Search Results (395)

Ageratina adenophora is a highly aggressive weed that originates from central Mexico and Costa Rica. It has invaded and become naturalized across tropical and subtropical regions, posing significant challenges for biodiversity conservation and ecological restoration. While substantial research has revealed its impacts on diverse ecosystems and enhanced understanding of its phytotoxicity, investigations in grassland landscapes remain limited. Consequently, this study focused on Chengjiang County in southwestern China, a region heavily invaded by A. adenophora. Based on a preliminary survey, five grassland plant species that commonly co-occur and compete with it were assessed through seedling growth bioassays and physiological measurements conducted under the treatments of its aqueous tissue extract. The findings revealed that the recipient plants exhibited dynamic changes dependent on concentration. Specifically, there was a negative correlation between the content of malondialdehyde (MDA) and proline (Pro) and seedling height as well as root length (p < 0.05; p < 0.01). This suggests that higher extract concentrations triggered more pronounced stress-related cellular responses, which were concurrently associated with diminished seedling growth. Notably, Saccharum arundinaceum demonstrated the most significant elevation in peroxidase (POD) and catalase (CAT) activities, along with the highest synthetical allelopathic effect (SE) index of −0.36, whereas Rumex hastatus followed with an SE index of −0.38, indicating that S. arundinaceum was the least sensitive to A. adenophora stress. Our research findings elucidate the responses of indigenous grassland plants to A. adenophora, offering valuable insights into the screening of tolerant native grassland species and developing vegetation replacement strategies aimed at restoring invaded grasslands. Full article

The Texas High Plains (THP) is a major cotton-producing region facing challenges from continuous cotton monoculture, which has increased weed pressure and reduced system sustainability. Over 90% of cotton acreage relies on herbicides, accelerating the evolution of herbicide-resistant weed development. Declining Ogallala Aquifer water levels and erratic rainfall further stress the system, highlighting the need for diversified, drought-resilient cropping systems. Sorghum, known for its drought tolerance and allelopathic properties, offers an effective rotational crop to suppress weeds and improve water-use efficiency. This study evaluated the effects of sorghum–cotton rotation on weed dynamics, crop growth, and yield. A two-year field experiment (2024–2025) was conducted at the Quaker Research Farm, Texas Tech University, Lubbock, TX, using a split-plot design with crop rotations [sorghum–cotton (S–C), sorghum–sorghum (S–S), and cotton–cotton (C–C)] as main plots and weed management treatments (weeded and unweeded) as subplots, with four replications. Results showed that the C–C system had 41% higher weed density and 57% greater early-season biomass than S–C; cotton growth improved in S–C with 17–22% taller plants and 36–90% more biomass compared to cotton monoculture. Under weeded conditions, lint yield increased by 53% and seed yield by 30% compared with cotton monoculture. Under unweeded conditions, yields were 21% to 41% greater in the S–C system due to lower weed density, biomass and reduced competition. Overall, integrating sorghum into cotton-based systems reduced weed pressure, increased cotton plant height and biomass, improved lint and seed yield, and minimized yield losses under limited weed control, supporting more sustainable production in the THP. Full article

