Potential of ACC-deaminase producing plant growth promoting rhizobacteria on water stress mitigation in lentil (Lens culinaris L. Medikus) under axenic conditions

Sixty five rhizobacteria isolated from lentil rhizosphere were evaluated for ACC-deaminase activity and other plant growth promoting traits and found belonging to genera Bacillus (24), Pseudomonas (37) and Serratia (4). Twenty seven of the isolates were able to utilize ACC as a sole N-source, measured in terms of growth (optical density ?600). Highest ACC-utilization was observed with seven isolates and maximum being in isolate 23-B (0.463) among the Bacillus spp. and 6-P (0.317) amongst Pseudomonas spp. Efficiency of phosphorous solubilization was recorded with six isolates which ranged from 14.6 to 21.6 mg/100 ml. All the isolates produced Indole-acetic-acid ranging from 4.4-22.8 µg/ml in presence of tryptophan. Two isolates 23-B and 6-P were evaluated for their PGP potential in lentil (LL 931) seedlings under PEG 6000 induced water stressed condition and were found to enhance root, shoot length, fresh and dry weight of seedlings over uninoculated seedlings. The most promising influence on lentil growth was observed in case of isolate 23-B which was molecularly characterized as Bacillus cereus on the basis of16S rRNA gene sequencing.