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Background: Endophytes play an important role in promoting plant growth. To date, although many reports provided insight into the function of endophytes in their hosts, few reports focus on their impact on nearby plants. Intraspecific allelopathy in plant community is common and presents a notable challenge to medicinal plant yield and productivity. Atractylodes lancea is a perennial herb that has relatively low yields due to intraspecific allelopathy. The bacterial endophyte Pseudomonas fluorescens ALEB7B has previously been found to increase essential oil content of A. lancea, but the role of ALEB7B in A. lancea allelopathy is still unknown. Results: Noninoculated A. lancea exhibited growth retardation when it was grown in a community, which was related to ethylene-induced intraspecific allelopathy. Further experiment showed that exposing A. lancea to volatile from noninoculated A. lancea or same concentration of ethylene reduced growth of A. lancea. P. fluorescens-inoculated plants showed reduced ethylene emission and relieved growth retardation on neighboring noninoculated A. lancea. Moreover, P. fluorescens inoculation had little allelopathic effect when receivers were treated with ethylene receptor inhibitor or when emitters were treated with ethylene production inhibitor. Transcriptomic analysis revealed that endophyte ALEB7B altered transcriptional response associated with ethylene response and essential oil production in neighboring A. lancea. Conclusions: Our results demonstrated that the bacterial endophyte ALEB7B provides fitness benefits for both hosts and neighbors. The allelopathic effect on nearby plants can be alleviated by altering airborne signals, such as ethylene, in endophytic bacteria. [ABSTRACT FROM AUTHOR]

Introduction: Microplastic pollution has emerged as a significant global change factor, with the potential to alter the biological, physicochemical properties of soil and to subsequently affect plant growth. Despite growing recognition of the impacts of microplastic pollution, the mechanisms by which microplastics modify plant leaf chemistry and influence allelopathic interactions among co-existing plant species remain unclear. Methods: We used the native perennial forb Achyranthes bidentata and the invasive annual forb Amaranthus spinosus as focal species. We grew the two species with and without competition with each other. This setup was further combined with a treatment involving the addition of polyethylene (PE). We then testd the effects of aqueous extract on seed germination and seedling growth for five invasive and five native species. Subsequently, metabolomic analysis was conducted on the aqueous extracts, in which significant allelopathic effects were observed on test species. Results and discussion: The presence of PE microplastics enhanced the biomass of both Achyranthes and Amaranthus under competitive and non-competitive growth conditions. Furthermore, PE microplastics were found to induce a negative allelopathic effect for the native plant Achyranthes on co-occurring plants, which appeared to be mediated through changes in leaf chemistry. Bisdemethoxycurcumin, ethylparaben, salicin 6'-sulfate and 5-hydroxy-3',4',7-trimethoxyflavone glucoside were proven important compounds for allelopathic enhancement. Overall, these results suggest that microplastic pollution has the capability to influence the co-existence of invasive and native plants by altering their allelopathic potential. This insight into the interactions between microplastics and plant allelopathy provides a novel perspective on how microplastic pollution could modify plant species interactions and ecosystem dynamics. Future studies could aim to answer how microplastics might affect plant root exudates and whether this process would mediate biological invasion. [ABSTRACT FROM AUTHOR]

The invasive Phytolacca americana L. poses a significant threat to local agroforestry ecosystems due to its allelopathic toxicity. However, the ecophysiological response mechanisms of crops to allelochemicals remain unclear. This study investigated the seedling growth, physiological, and biochemical responses of three gramineous crops to the root extracts of P. americana and identified potential allelochemicals of the invader. The germination and seedling growth of three crops were inhibited by extracts differently, with high-concentration extracts causing more severe inhibition on seedling roots in hydroponic (>57%) than soil culture experiments (>18%). This inhibition may be related to representative secondary metabolites such as fatty acyls, alkaloids, and phenols. Despite the significant inhibition of high-concentration extracts on seedling growth, the levels of soluble sugar, soluble protein, and antioxidant enzymes increased synergistically. Under allelopathic stress, three species enhanced antioxidant enzyme activities and metabolite contents at the cost of reducing their shoot, root biomass, and root/shoot ratio. This may be an ecophysiological growth-defense strategy to bolster their resistance to allelopathy. Interestingly, transgenic rice exhibited greater sensitivity to allelochemicals than wild-type rice, resulting in more pronounced growth inhibition and increased levels of most metabolites and antioxidant enzymes. This study highlights the adaptive strategies of three gramineous crops to the allelopathy of invasive P. americana. [ABSTRACT FROM AUTHOR]

Harmful algal blooms (HABs) represent a significant global marine ecological disaster. In the Yellow Sea, green and golden tides often occur simultaneously or sequentially, suggesting that interspecific competition involves not only spatial and resource competition but also allelopathy. This study investigated the allelopathic interactions between Ulva prolifera and Sargassum horneri using physiological and biochemical parameters, including relative growth rate (RGR), cell ultrastructure, chlorophyll fluorescence, enzyme activity, and metabolomics analysis. The results showed that S. horneri filtrate significantly inhibited U. prolifera growth, while U. prolifera filtrate had no significant effect on S. horneri. Both algal filtrates caused cellular damage and affected photosynthesis, enzyme activities, and metabolism. However, their allelopathic responses differed: U. prolifera may rely on internal compensatory mechanisms, while S. horneri may depend on defense strategies. These findings provide insights into the dynamics of green and golden tides and support the scientific control of HABs through allelopathy. [ABSTRACT FROM AUTHOR]

In the present work, the phytotoxic effects of secondary metabolites extracted from lichen Ramalina celastri (usnic acid) and lichen Stereocaulon ramulosum (a naturally occurring mixture of atranorin and perlatolic acid, approx. 3:1) on cultures of the aposymbiotically grown lichen photobiont Asterochloris erici were evaluated. Algae were cultivated on the surface of glass microfiber disks with applied crystals of lichen extracts for 14 days. The toxicity of each extract was tested at the two selected doses in quantities of 0.01 mg/disk and 0.1 mg/disk. Cytotoxicity of lichen extracts was assessed using selected physiological parameters, such as growth (biomass production) of photobiont cultures, content of soluble proteins, chlorophyll a fluorescence, chlorophyll a integrity, contents of chlorophylls and total carotenoids, hydrogen peroxide, superoxide anion, TBARS, ascorbic acid (AsA), reduced (GSH) and oxidized (GSSG) glutathione, and composition of selected organic acids of the Krebs cycle. The application of both tested metabolic extracts decreased the growth of photobiont cells in a dose-dependent manner; however, a mixture of atranorin and perlatolic acid was more effective when compared to usnic acid at the same dose tested. A higher degree of cytotoxicity of extracts from lichen S. ramulosum when compared to identical doses of extracts from lichen R. celastri was also confirmed by a more pronounced decrease in chlorophyll a fluorescence and chlorophyll a integrity, decreased content of chlorophylls and total carotenoids, increased production of hydrogen peroxide and superoxide anion, peroxidation of membrane lipids (assessed as TBARS), and a strong decrease in non-enzymatic antioxidants such as AsA, GSH, and GSSG. The cytotoxicity of lichen compounds was confirmed by a strong alteration in the composition of selected organic acids included in the Krebs cycle. The increased ratio between pyruvic acid and citric acid was a very sensitive parameter of phytotoxicity of lichen secondary metabolites to the algal partner of symbiosis. Secondary metabolites of lichens are potent allelochemicals and play significant roles in maintaining the balance between mycobionts and photobionts, forming lichen thallus. [ABSTRACT FROM AUTHOR]

This study evaluates the phytotoxic potential of methanolic extracts from six Asteraceae species: Wedelia chinensis, Helianthus annuus, Cosmos bipinnatus, Tagetes erecta, Tithonia diversifolia, and Zinnia elegans. The extracts were tested at concentrations of 0.03, 0.1, 0.3, and 1.0 g/mL to assess their inhibitory effects on the radicle and hypocotyl lengths of Echinochloa crus‐galli and Echinochloa colona. The two most potent species, C. bipinnatus and T. diversifolia, were further evaluated using extracts from their roots, stems, and leaves. Among these, C. bipinnatus leaf extracts showed the most significant phytotoxicity and were tested at 20, 40, and 60 days of plant age. At 0.03 g/mL, C. bipinnatus extract inhibited the hypocotyl and radicle lengths of E. colona by 23.01% and 56.45%, and E. crus‐galli by 8.5% and 36.35%, respectively. At 1.0 g/mL, the extract inhibited the hypocotyl lengths of E. colona and E. crus‐galli by 97.54% and 88.15%, and the radicle lengths by 93.52% and 99.99%, respectively. The 60‐day‐old C. bipinnatus leaf extract exhibited the highest inhibitory effect, correlating with the identification of key allelochemicals such as cinnamic acid, caffeic acid, coumaric acid, ferulic acid, 2‐4 dimethohydroxy benzoic acid, and salicylic acid. These findings suggest that the 60‐day‐old C. bipinnatus leaf extracts have strong potential for use in the biological control of these weed species, offering a promising avenue for the development of natural herbicides. [ABSTRACT FROM AUTHOR]