Solidago canadensis is one of the most destructive invasive plants in China, and current physical and chemical control methods are often costly, inefficient, and ecologically risky, highlighting the urgent demand for green and efficient ecological alternatives. The native vine Humulus scandens exhibits strong allelopathic potential. In this study, allelochemicals from its leaves and stems were extracted using petroleum ether, ethyl acetate, n-butanol, and n-hexane. Their allelopathic effects on S. canadensis were systematically evaluated through seed germination, seedling growth, and rhizome propagation assays, combined with widely targeted metabolomics. Leaf extracts showed markedly stronger allelopathic inhibition than stem extracts. Among all fractions, the ethyl acetate extract exerted the most potent suppression on seed germination, significantly reducing germination rate and root elongation in a concentration-dependent manner. At 100 g·L⁻¹, leaf extracts—especially the ethyl acetate phase—significantly decreased belowground fresh weight, rhizome number, and new seedling emergence. The ethyl acetate extract also significantly elevated root antioxidant enzyme activities at 25–100 g·L⁻¹, indicating induced oxidative stress. UPLC-MS/MS-based metabolomics identified 186 differential metabolites among extracts. Ten flavonoids were significantly upregulated in the ethyl acetate extract and were predominantly enriched in the kaempferol aglycone biosynthesis I pathway (MetMap 113) and the flavonoid biosynthesis pathway (ko00941), suggesting that these compounds may play a key role in the observed allelopathic inhibition. Collectively, the ethyl acetate extract of H. scandens leaves effectively suppresses S. canadensis growth by inhibiting seed germination and rhizome tillering and by inducing oxidative stress, probably with the 10 candidate flavonoid metabolites, highlighting its strong potential as a biological control agent against this invasive weed. Full article

Giant foxtail is a common weed in foxtail millet fields, and continuous cropping of foxtail millet increases its occurrence. Rotating foxtail millet with sorghum is a major practice in the dry farming regions of northern China. Given this situation, this study combined Petri dish germination tests with pot experiments to clarify the allelopathic effects of water extracts from different sorghum parts on giant foxtail. Distilled water (SCK) was used as the control, and treatments included stock solution (S1), as well as 10× dilution (S2), 50× dilution (S3), and 100× dilution (S4) of water extracts prepared from sorghum roots, stems, leaves, and rhizosphere soil. The results showed that water extracts from all sorghum parts exhibited promotion of giant foxtail seed germination at higher dilutions and inhibition at lower dilutions. The S3 treatment of rhizosphere soil extract achieved a germination rate of 62.22%, which was significantly higher than that of the SCK by 40.00%. The germination energy of root extract S1 was only 4.00%, which was significantly lower than that of the SCK by 86.67%. The S3 treatment showed the strongest allelopathic promotion effect. All dilution treatments promoted the plant height, stem diameter, and above ground fresh and dry weight of giant Foxtail, and these effects increased initially and then stabilized over time. The root extract exhibited higher allelopathic activity than the other extracts. The activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) first increased and then decreased as the dilution factor increased, while the S1 treatment inhibited enzyme activities and caused an imbalance in the antioxidant system. Sorghum root water extract had a significant effect on CAT activity in giant foxtail, with an increase of 98.82% under the S3 treatment compared with the SCK at 40 d. Malondialdehyde (MDA) content increased with decreasing dilution factor, and the undiluted extract induced membrane lipid peroxidation damage. In conclusion, the allelopathic effects of sorghum extracts on giant foxtail were closely related to the dilution level. Higher dilutions activated the antioxidant defense system and promoted growth, while lower dilutions disrupted enzyme system balance and exacerbated membrane damage. These findings provide basic data and theoretical support for the development and utilization of sorghum allelochemicals and for the green control of giant foxtail. Full article

The species that make up the intercrop interact with each other during their development, which can be beneficial, harmful, or indifferent to the participants. The aim of this study was to determine whether the developmental differences observed between intercropped and pure stands are already evident at early developmental stages. We conducted three experiments: (1) a laboratory germination test using filter paper rolls, (2) a laboratory growth test in plant pots, and (3) a small-plot field experiment comparing the development of mixtures and monocultures of winter cereals (winter wheat, winter durum wheat, winter einkorn, winter triticale, winter barley, and winter oats) and winter peas. Based on our results, only minor differences were observed (1–3%) in germination parameters (germination percentage, germination vigor, and seedling health). However, as plant development progressed, increasingly pronounced differences emerged (significance level of p < 0.05) between intercropped and pure stands based on which we assume allelopathic effects. Winter wheat and durum wheat had a positive effect on the initial development of winter pea, whereas barley, and oat had a clearly negative effect. Winter pea negatively affected the germination and early development of triticale and oat, while it had a positive effect on the initial development of durum wheat. Mutually beneficial interactions were identified in the winter wheat–pea and durum wheat–pea combinations during the early stages of plant association. Full article

