Effects of Fertigation with Untreated and Treated Leachates from Municipal Solid Waste on the Microelement Status and Biometric Parameters of Viola × wittrockiana

Abstract

Landfill leachate can release pollutants into the environment. Nevertheless, it can be treated using a phytodepuration system via constructed wetlands to reduce contaminants. Moreover, this leachate can also increase the availability of macro and micronutrients in soil and water. In this trial, the reuse of untreated and treated wastewater from municipal solid waste (MSW) for fertigation was assessed. Plantlets of Viola × wittrockiana (pansy) were grown in a greenhouse and five fertigation treatments were applied: W9.0 (pure wastewater, EC 9.0 dS m−1), W4.5 (diluted wastewater, EC 4.5 dS m−1), DW4.5 (depurated wastewater, EC 4.5 dS m−1), PW4.5 (phytodepurated wastewater, EC 4.5 dS m−1), and T (tap water, control, EC 1.5 dS m−1). The treatment with untreated wastewater had a negative effect on plant dry weight, leaf size, specific leaf area, water content, and the number of closed and open flowers, due to the high concentration of SO42− in the fertigation water. It also reduced the content of Cu, Mn, Fe, and Zn with respect to the control, because of the dry biomass diminution. Conversely, fertigation with phytodepurated wastewater enhanced root and shoot dry weight, water content, and the number of closed and open flowers. Cu and Mn contents in flowers surpassed the content detected in plants fertigated with untreated leachates. These findings demonstrate that phytodepurated wastewater obtained from MSW can be employed for the fertigation of this species.

Phytochemical, Nutritional and Mineral Content of Four Edible Flowers

“…Phosphorous was measured by spectrophotometry using the molybdenum blue method [ 28 ], while the cations and microelements were determined by atomic absorption spectrophotometry (SpectrAA 240FS, Varian Australia Pty Ltd., Mulgrave, Australia). The absorbance measurements were performed at specific wavelengths (λ): 766.5 nm (K), 589.0 nm (Na), 422.7 nm (Ca), 285.2 nm (Mg), 324.8 nm (Cu), 279.5 nm (Mn), 248.3 nm (Fe), and 213.9 nm (Zn) [ 29 ]. The organic nitrogen, total crude proteins and macroelements were expressed as mg/g of dry weight (DW), while the microelements were reported as µg/g DW.…”

“…The biplot of the PCA (Figure 4) analysis highlights V. cornuta's distinct position, influenced by the presence of unique compounds such as tricyclene (1), limonene (6), and 3-hexen-1-ol benzoate (29) in its flower emission. moschata, with V. cornuta located in the upper right quadrant (positive on both PC1 and PC2) and C. moschata positioned in the lower right quadrant (positive on PC1 and negative on PC2).…”

“…The biplot of the PCA (Figure 4) analysis highlights V. cornuta's distinct position, influenced by the presence of unique compounds such as tricyclene (1), limonene (6), and 3-hexen-1-ol benzoate (29) in its flower emission. Additionally, V. cornuta displayed higher manganese and zinc content compared to the other species.…”