Isolation and screening of Azotobacter Spp. for plant growth promoting properties and its survival under different environmental stress conditions

Because of detrimental changes in the soil condition, the substitution of chemical fertilizer is essential. Quite a lot of alternatives are available to improve the soil productivity now a day such as biofertilizers. Plant growth promoting rhizobacterias (PGPR) is being used as efficient biofertilizers known to influence plant growth by direct or indirect methods. Seeking competent PGPR strains with diverse activities, a total of six Azotobacter were isolated from Orissa University of Agriculture and Technology (OUAT) rice field of Odisha. All these test isolates were screened on the basis of morphological and biochemical characteristics. The result reveals that all isolates are gram negative small rods in shape; all were positive for catalase and oxidase but negative for starch and gelatine hydrolysis. Isolates were then screened for their plant growth promoting properties such as production of indoleacetic acid (IAA), nitrate reduction, ammonia (NH3), phosphate solubilization and antifungal activity. All isolates show IAA, nitrate and phosphate solubilization positive. One of the major constraints on agricultural yield is drought and this circumstance is likely to be intensified in the future due to water shortage worldwide. A number of mitigation approaches and alterations are involved to survive drought stress. Plant growth-promoting rhizobacteria (PGPR) could play a major role in decreasing different stress conditions in plants. From an overall study of six isolates A4 isolate shows significant PGPR and drought tolerant properties.