Search Results (89)

Phytoremediation is a sustainable approach for the remediation of heavy metal–contaminated soils; however, the management of contaminated biomass generated during this process remains an insufficiently addressed challenge. Such biomass constitutes a secondary waste stream that may release mobile pollutants and pose environmental risks. In this study, an integrated ecotoxicological assessment framework was applied to evaluate phytoremediation-derived biomass and its transformation products obtained via pyrolysis. Two types of woody biomass with different heavy metal contents and their corresponding biochars produced at 700 °C were investigated. A multitrophic battery of bioassays combining direct exposure assays using terrestrial organisms (higher plants, Eisenia fetida, and soil microbial activity) with leachate-based assays using aquatic organisms (Lemna minor, Daphnia magna, and Aliivibrio fischeri) was applied. Untreated biomass exhibited high to extreme toxicity in aquatic systems (toxic units, TU >100) and significant phytotoxic effects. Pyrolysis substantially reduced contaminant mobility and ecotoxicity of leachates, resulting in lower toxicity (TU typically <15) and no significant effects on plant growth, earthworm survival, or soil microbial functional diversity. Residual toxicity was linked to elevated pH and trace amounts of thermally generated organic substances. These results demonstrate that pyrolysis effectively reduces the environmental risk of contaminated biomass and supports the use of multitrophic ecotoxicological testing for safe waste valorization within circular economy strategies. Full article

Cadmium (Cd), a highly mobile and phytotoxic heavy metal, threatens plant growth and food safety and has increased interest in woody plant-based phytoremediation. However, the genome-wide characteristics of the NAC transcription factor family and its role in Cd tolerance remain largely unknown in pomegranate (Punica granatum L.), a stress-tolerant woody plant. In this study, 121 PgNAC genes were identified from the chromosome-level genome of the pomegranate cultivar ‘Tunisia’. Phylogenetic analysis classified these genes into two major groups and 16 subgroups. PgNAC genes were unevenly distributed across the eight chromosomes and showed evident clustered distribution patterns. Synteny and Ka/Ks analyses further revealed that segmental and tandem duplication jointly shaped the expansion of the PgNAC family, while the duplicated pairs have largely evolved under strong purifying selection. Conserved motif and gene structure analyses showed that PgNAC proteins possessed a highly conserved N-terminal NAM domain, whereas their C-terminal regions were relatively divergent. Promoter analysis further identified abundant hormone- and stress-responsive cis-elements, suggesting diverse regulatory roles of the PgNAC family. Transcriptome profiling identified PgNAC87, a member of the NAP subfamily, as a Cd-responsive candidate gene that was consistently upregulated in both roots and leaves under Cd stress. Heterologous overexpression of PgNAC87 in tobacco significantly enhanced Cd tolerance, as reflected by alleviated growth inhibition, increased antioxidant enzyme activities and osmotic adjustment substances, and reduced oxidative damage. Collectively, our results clarify the evolutionary features of the PgNAC family and its involvement in Cd-induced transcriptional regulation, while highlighting PgNAC87 as a potential genetic target for enhancing Cd tolerance in pomegranate and related woody species. Full article

In the framework of integrated pest management, plant-based insecticides represent a promising tool for the control of insect pests. Indeed, N-alkylamides extracted from Acmella oleracea (L.) RK Jansen (Asteraceae) have been recently studied for their insecticidal properties. The encapsulation of these substances into stable formulations, like nanoemulsions (NEs), could boost their efficacy and stability. Herein, a N-alkylamide-enriched fraction (AEF) encapsulated into a stable NE was tested against Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), a key tomato pest, able to develop resistance towards chemical insecticides. Acmella oleracea was reported to be effective against many target species, but this is the first time that this extract was tested against T. absoluta in terms of toxicity against eggs, ingestion toxicity on larvae and repellence on adults. The AEF, containing 42.8% of spilanthol, was prepared by combining two eco-friendly techniques, namely supercritical CO₂ extraction and wiped-film short path molecular distillation, and then encapsulated into a stable NE. Preliminary tests on the phytotoxicity of the AEF-NEs at 0.25 and 0.5% (w/w) a.i., compared with a control NE solution (i.e., the AEF-free NE) and a negative control (distilled water), showed a negative effect on tomato plants at the highest concentration. On this basis, three concentrations (0.06, 0.125, and 0.25% a.i.) were evaluated against eggs (topical toxicity), larvae of 2nd instar (ingestion and topical toxicity), and adults (ovideterrence) of T. absoluta. The results showed that all adopted AEF-NE concentrations caused a significant inhibition in egg hatching (>20%). The larval survival, at the end of the evaluation (72 h), in ingestion toxicity tests were significantly different in the AEF-NEs at 0.06, 0.12, and 0.25% (56.7, 33.3 and 26.7%, respectively) compared with control NE and distilled water (100% both). Similar results were obtained in the adult emergence in ingestion toxicity comparing AEF-NEs at 0.06, 0.12, and 0.25% (64.7, 50.0 and 75.0%, respectively) with control NE and distilled water (100% both). Finally, a significant ovideterrent effect was shown by the concentrations 0.125 and 0.25% of the AEF-NEs (% of egg laid: 7.5 and 27.4% respectively), compared with distilled water. Overall, the AEF-NE tested showed promising and encouraging effectiveness as ovicidal and larvicidal against T. absoluta. This supports its potential use as an effective alternative to synthetic products for the control of this important pest. Full article

