Effect of hydrogels on bean (Phaeolus vulgaris L.) growing under salt stress

Hydrogel polymers have garnered significant interest for their potential to improve water and nutrient retention under abiotic stress conditions. Similarly, the incorporation of biochar can enhance plant growth and development under such stresses. This study investigated the effects of a superabsorbent hydrogel (SAH), composed of alginate-based hydrogel and biochar derived from fruit peels, on common bean performance under salt stress. The experiment involved six treatments: T1 (control), T2 (salt), T3 (salt + 0.5 g SAH), T4 (salt + 1.5 g SAH), T5 (salt + 2.5 g SAH), and T6 (salt + 3.5 g SAH). Salt stress adversely affected plant morphological traits (e.g., plant height, leaf area, root length), physiological traits (e.g., photosynthesis, stomatal conductance, leaf temperature), nutrient uptake, and water absorption. Additionally, salt stress increased reactive oxygen species (ROS) concentrations, leading to enhanced lipid peroxidation and cellular damage. Treatment T3, which included 0.5 g of SAH, mitigated the effects of salt stress by improving root length, root fresh weight, shoot fresh weight, leaf area, number of leaves, leaf water potential, and stomatal conductance. T3 also enhanced water uptake, reduced membrane damage, and decreased sodium and chloride uptake. This treatment resulted in the lowest lipid peroxidation and the highest proline content, along with increased antioxidant enzymatic activity. Based on these findings, it can be concluded that the application of 0.5 g SAH could improve common bean growth and development under salt stress conditions. Since increasing doses of SAH cause Na accumulation in the root, the salt damage-reducing effect may not have been seen with increasing SAH doses. Keywords: Common Bean, Hydrogel, Biochar, Plant Growth, Stress Mitigation