Phenotypic characterization and symbiotic effectiveness test of chickpea (Cicer arietinum L.) rhizobia isolated from Dejen and Aneded Districts, East Gojjam Zone, Amahara Region, Ethiopia

Chickpea (Cicer arietinum L.) is an important leguminous crop grown in different parts of Ethiopia. It is a nutritionally valued and N2-fixing legume which forms a symbiotic association with Mesorhizobium. This study was conducted to characterize and evaluate symbiotic efficacy of chickpea rhizobia isolated from soil samples collected from the study area. Seventeen chickpea rhizobia were isolated by soil host plant trap method and characterized for edaphic stress tolerance. Five of the isolates were grown at high temperature of 45°C and salt concentration of 6%, whereas seven were grown at acidic pH of 4, and four were grown at basic pH of 9. All isolates were not resistant to kanamycin, while fair resistance to erythromycin and streptomycin and modest resistance to ampicillin and azithromycin were observed. Furthermore, most of the isolates showed a variation in nodulation with higher (22 NN/p) and lowest (9 NN/p) scores. Shoot dry weight (SDW) of the plant ranged from 1.18 to 1.84 g/p and isolates showed effective (67%) to highly effective (100%) N2-fixing performance. From these, four isolates showed multiple edaphic stress resistance and are recognized as promising candidate for chickpea production in stressed soil; however, further study in the filed is required. Key words: Chickpea, Rhizobium, edaphic stress, symbiotic effectiveness