This study was conducted to evaluate the efects of foliar-applied nano-silicon (Nano-Si, 0–50 mg/L) and silicon (Si, 25 mg/L) on growth and physiological characteristics of ginger mint (Mentha gracilis R.Br.) under diferent levels of drought stress (DS: 100%, 75%, 55%, and 35% FC). The traits examined included plant height, biomass, antioxidant enxymes (SOD, GPX, APX) activities, protein levels, MDA, proline, H2O2, essential oil production, and chlorophyll fuorescence indices (CFI: F0, Fv, Fm, Fv/F0, and Fv/Fm) using high-performance chlorophyll fuorometer. The esults showed that exposure to Si/ Nano-Si alleviated the negative efects of drought stress in ginger mint. Application of Si/Nano-Si increased plant height, biomass, proline, APX, SOD, CFIs and essential oil, and decreased H2O2, and MDA in exposed plants under DS. By applying of 25 mg/L of Si, plant height, biomass, essential oil, APX, SOD, Fm and Fv increased up to 22.0%, 3.5%, 18.0%, 37.0%, 38.0%, 27.0% and 98.0%, and H2O2, and MDA decreased by 8.5% and 32.0%, respectively under 35%FC. Overall, foliar application of 25 mg/L of Si or 50 mg/L of nano-Si alleviated the efects of drought stress and improved the physiological and morphological characteristics of ginger mint, especially under severe drought stress conditions. Application of NanoSi/Si can be benefcial as a strengthening substance for growth parameters under drought stress conditions by stimulating photosynthesis and inducing essential oil accumulation and antioxidant activity.
