Different forms of copper and kinetin impacted element accumulation and macromolecule contents in kidney bean (Phaseolus vulgaris) seeds

The relationship between engineered nanomaterials and plant biostimulants is unclear. In this study, kidney bean (Phaseolus vulgaris) plants were grown to maturity (90 days) in soil amended with nano copper (nCu), bulk copper (bCu), or copper chloride (CuCl2) at 0, 50, or 100mg kg(-1), then watered with 0, 10, or 100 mu M of kinetin (KN). Seeds were harvested and analyzed via ICP-OES and biochemical assays. While seed production was largely unaffected, nutritional value was significantly impacted. Accumulation of Cu was enhanced by 5-10% from controls by Cu-based treatments. Fe was the only macro/microelement significantly altered by nCu, which was similar to 29% lower than seeds from untreated plants. All forms of Cu combined with 10 mu M KN reduced Mg from 9 to 12%. Application of KN plus bCu or CuCl2 elevated concentrations of Mn (31-41%) and S (19-22%), respectively. Protein content of seeds was stimulated (11-12%) by bCu, on average, and depressed by CuCl2 + KN (up to 22%). Variations in sugar and starch content were insignificant, compared to controls. Our results indicate that the interaction Cu x KN significantly altered the nutritional value of common beans, which has potential implications to agricultural practices incorporating Cu as either a pesticide or fertilizer. (C) 2018 Elsevier B.V. All rights reserved.