Extended Abstract
Background and Aim: Drought stress is one of the most critical environmental constraints that severely limits plant growth and productivity, particularly in medicinal plants, which are highly valued for their bioactive compounds. In recent years, silver nanoparticles (AgNPs) have gained considerable attention due to their unique antioxidant properties and beneficial physiological effects on plants, emerging as a novel strategy for enhancing tolerance against abiotic stresses. The present study was designed to investigate the effects of biogenic silver nanoparticles synthesized from Saw Palmetto (Serenoa repens) fruit extract on the physiological and biochemical responses of a medicinal plant subjected to drought stress.
Material and methods: For the synthesis of nanoparticles, an aqueous extract of Saw Palmetto was used as a reducing and stabilizing agent following an eco-friendly green chemistry approach. The biosynthesized AgNPs were thoroughly characterized using UV-Vis spectroscopy, which revealed a characteristic absorption peak at 435 nm, FTIR analysis for identifying functional groups, and SEM analysis showing spherical morphology with an average particle size of 32.6 nanometers. The experimental plants were treated with three different concentrations of AgNPs (0, 25, and 50 mg L⁻¹) while being exposed to drought stress and maintained at 40% field capacity over a period of 15 days. Key physiological and biochemical parameters including relative water content, total chlorophyll, membrane stability index, antioxidant enzyme activities (SOD, CAT, POD), and malondialdehyde content were measured to evaluate treatment effectiveness.
Results: The results demonstrated that treatment with 50 mg L⁻¹ AgNPs significantly increased RWC by 28.3%, total chlorophyll by 21.7%, and MSI by 34.1% compared to the control group. Furthermore, the activities of SOD, CAT, and POD were enhanced by 47.5%, 39.2%, and 42.6%, respectively, while MDA content decreased by 31.8%, indicating reduced oxidative damage.
Conclusion: These findings collectively suggest that biogenic AgNPs synthesized from Saw Palmetto effectively improved water status, preserved membrane integrity, and strengthened the antioxidant defense system, thereby conferring enhanced drought tolerance in the studied medicinal plant. Therefore, these green-synthesized nanoparticles may serve as promising eco-friendly agents for sustainable management of drought stress and improving crop resilience under water-limited conditions.