EFFECT OF OSMOTIC STRESS ON PLANT GROWTH PROMOTING ACTIVITIES OF THE OSMOTOLERANT ENDOPHYTIC BACTERIABapi Das, Sangeeta Paul and Maheshwar Singh Rathi
The present investigation was conducted to find out the effect of osmotic stress on plant growth promoting activities of the osmotolerant endophytic bacteria. Out of the forty six endophytic bacteria from mustard, ten were highly osmotolerant and observed to be able to grow even in presence of 50% PEG 6000. Effect of osmotic stress on their plant growth promoting activities was determined. Most of these isolates were found to possess multiple plant growth promoting activities such as P-solubilization, phytohormone production and biocontrol traits. Beneficial effect of osmotic stress on P-solubilization, giberrellic acid, HCN and ammonia production was observed for most of the cultures. Amount of P-solubilised by isolates ranged from 6.44 to 46.02 μg P solubilized/mg protein. Highest P-solubilisation was observed for isolate MAL 3 under control conditions and MKL 4 under osmotic stress. Highest HCN production was shown by isolate MAL 3 under control as well as stress conditions. Ammonia production by isolates ranged from 3.72 to 86.47 μg ammonia/ mg protein. There was decrease in IAA production by most of the isolates on exposure to osmotic stress. Giberrellic acid production was observed only under osmotic stress conditions and ranged from 78.77 to 270.99 μg GA/mg protein. IAA production by isolates ranged from 108.65 to 406.96 μg IAA/ mg protein. Highest IAA production was observed for isolate MAS 1 and MAL 3 under control and osmotic stress conditions, respectively. Siderophore production ability of the cultures was not affected by osmotic stress.
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