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 100 mg kg-1, then watered with 0, 10, or 100 µM 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 ~29% lower than seeds from untreated plants. All forms of Cu combined with 10 µM 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 × KN significantly altered the nutritional value of common beans, which has potential implications to agricultural practices incorporating Cu as either a pesticide or fertilizer.

Physiological and biochemical effects of nanoparticulate copper, bulk copper, copper chloride, and kinetin in kidney bean (Phaseolus vulgaris) plants.

It is essential to understand the interactions of engineered nanoparticles (ENPs) with additives used in agriculture and their impacts on crop plants. In this study, kidney bean (Phaseolus vulgaris) plants were grown in potting soil amended with either nano copper (nCu), bulk copper (bCu), or copper chloride (CuCl2) at 0, 50, and 100mg/kg, combined with 0, 10, or 100µM of kinetin (KN). Plant growth, Cu, micro and macroelement concentrations, chlorophyll content, and enzymatic activity were examined in 55-day old plants. Results showed that root Cu content was at least 10-fold higher, compared to other tissues. Accumulation of Cu in roots was decreased by 100µM KN up to 25%. A concentration-dependent increase of Cu content in leaves by Cu×KN was observed. Chlorophyll production was diminished by CuCl2+KN between 22 and 30%, showing a hormetic response. Catalase activity was repressed by 65% to 82% in bCu and CuCl2 treatments. From all essential elements, Ca, Mn, and P were reduced by 33% to 97% in bCu, CuCl2, and CuCl2+KN treatments. However, this did not impact stem elongation and tissue biomass that increased up to 55% under exposure to bCu and CuCl2. Our results demonstrate that KN combined with ionic Cu could have negative implications in kidney bean plants, since this combination impacted chlorophyll production and nutrient element accumulation.