Abstract
Tomato (Solanum lycopersicum L.) is a globally important horticultural crop; however, inconsistent germination and weak early seedling vigour remain major bottlenecks to productivity. Seed nanopriming using zinc oxide nanoparticles (ZnO NPs) represents an emerging, eco-compatible strategy for enhancing seed performance by modulating early biochemical and physiological processes. This study investigated the influence of ZnO NPs seed priming on seed quality traits and physio-biochemical responses in three genetically distinct tomato varieties: Pusa Rohini, H-81, and Pusa Prasanskrit. The optimal concentration (50ppm) of ZnO NPs significantly enhanced germination percentage, speed of germination, seedling vigour indices, shoot and root elongation, and biomass accumulation while reducing mean germination time. Biochemically, ZnO nano-primed seedlings exhibited elevated levels of total chlorophyll, proline, and total phenol along with enhanced antioxidant enzyme activities (superoxide dismutase, catalase and peroxidase). A concurrent reduction in malondialdehyde content indicated lower lipid peroxidation and oxidative damage. These effects collectively suggest improved homeostasis and metabolic efficiency. The findings confirm that 50ppm ZnO nanopriming modulates germination-linked signaling and antioxidant defense pathways, accelerating early seedling establishment and enhancing seed quality through improved enzyme activity and seedling development in tomato, while offering a cost effective and environmentally sustainable approach.