Differential effects of copper nanoparticles/microparticles in agronomic and physiological parameters of oregano (Origanum vulgare)

The effects of metallic copper nanoparticles (nCu) in plants are notwell understood. In this study, soil grown oregano (Origanum vulgare) was exposed for 60 days to nCu and Cu microparticles (mu Cu) at 0-200 mg Cu/kg. At harvest, Cu accumulation, biomass production, nutrient composition, and Cu fractions in soil were measured. Except for mu Cu at 50 mg/kg, both nCu and mu Cu increased root Cu (28.4-116.0%) and shoot Cu (83.0-163.0% and 225.4-652.5%, respectively), compared with control. Copper accumulation from mu Cu increased as the external mu Cu increased. nCu and mu Cu did not affect shoot length, malondialdehyde, or chlorophyll, but increased water content (6.9-12.5%) and reduced shoot biomass (21.6-58.5%), compared with control. In addition, at 50 mg/kg, mu Cu decreased root biomass and length (48.6% and 20.5%, respectively) and water content (1.8% and 3.9% at 100 and 200 mg/kg, respectively). All treatments modified root and shoot Ca, Fe, Mg, and Mn (p <= 0.05). Additionally, all Cu treatments decreased starch (33.9-58.5%), total sugar (39.5-55.7%), and reducing sugar (13.6-33.9%) in leaves. Results showed that metallic Cu nanoparticles/microparticles affected agronomical and physiological parameters in oregano, which could impact human nutrition. However, smaller size particles do not necessarily imply greater toxicity. (c) 2017 Elsevier B.V. All rights reserved.