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We studied the allelopathic effects of aqueous extracts of two weed species viz., Ageratum conyzoides L. and Parthenium hysterophorus L. on seed germination and early seedling growth of bell pepper plants infected by Phytophthora capsici. The parameters studied were: Percent disease index (PDI), seed germination, seedling fresh weight and seedling height of bell pepper. The inhibition (%) of different aqueous extracts of both donor weed plants ranged from 74.82 % to 91.16 %. Of all 4-aqueous extracts, ethanolic extract of leaves showed the best antifungal effects. The GC-MS analysis revealed that these extracts had anti-fungal properties due to the presence of distinct groups of active compounds, suggesting their applied role in disease management. These allelochemicals can be potential tool to manage important plant diseases and replace synthetic fungicides for crop disease management. [ABSTRACT FROM AUTHOR]

We studied the allelopathic effects of mulch and aqueous extracts of Rice (Oryza sativa L.) straw and on growth of 8-weeds: Phalaris minor L., Cynodon dactylon L., Chenopodium album L., Rumex denticulate L., Anagalis arvensis L., Melilotus spp L., Parthenium hysterophorus L. and Cyperus rotundus (L.) was analyzed. Rice straw mulch at 4.0 t/ha and rice aqueous solution (10 g/L) spray significantly reduced these weeds density (Number/m2) (54, 55, 66, 79, 85, 73, 54 and 39 during 2020-21) respectively, than control. Rice straw mulch 4 t/ha followed by (metsulfuron methyl 4 g a.i./ha + clodinafop propargyl 60 g a.i./ha) and clodinafop propargyl 75 % of 60 g a.i./ha + rice aqueous solution (10 g/L) spray significantly reduced the density of test weeds. Density of grass weeds decreased in zero-till, but broad leaved weeds decreases in conventional tillage. Wheat growth (dry matter accumulation: g/plant), number of tillers per m, leaf area index (LAI) and yield) significantly increased by rice straw mulch at 4 t/ha followed by rice aqueous solution (10 g/L) spray than control. [ABSTRACT FROM AUTHOR]

In vitro culture experiments are crucial for studying chemically-mediated interactions in plants. However, the difficulty in distinguishing spores and sporelings of different bryophyte species hinders research on early developmental stages. Here we propose a modification of the sandwich technique, a standard method for studying plant allelopathic, and present a case study using two common mosses. As in the standard sandwich method, we have created a physical barrier using gelled medium, and inoculated spores of Tortula muralis and Syntrichia ruralis in two layers. To assess their intra- and interspecific interactions, we measured the green coverage of the protonemata using image analysis, and the degree of sporeling development using a categorical index. We successfully obtained physically separated sporelings of target and emitters from spores of these two species. The green coverage analysis showed no differences in any of the comparisons. However, the developmental index showed a negative effect of T. muralis on S. ruralis, whereas S. ruralis appeared to promote the development of T. muralis. The method proposed here is successful for culturing moss spores. The two inocula (the emitter and the receiver) are physically separated but the set-up allows the diffusion of water-soluble and volatile substances. For testing interactions at these early stages of the gametophyte, we recommend measuring the degree of development of moss sporelings rather than their coverage. Our results revealed both positive and negative interspecific interactions between T. muralis and S. ruralis sporelings. This supports that positive interactions in bryophytes may be more common than previously thought. [ABSTRACT FROM AUTHOR]

