedly higher under non - stress condition (19.04 mg g-1 dry weight) but decreased under stress condition due to inoculation of Rhizobium sp. VRE1 (7.20 mg g-1 DW). Blackgram seeds biotized with Rhizobium sp. VRE1 showed germination efficiency of 60% and vigor index of 1190 under induced moisture stress (-0.49MPa). Rhizobium sp. VRE1 produced higher levels of EPS (62.12 mg) under drought stress compared to non- stressed (11.37 mg). Hence, the study suggests the scope of enhancing the yield potential and fitness of blackgram by bio-augmenting Rhizobium sp. VRE1 as a biofertilizer for sustainable pulse production in rice fallow and rain-fed areas.