Agrochemicals are used worldwide in food production, but their use varies between countries due to the damage observed to nature and human health. Allelopathy is the primary pathway of chemical communication in plants, interfering with biome development through stimulation and/or inhibition mechanisms. Therefore, this study aimed to assess the biological activities of the ethanol extract (EE) and fractions of S. fluminensis leaves on monocotyledonous and eudicotyledonous models. The EE was obtained by percolation with ethanol, and the hexane (HEXF), dichloromethane (DCMF), ethyl acetate (EAF), and hydroethanol (HEF) fractions were obtained by liquid–liquid partition. The phytochemical characterization was performed by ¹H nuclear magnetic resonance (NMR). The allelopathic activity was evaluated on Allium cepa (onion) and Lactuca sativa (lettuce) seeds. The cytotoxic, genotoxic, and antigenotoxic effects on A. cepa meristematic cells were analyzed in vitro. Aliphatic compounds, saponins, and flavonoids derived from quercetin and kaempferol were characterized in the samples. All samples decreased the vigor, germination rate, and germination speed index (GSI) of A. cepa seeds. In contrast, they did not alter the vigor and viability of L. sativa seeds, but decreased the GSI, except for HEF. The samples inhibited the epicotyl and root growth of A. cepa and L. sativa, except HEXF, which stimulated the growth of epicotyls (750 µg/mL) and roots (750 and 1000 µg/mL). The cytotoxic assays showed that the EE and HEXF had cytotoxic action at low concentrations, and no sample showed a genotoxic effect. The following samples exhibited an antigenotoxic effect after pretreatment with atrazine (ATZ): EE (125 and 750 µg/mL), HEXF (750 and 1000 µg/mL), DCMF (125, 250, and 1000 µg/mL), EAF (at all tested concentrations), and HEF (125, 250, and 750 µg/mL). Furthermore, the EAF at 125 and 500 µg/mL and HEF at 125 µg/mL demonstrated the potential to reverse genetic damage induced by glyphosate (GLY). Full article

Interactions between cyanobacteria and eukaryotic algae are traditionally viewed as favoring cyanobacteria, which are often the dominant competitors in freshwater ecosystems. However, increasing evidence suggests that eukaryotic algae also possess effective chemical defenses capable of suppressing cyanobacterial proliferation. In this study, the anti-cyanobacterial potential of a methanolic biomass extract of the green microalga Chlorella vulgaris against the bloom-forming cyanobacterium Microcystis aeruginosa was investigated. Optical density measurements revealed the inhibition of cyanobacterial growth, with extract concentrations of 0.4–1.6 mg mL⁻¹ significantly reducing biomass accumulation. The lowest concentration (0.2 mg mL⁻¹) stimulated the accumulation of phycobiliproteins, whereas concentrations of 0.8–1.6 mg mL⁻¹ significantly decreased phycobiliprotein content, indicating progressive physiological impairment. The results suggest that the highest extract concentration applied may also cause alteration in phosphate acquisition. Lipid profiling of the Chlorella biomass showed that 97% of the extractable lipids consisted of methanol-soluble fatty acids, with C18 fatty acids predominating among the 20 identified compounds. These metabolites are reported to possess allelopathic activity and therefore represent plausible contributors to the observed inhibition. These findings support that anti-cyanobacterial activity may represent a widespread ecological trait of Chlorella and potentially other green microalgae, providing a promising foundation for environmentally friendly cyanobacterial bloom management. Full article

