Salt-Induced Stress Effects on Biomass, Photosynthetic Rate, and Reactive Oxygen Species-Scavenging Enzyme Accumulation in Common Bean

ABSTRACT

We studied the effects of salinity stress on biomass production, photosynthesis, water relations, and activity of antioxidant enzymes in two cultivars of common bean (‘HRS 516’ and ‘RO21’). Seedlings were raised in nutrient solution supplemented with increasing concentrations of sodium chloride (NaCl) at 0, 50, and 100 mM. After 10 days of salinity treatment, the plants were sampled to determine the enzyme activity, protein content and dry biomass. Plant biomass and activities of most antioxidant enzymes were adversely affected by salinity stress. Leaf osmotic potential was found to be directly proportional to salt stress. The cultivar, ‘HRS 516’ accumulated less sodium (Na⁺) than ‘RO21’. Under salinity, superoxide dismutase (SOD) enzyme activity increased 3 folds in both bean cultivars (‘HRS 516’ and ‘RO21’) compared to other antioxidants (APX, CAT, and GR). While not neglecting other possible factors, photosynthesis and biomass remains reliable indicators of plant functioning in response to salinity stress.

Keywords:

• common bean
• biomass
• photosynthesis
• salinity
• antioxidants

ACKNOWLEDGMENTS

We thank Prof. M. C. Saxena for his critical review of the manuscript. This research was supported by the Japanese Monbukagakusho scholarship (Ministry of Education, Culture, Sports, Science and Technology) through a scholarship award to the first author.