Application of Rhizobium Alleviates the Cadmium Stress-Induced Damage to Growth, Photosynthetic Efficiency, Cell Viability and Yield by Up-Regulating Antioxidants in Cicer arietinum L.

A new sustainable approach was aimed to explore the damage caused to legume grown in cadmium (Cd) polluted soil. Owing to the importance of chickpea (Cicer arietinum L.) as a source of protein which is exposed to Cd that imposes severe health hazards. A greenhouse pot experiment was designed to evaluate the potential of Rhizobium application in the amelioration of cadmium stress (Cd; 50 and 100 mg kg(- 1) soil) on chickpea cultivar namely Pusa-BG372 on growth (plant length; plant dry biomass; leaf area; and nodule number), photosynthetic pigments (total chlorophyll and carotenoids), stress biomarkers (malondialdehyde, MDA; superoxide radicles; cell viability), defense (proline, superoxide dismutase, SOD; peroxidase, POD; catalase, CAT; stomatal behaviour), and the major enzymes involved in nitrate assimilation (nitrate reductase; NR) and Calvin Cycle (carbonic anhydrase; CA). Among the different tested concentrations, 100 mg kg(-1) of Cd reduced the growth, photosynthetic variables, biochemical enzymes activity and increased oxidative stress under Cd stress. However, chickpea plants supplemented with Rhizobium-inoculation under the Cd toxicity revealed significantly increased chlorophyll, carotenoid, and proline contents, activity of CA, NR, and antioxidant enzymes. Aside from improved antioxidant enzyme performance and lower lipid peroxidation, cell viability and stomatal functioning were also improved in Rhizobium-inoculated plants. These observations depicted that application of Rhizobium inoculation to seeds could be useful approach to assist stress tolerance against Cd in crop plants grown in Cd contaminated sites.