River's Ulva intestinalis L. extract protects common bean plants (Phaseolus vulgaris L.) against salt stress

This study investigated the effect of Ulva intestinalis L. extract on common bean ( Phaseolus vulgaris L.) plants grown under salt stress. Two concentrations of Ulva intestinalis extract, 6% and 12% were applied by irrigation and spraying to plants under 51.33 mM of NaCl. The results indicated that the treated plants showed a great ability to tolerate salt stress (51.33 mM) by increasing plant growth and photosynthetic pigment content compared to plants irrigated only with NaCl. Additionally, there was a significant improvement in the expression of antioxidant metabolites, such as flavonoid content and ascorbic acid content. Furthermore, there was a significant improvement in antioxidant enzyme activities, such as superoxide dismutase (EC 1.15.1.1), glutathione peroxidase (EC 1.11.1.9), glutathione-S-transferase (EC 2.5.1.18), and glutathione reductase (EC 1.8.1.7) in stressed plants, especially those sprayed with 6% of Ulva intestinalis extract. Overall, our results suggest that the application of Ulva intestinalis extract could be a promising biostimulant for the growth of common bean plants under salinity stress.