Introduction: Casuarina equisetifolia is a common protective forest in coastal areas. However, artificial C. equisetifolia forests cannot self-renew, mainly due to the accumulation of allelochemicals. Endophytic bacteria may alleviate the root growth inhibition caused by allelochemicals in C. equisetifolia seedlings. B. amyloliquefaciens and B. aryabhattai were endophytic bacteria with strong allelopathy in C. equisetifolia root. The allelopathy mechanism of these two endophytes and their interaction with C. equisetifolia remains to be studied. Methods: Whole-genome sequencing of B. amyloliquefaciens and B. aryabhattai isolated from the roots of allelochemical-accumulating C. equisetifolia was performed using Illumina Hiseq and PacBio single-molecule sequencing platforms. Sterile seedlings of C. equisetifolia were treated with either individual or mixed bacterial cultures through root drenching. Transcriptional and metabolomics analyses were conducted after 3 days of infection. Results and discussion: Whole-genome sequencing of Bacillus aryabhattai and Bacillus amyloliquefaciens showed that the two strains contained various horizontal gene transfer elements such as insertion sequence, prophage and transposon. In addition, these two strains also contain numerous genes related to the synthesis and catabolism of allelochemicals. After these two strains of bacteria were individually or mixed infected with C. equisetifolia, metabolomics and transcriptomic analysis of C. equisetifolia showed the 11 important secondary metabolite biosynthesis among them alkaloids biosynthesis, phenylpropanoid and terpenes biosynthesis and related genes were putatively regulated. Correlation analysis revealed that 48 differentially expressed genes had strong positive correlations with 42 differential metabolites, and 48 differentially expressed genes had strong negative correlations with 36 differential metabolites. For example, CMBL gene showed positive correlations with the allelochemical (-)-Catechin gallate, while Bp10 gene showed negative correlations with (-)-Catechin gallate. Conclusion: The intergenerational accumulation of allelochemicals may induce horizontal gene transfer in endogenic bacteria of Casuarina equisetifolia root. Endophytic Bacillus plays an allelopathic role by assisting the host in regulating gene expression and the production and/or variety of allelochemicals. This comprehensive study sheds light on the intricate genetic and metabolic interactions between Bacillus endophytes and C. equisetifolia. These findings provide insights into endophyte-mediated allelopathy and its potential uses in plant biology and forest sustainability. [ABSTRACT FROM AUTHOR]

Rhododendron capitatum community expansion is a major threat to alpine meadow. Allelopathy is an important mediator in managing relationships between plants in natural ecosystems. However, allelopathy and specific allelochemicals of R. capitatum have not been studied yet. In this study, the allelopathy of the foliage litter of R. capitatum was explored on Elymus nutans, Poa pratensis and Medicago ruthenica, and the chemical composition and their allelopathy were studied. The results showed that the aqueous extract of the foliage litter of R. capitatum had an allelopathy of "low concentration promotion and high concentration inhibition" on the germination of E. nutans, P. pratensis, and M. ruthenica. Organic acids, fatty acids, terpenes, phenols, and phenolic acid compounds were identified, with Zanamivir (77.81%), alpha-linolenic acid (18%), Kaurenoic acid (23.50%), 4-hydroxyphenylglycolic acid (21.54%), and Quinic acid (28.24%) having the highest relative content, and all five compounds showed significantly inhibitory effects on seed germination and seedling growth of E. nutans, P. pratensis, and M. ruthenica, which further suggests that the five compounds are the critical allelochemicals for negative allelopathy of R. capitatum. These results highlight the crucial role of inhibitory allelopathy produced by R. capitatum in the establishment and expansion of its populations. [ABSTRACT FROM AUTHOR]

This study examines the allelopathic effects of wild barley (Hordeum spontaneum) on the growth and yield of bread wheat (Triticum aestivum), barley (Hordeum vulgare), and wild barley (Hordeum spontaneum). The experiment was conducted in a greenhouse at Shamamar-Hawler/Kurdistan Region of Iraq using a complete randomized factorial design (CRD) within 3 replications. The roots, shoots, and seeds of wild barley were dried, powdered, and added to the soil at different concentrations (0%, 10%, 20%, 30%, and 40%) in 500 g pots. Each pot was planted with 5 seeds, which were later reduced to 3 seedlings. Growth parameters such as shoot and root lengths, dry weights, number of tillers, weight of spikes, seeds number per plant, and biological yield was measured. The results indicated significant effects of wild barley residues on the studied crops. Wheat showed the highest roots, shoots and total lengths were (29.56 cm, 17.05 cm and 46.58 cm, respectively) and the highest shoots and roots dry weights were (0.24 g and 0.30 g). Barley showed the highest number of stems (1.96) but the lowest shoots and dry weights of roots were (0.11 g and 0.23 g). Wild barley had the highest biological weight and harvest index (HI). Among the plant parts, seed extracts significantly enhanced growth parameters, while roots and shoots extract had the greatest inhibitory effects as wild barley residue concentrations increased. Nevertheless, the HI showed a decline as the concentrations increased, suggesting a detrimental effect on growth efficiency. The study shows the potential of wild barley as a bio-herbicide, emphasizing its allelopathic effects. This suggests that agricultural practices should be carefully considered to maximize the efficiency of crops. Incorporating these results into precision agriculture can greatly improve crop management and increase yield. [ABSTRACT FROM AUTHOR]

Cyclamen (Cyclamen persicum Mill.) is an ornamental plant that is highly susceptible to pathogens, requiring high amounts of phytosanitary products. Therefore, the development of more sustainable alternatives has been required. The present study aimed to analyze the effect of C. canadensis root extract (aqueous and with dichloromethane) applied via foliar or soil, in C. persicum, on gas exchange and the SPAD index and on the biomass of cyclamen. The aqueous extract treatment increased net CO2 assimilation, the transpiration rates, and instantaneous carboxylation efficiency. The water use efficiency values were reduced in the treatments with both extracts. The greatest increases in the SPAD index were provided by the aqueous extract. The cyclamens that received the aqueous extract applied in soil or the dichloromethane extract applied in leaves showed an increase in total biomass and number of leaves. To identify the compounds present in the extracts, CG-MS and LC-MS/MS analyses were performed. The positive effects obtained indicated a high biostimulant effect of C. Canadensis. Thus, the root extracts of C. Canadensis, particularly the aqueous extracts, have the potential to be used to reduce the use of mineral fertilizers and pesticides, promoting agroecological practices and contributing to sustainable agriculture. [ABSTRACT FROM AUTHOR]

The elemental allelopathy hypothesis states that the metal‐rich litter of hyper‐accumulating species may have a detrimental impact on neighbouring plants giving a competitive advantage to hyper‐accumulators. Here, we aim to specify the conditions of application of this hypothesis in realistic field conditions, and its relative importance compared to other positive effects found in metalliferous systems.We disentangled the litter‐induced elemental allelopathy and canopy effects of two metallophyte species (Arenaria multicaulis and Hutchinsia alpina) with different levels of leaf Zn and Cd accumulation on two ecotypes of Agrostis capillaris with different levels of metal tolerance. The experiment was conducted in two habitats with contrasting pollution levels in a former mining valley in the Pyrenees (France).The metallophyte species that accumulates more metals (Hutchinsia alpina) showed a strong elemental allelopathy effect on the target with lower metal tolerance in the habitat with lower pollution level, while the metallophyte species that accumulates less metals (Arenaria multicaulis) had no litter effect. Both metallophyte species had positive canopy effects likely due to improvement of micro‐climatic conditions. The drought that occurred during the experiment may have influenced these canopy effects, increasing their importance during the course of the study. For Hutchinsia alpina, the positive canopy effects were stronger than the negative litter effects, resulting in overall positive effects on both target ecotypes.Synthesis. Our results brought a better understanding of the occurrence of elemental allelopathy in metallophyte communities and its relative importance as compared to micro‐climatic facilitation in a global warming context. [ABSTRACT FROM AUTHOR]

We revisit a deterministic model for studying the dynamics of allelopathy. The model is formulated in terms of a non-homogeneous linear system of differential equations whose forcing or source term is a piecewise constant function (square wave). To account for the inherent uncertainties present in this natural phenomenon, we reformulate the model as a system of random differential equations where all model parameters and the initial condition are assumed to be random variables, while the forcing term is a stochastic process. Taking extensive advantage of the so-called Random Variable Transformation (RVT) method, we obtain the solution of the randomized model by providing explicit expressions of the first probability density function of the solution under very general assumptions on the model data. We also determine the joint probability density function of the non-trivial equilibrium point, which is a random vector. If the source term is a time-dependent stochastic process, the RVT method might not be applicable since no explicit solution of the model is available. We then show an alternative approach to overcome this drawback by applying the Liouville–Gibbs partial differential equation. All the theoretical findings are illustrated through several examples, including the application of the randomized model to real-world data on alkaloid contents from leaching thornapple seed. [ABSTRACT FROM AUTHOR]