There is a growing demand for sustainable crop strategies that reduce the use of agrochemicals while improving productivity. This study investigates distillation residues of Salvia rosmarinus to develop a novel biostimulant with enhanced antifungal activity, together with natural additives that ensure homogeneity and water dispersibility. Accordingly, several residual by-products released from agroforestry processes and regarded as “plant protection products” were evaluated in phytotoxicity tests in seeds of Lactuca sativa and Lolium perenne. The tested substances included solvents (ethanol, glycerol, propylene glycol, and DMSO) and adjuvants (soy lecithin, polysorbate-20, acetic acid, and ascorbic acid). Those showing the lowest adverse effects were combined with the extract following a 3² factorial design. Most formulations exhibited good water dispersibility and significantly enhanced the germination index of Lactuca sativa, while simultaneously reducing the growth of Lolium perenne and the fungus Aspergillus flavus, all in a clear dose–response manner, as suggested by the four-parameter log-logistic (log₁₀(x)) models. These results indicate that both stimulatory and inhibitory effects were strongly influenced by concentrations, highlighting the importance of optimizing application doses. Among the evaluated carriers, the one lacking glycerol and containing high ratios of polysorbate-20 and soy lecithin demonstrated the most balanced overall performance in terms of physical stability, dispersibility, and biological activity, a response that can be attributed to the combined contribution of the extract and the selected carrier components. Overall, this study demonstrates that bioagrochemicals derived from agroforestry by-products can provide dual-function agricultural applications (biostimulant/antifungal or herbicide/antifungal), while supporting the framework of the circular bioeconomy. Full article

Landfill leachate (LL) is a complex wastewater characterized by high concentrations of organic matter and heavy metals, posing significant challenges to conventional treatment technologies. Electrochemical methods, particularly electrocoagulation (ECG), have shown promise for LL treatment; however, issues related to operational optimization and electrode durability remain insufficiently addressed. In this study, a novel electrocoagulation-based approach is proposed that systematically integrates process optimization with an explicit assessment of iron electrode reusability, which is an aspect that has been rarely explored in previous ECG studies on LL. Key operational parameters—current density, pH, inter-electrode distance, electrode surface area, and electrode material—were optimized to enhance treatment performance. Optimal conditions were achieved using iron electrodes at a current density of 256 A/m², pH 8, an inter-electrode distance of 1 cm, and an effective electrode surface area of 19.5 cm²/L. Under these conditions, removal efficiencies of 100% for zinc, 94.9% for copper, and 54.5% for total organic carbon (TOC) were obtained, demonstrating effective simultaneous removal of inorganic and organic contaminants. The electrode reusability tests showed stable removal efficiencies over ten consecutive operational cycles, highlighting the potential for reduced operational costs and improved process sustainability. Additionally, the treated effluent exhibited reduced phytotoxicity, as evidenced by lower germination inhibition (GI), reduced root growth inhibition (RGI), and enhanced removal of humic substances. Overall, the results demonstrate that the proposed ECG approach is a robust, flexible, and environmentally sustainable solution for LL treatment, with clear advantages over conventional EC systems in terms of long-term performance and resource efficiency. Full article

