An Innovative Approach: Alleviating Cadmium Toxicity in Grapevine Seedlings Using Smoke Solution Derived from the Burning of Vineyard Pruning Waste.

Although plant-derived smoke solutions (SSs) have exhibited growth-promoting properties in various plant species, their potential role in mitigating heavy metal stress, specifically in grapevines, has remained unexplored and unreported. This knowledge gap prompted the present study to evaluate the efficacy of foliar application of SSs derived from vineyard pruning waste at concentrations of 0%, 0.5%, 1%, and 2% in mitigating Cadmium (Cd) phytotoxicity in grape saplings. In our study, cadmium stress was induced by applying 10 mg/kg CdCl₂ to the root area of the saplings, in conjunction with fertilizers. Our findings showed that exposure to Cd toxicity impeded the growth of grapevine saplings, adversely affecting shoot and root length, as well as fresh weight. Furthermore, it resulted in a reduction in chlorophyll content, stomatal conductance, and leaf water content while significantly increasing membrane damage and lipid peroxidation. Notably, the application of 0.5% SS enhanced grapevine sapling growth and alleviated Cd stress-induced damage by more effectively regulating physiological and biochemical responses compared to the control and other concentrations. Based on our results, under Cd stress conditions, the application of 0.5% SS effectively increased chlorophyll content, relative water content (RWC), stomatal conductance (1.79 mmol.m^-2.sn^-1), and total phenolic content (1.89 mg.g^-1), whereas it significantly reduced malondialdehyde (MDA) levels and membrane damage (1.35 nmol.g^-1). Additionally, it significantly elevated the activities of antioxidant enzymes, including superoxide dismutase (SOD) (2.16 U.mg^-1), catalase (CAT) (1.55 U.mg^-1), and ascorbate peroxidase (APX) (3.03 U.mg^-1). The study demonstrated that plant-derived SS mitigates Cd stress in grapevines by enhancing antioxidative defence mechanisms.