Decoding Plant Hormesis: Cerium Oxide Nanoparticles and the Role of Soil EPS in the Growth Dynamics of Allium sativum L.

Abstract

The extensive production of cerium oxide nanoparticles (CeO₂ NPs) for agro-industrial purposes has led to their inevitable release into the environment, yet their ecological and threshold implications on plants are not fully understood. This study investigated the hormetic effects of CeO₂ NPs (0.125–4 mg·L^–1) on Allium sativum L. and how extracellular polymeric substances (EPS) modulate their effects. From the results, CeO₂ NPs exerted a hormetic effect on growth, physiological, and biochemical parameters, i.e., stimulatory at low concentration (0.25 mg·L^–1) and inhibitory at the highest concentration (4 mg·L^–1). Further, the toxicity observed at higher concentrations was alleviated upon EPS addition, resulting in an overall improved growth and reduced oxidative stress. Hence, our findings aim to depict the possible outcomes of EPS-NP-plant interaction that could prevail in the environment, offering insights for safer and more effective usage of NPs in agriculture to improve food safety.