The infestation of Echinochloa crus-galli (L.) P.Beauv. in crop fields results in significant yield loss in many agricultural systems. Currently, the most effective strategy for controlling E. crus-galli is the application of synthetic herbicides. However, biotypes of E. crus-galli that are resistant to different modes of herbicide action often emerge. Thus, it is necessary to develop alternative control methods and address ecological concerns about synthetic herbicides. During the field survey, we observed diseased E. crus-galli exhibiting symptoms of leaf blight. These symptoms indicate a potential pathogen infection and subsequent phytotoxin production during the pathogenesis. Therefore, we aimed to isolate and identify the phytotoxic substances present in the diseased leaves. Aqueous extracts of the diseased leaves exhibited phytotoxicity, suppressing the growth of Echinochloa crus-galli seedlings in a concentration-dependent manner. A phytotoxic substance was isolated from the leaf extracts through a bioassay-guided separation process using the E. crus-galli bioassay. Spectrum analysis revealed that the phytotoxic substance was monocerin. Monocerin inhibited the growth of coleoptiles and roots of E. crus-galli seedlings at concentrations greater than 30 and 10 μM, respectively, and inhibited germination at concentrations greater than 100 μM. Therefore, monocerin may be involved in the phytotoxic activity exhibited by the extracts of E. crus-galli leaves with blight symptoms. Creating bioherbicides based on the monocerin structure could be an environmentally friendly approach to weed management. Full article

Landfill leachate reverse osmosis (RO) treatment generates a highly concentrated stream rich in recalcitrant organic matter, particularly humic substances (HS), which present potential for recovery and reuse as a biofertilizer. This study evaluated HS recovery from the RO concentrate of the Seropédica Landfill (Rio de Janeiro, Brazil) using a nanofiltration (NF) process with a polyethersulfone membrane (MWCO = 1000 Da) operated at 9 bar. The NF system achieved a volume reduction factor of 2.5, rejecting 70–75% of the organic matter. At the same time, salts were predominantly transmitted to the permeate. The phytotoxicity of recovered HS solution was evaluated through maize (Zea mays L.) germination assays at concentrations ranging from 20 to 100 mg HS/L. All treatments showed germination indices above 100%, indicating the absence of phytotoxicity, and seedling growth significantly improved relative to the control, especially at 20 mg HS/L. Trace metal concentrations in the recovered HS complied with Brazilian standards for irrigation water. Overall, the results show that nanofiltration is highly effective in concentrating humic substances from leachate RO concentrate, minimizing the presence of salts, and contributing to strategies for landfill leachate management. Full article

Waste tyre fires are a significant environmental issue that leads to the release of toxic substances into the soil, particularly polycyclic aromatic hydrocarbons and heavy metals. These contaminants can adversely affect the physicochemical properties of the soil, its microbial activity, and plant growth. The aim of this study is to assess the degree of phytotoxicity in soils affected by tyre waste fires using acute and biological tests, while simultaneously measuring microbial respiration as an indicator of soil biological activity. Furthermore, the effectiveness of the application of a 5% dose of biochar as a remediation measure was evaluated. The results showed that leachates from contaminated soils exhibited phytotoxic effects, with growth inhibition of 26.94–28.12% and reduced seed germination of 55.6–55.9%. The application of biochar to the soil under study significantly reduced phytotoxicity-induced growth inhibition (20–23.11%) and improved seed germination rates (79.76–83.71%). Microbial respiration gradually increased following the application of biochar; after 28 days it was over 30% higher compared to soils without biochar amendment. This study confirms that biochar can be an effective amendment that improves the biological quality of soils impacted by tyre waste fires. Full article

Natural and modified clay minerals are widely used in environmental technologies to remove a wide range of toxic substances from aquatic and soil ecosystems. This study assessed the toxicity of synthesized organoclays compared to pure bentonite using microbiological, phytotoxic, and instrumental (biosensor) methods. Organoclay containing lauramine oxide (a non-ionic surfactant) was found to have an increased toxic effect on all test organisms analyzed. Based on the phytotesting parameters, radish was found to be the most sensitive test organism in these experiments, as it was significantly affected by toxic substances, demonstrating noticeable changes in its morphology and morphometry. Minimal toxicity was demonstrated for organoclay containing alkyl polyglucoside (a non-ionic surfactant), which was used in all tests. Furthermore, organoclay containing disodium cocoamphodiacetate (an amphoteric surfactant) also exhibited minimal toxicity in phytotesting, including germination assessment (radish) and evaluation of morphometric characteristics using a biosensor method. The study confirms that the type of organic modifier significantly impacts the biocompatibility of organoclays. Using fewer toxic surfactants can improve the environmental acceptability of these materials for use in cleaning up contaminated ecosystems. Full article