Blooms of the dinoflagellate Karenia selliformis in Chile, often associated with massive fish kills, have been noted alongside other species from the Kareniaceae family, such as Karenia spp. and Karlodinium spp. However, the potential allelopathy impact of Chilean K. selliformis on other phytoplankton species remains unexplored. Here, we assessed the allelopathic effects of cell-free exudates from a Chilean K. selliformis strain on six phytoplankton strains representing diverse microalgal groups. The findings of these experiments offer valuable insights into the varied responses of both non-toxic and toxic microalgae to allelochemicals produced by a toxic microalga, showcasing the intricate and multifaceted nature of allelopathic interactions in microalgal communities. The study revealed species-dependent effects, with variable response in cell growth, photosynthetic efficiency (i.e., Fv/Fm), and intracellular reactive oxygen species (ROS) production. While certain strains exhibited significant growth inhibition in response to the allelochemicals, others demonstrated no apparent effect on cell proliferation, indicating varying sensitivity to specific allelochemicals or potentially distinct detoxification mechanisms. Similarly, the diverse effects on Fv/Fm highlight the complexity of allelopathic interactions, with some species showing reduced efficiency without alterations in intracellular ROS production, while others displayed increased ROS production alongside impaired photosynthesis. [ABSTRACT FROM AUTHOR]

[Objective] The study aims to explore the antibacterial activity and allelopathy of flavonoids from leaves of Eleutherococcus brachypus, and to provide the basis for the development of plant-derived antimicrobial agents and the application of their allelopathy in plant protection and agricultural production. [Methods] Leaf flavonoids was extracted by an ultrasonic-assisted method from E. brachypus leaves, then the antibacterial sphere, the minimum inhibitory concentration (MIC), the apoptosis rate, MDA content, ROS content, and the activity of antioxidant enzymes of epidermal cells from onion scaly leaves, as well as the inhibitory rate of the onion root and shoot growth were determined with different concentrations of leaf flavonoid extracts (100%, 50%, and 25%). [Results] (1) The yield of leaf flavonoids from E. brachypus was 42.3 mg/g. (2) At same concentration, the diameter of the inhibition zone was S. aureus > B. subtilis > Salmonella, respectively, and expanded with the increase in the extract concentrations with the same strain. The minimum inhibitory concentration of the three strains was also S. aureus < B. subtilis < Salmonella, respectively. (3) Each concentration of leaf flavonoids from E. brachypus induced apoptosis in the upper epidermal cells of Allium cepa. Meanwhile, as the concentration of flavonoid extracts increased, the apoptosis rate, MDA content, and H2O2 content were increased. POD activity and CAT activity were increased first and then decreased during the same time of treatment, which were higher in treatment groups than the control. (4) The growth of root and shoot of the onion scale leaves were inhibited under the treatment of flavonoids extracts, which was negatively correlated with the treatment dose. [Conclusion] The antibacterial effects of the leaf flavonoid extracts of E. brachypus on Gram-positive bacteria are better than that of Gram-negative bacteria, and the antibacterial effects are positively correlated with the concentration of flavonoid extracts. Moreover, all these changes suggest that the allelopathic mechanism of flavonoid extracts from E. brachypus may be due to the overproduction of ROS and the inhibition of antioxidant enzyme activity, which cause oxidative damage to membrane lipids and cell death.

In general, allelopathy can be defined as a biological process by which an organism produces one or more metabolites that can change the germination, growth, survival, and reproduction of other organisms, and thus influencing the stability of agroecosystems. Cholesterol is a very abundant sterol isolated from the marine red alga Plocamium brasiliense that has been studied regarding its potential inhibitory effects on seed germination, radicle elongation, and hypocotyl development of the weeds Mimosa pudica (malicia) and Senna obtusifolia (mata-pasto). Cholesterol was isolated from a hexane extract by chromatographic methods. Over a 15-day period, germination bioassays were performed at 25 ºC with a 12-h photoperiod. Radicle elongation and hypocotyl development were assayed at 25 ºC with a 24-h photoperiod. Later, Petri dishes 9.0 cm in diameter were coated with filter paper, and 25 seeds were placed in a germination chamber. Six pregerminated seeds were placed in the Petri dish for 2-3 days. After 10 days, radicle and hypocotyl extensions were measured, and the inhibitory potential of cholesterol was assessed at 5, 10, 15, and 20 ppm. In both herbs, M. pudica and S. obtusifolia, they were significantly affected by the action of cholesterol, achieving higher percentages of inhibition in seed germination (50% and 33%, respectively), radical germination (68% and 60%, respectively), and hypocotyl development (66% and 55%, respectively). The inhibition effects were dose-dependent in all experiments, having more pronounced allelopathic effects at 20ppm. [ABSTRACT FROM AUTHOR]

Medicinal plants have been used historically for various treatments and in human nutrition. Due to their natural occurrence and biodegradability, medicinal plants can be an eco-friendly alternative to toxic chemicals such as pesticides, fungicides, and herbicides. An in vitro experiment was conducted to test the impact of six medicinal plant extracts on tomato growth and callus induction. Two concentrations of each extract (50 and 100 mg L-1) were added to the Murashige and Skoog (MS) medium culture. Results showed that Juniperus sabina extract (50 mg L-1) accelerated tomato seed germination by 100% in vitro, compared to the control group in MS basal medium. Callus growth index (CGI) and callus weight (CW) increased by 50% and by more than 200% when using Taraxacum officinale (100 mg L-1) and Conocarpus erectus (50 mg L-1) extracts, respectively. Biochemical analysis revealed that the extracts were rich in phenolic compounds (348 mg g-1 of total phenol), flavonoids (162 mg g-1), antioxidants (61%), and auxin. A rise in antioxidant activity, plant growth regulators (PGR), and plant defense elicitation probably contributed to these outcomes. Plant extracts also affected the biochemical content of calluses, except for their total phenol. We recommend using these plant extracts to increase growth, accelerate seed germination, and promote callus induction. Optimizing concentrations and combinations of medicinal plant extracts require further research to maximize their benefits to different plant species and their growth-related values. [ABSTRACT FROM AUTHOR]

Abstract [Objective] The study aims to investigate the chemosensory effect of fading leaves of Ziziphus jujuba, Juglans regia, and Malus pumila in northern Shaanxi, and to provide theoretical guidance for the selection of suitable grass species under economic forests. [Methods] Outdoor potting forage Lolium perenne and Medicago sativa were set up with different concentrations of Z. jujuba, J. regia, and M . pumila withered leaf extracts (0.1, 0.05, 0.025, 0.012 5 g/mL) treatments to determine the growth and physiological indexes of the forage. [Results] (1) The dry mass of forage monocultures was significantly lower than the control in most of the three types of withered leaves treated with each concentration of leachate, and the decrease was smaller in the Z. jujuba leachate. (2) Forage malondialdehyde content was higher than the control under all three types of leachate treatments, while the increase in Z. jujuba leachate was smaller, and the changes in its chlorophyll content, ascorbic acid content and antioxidant enzyme activity differed significantly among the three types of leachates, and the variability of L. perenne was significantly greater than that of M . sativa. (3) There were significant differences in the effects of the three types of extracts on the root traits of the forages, all of which inhibited their root length growth, significantly inhibited the number of L. perenne root tips, and promoted the number of M . sativa root tips. [Conclusion] Three kinds of fruit tree leaf extract showed significant inhibition on the growth of two kinds of forage grasses, and the inhibitory effect of Z. jujuba extract was the smallest, and the growth of L. perenne was less inhibited than that of M . sativa.

Phosphorus (P) levels alter the allelopathic activity of rice seedlings against lettuce seeds. In this study, we investigated the effect of P deficiency on the allelopathic potential of non-pigmented and pigmented rice varieties. Rice seedlings of the white variety Khao Dawk Mali (KDML105, non-pigmented) and the black varieties Jao Hom Nin (JHN, pigmented) and Riceberry (RB, pigmented) were cultivated under high P (HP) and low P (LP) conditions. Morphological and metabolic responses to P deficiency were investigated. P deficiency inhibited shoot growth but promoted root growth of rice seedlings in all three varieties. Moreover, P deficiency led to decreased cytosolic phosphate (Pi) and total P concentrations in both shoot and root tissues. The subsequent reduction in internal P concentration enhanced the accumulation of phenolic compounds in both shoot and root tissues of the seedlings. Subsequently, allelopathy-based inter- and intra-specific interactions were assessed using water extracts from seedlings of the three varieties grown under HP and LP conditions. These extracts were tested on seeds of lettuce, the weed Dactyloctenium aegyptium, and the same rice variety. The shoot and root extracts from P-deficient seedlings reduced the germination of all recipient plants. Specifically, the shoot extract from P-deficient KDML105 seedlings reduced the germination index (GI) of lettuce seeds to 1%, while those from P-deficient RB and JHN seedlings produced GIs of 32% and 42%, respectively. However, when rice seeds were exposed to their own LP shoot and root extracts, their GIs increased up to 4-fold, compared with the HP extracts. Additionally, the shoot extracts from P-deficient plants also stimulated the germination of D. aegyptium by about 2–3-fold, whereas the root extracts did not have this effect. Therefore, P starvation led to the accumulation and exudation of phenolics in the shoots and roots of rice seedlings, altering their allelopathic activities. To adapt to P deficiency, rice seedlings potentially release signaling chemicals to suppress nearby competing species while simultaneously promoting their own germination and growth.

