Seed Nanopriming with ZnO and SiO₂ Enhances Germination, Seedling Vigor, and Antioxidant Defense under Drought Stress: Implications for Water Use Efficiency in Jalapeño Pepper

Drought stress is a critical constraint limiting seed germination and seedling establish-ment in field crops such as jalapeño pepper (Capsicum annuum L.). Nanopriming, a seed enhancement technique using nanoparticle suspensions, has emerged as a sustainable approach to improve water-use efficiency during early development. This study evaluated the effects of zinc oxide (ZnO, 100 mg·L⁻¹), silicon dioxide (SiO₂, 10 mg·L⁻¹), and their com-bination (ZnO + SiO₂), stabilized with chitosan, on the germination performance and stress tolerance of four commercial jalapeño hybrids under mannitol-induced drought conditions (0%, 15%, and 30%). Seeds were primed for 12 hours, and physiological, mor-phological, and biochemical responses were measured. Nanopriming significantly im-proved germination percentage, speed, and seedling vigor under both moderate (15%) and severe (30%) osmotic stress. SiO₂ enhanced chlorophyll content and germination rate un-der 15% stress, while ZnO promoted proline and flavonoid accumulation under 30%. The combined ZnO + SiO₂ treatment delivered the most consistent improvements across all traits and stress levels. Multivariate analysis revealed clear treatment-specific and drought-dependent response patterns, emphasizing the role of osmolytes and antioxidant activity. These results highlight the potential of nanopriming as a low-cost, scalable strat-egy to enhance early-stage drought resilience and promote efficient water use in jalapeño cultivation under semi-arid conditions.