A total of 17 bacterial isolates including Azotobacter chroococcum (N=5), Azotobacter beijerinckii (N=4), Pseudomonas aeruginosa (N=4), and Bacillus sp (N=4) were isolated and tested for siderophore, HCN, ammonia and indole acetic acid production in vitro. The bacterial cultures were positive for siderophore, HCN and ammonia. Among the isolates, The amount of IAA produced by Azotobacter chroococcum and Azotobacter beijerinckii were 23.6 and 17.6 μg ml-1 respectiviely, whereas the phosphate solubilizers Pseudomonas aeruginosa and Bacillus sp showed maximum IAA production of 26.5 and 19.8 μg ml-1 of IAA in Luria Bertani broth. The single inoculation effects of N2-fixing and PS bacteria on the growth, chlorophyll content, P and N content of black gram plants in green house experiments varied considerably between the treatments. The N contents in roots and shoots differed considerably among the treatments.