Many allelopathic crops are cultivated in agricultural fields, and these plants can influence the growth of other plants in the cultivation environment with their phytotoxic compounds. One of these plants is the faba bean. In this study conducted under the ecological conditions of Sakarya/Arifiye, the allelopathic effects of Eresen-87, Salkim, Bilecik, and Sakarya faba bean genotypes on weeds such as Johnson grass (Sorghum halepense L.), curly dock (Rumex crispus L.), purslane (Portulaca oleracea L.), and wild mustard (Sinapis arvensis L.) were investigated. Weed seeds used in the experiment were collected from agricultural fields in the Sakarya province. Extracts from dried plant parts of faba bean genotypes were prepared and applied to petri dishes containing weed seeds at concentrations of 5% and 10%, with four replications. At the end of the research, it was observed that all faba bean genotypes at all application doses caused a decrease in germination rate (%), root length (cm), and shoot length (cm) parameters in the four weed species tested. The best results were determined as Eresen-87 and Bilecik at 10% concentration. When the activities of fresh and dry extracts of faba bean genotypes was compared, it was determined that dry application had a higher allelopathic effect.

Abstract Allelopathy is a biological process in which one organism releases biochemicals that affect the growth and development of other organisms. The current investigation sought to determine the allelopathic effect of Rumex acetosella on white clover (Trifolium repens) growth and development by using its shoot extract (lower IC50 value) as a foliar treatment. Here, different concentrations (25, 50, 100, and 200 g/L) of shoot extract from Rumex acetosella were used as treatments. With increasing concentrations of shoot extract, the plant growth parameters, chlorophyll and total protein content of Trifolium repens decreased. On the other hand, ROS, such as O2 .− and H2O2, and antioxidant enzymes, including SOD, CAT, and POD, increased with increasing shoot extract concentration. A phytohormonal study indicated that increased treatment concentrations increased ABA and SA levels while JA levels were reduced. For the identification of allelochemicals, liquid‒liquid extraction, thin-layer chromatography, and open-column chromatography were conducted using R. acetosella shoot extracts, followed by a seed bioassay on the separated layer. A lower IC50 value was obtained through GC/MS analysis. gammaSitosterol was identified as the most abundant component. The shoot extract of Rumex acetosella has strong allelochemical properties that may significantly impede the growth and development of Trifolium repens. This approach could help to understand the competitive abilities of this weed species and in further research provide an alternate weed management strategy.

Summary. Some weeds have parasitic lifestyles, causing severe problems in agriculture. These plants include Phelipanche ramosa (L.) Pomel (branched broomrape). Green house and nursery trials were carried out to assess control of P. ramosa using organic extracts from 14 plant species. The parameters recorded were counts of living and dead tubercles of P. ramosa and fresh weights of living tubercles. Organic extract of Olea europea reduced lengths of germ tubes during P. ramosa seed germination, and extracts of Bidens bipinnata and Dittrichia viscosa reduced production and development of the parasite’s tubercles, with very encouraging results in reducing seed germination rates. This research provides knowledge insights on the potential use of plant secondary metabolites to limit spread of P. ramosa, addressing an increasing challenge for organic crop production. [ABSTRACT FROM AUTHOR]

The inhibitory potential of allelopathic plants is the subject of increasing research attention for their application in weed management. The sugarcane leaf is an agricultural waste product that has been reported to have allelopathic potential. Therefore, the present study determined the optimal organic solvent system and fractionation procedure to enhance the quantity of this extract and its allelopathic efficiency. Sugarcane leaves were extracted using five ethanol/water solvent ratios (v/v): 00:100, 25:75, 50:50, 75:25, and 100:00. Their allelopathic effects on seed germination and seedling growth were assayed in two major weeds, Echinochloa crus-galli (L.) Beauv. and Amaranthus viridis L. The results showed that the extract concentration, solvent ratio, and their interaction significantly inhibited the growth parameters in A. viridis. Consequently, a crude ethanol/water ratio of 00:100 was used to separate the active fraction via acid–base solvent partitioning. The acidic fraction (AE) exerted the greatest inhibitory effect and completely (100%) inhibited A. viridis at all concentrations, followed by the original crude fraction, neutral fraction, and aqueous fraction. Moreover, all of the fractions had selective effects, inhibiting A. viridis much more than E. crus-galli in the laboratory tests. The chemical analysis using gas chromatography/mass spectrometry indicated that the AE fraction contained 20 different compounds. The five major compounds included alkaloids, organic acids, and phenols. Therefore, the AE fraction was selected for formulation in a concentrated suspension and tested for its herbicidal characteristics. The formulation exhibited early post-emergence activities and had a stronger effect on A. viridis compared to E. crus-galli. The physiological mechanism of the formulation was tested against A. viridis. The thiobarbituric acid reactive substances and H2O2 occurred in the A. viridis leaf, which suggests lipid peroxidation and cell disruption. [ABSTRACT FROM AUTHOR]

A greenhouse experiment was conducted to determine the potential of arbuscular mycorrhizal fungi (AMF) to mitigate the allelopathic effects of invasive Nicotiana glauca on the growth of Acacia gerrardii seedlings. Aqueous extracts from N. glauca leaves and flowers (at concentrations of 20, 60, and 100 g/L) and AMF treatment (±AMF) were applied to A. gerrardii seedlings arranged in a factorial experiment with four replicates. After 6 months, vegetative (plant fresh and dry weight, height, leaf number area), physiological (photosynthesis, stomatal conductance, transpiration rate), chlorophyll a and b, proline, and root (length, surface area, diameter, volume, tip number) parameters as well as root distribution in five root diameter classes (0–5 mm, in 1 mm increments) were examined. The presence of AMF increased the seedling growth parameters. The 20 g/L treatment stimulated most of the vegetative growth, root, chlorophyll, and photosynthesis parameters at both inoculant levels for all extract types and concentrations, and the 100 g/L treatment inhibited seedling growth whether inoculated with AMF or not. This decline was alleviated in AMF-treated seedlings. For both extract sources, root length decreased as extract concentration increased, and roots <1 mm accounted for the greatest proportion of total root length, surface area, and tip number, with higher values observed in AMF-treated seedlings compared to their untreated counterparts. Further research is required at the field level to identify AMF strains and their interaction effects in alleviating the allelopathic impact of N. glauca on A. gerrardii seedling growth. [ABSTRACT FROM AUTHOR]

Ludwigia decurrens Walter, belonging to the Onagraceae family, is native to southeastern and southcentral USA and has spread quickly, colonizing wetlands in South and Central America, East and South Asia and Africa. Ludwigia decurrens also infests rice paddy fields and causes serious damage to rice production. The phenomenon of allelopathy is often observed in invasive plant species and contributes to their invasive characteristics. However, no information has been made available on the allelopathy of L. decurrens against wetland species, including Oryza sativa (rice), or on its allelochemicals. Aqueous methanol extracts of whole L. decurrens plants showed allelopathic activity against O. sativa and paddy weeds, Echinochloa crus-galli and Monochoria vaginalis in an extract-concentration-dependent manner. Two allelochemicals, loliolide and dehydrololiolide, were isolated from the L. decurrens extracts through a bioassay-guided separation process using O. sativa as the test plant species. Loliolide and dehydrololiolide also suppressed the growth of O. sativa and E. crus-galli in a concentration-dependent manner. Thus, loliolide and dehydrololiolide may be involved in the allelopathy of L. decurrens and may provide a competitive advantage for L. decurrens due to their growth inhibitory activity. However, the inhibitory activity of loliolide was about 3-fold greater than that of dehydrololiolide. These investigations suggest the allelopathy of L. decurrens may play an important role in the invasion of the species into rice paddy fields and other wetlands. This is the first report on the allelopathy of L. decurrens against wetland species and the isolation and identification of the allelochemicals in L. decurrens. [ABSTRACT FROM AUTHOR]

The present study evaluates the phytotoxic effects of phloretin, a prevalent secondary metabolite of apple trees, on the broadleaf weed Capsella bursa-pastoris (L.) Medik. known for its resistant myxospermous seeds that form a long-lasting soil bank. The results indicate a significant, dose-dependent inhibitory effect of phloretin on the growth and morphological parameters of weed seedlings grown in vitro. Although the applied phloretin concentrations (250–1000 µM) were not lethal to the C. bursa-pastoris seedlings after two weeks, the metabolism of the seedlings was impaired, resulting in an accumulation of lipid droplets in the root tips and root hairs. Histochemical analysis shows deposits of phenols in the root epidermal cells, which are probably aggregates of phloretin or its metabolic derivatives. The accumulation of pectin in the cell walls of root border cells in phloretin-treated seedlings indicates an attempt to reduce the uptake of phloretin and reduce its concentration in the cells. Inhibition of shoot growth associated with chlorosis and reduced photosynthetic pigment content is a consequence of seedling exposure to phloretin. This study provides a basis for further evaluation of phloretin as a new bioherbicidal compound and for elucidating the mechanism underlying its phytotoxic activity. [ABSTRACT FROM AUTHOR]

