STRESS-TOLERANT BACTERIA WITH MULTIPLE PLANT GROWTH PROMOTING ATTRIBUTES FROM PEA RHIZOSPHEREAmandeep Kaur and Pratibha Vyas
Screening for stress tolerance is an important attribute in the selection of bacteria for the development of microbial inoculants. A total of 25 salt-tolerant bacteria were isolated on nutrient agar plates with 2.5% NaCl from the rhizosphere of pea growing in Dharamshala, Himachal Pradesh, India. Sixteen salt-tolerant bacterial isolates showed zone of phosphate solubilization ranging from 2-14 mm on modified Pikovskaya agar on fifth day of incubation. These isolates were screened for the production of auxins, ACC-deaminase, ammonia and hydrogen cyanide. Of these 16 salt-tolerant and phosphate solubilizing isolates, auxin production was shown by 100% isolates, ACC deaminase activity by 75%, ammonia production by 62.5% and HCN by 31% isolates. Phosphate solubilization in liquid medium ranged from 17 to 179 μg/mL while auxin production ranged 4.5 to 48.3 μg/mL. Eleven isolates showing all the tested attributes were screened for abiotic stress conditions of salinity, temperature, pH and calcium salts. Two bacterial isolates showing tolerance against all tested stress parameters were tested for their ability to tolerate different levels of desiccation with PEG 6000. The bacterial isolate P2H1 showing highest stress tolerance and multiple growth promoting activities was selected as a potential candidate for the development of microbial inoculants for stressed environments.
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