Journal of Pure and Applied MicrobiologyVol. 3 No. 2

Response of Halotolerant Rhizobia of Glycine max (L.) to Various Salts and pH Values

N.R. Shaikh and M.B. Gandhi

Department of Microbiology, Yashwantrao Chavan College of Science, Karad Vidyanagar, Karad - 415 124, India.

Received on 12 July 2009 and accepted on 14 August 2009

 

ABSTRACT

Over irrigation and poor water drain of agricultural land may create a problem of soil salinity. In Maharashtra the problem is increasing day by day. Salinity affects soil qualities adversely. Many microbial interactions in soil are victims of salinity. Symbiotic nitrogen fixation, fertility determining factor in the soil, can be one of them. The effect is not only due to decrease in the plant growth but also due to decrease in the useful microbial population in soil. However, new salt tolerant varieties of useful microbes may develop in such soils. If screened properly, they can be of use in saline soils. Halotolerant rhizobia can be of use in saline soils, if used along with their legume partners. This can add in to nitrogen content of the soil and help in reclaiming soil fertility. Four halotolerant rhizobial strains namely GMNW1, GMNW2, GMB2 and GMB1 of Glycine max (L.) have been isolated from few of such saline soils in Maharashtra in the Krishna river basin area at Satara and Sangli districts. The NaCl tolerance of the isolates was ranging from minimum up to 5 % in case of GmNW1 and GmNW2 to maximum up to 8% in GmB1 and GmB2. The isolate namely, GmNW1 tolerated 8% of KCl while remaining three isolates tolerated KCl up to 9%. Tolerance to carbonates and bicarbonates was variable for different isolates and was ranging from 0.1 % in case of GmNW1 to 0.5 % in case of GmB2. Presence of KCl in the medium lowered NaCl tolerance of the isolates. Although pH of the medium influenced NaCl tolerance of the isolates, it was variable at different pH. However, the tolerance was maximum at pH 7 for all the isolates.

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