Modulation of CuO nanoparticles toxicity to green pea (Pisum sativum Fabaceae) by the phytohormone indole-3-acetic acid

The response of plants to copper oxide nanoparticles (nano-CuO) in presence of exogenous phytohormones is unknown. In this study, green pea (Pisum sativum) plants were cultivated to full maturity in soil amended with nano-CuO (10-100 nm, 74.3% Cu), bulk-CuO (bCuO, 100-10,000 nm, 79.7% Cu), and CuCl2 at 50 and 100 mg/kg and indole-3-acetic acid (IAA) at 10 and 100 M. Results showed that IAA at 10 and 100 mu M, averaged over all Cu treatments, reduced the number of plants by similar to 23% and similar to 34%, respectively. IAA at 10 pM, nano-CuO at 50 mg/kg, b-CuO at 50 mg/kg, and CuCl2 at 100 mg/kg reduced pod biomass by about 50%. Although some combinations of IAA, mainly at 100 pM, with the Cu compounds altered nutrient accumulation in tissues, none of them affected pod elements. Conversely, without IAA, nano-CuO at 50 mg/kg, increased pod Fe and Ni by 258% and 325%, respectively, while bCuO at 100 mg/kg increased pod Ni by 275%, compared with control. With IAA at 10 mu M, nano-CuO (100 mg/kg) and bCuO (50 mg/kg) increased stem Cu by similar to 84% and similar to 78%. When IAA increased to 100 mu M, nano-CuO and bCuO reduced stem Ca by 32% and 37%, and Mg by similar to 35%. Results suggest that both the nano-CuO and bCuO could.improve the nutritional quality of pea pods, while exogenous IAA combined with Cu-based compounds could impact green pea production since these treatments reduced the number of plants and pod biomass. (C) 2017 Elsevier B.V. All rights reserved.