Physiological and Biochemical Responses of Four Genotypes of Common Bean (Phaseolus vulgaris L.) under Salt Stress

This investigation was conducted to determine the impact of salinity stress on some physiological and biochemical parameters of common bean (Phaseolus vulgaris L.) genotypes. Three levels of NaCl (0, 100, and 200 mM) were applied to four common bean genotypes. Chlorophyll content, Relative Water Content (RWC) of leaves, Electrolyte Leakage Index (ELI), Na+ and K+ concentrations, the K+/Na+ ratio, Malondialdehyde (MDA) content, total protein content, and proline concentration were determined and compared. Moreover, the activity of some antioxidant enzymes, including: Catalase (CAT), Ascorbate Peroxidase (APX), Polyphenol Oxidase (PPO), and Guaiacol Peroxidase (GPX) were analyzed. Content of chlorophyll a, chlorophyll b and carotenoid decreased by increasing the intensity of salinity stress along with the SPAD value. RWC dropped and ELI incremented by augmenting salinity together with the K+/Na+ ratio. The results revealed that MDA and proline concentrations significantly increased under the mentioned conditions. Activities of antioxidant defense enzymes were altered notably and total protein content decreased under salt stress. Consequently, genotypes Jules and 201 were found as, respectively, tolerant and semi-tolerant genotypes during this experiment.