The induction of resistance in plants involves prior activation of physiological and biochemical systems in the face of external stimuli, promoting greater tolerance to biotic stresses. Faced with the growing challenge of emerging diseases in agricultural plants and the search for more sustainable phytosanitary practices, natural substances are promising alternatives. Xylopia frutescens, known as “pindaiba-da-folha-pequena”, native to the Brazilian Cerrado and traditionally used as an antimicrobial treatment, is still little-explored in the literature and presents potentially effective compounds for the control of plant diseases. This study characterized the chemical composition and thermal stability of the X. frutescens essential oil (XEO), while evaluating its physiological and phytotoxic effects and the potential for disease control in maize and cowpea plants. The main constituents found in X. frutescens essential oil were nopinone (13.75%), spatulenol (12.94%), myrtenal (12.47%), and β-pinene (11.02%). Thermogravimetric analysis indicated that X. frutescens is highly volatile, with a large mass loss at 94.74 °C. In bioassays, the oil preserved chlorophyll levels at adequate amounts and activated several antioxidant mechanisms, but also showed a dose-dependent phytotoxic effect. In vitro assays further confirmed its antifungal activity against key phytopathogens, supporting its potential use in disease control. A general increase in the activities of the enzymes superoxide dismutase (SOD), ascorbate peroxidase (APx) and—partially—chitinase (CHIT) was observed. Catalase (CAT) decreased in both maize and cowpea plants treated with this essential oil but was higher in untreated infected plants. Such enzymatic changes suggest that the oil acts as a natural elicitor of resistance, strengthening biochemical and physiological defenses. Finally, disease severities, as measured by AUDPCs, demonstrated significant reductions in the progress of maize “Curvularia leaf spot” (Curvularia lunata) and cowpea “Web blight” (Rhizoctonia solani). The results highlight the potential of X. frutescens essential oil as an active compound stimulating defense mechanisms for applications in sustainable agricultural systems. Full article

Active compounds used in agriculture are mainly in the form of acids. This applies primarily to substances that are inducers of systemic acquired resistance, which is one of the most promising methods of supporting plants in the fight against pathogens. The physicochemical properties and biological activity of such substances can be improved by derivatizing them to salt forms. We used the concept of ionic liquids to obtain novel compounds in the form of chlormequat ionic liquids. In this study we present synthesis and characterization of a series of novel ionic liquids composed of the chlormequat cation paired with plant resistance-inducing anions, including salicylic acid and its chlorinated derivatives, nicotinic acid and isonicotinic acid. The results indicate that the new compounds in the form of salts are characterized by better biological activity related to SAR induction and lower phytotoxicity compared to the parent compounds as their equivalents in acid forms. The obtained compounds demonstrated the ability to activate defense responses in tobacco and to reduce susceptibility to viral infection, highlighting their potential for further application in crop protection. Full article

The increasing demand for sustainable agricultural practices has led researchers to explore alternative methods for controlling plant diseases and pests. Among these alternatives, essential oils (EOs) derived from various plant species have gained significant attention due to their broad-spectrum antimicrobial properties, which can be utilized in plant protection. Essential oils are volatile compounds that possess strong aromatic characteristics and are found in many medicinal and aromatic plants. They are known for their antifungal, antibacterial, and insecticidal activities, making them viable candidates for eco-friendly pest and disease management strategies. In this research, six essential oils—pine, patchouli, geranium, spruce, coriander, and eucalyptus oil—have been tested in vitro for controlling mycelium growth of Sclerotinia sclerotiorum, Botrytis cinerea, Alternaria brassicicola, and Cylindrosporium concentricum. The study also covers experiments in controlling pollen beetle and cabbage seed weevil (laboratory trials). In greenhouse conditions, the phytotoxicity of EOs to oilseed rape (Brassica napus L.) and the effect of these substances on the control of cornflower (Centaurea cyanus) were also tested. The results obtained indicate a large diversity of different essential oils in terms of their action on pathogens, pests, weeds, and winter rapeseed. Differences in their effectiveness were also found, depending on the applied dose. Full article

