Nanoceria versus bulk cerium oxide: differential effects on growth, antioxidants, pigments, and essential oil of Dracocephalum kotschyi Boiss.

Abstract Background Dracocephalum kotschy Boiss., an endemic and vulnerable herb native to Iran, is highly valued for its distinctive botanical features and wide range of pharmacological properties. However, its growth and metabolite production can be affected by environmental conditions, necessitating strategies to improve agronomic performance and phytochemical quality. This study aimed to investigate the effects of cerium oxide nanoparticles (CeO 2 NPs) and bulk CeO 2 at different concentrati