Seed Nanopriming with ZnO and SiO2 Enhances Germination, Seedling Vigor, and Antioxidant Defense Under Drought Stress

Drought stress is one of the main factors limiting seed germination and seedling establishment in field crops such as jalapeño peppers (Capsicum annuum L.). Nanopriming, a seed improvement technique using nanoparticle suspensions, has emerged as a sustainable approach to improving water use efficiency during the early stages of development. This study evaluated the effects of zinc oxide (ZnO, 100 mg·L−1), silicon dioxide (SiO2, 10 mg·L−1), and their combination (ZnO + SiO2), stabilized with chitosan, on the germination yield and drought tolerance of jalapeño seeds under mannitol-induced water stress (0%, 15%, and 30%). Compared to the hydroprimed control (T1), nanoparticle treatments consistently improved seed yield. Priming with ZnO (T2) increased the germination percentage by up to 25%, priming with SiO2 (T3) improved the germination rate by 34%, and the combined treatment (T4: ZnO + SiO2) improved the fresh weight of the seedlings by 40%. Proline accumulation increased 7.5 times, antioxidant capacity (DPPH) increased 6.5 times, and total phenol content increased 4.8 times in the combined treatment. Flavonoid levels also showed notable increases, suggesting enhanced antioxidant defense. These results clearly demonstrate the superior efficacy of nanoparticle pretreatment compared to conventional hydraulic pretreatment, especially under drought conditions. Multivariate analysis further highlighted the synergistic role of ZnO and SiO2 in improving osmolite accumulation, antioxidant activity, and water use efficiency. Nanopriming with ZnO and SiO2 offers a promising, economical, and scalable strategy to improve germination, early growth, and drought resistance in jalapeño pepper cultivation under semi-arid conditions.