Ananda Kumar Saha* and Md. Fazlul Haque

Abstract

Nitrogen fixing bacteria (Rhizobium) was isolated from the healthy nodules of bean, Dolichos lablab. Pure culture of isolated bacteria was subjected to cultural, morphological, biochemical and nodulation tests for characterization. All tests showed positive results indicating that the isolated bacteria was Rhizobium. In inoculation test the highest count of nodules was on plant bacterized seed with adhesive but the lowest count was on nonbacterized seed. However, presence of few nodules on plants of nonbacterized seeds cultivated on natural soil indicating that few suitable native Rhizobium was present in that soil. Count of nodules on plants of preinoculated seeds was lower than that on plants cultivated on preinoculated soil, indicating that Rhizobium can survive well in soil than on seeds. In all cases of inoculation, nodules number was higher on plants cultivated on sterile soil mixed with Rhizobium than on natural soil. The present finding indicates that the plant growth was related to the number of nodules on roots of plant.

Key words:Inoculation, Nodulation, Growth, Rhizobium