Seed Priming with Biosynthesized Zinc Oxide Nanoparticles for Enhancing Seed Germination and Vigour through Promoting Antioxidant and Hydrolytic Enzyme Activity in Green gram (Vigna radiata)

The impact of seed priming treatment using biosynthesized zinc oxide nanoparticles from (Coriandrum sativum L.) leaves on seed germination and seedling vigour parameters in green gram was assessed at the Seed Centre, TNAU, Coimbatore, from 2020 to 2021. The green gram seeds were primed with various concentrations of biosynthesized zinc oxide nanoparticles (ZnO NPs), namely, 100 mg/lit, 200 mg/lit, 300 mg/lit, 400 mg/lit, 500 mg/lit, and 600 mg/lit, for 3 h. Regardless of the concentration, the ZnO NPs-primed seeds exhibited a significant positive effect on seed germination, seedling vigour, and dry matter production compared to unprimed control and hydro-primed seeds. Seed priming with ZnO NPs at a concentration of 500 mg/lit resulted in an enhanced water imbibition rate in seeds (25.8%), which promoted the synthesis of the hydrolytic enzyme α-amylase (14.73 mg maltose min⁻¹) and the respiratory enzyme dehydrogenase (0.312 units g⁻¹). The ZnO NPs-primed seeds at 500 mg/lit also demonstrated a pronounced effect on antioxidant enzyme activity, including catalase (2138 units g⁻¹), peroxidase (0.342 mg g⁻¹ min⁻¹), superoxide dismutase (2.86 mg protein⁻¹ min⁻¹), and reduced lipid peroxidation value (0.105 units g⁻¹) compared to hydro-primed and control seeds. The analysis of Zn content confirmed a higher concentration of Zn in the treated seeds, ranging from 52 to 104 ppm, and in growing seedlings from 103 to 357 ppm. These results indicate that ZnO NPs seed priming treatment enhances seed quality parameters by accelerating the hydrolytic enzyme and antioxidant defence system in green gram seeds.