To explore strategies for the safe utilization of farmland co-contaminated with cadmium (Cd) and lead (Pb), this field study systematically evaluated the impacts of humic acid (HA) and potassium fulvate (PF) at different application rates (0, 1500, 3000, and 4500 kg·ha⁻¹) on the growth, yield, and translocation of Cd and Pb within the soil–plant system of maize (Zea mays L.). The results showed that while HA and PF did not significantly alter total soil Cd and Pb concentrations, they markedly reduced their bioavailable fractions. This mitigation of heavy metal phytotoxicity significantly promoted maize growth and yield, with the high-dose HA treatment increasing yield by a maximum of 32.9%. Both amendments dose-dependently decreased Cd and Pb concentrations, bioconcentration factors (BCF), and translocation factors (TF) in all maize tissues, particularly in the grains. At equivalent application rates, PF was slightly more effective than HA in reducing heavy metal concentrations in the grains. Notably, a significant positive correlation was observed between Cd and Pb concentrations across all plant parts, confirming a synergistic accumulation and translocation mechanism. This synergy provides a physiological explanation for the broad-spectrum immobilization efficacy of these humic substances. In conclusion, applying HA and PF presents a dual-benefit strategy for increasing yield and reducing risks in Cd- and Pb-contaminated farmlands. This study proposes a differentiated application approach: PF is the preferred option when ensuring food-grade safety is the primary goal, whereas high-dose HA is more advantageous for maximizing yield in soils with low-to-moderate contamination risk. Full article

The EU’s Circular Economy Action Plan promotes the use of organic waste as fertilizer, thus allowing the recycling of nutrients in the agricultural system. Research on the agronomic reuse of composted substrates previously employed for mushroom cultivation remains limited, despite their rich content of plant residues and fungal biomass, which could be repurposed as soil amendments under suitable conditions. This study evaluated the agronomic potential of spent mushroom substrates from Agaricus bisporus and Pleurotus ostreatus, including recomposted A. bisporus residues. A range of analytical procedures was employed to assess their suitability for soil improvement and the formation of humic-like substances, including physical, chemical, microbiological, phytotoxicity, and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) analyses. The spent Pleurotus substrate exhibited low nutrient content (1.1% N, negligible P, 0.9% K), but high water retention (820 kg water Mg⁻¹) and 48% organic carbon (OC), indicating its potential as a soil amendment or seedling substrate. In contrast, spent and composted Agaricus substrates showed moderate nutrient content (1.8–2.7% N; 0.8–0.7% P and 1.3–1.8% K), appropriate C/N ratios (10–15), and sufficient OC levels (24–30%), supporting their use as fertilizers. However, elevated salinity levels (18–23 dS m⁻¹) may restrict their application for salt-sensitive crops. No significant phytotoxic effects on seed germination were observed, and microbiological analyses confirmed the absence of Salmonella spp. in the three substrates. Py-GC/MS revealed a humic acid-like fraction comprising altered lignin structures enriched with lipid and nitrogen compounds. Overall, the studied materials demonstrate promising agronomic value and the capacity to contribute to long-term soil carbon storage. Full article

Crop diseases negatively affect the quality and quantity of agricultural products, with significant economic and social consequences. These problems become emergencies in a world where the safe production of food for human health is becoming increasingly pressing. Microorganisms, including phytopathogenic fungi, are the main organisms responsible for these diseases, which cause devastating damage. Environmental pollution generated by human activities causes further significant reductions in agricultural production, as well as the expansion of metropolitan areas, and climate change. Phytotoxins produced by pathogenic fungi play a fundamental role in the induction of diseases by directly interfering with the physiological processes of agricultural plants. They are secondary metabolites that can belong to all the different classes of natural compounds, and their structures and biological activities have been extensively studied. These substances have often been shown to possess other interesting biological activities for potential applications both in agriculture and in other fields, such as biotechnology and medicine. This review focuses on phytotoxic α-pyrones produced by plant pathogenic fungi, describing in detail all their chemical and biological properties and, in some cases, the results of studies on their structure-activity relationship and on the potential practical applications in various sectors. Full article