Rhizobial strain involvement in symbiosis efficiency of chickpea-rhizobia under drought stress: plant growth, nitrogen fixation and antioxidant enzyme activities

Chickpea plants were inoculated with two strains of Mesorhizobium ciceri: local strain (C-15) and non-local strain (CP-36) in order to evaluate plant growth parameters, activities of nitrogenase and antioxidant enzymes under drought stress as well as control condition within 15 days of imposition of drought stress. Biomass production, nodulation, nitrogen fixation and antioxidant enzyme activities under drought condition were compared. Under control condition, symbiotic efficiency in symbiosis formed by C-15 was higher than that in symbiosis derived by CP-36. Although drought stress decreased shoot dry weight, root dry weight, nodule dry weight and nitrogen fixation in both symbioses, the rate of decline in plants inoculated with CP-36 was higher than that in symbiosis chickpea with C-15. Therefore, symbioses showed different tolerance level under drought condition which was essentially correlated with symbiotic performance at non-stressful conditions. Under drought stress, nodular peroxidase (POX) activity increased in both symbioses but was higher in nodules produced by C-15. Ascorbate peroxidase (APX) increased significantly in nodules of symbiosis of chickpea with C-15. Catalase (CAT) and glutation reductase (GR) declined in both symbioses which decline extent in symbiosis with C-15 was lower than that in the nodules of CP-36. These results suggested contribution of rhizobial partner in enhancing the tolerance of symbioses to drought stress, which was related with the increase of antioxidant enzyme activities (APX and POX) under drought conditions.