CHARACTERIZATION OF INDEGENOUS COASTAL COWPEA RHIZOBIUM STRAINS AND THEIR GROWTH IN DIFFERENT SALINITY AND pH


Authors: M.S.I. Khan*, Zahed U.M. Khan and D. Khanam
*Correspondence author;  Email: shahidul050169@yahoo.com

Abstract
The experiment was conducted at Soil Microbiology Laboratory of Soil Science Division of Bangladesh Agricultural Research Institute, Joydebpur, Gazipur during 2007. Ten Rhizobium strains namely; S1 (KKP/06), S2 (SKP/06), S3 (CHB/07), S4 (MKP/07), S5 (SMP/07, S6 (MNP/07), S7 (KAB/07), S8 (BAB/07), S9 (LLB/07) and S10 (PAB/07) were isolated from coastal saline areas of Bangladesh. Morphological and bio-chemical characteristics of the strains were studied in the experiment. It was identified that the Rhizobium strains in the study were rod shaped, motile and gram negative. The isolates S1, S3, S5 and S7 showed heavy and S2 and S10 showed medium growth in mannitol and sucrose and minimum growth in glucose. The strains did not absorb dye. Most of the strains hydrolyzed starch but not gelatin. The multiplication of the strains decreased with increasing levels of salinity. The strains S1, S3 and S10 showed more salt tolerance up to 12 dS m-1 salinity followed by the strains S2, S5 and S6 (<8 dS m-1) and S4 (<4 dS m-1). But all the strains were tolerant or partially tolerant to acid medium and disliked alkaline medium.


Key word: Rhizobium, Morphology, Salinity, pH, and Growth.

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