Enhancing jalapeño pepper seedling quality for transplantation and potential stress tolerance through seed nanopriming

The use of nanoparticles as a tool for improving horticultural seedling production has generated growing interest, but their overall impact on seedling physiology still needs further exploration. This study evaluated the effect of nanopriming with ZnO, SiO₂, and ZnO + SiO₂ on the physiological, photosynthetic, and biochemical profile of Capsicum annuum L. seedlings, with the aim of strengthening their quality for transplanting. Growth parameters such as root biomass, shoot biomass, total biomass, stem length and diameter, and number of leaves were evaluated, as well as the content of photosynthetic pigments (chlorophyll a, b, total, carotenoids, SPAD index) and nitrate reductase (NR) activity. Seedlings treated with nanoparticles, especially ZnO and ZnO + SiO₂, showed more robust root development, higher levels of total chlorophyll and SPAD, and higher NR activity compared to treatments with commercial biostimulants, hydropriming, and the control. These results show that the use of nanoparticles not only enhances a specific variable but also strengthens key processes in seedlings in a comprehensive manner, generating a more balanced and functional physiological profile for transplanting. Multivariate analysis using heat mapping, principal component analysis (PCA), and radar charts confirmed the positive interaction between the different variables, highlighting the ZnO + SiO₂ treatment as the most effective strategy for improving the physiological quality of jalapeño seedlings. This work provides new evidence on the potential of nanopriming as a biotechnological tool in horticulture.