Multi-walled Carbon Nanotubes as Elicitors in Tomato Seedlings (Solanum Lycopersicum L.): Impact on Biocompounds and Amino Acids Production, Nutrient Uptake, Growth of Seedlings, and Biological Quality of the Soil

Abstract Purpose The present study evaluated the effects of multi-walled carbon nanotubes (MWCNTs) applied directly to the soil on the content of biocompounds, amino acids, nutrient uptake, and growth in tomato seedlings, and the impacts of MWCNTs on soil biological quality. Methodology The experiment was conducted in a greenhouse using a randomized complete block design. Treatments included direct soil suspensions containing 0.25, 0.50, 1.0, or 2.0 mg of MWCNTs. Destructive sampling and soil samples were taken twenty days after exposure. Chemical and biochemical variables of the seedlings, as well as soil quality parameters, were evaluated using analytical techniques such as chromatography and spectroscopy. Results Treatments 0.25 and 0.50 MWCNTs favored urease enzyme activity, and 1.0 MWCNTs increased soil dehydrogenase activity and iron (Fe 2+ ) uptake in tomato seedlings. The 2.0 MWCNTs improved the activity of dehydrogenase and phosphatase in soil. The MWCNTs changed the chemical composition and favored the synthesis of chlorophylls and carotenoids in seedlings in a concentration-dependent manner. MWCNTs improved the concentration of biocompounds (gallocatechin, resorcinol, catechol, caffeic acid, and metoxybenzoic acid), and amino acids in tomato seedlings, such as proline, histidine, glycine, serine, and tryptophan. The 1.0 MWCNTs treatment favored a greater content of biocompounds in tomato seedlings. Conclusion Based on these results, MWCNTs could be used as elicitors in soil enzymatic activity and production of biocompounds and osmoprotective amino acids in seedlings.