A suite of plant traits is thought to make weed populations highly invasive, including vigorous growth and reproduction, superior competitive ability, and high dispersal ability. Using a breeding design and a common garden experiment, we tested whether such an "invasion syndrome" has evolved in an invasive range of Solidago altissima, and whether the evolution is likely to be genetically constrained. We found an overall shift in invasive phenotypes between native North American and invasive Japanese populations. The invasive populations were taller and produced more leaves, suggesting a superior ability to exploit limited resources. The populations also produced more allelopathic compounds that can suppress competitor growth. Finally, invasive populations produced more seeds, which are smaller and are released from a greater height, indicating a potential for superior dispersal ability than the native populations. Quantitative genetics analyses found a large amount of additive genetic variation in most focal traits across native and invasive populations, with no systematic differences in its magnitude between the ranges. Genetic covariances among three traits representing invasion strategies (leaf mass, polyacetylene concentration and seed size) were small. The R metric, which measures the effect of genetic covariances on the rate of adaptation, indicated that the covariance neither constrains nor accelerates concerted evolution of these traits. The results suggest that the invasion syndrome in S. altissima has evolved in the novel range due to ample additive genetic variation, and relatively free from genetic trade‐offs. [ABSTRACT FROM AUTHOR]

Phosphorus (P) levels alter the allelopathic activity of rice seedlings against lettuce seeds. In this study, we investigated the effect of P deficiency on the allelopathic potential of non-pigmented and pigmented rice varieties. Rice seedlings of the white variety Khao Dawk Mali (KDML105, non-pigmented) and the black varieties Jao Hom Nin (JHN, pigmented) and Riceberry (RB, pigmented) were cultivated under high P (HP) and low P (LP) conditions. Morphological and metabolic responses to P deficiency were investigated. P deficiency inhibited shoot growth but promoted root growth of rice seedlings in all three varieties. Moreover, P deficiency led to decreased cytosolic phosphate (Pi) and total P concentrations in both shoot and root tissues. The subsequent reduction in internal P concentration enhanced the accumulation of phenolic compounds in both shoot and root tissues of the seedlings. Subsequently, allelopathy-based inter- and intra-specific interactions were assessed using water extracts from seedlings of the three varieties grown under HP and LP conditions. These extracts were tested on seeds of lettuce, the weed Dactyloctenium aegyptium , and the same rice variety. The shoot and root extracts from P-deficient seedlings reduced the germination of all recipient plants. Specifically, the shoot extract from P-deficient KDML105 seedlings reduced the germination index (GI) of lettuce seeds to 1%, while those from P-deficient RB and JHN seedlings produced GIs of 32% and 42%, respectively. However, when rice seeds were exposed to their own LP shoot and root extracts, their GIs increased up to 4-fold, compared with the HP extracts. Additionally, the shoot extracts from P-deficient plants also stimulated the germination of D. aegyptium by about 2–3-fold, whereas the root extracts did not have this effect. Therefore, P starvation led to the accumulation and exudation of phenolics in the shoots and roots of rice seedlings, altering their allelopathic activities. To adapt to P deficiency, rice seedlings potentially release signaling chemicals to suppress nearby competing species while simultaneously promoting their own germination and growth. [ABSTRACT FROM AUTHOR]

Plant communities may be co-invaded by invasive plants, sometimes even by congeneric invasive plants (CIPs). Despite the growing understanding of co-invasion in the environment, little is known about how CIP interactions and mechanisms regulate co-invasion. Darwin's naturalisation conundrum predicts that the coexistence of closely related species is difficult due to their structural and behavioural similarities. Nevertheless, communities containing closely related species are more susceptible to being invaded because close relatives may favour similar environments; therefore, this hypothesis should be followed in the co-invasion of CIPs. To explore whether the phylogenetic relatedness and origins of invasive species to CIPs can promote or hinder co-invasion, we conducted a controlled interaction and soil-legacy greenhouse experiment to quantify the growth response of invasive plants and their congeners. We consistently found that CIPs of identical origin were more likely to co-invade compared to CIPs of distinct origins. CIPs of distinct origins exhibited an antagonistic effect on co-invasion by allelopathy. Invasive plant-conditioned soil was more conducive to the growth of CIPs of identical origin than CIPs of distinct origins. Our results revealed the different effects of invader–invader phylogenetic relatedness on co-invader success and impact, suggesting the operation of different mechanisms across co-invasion. [ABSTRACT FROM AUTHOR]

The spontaneous plant landscape is a key focus in the development of urban environments. While many spontaneous plants can coexist with bryophytes to create appealing wilderness landscapes, the potential allelopathic effects of bryophytes on the growth of neighboring spontaneous plants remain uncertain. This study evaluated the allelopathic impact of Thuidium kanedae aqueous extracts on the germination and seedling growth of prevalent urban spontaneous plants by analyzing seed germination, seedling growth morphology, and associated indices. We also investigated the allelopathic potential of the predominant compounds in the extract on seed germination. Our findings reveal that the aqueous extract significantly impeded the seed germination of Ophiopogon japonicus, Taraxacum mongolicum, and Viola philippica, with the level of inhibition correlating positively with concentration. In contrast, Senecio scandens seed germination showed a concentration-dependent reaction, with low concentrations promoting and high concentrations hindering germination. The extract consistently reduced root length in all four species, yet it appeared to increase root vigor. The chlorophyll content in O. japonicus and V. philippica seedlings reached a maximum at a concentration of 5 g/L and decreased with higher extract concentrations. The treatment resulted in elevated catalase and soluble protein levels in the seedlings, indicating that the extract induced stress and enhanced the stress resistance index. L-phenylalanine and 2-phenylethanol, substances present in the extract, were notably inhibitory to seed germination across all species, except for O. japonicus. Notably, 2-phenylethanol exhibited a stronger allelopathic effect than L-phenylalanine. Allelopathy synthetical effect evaluation showed that high concentration of aqueous extract allelopathic inhibition effect on seed germination of four plant species, but allelopathic promotion effect on physiological and biochemical growth of Taraxacum mongolicum, Senecio scandens and Viola philippica. In summary, the study demonstrates that bryophytes exert allelopathic effects on neighboring spontaneous plants, with the degree of influence varying among species. This suggests that the germination and growth of spontaneous plant seeds may be selective in bryophyte-dominated habitats and that the density of bryophytes could shape the evolution of these landscapes. [ABSTRACT FROM AUTHOR]

Beyond ecological and health impacts, invasive alien plant species can generate indirect and direct costs, notably through reduced agricultural yields, restoration, and management of the invaded environment. Acacia dealbata and Ailanthus altissima are invasive plant species that cause particularly significant damage to the railway network in the Mediterranean area. The allelopathic properties of Mediterranean plant species could be used as nature‐based solutions to slow down the spread of such invasive plant species along railway borders. In this context, a mesocosm experiment was set‐up: (i) to test the potential allelopathic effects of Cistus ladanifer, Cistus albidus, and Cotinus coggygria leaf aqueous extracts on seed germination and seedling growth of A. dealbata and A. altissima; (ii) to evaluate whether these effects depend on the extract dose; and finally, (iii) to estimate whether these effects are modified by soil amendment. Leaf aqueous extracts of the three native plant species showed negative effects on both seed germination and seedling growth of the two invasive species. Our results show that the presence of allelochemicals induces a delay in seed germination (e.g., A. dealbata germination lasted up to 269% longer in the presence of high‐dose leaf aqueous extracts of C. coggygria), which can lead to a decrease in individual recruitment. They also highlight a decrease in seedling growth (e.g., high‐dose C. coggygria leaf aqueous extracts induced a 26% decrease in A. dealbata radicle growth), which can alter the competitiveness of invasive species for resource access. Our results also highlight that compost addition limits the inhibitory effect of native Mediterranean plants on the germination of invasive alien plants, suggesting that soil organic matter content can counteract allelopathic effects on invasive alien plants. Thus, our findings revealed that the allelopathic potential of certain Mediterranean plant species could be a useful tool to manage invasive plant species. [ABSTRACT FROM AUTHOR]

Allelopathy is a biological process in which one organism releases biochemicals that affect the growth and development of other organisms. The current investigation sought to determine the allelopathic effect of Rumex acetosella on white clover (Trifolium repens) growth and development by using its shoot extract (lower IC50 value) as a foliar treatment. Here, different concentrations (25, 50, 100, and 200 g/L) of shoot extract from Rumex acetosella were used as treatments. With increasing concentrations of shoot extract, the plant growth parameters, chlorophyll and total protein content of Trifolium repens decreased. On the other hand, ROS, such as O2.− and H2O2, and antioxidant enzymes, including SOD, CAT, and POD, increased with increasing shoot extract concentration. A phytohormonal study indicated that increased treatment concentrations increased ABA and SA levels while JA levels were reduced. For the identification of allelochemicals, liquid‒liquid extraction, thin-layer chromatography, and open-column chromatography were conducted using R. acetosella shoot extracts, followed by a seed bioassay on the separated layer. A lower IC50 value was obtained through GC/MS analysis. gammaSitosterol was identified as the most abundant component. The shoot extract of Rumex acetosella has strong allelochemical properties that may significantly impede the growth and development of Trifolium repens. This approach could help to understand the competitive abilities of this weed species and in further research provide an alternate weed management strategy. [ABSTRACT FROM AUTHOR]

