Tapping of nativeBradyrhizobiumandEnsifersp. diversity for functional traits in soybean [Glycine max(L.) Merrill

Abstract

Experiment was conducted to investigate native Bradyrhizobium and Ensifer sp. isolates for their functional traits in soybean. Soybean rhizobial isolates were tested for their ability to produce indole acetic acid (IAA) both in the presence and absence of precursor L- tryptophan. A low amount of IAA was produced by all isolates in the absence of L- tryptophan, which ranged from 7.96- 19.26 µg ml-1. In the presence of L- tryptophan (0.01%) the amount of IAA produced by all isolates was found to be increased (12.89-30.90 µg ml-1). Maximum IAA was produced by Ensifer sp. LSER 8 (30.90 µg ml-1) followed by LSER 7 (28.58 µg ml-1). The maximum phosphate solubilization (Po4-3) was observed with LSER 8 (6.59 mg 100 ml-1) on 12th day. Maximum resistance of 66.7% was recorded with tetracycline (30 µg disc-1). Ensifer sp. were sensitive to more antibiotics than Bradyrhizobium sp. Three isolates of Bradyrhizobium sp. (LSBR 3) and Ensifer sp. (LSER 7 and LSER 8) and SB 271 and DS 1 were evaluated for plant infectivity test and were found effective on root nodulation and total nitrogen content. The use of effective rhizobia as biofertilizer could be highly sustainable practice for soybean cultivation.