Broad infestations of invasive, non-native vegetation have transformed wetlands around the world. Ludwigia hexapetala is a widespread, amphibious invasive plant with a creeping growth habit in open water and an erect growth habit in terrestrial habitats. In the upper San Francisco Estuary of California, L. hexapetala is increasingly terrestrializing into marshes and this expansion may be facilitated by allelopathy. We conducted the first field-based study on L. hexapetala allelopathy to determine whether (1) three allelochemicals known to be exuded by L. hexapetala are expressed in situ, (2) the allelochemicals are detectable in leaves, soil, and water, and (3) allelopathic expression varies by season, salinity, and growth habit (open water "patch" vs. terrestrial marsh "interface" locations). Water, soil, and L. hexapetala leaves were collected in two freshwater sites and two oligohaline sites in the upper San Francisco Estuary in summer 2021, fall 2021, and spring 2022. Myricitrin and quercitrin, known allelochemicals, and salipurposid, a newly identified polyphenol, were detected in water, soil, and leaves. There were significant differences in allelochemical concentrations under fresh versus oligohaline conditions in water and soil, but not leaves. All three allelochemicals generally had higher concentrations in patch versus interface locations, suggesting that L. hexapetala allelopathy plays a greater competitive role in open water than terrestrial habitats. Leaf concentrations of each allelochemical varied seasonally; however, both myricitrin and salipurposid had heightened concentrations in spring. These results suggest that herbicide application in early spring may be most effective in controlling L. hexapetala terrestrialization from open water to marshes. [ABSTRACT FROM AUTHOR]

Essential oil (EO) allelopathy has been considered as potential applications in organic agriculture and weed management, where the EOs can be used as eco-friendly natural herbicides. Rhazya stricta is a widely distributed dwarf shrub in the Arabian Peninsula and is characterized by its toxicity. The present study aimed to investigate the chemical composition of the R. stricta EO using quantitative and qualitative analysis via Gas chromatography/ mass spectroscopy (GC-MS) and GC-flame ionization detection (GC-FID) as well as assess its phytotoxicity on weeds. Fifty-four volatile components were identified, representing 97.5% of total oil. The terpenes were found as the backbone of the oil constituents including mono- (55.28%) and sesqui-terpenes (27.35%), alongside non-terpenoid constituents (13.63%). From the overall identified oil constituents, trans-chrysanthenyl acetate (31.57%), cis-verbenol (11.84%), octadecenoic acid, methyl ester (4.84%), cubenol (4.82%), davana ether (4.79%), (E)-9-octadecenoic acid ethyl ester (3.93%) represented the abundant compounds. The EO exhibited strong phytotoxicity on the germination and seedling growth of weeds Dactyloctenium aegyptium and Chenopodiastrum murale compared to the crop Triticum aestivum. The EO showed an IC50 of 6.66, 7.75, and 6.45 mg/L for seed germination, shoot growth, and root growth, respectively for the weed D. aegyptium, while it showed 5.41, 8.33, and 6.82 mg/L for C. murale compared to 16.9, 18.5, and 19.5 for T. aestivum mg/L for seed germination, shoot growth, and root growth, respectively. The observed strong phytotoxicity could be ascribed to the higher content of the oxygenated terpenoid compounds, whereas, further study is recommended to evaluate the phytotoxicity of the major compounds either singularly or in combination against weeds and determine their mode(s) of action as bioherbicides. [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]

Compounds exuded from roots play a key role in regulating plant allelopathic interactions. However, phytochormone profiling of root exudates and their contribution to an overall allelochemical activity of specific plant species is neglected topic in allelochemical research. Hairy root growth media of two different species, the fruit tree species Malus × domestica Borkh. and the herbaceous weed species Chenopodium murale L. were collected and analyzed by high-performance liquid chromatography coupled with tandem mass spectrometry (LC–MS/MS). We found that most of the phytohormones exuded by the hairy roots of C. murale and M. domestica were associated with the acidic fraction (96.8% and 98.9%, respectively), including 2-oxindole-3-acetic acid, phenylacetic acid, salicylic acid (SA), benzoic acid (BzA), and abscisic acid, with SA and BzA being the most abundant, while those associated with the basic fraction, including cytokinins and the ethylene precursor 1-aminocyclopropane-1-carboxylic acid, accounted for only 1% of the plant growth substances detected in both species. Exogenous application of 0.2 µM SA, which was released from the hairy roots of C. murale and accumulated in the culture media for four weeks, significantly impaired hairy root growth of M. domestica and also shoot and root growth of Arabidopsis seedlings. The disruptive effect of 0.2 µM SA on the membrane potential of M. domestica hairy root and Arabidopsis root cells was determined. The data obtained could be useful for planning further studies aimed at clarifying the contribution and role of exuded phytohormones to the overall allelopathic potential of these two plant species. [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]

