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.

Nutritional quality assessment of tomato fruits after exposure to uncoated and citric acid coated cerium oxide nanoparticles, bulk cerium oxide, cerium acetate and citric acid

Little is known about the effects of surface modification on the interaction of nanoparticles (NPs) with plants. Tomato (Solanum lycopersicum L.) plants were cultivated in potting soil amended with bare and citric acid coated nanoceria (nCeO_2, nCeO₂+CA), cerium acetate (CeAc), bulk cerium oxide (bCeO₂) and citric acid (CA) at 0-500 mg kg^-1. Fruits were collected year-round until the harvesting time (210 days). Results showed that nCeO₂+CA at 62.5, 250 and 500 mg kg^-1 reduced dry weight by 54, 57, and 64% and total sugar by 84, 78, and 81%. At 62.5, 125, and 500 mg kg^-1 nCeO₂+CA decreased reducing sugar by 63, 75, and 52%, respectively and at 125 mg kg^-1 reduced starch by 78%, compared to control. The bCeO₂ at 250 and 500 mg kg^-1, increased reducing sugar by 67 and 58%. In addition, when compared to controls, nCeO₂ at 500 mg kg^-1 reduced B (28%), Fe (78%), Mn (33%), and Ca (59%). At 125 mg kg^-1 decreased Al by 24%; while nCeO₂+CA at 125 and 500 mg kg^-1 increased B by 33%. On the other hand, bCeO₂ at 62.5 mg kg^-1 increased Ca (267%), but at 250 mg kg^-1 reduced Cu (52%), Mn (33%), and Mg (58%). Fruit macromolecules were mainly affected by nCeO₂+CA, while nutritional elements by nCeO₂; however, all Ce treatments altered, in some way, the nutritional quality of tomato fruit. To our knowledge, this is the first study comparing effects of uncoated and coated nanoceria on tomato fruit quality.