Silicon Nanoparticles (SiO2 NPs) Boost Drought Tolerance in Grapevines by Enhancing Some Morphological, Physiological, and Biochemical Traits

Abstract Drought is a significant abiotic stress that adversely affects plant growth, development, and metabolic processes, posing a global threat to food security. In recent years, nanotechnology has emerged as a promising strategy to mitigate environmental challenges and has been tested on various plant species; however, its application to grapevines remains largely unexplored. This study aims to investigate the potential of silicon nanoparticles (SiO 2 NPs) to modulate morphological, physiological, and biochemical parameters in grapevine saplings (5 BB/Crimson Seedless, 41 B/Crimson Seedless, and 1103 P/Crimson Seedless) under drought stress conditions. Saplings were treated with foliar applications of different concentrations of SiO 2 NP solutions (0 (control), 1, 10, and 100 ppm) under well-irrigated (90–100% field capacity) and drought stress (40–50% field capacity) conditions. The results indicated that the application of SiO 2 NPs at 10 ppm concentration enhanced growth parameters (such as leaf area, leaf number, shoot fresh and dry weight, root fresh and dry weight) and chlorophyll content under both well-irrigated and drought conditions. Additionally, there was an improvement in leaf relative water content (RWC) and stomatal conductance, correlating with increased protein content. Under drought conditions, oxidative stress indicators, including drought index, leaf temperature, membrane injury index, hydrogen peroxide (H 2 O 2 ) content, and malondialdehyde (MDA) levels, showed a significant decrease. Concurrently, proline content, total phenolic compounds, and activities of antioxidant enzymes (SOD, CAT, and APX), which increased under drought stress, were reduced in the presence of 10 ppm SiO 2 NPs, suggesting a mitigation of oxidative stress. To comprehensively evaluate the effects of SiO 2 NP concentrations, irrigation regimes, and rootstock/variety combinations, correlation analysis, principal component analysis (PCA), and hierarchical clustering heatmap analysis were performed. Collectively, the findings suggest that the observed drought-induced oxidative stress tolerance in grapevine saplings in the presence of 10 ppm SiO 2 NPs may result from the influence of antioxidant systems leading to a balanced redox potential. These results support the argument that SiO 2 NPs play a crucial role in enhancing drought tolerance, with implications for managing drought stress in other agricultural crops as well.