The majority of allelopathic studies on invasive plants have focused primarily on their leaf-mediated allelopathy, with relatively little attention paid to their root-mediated allelopathy, especially co-allelopathy mediated by both leaves and roots. It is conceivable that the diversified composition of acid rain may influence the allelopathy of invasive plants. This study aimed to evaluate the leaf and root-mediated co-allelopathy of the invasive plant Solidago canadensis L. under acid rain with different nitrogen-sulfur ratios (N/S) on Lactuca sativa L. via a hydroponic incubation. The root-mediated allelopathy of S. canadensis was found to be more pronounced than the leaf-mediated allelopathy of S. canadensis with nitric acid at pH 4.5, but the leaf-mediated allelopathy of S. canadensis was observed to be more pronounced than the root-mediated allelopathy of S. canadensis with sulfuric-rich acid at pH 4.5. The leaf and root-mediated co-allelopathy of S. canadensis was more pronounced than that of either part alone with sulfuric acid at pH 5.6 and nitric acid at pH 4.5, but not with nitric-rich acid at pH 4.5 and sulfuric-rich acid at pH 4.5. Sulfuric acid and sulfuric-rich acid with stronger acidity intensified the leaf-mediated allelopathy of S. canadensis. Nitric acid and nitric-rich acid attenuated the leaf-mediated allelopathy of S. canadensis, and most types of acid rain (especially nitric acid and nitric-rich acid) also attenuated the root-mediated allelopathy of S. canadensis and the leaf and root-mediated co-allelopathy of S. canadensis. Sulfuric acid and sulfuric-rich acid produced a more pronounced effect than nitric acid and nitric-rich acid. Hence, the N/S ratio of acid rain influenced the allelopathy of S. canadensis under acid rain with multiple N/S ratios. [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]

BACKGROUND RESULTS CONCLUSION Borreria latifolia (Aubl.) K. Schum (Rubiaceae) is an annual weed with a strong allelopathic inhibitory effect on malignant weeds in orchards in southern China. This study was carried out to investigate its allelopathic potential and to identify allelochemicals present in B. latifolia.Aqueous extracts of B. latifolia inhibited the germination and radicle growth of Eleusine indica and the radicle growth of Bidens alba in a dose‐dependent manner. However, only the high‐concentration treatment at 50 mg mL−1 delayed the germination of B. alba and Digitaria sanguinalis. Among the root, stem, and leaf aqueous extracts of B. latifolia, the leaf extract had the strongest inhibitory effects on the germination and seedling growth of E. indica, followed by stem extract and then root extract. A total of 47 published allelochemicals, including coumarin, 4‐hydroxybenzoate, salicylic acid, 4‐hydroxycinnamic acid, and vanillic acid, were identified in the leaf extract. Among the five allelochemicals, coumarin was found to be present in the highest concentration in the leaf extract. Furthermore, coumarin exhibited a significantly greater inhibitory effect on E. indica (EC50 = 36.87 mg L−1) than did the other allelochemicals (EC50 = 100.87–156.30 mg L−1).This study indicates that the leaf extracts of B. latifolia and their allelochemicals have excellent potential as bioherbicides and that coumarin is one of the key allelochemicals in B. latifolia. © 2024 Society of Chemical Industry. [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]

