Ecological Competence, Plant Growth Promoting and Symbiotic Characteristics of Different Mesorhizobium Strains Nodulating Chickpea (Cicer arietinum L.) from Ethiopia

Chickpea provide multiple benefits, due to high nutritive value as well as the ability of the crop to enrich nitrogen poor soils. In spite of its yield potential this legume depends on the rhizobial association. The objective of this study was to identify indigenous promising elite Mesorhizobium strains that impart variation eco-physiologically and symbiotically for enhancing nitrogen fixation in chickpea. 20 symbiont strains represented 64 genetically diverse indigenous Mesorhizobium species were tested at laboratory and greenhouse. Based on their eco-physiological competence (35%) of the strains grown at 1.5% NaCl, 25% of strain at pH4 and fewer strains (20%) tolerant to 40°C. Most strains (60%) able to utilize D-Sorbitol and D-Glucose carbon substrates and better utilized the amino acids Phenylanine (60%). Most of the Mesorhizobium strains exhibited (67%) resistance to antibiotics and up to (83%) heavy metal resistance. Three strains able to release available soluble phosphates from Ca3 (PO4 )2 (118.0 μg/ml) and FePO4 (93.3 μg/ml) after 8 days of incubation and all strains produced the phytohormone ranging from (7.7-28.4 μg/ml). The results highlighted more nodules were recorded from the Natoli variety (32-62 nodules) compared to fewer nodules (31-46) formed on Arerti variety. Moreover, 85% of the strains showed highly effective symbiosis on both Natoli and Arerti varieties. The data provided an important complement to select representative distinct symbiont strains to tested in multi-location field trials for enhance nitrogen fixation activities in chickpea production