Foliar Application of Se and TiO2 Nanoparticles Induces Physiological Stability and Stem Anatomical Remodeling Without Affecting Vegetative Growth in Lilium cv. Concador

Lilium sp. is one of the most commercially important ornamental species; however, improving its ornamental quality remains a challenge for production systems. In this context, nanoparticles have been proposed as an innovative alternative to optimize the agronomic performance of ornamental crops. The objective of this study was to determine how the foliar application of selenium nanoparticles (SeNPs) and titanium dioxide nanoparticles (TiO2NPs) modifies the physiological response and stem morphoanatomy of Lilium cv. Concador. Plants were grown under greenhouse conditions using conventional agronomic management for commercial Lilium production. We evaluated vegetative growth variables, relative chlorophyll content (SPAD), root biomass, flowering characteristics, and quantitative stem anatomy using histological, morphometric, and multivariate statistical analyses. Most agronomic variables, including plant height, number of leaves, shoot biomass, and flower opening, did not differ significantly between treatments, indicating that the nanoparticles did not compromise vegetative development. In contrast, root biomass and stem anatomical organization responded differently depending on nanoparticle type and applied dose. SeNPs, particularly at the highest dose, promoted greater development of parenchyma and vascular tissue, while TiO2NPs induced dose-dependent anatomical responses, with less parenchyma expansion and less pronounced vascular remodeling. Taken together, these results demonstrate that foliar application of nanoparticles induces early remodeling of the stem’s functional architecture without affecting vegetative growth and show that quantitative anatomy is a sensitive tool for detecting early responses to nano-inputs in ornamental species.