Enhancing Jalapeño Pepper Seedling Quality for Transplantation and Potential Stress Tolerance through Seed Nanopriming

The application of nanoparticles (NPs) has become a promising strategy for improving the physiological quality of horticultural seedlings and increasing their tolerance to abiotic stress. In this study, the effects of hydropriming and nanopriming with ZnO, SiO2, and ZnO+SiO2, as well as a nanofertilizer containing zinc and molybdenum (ZnMo), and two commercial biostimulants (Osmoplant and Codasil), on the morphological, photosynthetic, and biochemical performance of Capsicum annuum L. seedlings, with the aim of improving both transplant success and stress resistance. Key parameters such as root, stem, and total biomass, stem length and diameter, number of leaves, photosynthetic pigments (chlorophyll a, chlorophyll b, total chlorophyll, carotenoids, SPAD index), and nitrate reductase (NR) activity were measured under controlled conditions. Seedlings treated with NP, particularly ZnO and ZnO+SiO2, showed superior root development, higher chlorophyll content, and higher NR activity compared to hydropriming, commercial biostimulants, and the untreated control. Multivariate analyses (heat maps, principal component analysis, and radial graphs) revealed synergistic improvements in morphological and physiological traits, with ZnO+SiO2 emerging as the most effective treatment for promoting a robust and stress-adapted seedling profile. These findings provide strong evidence that nanopriming represents a valuable biotechnological tool for improving seedling vigor and abiotic stress tolerance, contributing to sustainable and efficient horticultural production systems.