Simple Summary: The spread of large green algae in oceans causes green tides, particularly in the South Yellow Sea of China, where Ulva prolifera has led to the world's largest green tide events. This review looks at how allelopathy, a process where plants release chemicals to affect the growth and development of other plants, influences green tide dynamics. We focus on four main types of these allelochemicals—fatty acids, aldehydes, phenols, and terpenes—explaining how they influence the algae's growth and behavior. We also discuss new methods for quickly detecting these allelochemicals and how these methods can help monitor green tides. By combining allelochemical detection with advanced technologies like satellite observations and environmental DNA analysis, we can better understand and manage green tides. The proliferation of large green macroalgae in marine environments has led to the occurrence of green tides, particularly in the South Yellow Sea region of China, where Ulva prolifera has been identified as the primary species responsible for the world's largest green tide events. Allelopathy among plants is a critical factor influencing the dynamics of green tides. This review synthesizes previous research on allelopathic interactions within green tides, categorizing four extensively studied allelochemicals: fatty acids, aldehydes, phenols, and terpenes. The mechanisms by which these compounds regulate the physiological processes of green tide algae are examined in depth. Additionally, recent advancements in the rapid detection of allelochemicals are summarized, and their potential applications in monitoring green tide events are discussed. The integration of advanced monitoring technologies, such as satellite observation and environmental DNA (eDNA) analysis, with allelopathic substance detection is also explored. This combined approach addresses gaps in understanding the dynamic processes of green tide formation and provides a more comprehensive insight into the mechanisms driving these phenomena. The findings and new perspectives presented in this review aim to offer valuable insights and inspiration for researchers and policymakers. [ABSTRACT FROM AUTHOR]

Faba bean is an important legume crop worldwide, which is grown both for food and feed. As for many legume crops, postemergence weed control is difficult. The aim of this work was to assess the potential of intercropping in weed management by assessing the effect of mixing faba bean with different crops (wheat, barley, and pea) on weeds in the South of Spain. Four field trials were conducted over four consecutive seasons, and the results found that the addition of alternate intercropping of faba bean and barley achieved high levels of weed control, both for coverage and biomass (92.7% and 76.6%, respectively). Intercropping with wheat did not reduce weed coverage but did decrease weed biomass by 46.1% as compared with the faba bean monocrop. Intercropping with pea did not provide significant reductions in weed coverage or weed biomass. The diversity of the weed community was not altered by the different crop combinations tested. Additional experiments under controlled conditions were carried out to determine the possible role of barley allelopathy in weed suppression. A strong allelopathic effect entailing a reduction in the number of plants and biomass was detected for four weeds including Sinapis arvensis, Polypogon monspeliensis, Matricaria camomilla, and Medicago truncatula. It can be concluded that intercropping faba bean with barley is an excellent strategy for weed control in Southern Spain. [ABSTRACT FROM AUTHOR]

Nano solutions are widely used in medicine and also have the potential to be used when performing allelopathy screening studies. The present experiment aimed to test the effectiveness of colloidal nano silver Silver–Amber© with nanoparticles of 20 nm (>20 mg/L at a purity level of 99.99%) as a carrier of allelochemicals in laboratory conditions. The influence of eleven concentrations of Silver–Amber© (0.10, 0.20, 0.39, 0.78, 1.56, 3.13, 6.25, 12.5, 25.0, 50.0 and 100.0% v/v) on the germination and initial development of test plant Lactuca sativa L. in 0.75% agar medium was studied. Data revealed that when increasing the quantitative ratio of Silver–Amber©, an inhibitory effect on seed germination (from 37.8 to 94.3%) and on the plant growth (from 54.0 to 98.9%) appeared. Lower concentrations (0.63 to 0.04 ppm) had an indifferent to statistically unproven stimulatory effect on the germination and initial development of L. sativa (GI ranged from 88.7–94.6%). Therefore, nano silver can be used as carrier of allelochemicals in allelopathic studies in laboratory conditions. [ABSTRACT FROM AUTHOR]

Tanacetum vulgare is a perennial plant growing wild along roadsides, pastures, and agricultural fields. Its prevalence is due to several factors: good climatic adaptability, high self-seeding potential, phenotypic plasticity, multiplying via underground rhizomes and its allelochemicals, which influence the seed germination, root development and the overall vegetation of the surrounding plants. The phytochemistry of tansy extracts and their allelopathic activity on the seed germination and growth of garden pepper cress (Lepidium sativum L.) and lettuce (Lactuca sativa L.) were investigated. The major volatile compounds, 1,8-cineole, camphor and borneol were determined in tansy flower extracts. The leaf extracts contained appreciable amounts of 1,8-cineole and borneol. Feruloylquinic, (di)ferulic and dehydrocaffeoyl-5-caffeoylquinic acids, acacetin, ludovicin C and tanacetin were determined both in leaf and inflorescence extracts. Root extracts contained minor quantities of some terpenoids and polyphenols. Extracts of T. vulgare's aerial parts showed strong allelopathic effects on model plants. The flower and leaf water extracts inhibited lettuce and pepper cress seed germination and growth the most. According to the fractions, the acidic solution had the strongest effect, followed by neutral and alkaline solutions. At the highest relative concentrations of 0.5 and 1.0 tansy leaf acidic fraction, lettuce seed germination and growth decreased by 89.93% (from 35.07 ± 4.79 to 3.53 ± 2.10 mm) and by 98.46% (from 35.07 ± 4.79 to 0.57 ± 0.98 mm) compared to the control, respectively. Tansy root extracts showed weak effects. Our results demonstrated that the allelopathic inhibitory potential of tansy extracts was higher on garden pepper cress than on lettuce. The presence of allelochemicals in T. vulgare may have a significant impact on plant communities and ecosystems. [ABSTRACT FROM AUTHOR]

The aim of the present study is to: i) analyze the water absorption capacity of seeds of some Tagetes sp.; ii) compare the water absorption of Tagetes sp. and Lactuca sativa L. seeds in order to assess the potential of genus Tagetes as test object for laboratory screening studies for establishing allelopathic interference in plant communities. Tagetes erecta (local population from Germany), Tagetes patula (local population from Germany), and Tagetes patula variety “Usmivka” (Bulgarian variety) have been included in the study. Equivalence in the water absorption capacity (Ws%) of the seeds of studied Tagetes sp. and Lactuca sativa L. variety “Great Lakes” was found, with the maximum of water absorption occurring at the first hour and stopping by the fourth hour, regardless of the temperature range in which the imbibition takes place. The significant differences in the cumulative values of the average water absorption capacity of the Tagetes sp. seeds compared to Lactuca sativa L. variety “Great Lakes” (Ws% average ranged from +5.68 to +83.27%), indicate that the species of genus Tagetes can be successfully used in laboratory screening studies to establish allelopathic interference under in vitro conditions. Further research is needed to establish seed water absorption capacity (Ws%) of Tagetes sp. depending on the type of aqueous extracts used in allelopathic studies (cold or temperate), as well as of the concentrations applied. [ABSTRACT FROM AUTHOR]

The coastal Casuarina equisetifolia is the most common tree species in Hainan's coastal protection forests. Sequencing the genomes of its allelopathic endophytes can allow the protective effects of these bacteria to be effectively implemented in protected forests. The goal of this study was to sequence the whole genomes of the endophytes Bacillus amyloliquefaciens and Bacillus aryabhattai isolated from C. equisetifolia root tissues. The results showed that the genome sizes of B. amyloliquefaciens and B. aryabhattai were 3.854 Mb and 5.508 Mb, respectively. The two strains shared 2514 common gene families while having 1055 and 2406 distinct gene families, respectively. The two strains had 283 and 298 allelochemical synthesis-associated genes, respectively, 255 of which were shared by both strains and 28 and 43 of which were unique to each strain, respectively. The genes were putatively involved in 11 functional pathways, including secondary metabolite biosynthesis, terpene carbon skeleton biosynthesis, biosynthesis of ubiquinone and other terpene quinones, tropane/piperidine and piperidine alkaloids biosynthesis, and phenylpropanoid biosynthesis. NQO1 and entC are known to be involved in the biosynthesis of ubiquinone and other terpenoid quinones, and rfbC/rmlC, rfbA/rmlA/rffH, and rfbB/rmlB/rffG are involved in the biosynthesis of polyketide glycan units. Among the B. aryabhattai-specific allelochemical synthesis-related genes, STE24 is involved in terpene carbon skeleton production, atzF and gdhA in arginine biosynthesis, and TYR in isoquinoline alkaloid biosynthesis. B. amyloliquefaciens and B. aryabhattai share the genes aspB, yhdR, trpA, trpB, and GGPS, which are known to be involved in the synthesis of carotenoids, indole, momilactones, and other allelochemicals. Additionally, these bacteria are involved in allelochemical synthesis via routes such as polyketide sugar unit biosynthesis and isoquinoline alkaloid biosynthesis. This study sheds light on the genetic basis of allelopathy in Bacillus strains associated with C. equisetifolia, highlighting the possible use of these bacteria in sustainable agricultural strategies for weed management and crop protection. [ABSTRACT FROM AUTHOR]

