Phytotoxic effects of copper oxide nanoparticles on two Brassica species during the seedling stage

Nanotechnology has the potential to increase global food production.However, the widespread application of nanoparticles (NPs) in agriculture is relatively slow due to concerns on accumulation, translocation, and toxicity in food crops.One such NP is the Cu-based NPs since Cu is a micronutrient and exhibits antimicrobial and antifungal activities.In this study, the uptake of CuONP (vs.bulk CuO) and their toxicological effects in cabbage (Brassica oleracea L. var.capitata) and pechay (B.rapa L. var.chinensis) were investigated.High concentrations of CuONP and bulk CuO resulted in the overproduction of ROS, causing elevated catalase, ascorbate peroxidase, and malondialdehyde, which are consistent with the observed inhibition of seedling growth.All treatments, however, had no significant effect on levels of chlorophyll and carotenoids.AAS analysis confirmed that the phytotoxic symptoms may be attributed to the accumulation of Cu.Overall, results showed that CuONP is more toxic than bulk CuO in both crops, particularly in cabbage.The estimated TC50 values are 29.06 ± 1.75 mg/L for CuONP and 353.58 ± 16.41 mg/L for bulk CuO in cabbage, and 71.72 ± 3.03 mg/L for CuONP and 371.52 ± 22.79 mg/L for bulk CuO in pechay.This study demonstrates that Cu-based NPs can be taken up by crop seedlings, indicating a potential pathway for entry into the food chain.