Functional Analysis and Molecular Characterization of Salt-Tolerant Microorganisms of Agricultural Importance
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Date
2012
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UAS Dharwad
Abstract
Salt-tolerant agriculturally important microorganisms (AIMs) isolated from stressecosystems
of Karnataka were identified and assessed for their functional properties under
salt stress. The biochemical basis for salt tolerance was also analyzed under salt stress.
Besides, their plant growth promotional activities were assessed at different soil ECe levels in
wheat under green house as well as field conditions. Plant growth promotional traits (N2
fixation, P-solubilization, phytohormone production) of each isolate were found to be
affected with increased addition of NaCl to the growth medium. The amount of N2 fixed by
the isolates, in general, was found to decrease with increase in NaCl concentration. While, the
amount of Pi released from TCP was found to increase with increase in NaCl concentrations
up to 7.5 per cent and declined thereafter. It was observed that, all the isolates were found to
accumulate higher amounts of compatible solutes (proline and glycine betaine) and sugars in
the presence of increasing NaCl concentrations as compared to control (without added salts),
besides maintaining their intracellular Na to K ratio between 0 to 0.5. The field performance
of salt-tolerant AIMs was assessed in wheat (cv. DWR-162) under gradient of soil salinity. In
general, the inoculation treatments significantly enhanced both growth and yield parameters
over un-inoculated control (UIC) at all the soil ECe levels tested. Field efficacy of salt
tolerant AIMs gave 6.5 to 27.8% increase in dry matter production and 13.9 to 80.5%
increase in grain yield of wheat over UIC at soil EC of 2.4 - 14.3 dS/m. It was also observed
that, activity of antioxidative enzymes (AOE) viz., catalase, superoxide dismutase and
peroxidase were decreased with inoculation but increased with soil salinity. Inoculated wheat
plants recorded significantly lower proline and polyols content but higher glycine-betaine and
total sugar contents as compared to UIC plants. Similarly, inoculated plants also recorded
significantly higher potassium content and K to Na ratio but lower Na content as compared to
UIC plants. It was also observed that, inoculation of salt-tolerant AIMs recorded significantly
higher microbial biomass (C and N) and soil enzyme activities over UIC. In conclusion, these
data suggest that the salt-tolerant functional groups of AIMs tested in the present study can
play an important role in conferring salt tolerance in crops.