There is limited evidence on bryophyte-tracheophyte allelopathic interactions. Even less is known about such relationships among commercially important plants and mosses. With the aim of screening such interactions, various extract concentrations of nine different mosses were tested on the seed germination and seedlings, i.e., hypocotyl elongation and total chlorophyll content of lettuce and radish. The allelopathic effects are documented to be pairwise (moss-vegetable) and species-specific. Based on the results, the extracts of Leucodon sciuroides and Dicranum polysetum are not harmful to lettuce and radish. Lower extract concentrations of Leucodon sciuroides and Ctenidium molluscum have a positive effect on lettuce development, while those of Thuidium delicatulum, Ctenidium molluscum, and Dicranum polysetum showed to be effective on radish. Further, negative effects were noticed when applying higher extract concentration of Abietinella abietina, Isothecium alopecuroides, Dicranum polysetum, and Racomitrium elongatum to lettuce and Isothecium alopecuroides to radish. The dataset presented in this study offers numerous possibilities for further target pest/vegetable type applications since some of the moss extracts are shown to be positive, negative, or indifferent to the tested features in lettuce and radish. [ABSTRACT FROM AUTHOR]

Replant diseases (RDs), intraspecific negative plant–soil feedback, often stem from nutrient deficiency, allelopathy, or pathogen accumulation. However, the RDs of certain crops are long-lasting and their causes remain unknown. We examined Panax quinquefolius RD in a space-for-time soil sequence representing crop rotation restoration over 1, 10, and 20 years using multiomics and bioassays. Compared with the soils with no ginseng cultivation history, we found 110 significant potential factors related to RD, surprisingly, 53 of which remained unrestored after 20 years. Soil pH and the levels of organic nutrients (amino acids, carbohydrates, and alditols), allelopathic-promoting metabolites (phenolic acids, amines, pyridines, etc.), and beneficial bacteria (Sphingomonas, Burkholderia-Caballeronia-Paraburkholderia, and Terrabacter) and fungi (Acremonium, Penicillium, and Naganishia) decreased, while the levels of allelochemicals (pyruvic and fatty acids) increased. The expression of all metabolic pathways was significantly down-regulated, with the exception of the up-regulated fatty acid-related metabolic pathways. We confirmed that decreased organic nutrient levels and increased levels of allelochemicals impaired P. quinquefolius growth. Soil metabolic factors rather than microbial factors were dominant by network analysis. In conclusion, we found that the overall changes in nutrient levels and metabolic and microbial factors contributed to short-term RD (1–10 year) persistence, whereas long-term RD (after 20 years) primarily resulted from disordered soil metabolite levels and pathways. This research will help deepen our understanding of the relationship between RD and potential changes in the factors influencing RD that are caused by soil legacy effects of valuable plants and provide theoretical guidance for effective soil quality improvement.

Abstract This study evaluates the phytotoxic potential of methanolic extracts from six Asteraceae species: Wedelia chinensis, Helianthus annuus, Cosmos bipinnatus, Tagetes erecta, Tithonia diversifolia, and Zinnia elegans. The extracts were tested at concentrations of 0.03, 0.1, 0.3, and 1.0 g/mL to assess their inhibitory effects on the radicle and hypocotyl lengths of Echinochloa crus‐galli and Echinochloa colona. The two most potent species, C. bipinnatus and T. diversifolia, were further evaluated using extracts from their roots, stems, and leaves. Among these, C. bipinnatus leaf extracts showed the most significant phytotoxicity and were tested at 20, 40, and 60 days of plant age. At 0.03 g/mL, C. bipinnatus extract inhibited the hypocotyl and radicle lengths of E. colona by 23.01% and 56.45%, and E. crus‐galli by 8.5% and 36.35%, respectively. At 1.0 g/mL, the extract inhibited the hypocotyl lengths of E. colona and E. crus‐galli by 97.54% and 88.15%, and the radicle lengths by 93.52% and 99.99%, respectively. The 60‐day‐old C. bipinnatus leaf extract exhibited the highest inhibitory effect, correlating with the identification of key allelochemicals such as cinnamic acid, caffeic acid, coumaric acid, ferulic acid, 2‐4 dimethohydroxy benzoic acid, and salicylic acid. These findings suggest that the 60‐day‐old C. bipinnatus leaf extracts have strong potential for use in the biological control of these weed species, offering a promising avenue for the development of natural herbicides.

IntroductionMicroplastic pollution has emerged as a significant global change factor, with the potential to alter the biological, physicochemical properties of soil and to subsequently affect plant growth. Despite growing recognition of the impacts of microplastic pollution, the mechanisms by which microplastics modify plant leaf chemistry and influence allelopathic interactions among co-existing plant species remain unclear.MethodsWe used the native perennial forb Achyranthes bidentata and the invasive annual forb Amaranthus spinosus as focal species. We grew the two species with and without competition with each other. This setup was further combined with a treatment involving the addition of polyethylene (PE). We then testd the effects of aqueous extract on seed germination and seedling growth for five invasive and five native species. Subsequently, metabolomic analysis was conducted on the aqueous extracts, in which significant allelopathic effects were observed on test species.Results and discussionThe presence of PE microplastics enhanced the biomass of both Achyranthes and Amaranthus under competitive and non-competitive growth conditions. Furthermore, PE microplastics were found to induce a negative allelopathic effect for the native plant Achyranthes on co-occurring plants, which appeared to be mediated through changes in leaf chemistry. Bisdemethoxycurcumin, ethylparaben, salicin 6’-sulfate and 5-hydroxy-3’,4’,7-trimethoxyflavone glucoside were proven important compounds for allelopathic enhancement. Overall, these results suggest that microplastic pollution has the capability to influence the co-existence of invasive and native plants by altering their allelopathic potential. This insight into the interactions between microplastics and plant allelopathy provides a novel perspective on how microplastic pollution could modify plant species interactions and ecosystem dynamics. Future studies could aim to answer how microplastics might affect plant root exudates and whether this process would mediate biological invasion.

The potential of the most prevalent weeds should be characterized biologically and chemically in infected soil and crops for sustainable agriculture. Therefore, the allelopathic potential of Avena fatua L. and Lolium temulentum L. weeds were compared via leachates, root exudates, decayed residues in soil, and the decomposition in water pathways. Chemical measurements were taken on wheat (Triticum aestivum L.), and soil decomposed solution. Based on EC50, the allelopathic effect of leachates were higher in aboveground parts than in subterranean parts, influenced by plant parts and concentrations. The root exudates show EC50 by 655.9 μg. ml−1 for A. fatua and 625.66 μg. ml−1 for L. temulentumin the seedling biomass fresh weights of T. aestivum. The systematic inhibition by decayed residues was affected by plant types, concentration, and time and correlated with soil parameters and crop performance. The decomposition rate was higher under aerobic conditions than anaerobic conditions, with the inhibition pattern showing the reverse trend. These finding highlight the importance of environmental conditions in mediating allelopathic effects. The highest quantities of phenolic acids determined by LC-ES/MS in decomposed solutions were citric acid, with concentrations of 7.71 and 13.31 μg/ml in A. fatua under aerobic conditions, and coumaric acid, with concentrations of 9.21 and 16.99 μg/ml in L. temulentum under aerobic conditions. The allelopathic potentials of A. fatua and L. temulentum may play a crucial role in T. aestivum crop growth and soil parameters. In general weed residues can suppress crop growth and negatively affect soil parameters based on their quantity and type, therefore they should be managed carefully for sustainable crop production.

Allelopathy, a biological phenomenon involving the production and release of secondary metabolites known as allelochemicals, plays a critical role in plant interactions and agroecosystem dynamics. Phenolic compounds are a significant class of allelochemicals that profoundly affect plant competition, soil health, and microbial communities. When released into the soil, their action depends on the soil's physico-chemical characteristics and microbial communities. This review comprehensively inspects phenolic allelochemicals’ structure-function relationship, their direct combat with root cells in the rhizosphere, ecological functions, and their role in plant succession and stress tolerance. Phenolic allelochemicals, characterized by their diverse structures and ecological roles, offer a sustainable alternative to synthetic herbicides due to their minimal residual impact on the environment and rapid biodegradation. Additionally, the review addresses the challenges and future directions in applying phenolic allelochemicals, aiming to bridge the gap between ecological theory and practical agricultural applications for environmental protection and crop productivity enhancement.

