Phenotypic characteristics of common bean (Phaseolus vulgaris)-nodulating rhizobia from some parts of southern Ethiopia

Eighteen strains of common bean rhizobia from Konso (GI), Arbaminch (GII), Sodo (GIII) and Ziway-Awassa-Dilla (GIV) areas in southern Ethiopia were isolated. The strains were characterized by sixty-four phenotypic traits. These traits were tested for cluster analysis using unweighted pair group method with average (UPGMA) with NTSYS version 2.1. pH tolerance/sensitivity, antibiotic tolerance/sensitivity together with the numerical analysis results clearly showed diversity among the strains. The cluster analysis grouped the strains into two clusters that included 78% of the strains at 85% similarity level, except four strains which were not clustered. These strains were less related to the clustered strains and to each other. The clustered stains were with the presumed similar characters of Rhizobium leguminosarun/Rhizoium etli group except AUPR10. Two isolates, AUPR9 (unclustered) and AUPR10 (cluster I), exhibited rough colony appearance on Peptone Yeast Extract Agar medium (PY) that resemble the characteristics of Rhizobium gallicum . Strain AUPR8 (from unclustered strains) displayed creamy colony appearance on PY, tolerance to extreme pH, salt, and temperature and inability to utilize dulcitol and utilization of glycine that resembled with characters of Rhizobium tropici . This result, therefore, indicates the possibility of obtaining inoculant strains with tolerance to environmental conditions of common bean-producing areas of Ethiopia.