Species- and Metal-Specific Responses of the Ionome of Three Duckweed Species under Chromate and Nickel Treatments

Beneficial or detrimental? How nickel application alters the ionome of soybean plants

The use of nickel (Ni) in agriculture may represent one of the most significant cases of plant hormesis ever reported, as plants exhibit both positive and negative responses depending on the level of exposure to this element. For a more comprehensive understanding of this effect, the next step is to conduct studies on the dynamics of pre-existing chemical elements in the system (ionomic profile), especially when introducing Ni as a novel nutrient for the plants. This micronutrient is of particular interest to the fertilization of leguminous plants, such as the soybean, due to its additional effects on the biological nitrogen fixation process. This study thus evaluated the influence of five doses of Ni (0.0, 0.5, 1.0, 3.0, and 9.0 mg of Ni kg-1) on the ionomic profile of soybean genotypes using modern quantification techniques. The results revealed that the addition of Ni reduced the concentration of cationic micronutrients manganese (Mn), iron (Fe), zinc (Zn), and copper (Cu), while it increased the concentration of macronutrients nitrogen (N) and magnesium (Mg). The application of Ni also resulted in a reduction of the potentially toxic element aluminum (Al). Correlations were also observed for these elements, indicating that Ni could be a controlling agent in elemental absorption and translocation. The ionome of the leaf tissues exhibited the most significant alterations, followed by the grains, nodules, and roots. Exogenous agronomic doses of Ni proved beneficial for the growth and production of soybean plants, although a genotypic effect was observed. The treatment with 9.0 mg of Ni kg-1, resulted in a new ionomic profile related to toxicity, demonstrating suboptimal plant development. Thus, the application of Ni in appropriate doses had a significant impact on the ionomic profile of soybeans, improving plant development and implying resistance to potentially toxic elements such as Al.

Heavy metals/-metalloids (As) phytoremediation with Landoltia punctata and Lemna sp. (duckweeds): coupling with biorefinery prospects for sustainable phytotechnologies

Heavy metals/-metalloids can result in serious human health hazards. Phytoremediation is green bioresource technology for the remediation of heavy metals and arsenic (As). However, there exists a knowledge gap and systematic information on duckweed-based metal phytoremediation in an eco-sustainable way. Therefore, the present review offers a critical discussion on the effective use of duckweeds (genera Landoltia and Lemna)-based phytoremediation to decontaminate metallic contaminants from wastewater. Phytoextraction and rhizofiltration were the major mechanism in 'duckweed bioreactors' that can be dependent on physico-chemical factors and plant-microbe interactions. The biotechnological advances such as gene manipulations can accelerate the duckweed-based phytoremediation process. High starch and protein contents of the metal-loaded duckweed biomass facilitate their use as feedstock in biorefinery. Biorefinery prospects such as bioenergy production, value-added products, and biofertilizers can augment the circular economy approach. Coupling duckweed-based phytoremediation with biorefinery can help achieve Sustainable Development Goals (SDGs) and human well-being.

Duckweed: Research Meets Applications

The Special Issue "Duckweed: Research Meets Applications" of the journal Plants (ISSN 2223-7747) presents a comprehensive update of the current progress in the field [...].