Rupa Guha Nandi, Khyati Shrivastava and Shachi Agrawal

Department of Biotechnology Sri Sathya Sai College for Women, Bhopal-462024 (India),,


Soybean is cultivated as subsistence crop in central India, this crop could also adapt as well to different environmental conditions and soil types. The most important agent of symbiotic nitrogen fixation is bacteria of genus Rhizobium japonicum for soybean. Temperature seems to be an important factor affecting the Rhizobium japonicum population and their distribution. The survival of Rhizobium japonicum at high temperature is a challenging problem especially for tropical and subtropical regions with extreme temperature ranges 35-50 C. Presently lignite is one of the most commonly used carriers in production of Bio-fertilizer. It has been observed that lignite shows low moisture holding capacity and proper maintenance of moisture is essential for growth of Rhizobium japonicum. In the present investigation a new approach has been made of using different types of gums. It is an important parameter to know effective symbiosis. It is a need to isolate and identify temperature tolerant strains of Rhizobium japonicum. In the present study the effects of high temperatures 35-50 C was studied on different Rhizobium japonicum strain mixed with the lignite, which is taken as control. The strains is mixed with two different nutritive gums, they are Arabic and Guar followed by incubation to achieve the temperature in water bath for four hours daily for 10 days at 35-50 C. The growth and viability of strains was observed daily before and after heat treatment with the help of viable plate count method. The outcome of this study suggests that screening of high temperature tolerant strain of Rhizobium japonicum in gums as carrier in compared to lignite could be key to sustain legume productivity in tropical regions of our country. Liquid bio-fertilizer formulation could be considered as one potential strategy for improving the shelf-life of bio-fertilizer. Further, solid carrier based bio-fertilizers are less thermo-tolerant where as liquid formulations can tolerate the temperature as high as 55°C. Hence, improved shelf-life could be achieved by the application of a liquid bio-fertilizer formulation. Process cost of liquid bio-fertilizer is significantly higher than a solid formulation. Thus, successful commercialization of less expensive liquid bio-fertilizer is a challenge and shelf-life of such products is still a concern.

Key words : Rhizobium japonicum, screening, viability, symbiosis, lignite, Arabic, Guar.

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