Rhus typhina L. is widely recognized as a landscape ornamental plant and its extracts have demonstrated biological activity against multiple weed types. This makes it a promising candidate in sustainable agriculture as a bioherbicide by offering a solution to mitigate the growing problem of herbicide resistance. Therefore, this study was designed in agar culture to analyze the effect of powders of the branch, fallen leaf, and pericarp from Rhus typhina L. against seed germination of Portulaca oleracea L. and evaluate its inhibitory mechanisms based on anatomical structure and the activities of antioxidative enzymes, α-amylase, and β-amylase. The main allelopathic compounds were also identified based on high-performance liquid chromatography–mass spectrometry (LC-MS), and their bioherbicidal effects were evaluated. Brassica napus L. was used as the object for biosafety evaluation. The results showed that the seed germination of Portulaca oleracea L. under treatment with powder extract from Rhus typhina was inhibited by exhhibting swelling and deformation in endosperm cells and chaotically scattered starch granules in seed embryos with a shorter radicle length than the control. During the period of treatment, antioxidative enzymes were quickly activated to scavenge the suddenly surging reactive oxygen species (ROS) as a measure of boosted malonaldehyde (MDA) content. Antioxidative enzyme (POD, SOD, and CAT) activities were also activated to mitigate the oxidative damage. In contrast, both α-amylase and β-amylase activities were significantly suppressed. A total of 16 allelochemicals were identified in the branch, fallen leaf, and pericarp of Rhus typhina L. Among these, gallic acid, methyl gallate, and tyrosol were identified as exhibiting the most significant inhibitory effect during the whole germination process of Portulaca oleracea L., resulting in browned seedlings and stunted radicle length compared with the control, while far weaker inhibitory effects were found against Brassica napus L. In summary, extracts from Rhus typhina L. targeted α-amylase and β-amylase activities rather than antioxidative enzyme activities to inhibit the germination of Portulaca oleracea L. Gallic acid, methyl gallate, and tyrosol were the key compounds that inhibited its germination. Full article

Phenolic acids are considered important allelochemicals that can restrict nutrient uptake and inhibit plant growth. Most existing studies have focused on growth phenotypes and single nutrient changes under phenolic acid stress, while the coupled C:N:P balance responses of plant–soil systems remain poorly characterized. Ecological stoichiometry offers a holistic perspective to reveal the nutrient supply–demand mismatch underlying allelopathic inhibition by analyzing elemental ratio dynamics, thus deepening the mechanistic understanding of allelopathy beyond traditional single-indicator observations. Using lettuce (Lactuca sativa L.) as the test plant, this study investigated the effects of cinnamic acid (CA) and p-hydroxybenzoic acid (PHA) stress, combined with nitrogen (N), phosphorus (P), and their combined application (NP) on plant growth and plant C, N, and P stoichiometric characteristics. Soil C, N, and P contents and stoichiometric characteristics were further analyzed as supplementary indicators. The results showed that phenolic acid stress significantly reduced lettuce biomass: PHA decreased aboveground biomass by 40.11% and belowground biomass by 44.14%, with a stronger inhibitory effect than CA. Both phenolic acids induced marked stoichiometric imbalance, characterized primarily by a sharp decline in leaf nitrogen content; N content dropped by 49.80% under CA and 70.75% under PHA, corresponding to a 64.43% and 162.79% increase in leaf C:N ratio, and a 37.63% and 63.19% decrease in leaf N:P ratio, respectively. Nutrient addition alleviated these responses to varying degrees: N addition mainly promoted biomass recovery and elevated plant N status, P addition optimized elemental ratios, and combined NP application yielded the strongest overall recovery. Correlation and redundancy analyses indicated that soil C, N, and P stoichiometric characteristics were closely associated with plant growth, with soil organic carbon and total phosphorus identified as major explanatory variables associated with plant growth. Overall, phenolic acid stress altered plant stoichiometric characteristics and growth, as well as soil C, N, and P stoichiometric characteristics, while nutrient addition partially alleviated these responses. These findings provide a stoichiometric perspective for understanding allelopathic stress and may offer a theoretical basis for nutrient management under continuous cropping conditions. Full article

