Isolation, Characterization of Salt Tolerant Azotobacter and its Potential Role in Promoting Seed Germination of Indian Mustard Under Salt Stress

摘要

Indian mustard (Brassica juncea) is one of the important oilseeds produced in India. It is used as an ingredient in the preparation of various cuisines and used as a green manure by vegetable growers. Overuse of chemical fertilizers, poor irrigation facilities, and other anthropogenic activities has led to increased salt concentrations in the soil. Salt stress has been found to decline the growth and yield of Indian mustard. Salinity negatively affects seed germination, which is the first stage of the plant's life cycle. Excessive salt has a huge impact on plant physiology. Mangrove soil provides shelter to various halotolerant plant growth-promoting bacteria like Azotobacter, which may provide a tool for sustainable crop improvement due to their multifarious features. Two fast-growing efficient isolates of halotolerant Azotobacter spp viz., AI, and AII were isolated from mangrove rhizospheric soil. Microscopic and biochemical characteristics of the isolates were studied. Both isolates showed PGP activities like phosphate solubilization, IAA, and ammonia production. A1 isolates tolerated salt concentration up to 0.5% and A2 till 2%. Seed germination parameters of uninoculated and isolate inoculated seeds under salt stress (0%, 0.1%, 0.2%, 0.3% and 0.4% of NaCl) were recorded. Salt stress significantly affected the germination traits. However, inoculation favored germination of mustard seeds in comparison to uninoculated ones under salt stress.