Phytotoxicity of multi-walled carbon nanotubes on red spinach (Amaranthus tricolor L) and the role of ascorbic acid as an antioxidant

► MWNTs are selected for study of the systemic toxicity and the potential influence on red spinach. ► Microscopic observation revealed some adverse effects on root and leaf. ► Cell damage were detected on 15 days after the exposure to MWNTs. ► ROS increase ceased once ascorbic acid was added into media. ► Oxidative stress seems to be the key element responsible for causing the toxicity.