Isolation and phenotypic characterization of Rhizobium species from root nodules of haricot bean (phaseolus vulgaris l.) at arba minch, southern Ethiopia

Haricot bean (Phaseolus vulgaris L.) is the most widely distributed and has the broadest range of genetic resources. In Ethiopia, the yield of haricot bean is extremely low mainly due to nitrogen deficiency and also little information is available regarding diversity of rhizobia nodulating haricot bean. Hence, this study was conducted to isolate and characterize of Rhizobium Species phenotypically and biochemically from Root Nodules of Haricot bean (Phaseolus vulgaris L.) at Arba Minch, Southern Ethiopia to know their diversity, efficiency of infectivity and effectiveness using haricot bean variety Omo-90. The results of the study revealed that isolates were able to form nodules on the roots of the haricot bean variety. The colony morphology of isolates was found to be viscous in consistency, round in shape and watery translucent pigmentation. The cells were also found to be gram negative and cocci in shape. The biochemical test revealed that the bacterial isolates were positive to catalase test. The result of this project activity is believed to provide information for isolating efficient nitrogen fixing strains of rhizobium species from Arba Minch and it also have some contribution for the effort being made in using leguminous plants to increase soil fertility as a substitutes for commercial fertilizers, which are costly and not environmentally friendly. However, to come with sound conclusion, the study should be repeated.