Biochemical and physiological effects of copper compounds/nanoparticles on sugarcane (Saccharum officinarum)

The widespread use of copper based nanomaterials has been accompanied by an increasing interest in understanding their potential risks. It is essential to understand the effects of these nanoparticles on edible crops by performing long-term experiments at relevant exposure concentrations. Sugarcane is the source of 70% of the world's sugar supply and the widespread use of refined sugar and the consumption of raw sugarcane can provide a route for nanoparticles to enter the food supply. In order to evaluate the biochemical and physiological effects of copper nanoparticle exposure, sugarcane was grown for one year in soil amended with 20, 40, and 60 mg/kg of Kocide 3000 (a copper based fungicide), copper metal nanoparticles, micro-sized CuO, and CuCl₂. The results show that stress indicators such as catalase and ascorbic peroxidase enzymatic activity in the sugarcane plant were activated by all the copper based materials at different concentrations. Sugarcane plants exposed to nearly all copper treatments showed dosage dependent increases in copper concentrations in root tissues. Translocation of copper to aerial tissues was minimal, with copper concentrations not being significantly different from controls. In addition, Chlorophyll A content was higher in plants treated with Kocide 3000 at 20 and 60 mg/kg, μCuO at 20 mg/kg, and CuCl₂ at 20 and 60 mg/kg. To our knowledge, this is the first report on the effects of nano-copper compounds in sugarcane crop.