The PGPR have been divided into two groups based on their involvements in (i) nutrient cycling and phytostimulation, and (ii) the biocontrol of plant pathogens. A total of 72 rhizobacterial isolates belonging to genera Bacillus,Pseudomonas and Rhizobium were isolated from Wheat (Triticum aestivum L.) rhizospheric soils collected from various locations of Kanpur region, India. These rhizobacterial isolates were characterized biochemically and screened for their PGP (plant growth promoting) activities in vitro. Plant growth promoting traits screened with the test rhizobacteria included production of indole acetic acid (IAA), ammonia (NH3 ), hydrogen cyanide (HCN), siderophore and catalase. All test isolates turned positive for catalase production. The rhizobacterial isolates of Pseudomonas spp. (100%), Bacillus spp. (100%) and Rhizobium spp. (67%) produced IAA. Production of ammonia (NH3 ) was commonly detected in the rhizobacterial isolates of Bacillus (100%), Pseudomonas (85%) and Rhizobium (70%). Bacillus Spp. sample KNP-7 showed high level of tolerance to the multiple heavy metals tested whileas tolerance to heavy metals was observed less frequently in Rhizobium spp. sample KNP-36 and KNP-5. Rhizobacteria tolerant to multiple heavy metals and exhibiting a couple of PGP traits in the present study hold promise as effective PGPR with wheat and/or other compatible crops.

Keywords: Ammonia; HCN; Heavy Metal Tolerance; Indole Acetic Acid; Plant Growth-Promoting Rhizobacteria; Siderophore; Triticum aestivum L.