Copper Oxide Nanoparticles Influenced Ionome, Reduced Growth, Altered Pigments and Stomatal Morphology in Mentha arvensis L.

Abstract

Copper oxide nanoparticles (CuO NPs) are being enormously used in agriculture, aquaculture, textile, cosmetic, food and pharmaceutical industries. CuO NPs are reported to make their presence in soil water and air due to their release in the environment. Mentha arvensis L. (Lamiaceae) is commercially grown for essential oil across the world due to its medicinal value. The present study reports the responses of M. arvensis to CuO nanoparticles (0.0–5.0 μg mL-1) after 18 d exposure. The build-up of high copper concentrations in M. arvensis plant tissues (roots and leaves) confirms the internalization and movement of CuO NPs in shoots. CuO NPs modified ionomes of roots and leaves of M. arvensis. Both roots and leaves of M. arvensis plants exposed to CuO NPs exhibit altered levels of micro (reduced Fe, Mn, and upregulated Zn and Mo contents) and macronutrients (decreased Ca, Mg and K levels). Further, CuO NPs decreased biomass, total chlorophyll, chlorophyll a, chlorophyll b and relative water contents and increased carotenoids and anthocyanin contents in M. arvensis leaves. Besides, CuO NPs caused alteration in stomatal morphology of test plant. The present study suggests sustainable use and environmental release of CuO NPs due to their possible bio-toxic consequences.