Abstract Invasive alien species are becoming more and more prevalent worldwide, Erigeron bonariensis and Bidens pilosa are two invasive species of Asteraceae in Egypt. To mitigate their detrimental effects and understand their differences in invasiveness, we compared the allelopathic potentials of E. bonariensis and B. pilosa using leachates, decaying residues, and volatilization processes. Notably, the allelopathic variances in leachates were significant, influenced by plant types, concentrations, and response patterns of target plant traits, as indicated by EC50. The relative phytotoxicity of the invasive species decayed residues peaked between 20 and 25 days in the soil, with a positive correlation with concentrations and soil properties. The highest quantities of phenolic acids were chlorogenic acid and caffeic acid reaching (5.41 and 4.39 µg g−1) E. bonariensis and (4.53 and 4.46 µg g−1) B. pilosa, in leachates extracts respectively, while in the soil extract of decayed residues were coumaric acid and ferulic acid measuring (1.66 and 1.67 µg g−1) E. bonariensis and (1.47 and 1.57 µg g−1) B. pilosa, respectively. Using GC/MS analysis, the main volatile components in E. bonariensis were 1, 8 cineole (5.62%), and α-terpinene (5.43%) and iso-Caryophyllene (5.2%) which showed the greatest inhibitory effects. While B. pilosa main constituents were trans-sabinene (5.39%) and Camphene (5.11%), respectively. Finally, the high invasion level displayed from E. bonariensis (0.221) compared with B. pilosa (0.094) which correlated with the stronger allelopathic activities against plant species, and soil properties. Therefore, the allelopathic potentialities of these species are critically relevant to their invasion success.

Abstract Allelopathy has been considered as a natural method of weed control. Despite the nature of allelochemical compounds has been studied, little is known about the genetic basis underlying allelopathy. However, it is known that rice exhibits diverse allelopathic potentials across varieties, and breeding for rice plants exhibiting allelopathic potential conferring an advantage against weeds in paddy fields would be highly desirable. Knowledge of the gene factors and the identification of the genomic regions responsible for allelopathy would facilitate breeding programs. Taking advantage of the existing genetic diversity in rice, particularly in temperate japonica rice, we conducted a comprehensive investigation into the genetic determinants that contribute to rice allelopathy. Employing Genome-Wide Association Study, we identified four Quantitative Trait Loci, with the most promising loci situated on chromosome 2 and 5. Subsequent inspection of the genes located within these QTLs revealed genes associated with the biosynthesis of secondary metabolites such as Phenylalanine Ammonia Lyase (PAL), a key enzyme in the synthesis of phenolic compounds, and two genes coding for R2R3-type MYB transcription factors. The identification of these two QTLs associated to allelopathy in rice provides a useful tool for further exploration and targeted breeding strategies.

Allelopathy is the main chemical means in the invasion process of exotic plants and one of the key factors in grassland degradation. In this experiment, we investigated the effects of ethyl acetate phase extract (EAE), n-butanol phase extract (BE) and aqueous phase extract (AE) from the aboveground (stems and leaves) and roots of Ligularia sagitta on seed germination and seedling growth of four Gramineae forages (Poa pratensis L. Festuca ovina L. Elymus nutans Griseb. Agropyron cristatum (L.) Gaertn.) in their sympatric domains and one Legosuminae forage (Medicago sativa L.). The chemical components in each phase extract of L. sagitta were determined with UHPLC-MS/MS non-targeted metabolomics, and the differential compounds were screened using Orthogonal Partial Least Squares-Discriminant Analysis (OPLS-DA). Within a set concentration range, EAE significantly inhibited seed germination and seedling growth of four Gramineae forages. BE and AE acted mainly in the seedling growth stage and did not significantly inhibit forage seed germination. P. pratensis was most sensitive to L. sagitta extracts; at 2.0 mg/mL of EAE from roots, germination energy and germination rate of P. pratensis seeds were 0. L. sagitta extracts inhibited the growth of M. sativa seedlings and did not inhibit its seed germination. A total of 904 compounds were identified with UHPLC-MS/MS, among which 31, 64, 81 and 66 metabolites displayed different accumulation patterns in the four comparison groups (R.EAE vs. R.BE, R.EAE vs. R.AE, SL.EAE vs. SL.BE, SL.EAE vs. SL.AE), respectively. In particular, 9 compounds were found to be common up-regulated differential metabolites in the four comparison groups and were enriched in EAE. Additionally, N,N-dimethylaniline, Caffeic acid, 4-Hydroxybenzoic acid, 4-Hydroxybenzaldehyde and cis-9-Octadecenoic acid as potential allelochemicals in L. sagitta. The results of this study support efforts at finding alternative control plants for the restoration of poisonous grass-type degraded grasslands.

The study investigated compounds present in the invasive grass Hordeum murinum L. subsp. murinum and tested the allelopathic potential of this plant against common meadow species Festuca rubra L. and Trifolium repens L. Gas chromatography–mass spectrometry (GC–MS) performed separately on the ears and stalks with leaves of wall barley revealed 32 compounds, including secondary metabolites, that may play an important role in allelopathy. Two compounds, N-butylbenzenesulfonamide (NBBS) and diphenylsulfone (DDS), were described for the first time for wall barley and the Poaceae family. The presence of 6,10,14-trimethylpentadecan-2-one (TMP) has also been documented. Aqueous extracts of H. murinum organs (ears and stalks with leaves) at concentrations of 2.5%, 5%, and 7.5% were used to evaluate its allelopathic potential. Compared to the control, all extracts inhibited germination and early growth stages of meadow species. The inhibitory effect was strongest at the highest concentration for both the underground and aboveground parts of the seedlings of the meadow species tested. Comparing the allelopathic effect, Trifolium repens proved to be more sensitive. In light of the results of the study, the removal of wall barley biomass appears to be important for the restoration of habitats where this species occurs due to its allelopathic potential. [ABSTRACT FROM AUTHOR]

Heracleum mantegazzianum is an invasive species in middle Europe. The mode of action of its invasiveness is still not known. Our study focuses on observation of potential allelopathic influence by the production and release of phytochemicals into its environment. Plant material was collected four times within one season (April, May, June, July 2019) at locality Lekárovce (eastern Slovakia) for comparison of differences in composition and potential allelopathy. Water extracts from collected samples were used for different biological assays. The total phenols and flavonoids were determined spectrophotometrically. The profile and content of phenolic components, including coumarins, were determined by two techniques of liquid chromatography along with in vitro evaluation of the free radical scavenging activity of extracts (DPPH, Hydroxyl, Superoxide, and FRAP). The changes in composition in extracts in different seasonal periods were evident as well as potential phytotoxic activity in some concentrations on specific model plants. The slight antioxidant activity was noted. The invasiveness of the current species could be supported by the excretion of its phytochemicals into its surroundings and by different modes of action influencing living organisms in its environment. [ABSTRACT FROM AUTHOR]

Straw covering is a protective tillage measure in agricultural production, but there is relatively little research on the allelopathic effects of corn straw on weeds and foxtail millet. This experiment studied the allelopathic effects of corn straw on four weeds (Chenopodium album, Setaria viridis, Echinochloa crus-galli and Amaranthus retroflexus) in foxtail millet fields, and also measured the growth indicators of foxtail millet. The study consisted of Petri dish and field experiments. Five treatments were used in the Petri dish experiment: clear water as control (0 g/L, TCK) and four types of corn straw water extracts. They were, respectively, the stock solution (100 g/L, T1), 10 X dilution (10 g/L, T2), 50 X dilution (2 g/L, T3), and 100 X dilution (1 g/L, T4) of corn straw water extracts. Additionally, seven treatments were set up in the field experiment, consisting of three corn straw covering treatments, with covering amounts of 3000 (Z1), 6000 (Z2) and 12,000 kg/ha (Z3), and four control treatments—one treatment with no corn straw cover (CK) and three treatments involving the use of a black film to create the same shading area as the corn straw covered area, with black film coverage areas of 50% (PZ1), 70% (PZ2), and 100% (PZ3), respectively. The results showed that the corn straw water extract reduced the germination rate of the seeds of the four weeds. The T1 treatment resulted in the allelopathic promotion of C. album growth but the inhibition of S. viridis, E. crus-galli, and A. retroflexus growth. Treatments T2, T3, and T4 all induced the allelopathic promotion of the growth of the four weeds. The order of the effects of the corn straw water extracts on the comprehensive allelopathy index of the four weed seeds was as follows: C. album > S. viridis > A. retroflexus > E. crus-galli. With an increase in the corn straw mulching amount, the density and total coverage of the four weeds showed a gradual downward trend, whereas the plant control effect and fresh weight control effect showed a gradual upward trend. All indices showed the best results under 12,000 kg/ha of mulching and returning to the field. Overall, corn straw coverage significantly impacted the net photosynthetic rate and transpiration rate of foxtail millet and increased the yield of foxtail millet. Under coverages of 6000 and 12,000 kg/ha, the growth of foxtail millet is better. Based on our findings, we recommend a corn straw coverage of 12,000 kg/ha for the allelopathic control of weeds in foxtail millet fields. [ABSTRACT FROM AUTHOR]