Allelopathy—the release of biologically active secondary metabolites by plants—is a key mechanism regulating plant community dynamics in forest and agro-forestry ecosystems, yet the physiological basis of allelochemical effects of angiosperm trees on acceptor plants remains insufficiently understood. This systematic review synthesises knowledge on the physiological effects of angiosperm tree allelochemicals, focusing on photosynthesis, respiration, water relations, mineral nutrition, and growth and development. Following PRISMA 2020 guidelines, five databases (Web of Science, ScienceDirect, SpringerLink, Wiley Online Library, and Scopus) were searched between October 2025 and June 2026 for English-language peer-reviewed articles on allelopathic effects on plant physiological processes; risk of bias was assessed via methodological transparency, and, given design heterogeneity, a qualitative narrative synthesis was performed. Of 7748 records identified, 99 met the eligibility criteria. Allelochemicals, including phenolic acids, flavonoids, naphthoquinones, terpenoids, alkaloids, and coumarins, were associated with disrupted photosynthetic efficiency, impaired mitochondrial electron transport, altered stomatal functioning, reduced nutrient uptake, and suppressed cell division, with oxidative stress—often linked to reactive oxygen species accumulation—recurring as a shared mechanism; effects were concentration-dependent, with synergistic interactions noted between allelochemicals. These findings advance mechanistic understanding of angiosperm tree allelopathy and highlight its relevance for sustainable agriculture and biological weed management. Full article

Sonoplasma treatment (SPT), which combines hydrodynamic cavitation with low-temperature plasma discharge in water, has been proposed as an advanced oxidation process for reducing biological contamination. By generating physical stressors and reactive oxygen species, including hydrogen peroxide (HP), SPT may inactivate microorganisms, but its effects on stress-resistant filamentous fungi remain insufficiently characterized. We examined two phytopathogenic fungi with contrasting pigmentation: melanized Alternaria alternata and hyaline Fusarium solani. Spore suspensions were exposed to direct and indirect SPT at 30 kHz, and viability, biomass accumulation, conidial production, allelopathic activity, and pigmentation-associated spectral responses were assessed immediately after treatment and after storage. Fungus F. solani showed greater susceptibility, with reduced colony-forming capacity and suppressed biomass production, although surviving propagules showed increased sporulation. In contrast, A. alternata maintained viable growth under the tested conditions and showed stimulation of growth-related and reproductive endpoints, together with darker colony pigmentation. These responses are consistent with pigmentation-associated tolerance to SPT-induced physical and oxidative stress, but do not establish melanin as the sole causal mechanism. SPT efficacy against filamentous fungi is therefore species-dependent and may be limited when resistant melanized taxa are present. Full article

Phenolic acids are known allelopathic compounds that may serve as the primary cause of continuous cropping obstacles in Coix lacryma-jobi L. (Coix). However, the concentrations, types, and specific stress responses of Coix to these phenolic acids still require further investigation. In this study, the cultivar ‘Wanyi 2′ was used to examine the effects of different phenolic acids and their concentrations on the growth of Coix. Four concentrations (0 mg/L, 10 mg/L, 100 mg/L, and 1000 mg/L) and four phenolic acid types (p-hydroxybenzoic acid, salicylic acid, cinnamic acid, and ferulic acid) were used to assess their influences on plant growth, leaf physiological parameters, and metabolic pathways under greenhouse conditions. In this greenhouse pot experiment, the effects of the four phenolic acids showed a similar tendency: a low concentration (10 mg/L) tended to promote the growth and root development of Coix seedlings, whereas high concentrations (100 and 1000 mg/L) generally showed inhibitory effects. Among these phenolic acids, ferulic acid exhibited the strongest inhibitory effect at the highest concentration (1000 mg/L), while salicylic acid showed the most pronounced growth-promoting effect at low concentrations (10 mg/L). In addition, high levels of phenolic acids markedly increased antioxidant enzyme activities and oxidative stress-related substances in Coix leaves, while reducing soluble sugar (SS) and soluble protein (SP) contents. Our data suggest that under phenolic acid stress, Coix leaves exhibited changes in the metabolism of phenolic acids (e.g., 4-methoxysalicylic acid, gallic acid) and amino acids (e.g., glutathione, proline), which may be associated with the adaptive response to allelochemical-induced stress. Overall, this study provides insights that may support strategies to optimize plant growth regulators and mitigate continuous cropping barriers in Coix. Full article

