Volume No. 3 Issue No.: 4 Page No.: 1154-1163 April-June 2009




N.R. Shaikh* and M.B. Gandhi

Department of Microbiology, Yashwantrao Chavan College of Science, Karad
Vidyanagar, KARAD


Received on : February 17, 2008




Salinity of agricultural land is one of the stressful environmental conditions that adversely affect the agricultural productivity. In spite of the adverse effects of salinity, many microorganisms of a potential use in agricultural biotechnology can occur naturally in these environments. Salt tolerant rhizobia from such environment can be of use in symbiotic nitrogen fixation in saline soils. This may help in increased agricultural productivity and in reclamation of saline soils.
Hence a research project was undertaken to screen and study salt tolerant rhizobia nodulating Vigna mungo (L). Four salt tolerant rhizobial strains nodulating Vigna mungo were isolated from saline soils in the regions of Krishna river basin in Satara and Sangli districts of Maharashtra. The isolates were studied for their tolerance to various salts of sodium and potassium such as NaCl, KCl, Na2CO3, NaHCO3 and mixture of NaCl and KCl. The tolerance of the isolates ranged from 4 to 9 % to chlorides and 0.1 to 0.4% to carbonates and bicarbonates. Presence of KCl influenced the NaCl tolerance of the isolates. Studies of pH and temperature of incubation on the NaCl tolerance of the isolates showed that both the factors influenced NaCl tolerance of the isolates. Variation in incubation temperature from 23?C to 42?C was found showing variable effect on NaCl tolerance of the isolates.
All the four rhizobial isolates could nodulate Vigna mungo (L) plant with variable degree of nodulation. In terms of plant-dry weight, three salt-tolerant rhizobial isolates were seen symbiotically equally effective to that of normal non-tolerant one, while in terms of nitrogen content of the plant two of the isolates were symbiotically more effective than that of non-tolerant rhizobia. Thus the salt tolerant rhizobia can be used in agricultural biotechnology for improving productivity of Vigna mungo in saline soils through symbiotic association.


Keywords : Saline-environments, Salt-tolerance, Rhizobia, Vigna mungo (L), Symbiotic nitrogen fixation.