Plant–plant interactions in agroecosystems are shaped by both biochemical interference and resource-mediated competition, yet the relative contribution of these mechanisms under field conditions remains unclear. This study evaluated whether allelopathic activity expressed by winter cereal rye (Secale cereale L.) and grain legumes under controlled conditions is associated with competitive outcomes in relay-row intercropping under organic farming. Greenhouse bioassays and laboratory screening assays were combined with a field experiment conducted under certified organic farming conditions. Aqueous leachates and biomass extracts influenced early root development of a sensitive recipient species in a time- and concentration-dependent manner, indicating measurable biological activity. Secondary metabolite profiles differed significantly among species, particularly in belowground biomass. However, under field conditions, no persistent suppression of grain legumes was observed. Aboveground biomass accumulation and land equivalent ratio (LER) values exceeded 1.0 in all intercrops, with the highest LER recorded for the cereal rye–lentil combination. The results suggest that under the conditions of this study, resource partitioning, species compatibility, and other ecological interactions may have had a greater influence on intercrop performance than the allelopathic effects detected under controlled conditions. Full article

Although numerous studies have explored the effects of various sounds on plants, a comparative understanding of how long-term exposure to low-intensity sound and rhythmic versus non-rhythmic sound impact on plants is still lacking. In this study, we conducted a field experiment to determine the growth, physiological responses, and allelopathic intensity of an invasive plant Alternanthera philoxeroides under prolonged exposure to different sound rhythms and intensities. The results showed that even at low intensity, long-term sound exposure inhibited the growth of A. philoxeroides while activating its defense mechanisms; these responses intensified with increasing sound intensity. However, the plant could not well distinguish between rhythmic and non-rhythmic sound treatments, although its allelopathic intensity also increased with sound intensity. This study extends the knowledge of plant response to acoustic stimuli, highlights the limited ability of plants to discriminate sound rhythms, and underestimates the negative impacts of prolonged low-intensity sound on plant performance. Therefore, the application of acoustic treatment techniques in future horticulture and agriculture requires a careful trade-off between their potential benefits and adverse effects on plants. Full article

Leucaena leucocephala is a nitrogen-fixing legume widely used in agroforestry systems, although its invasive potential poses increasing risks to wetlands and riparian ecosystems. This systematic review synthesizes current knowledge on the ecological mechanisms, environmental stressors, and management strategies associated with the invasion of L. leucocephala in humid tropical environments. Following PRISMA guidelines, 60 studies retrieved from Scopus, Web of Science, and Consensus were qualitatively analyzed. The results indicate that invasion success is strongly associated with environmental disturbances and stress conditions, particularly drought stress, altered hydrological regimes, fire occurrence, and land-use change, which reduce ecosystem resistance and facilitate species establishment. Key invasion mechanisms include high seed production, persistent soil seed banks, rapid growth, allelopathic effects, and strong resprouting capacity, leading to suppression of native vegetation and structural simplification of plant communities. Integrated management strategies combining mechanical and chemical control with active revegetation consistently showed higher effectiveness than isolated approaches. The evidence further suggests that climate-related stressors may intensify invasion dynamics and increase ecosystem vulnerability under future climate scenarios. Despite recent advances, important knowledge gaps remain regarding long-term ecosystem functioning, hydrological feedback, and adaptive management in invaded wetlands. Full article