Wheat is often planted directly after maize in fields following the maize harvest, and maize residues decompose in the soil by various biological factors, releasing phenolic compounds that affect the germination and growth of some crops planted with or after it. This research aimed to identify the effect of Zea mays leaf extract on seed germination physiological and anatomical features of Z. mays var. (Drachma, Mahali) and Triticum aestivum var. (Baraka, Abu Ghraib). The results showed Z. mays leaf extract stimulated some traits germination (100%) in Drachama at control, plumule length (7.8cm) in Abu-Graib, radicle length (11.6cm) in Baraka at 2%, fresh weight of plumule and radical (0.0113, 0.0148gm) respectively in Drachama at control. There was highest reduction germination (60%) in Drachama at 6% extract [plumule length (1.0)cm, radicle length (4.2cm), fresh weight of plumule (0.0052cm) in Mahali at 4%], fresh weight of radical (0.00026gm) in Abu-Graib at 6%. There was a difference in response in greenhouse experiments. Anatomical traits of the two corn cultivars differed at 2% and 4% concentrations. The highest increase in germination (96.7%) was in Baraka at 4%, shoot length (22.1cm) in Drachama at 4%, fresh weight of root (0.254gm) in Abu-Graib at 4%, [root length (44cm), fresh weight of root (0.052 gm) in Abu-Graib at 4%], the highest reduction in germination (80%) in Abu-Graib, dry weight of root (23gm) in Abu-Graib at 2%. Using HPLC, compounds tannic acid, gallic acid, benzoic acid, and salicylic acid were identified from Z. mays L. extracts. The study will help to develop sustainable agricultural practices, such as crop rotation, to increase crop productivity and reduce reliance on chemicals. [ABSTRACT FROM AUTHOR]

This review consists of life cycle of Cuscuta its impact on main plants and its management techniques. There are various methods (physical, mechanical, chemical and biological) to control the infection of Cuscuta. Furthermore, the Integrated used management IWM of Cuscuta is a superior for productivity of both crops and ecosystems. The IWM has various elements (cultural practices, physical removal, biological control and chemical control). In addition, the impact of allelopathy and the use of genetic engineering stops the proliferation of Cuscuta. The IWM combined with allelopathy and biotechnology can effectively limit the infection of Cuscuta. [ABSTRACT FROM AUTHOR]

We investigated the allelopathic inhibitory effects of harmala (Peganum harmala L.) seeds, seed powder and water extracts on barley (Hordeum vulgare L.) seed germination and seedling growth. The harmala seeds inhibited the barley germination and seedling growth and also significant effected the on root growth than on shoot growth. Ground harmala seed (0.06-0.72 g) had highly significant inhibitory effects on barley germination, except at the lowest concentrations (0.06 and 0.12 g/dish). Water extracts of harmala seeds concentrations (0.6-7.2 %) inhibited the barley germination and seedling growth by 2.4 %. There were clear inhibitory effects on root elongation and plumule growth. Additionally, the harmala extract caused radicle decay in barley seedlings. In the field, 1 g of ground harmala seeds inhibited the germination and growth of barley seeds and monthly irrigation with 5 g/L inhibited the fresh and dry weight of barley plants. The inhibitory effects were also on spikes and roots, number and weight of seeds. The germination and growth of new seeds were also inhibited. Similarly, adding 5 g of ground harmala seeds significantly affected the fresh and dry weight of barley plants, with leaves, stems and roots were more affected than spikes. Overall, this study provides an explanation for the absence of barley growth in harmala-infested soil. [ABSTRACT FROM AUTHOR]

We did a preliminary investigation of the allelopathic activity of 60 invasive and medicinal plants in Sri Lanka on Lactuca sativa (lettuce) and Raphanus sativus (radish). Out of 60 plants, 14 significantly reduced lettuce seedling lengths than distilled water, and 55 plants reduced radish seedling growth. In consideration of all the parameters tested, Cardiospermum halicacabum and Canarium zeylanicum Blume showed the highest phytotoxicity. C. zeylanicum (family Burseraceae), an endemic plant in Sri Lanka was selected for the isolation of phytotoxic compounds. The whole tree has a distinct fragrance bears edible seeds and has potential health benefits. This plant is used for medicinal purposes and its bark contains 3-hydroxy-12-methoxy-8,11,13-podocarpatrien-3-one and acetyl aleuritolic acid. This is the first report of the aforementioned two compounds from C. zeylanicum. These compounds exhibited phytotoxicity against lettuce. [ABSTRACT FROM AUTHOR]

The microspectrophotometer/microspectrofluorimeter was used to find the azulenes on the intact surface of 30 allelopathic and medicinal plant species growing in moderate or drought climatic conditions. Here in the maxima range of 580-620 nm, peculiar to blue pigments (azulenes), were clearly observed. The pigments were found in blue or silver leaves (needles) or plant parts (petioles, flowers and pollen). The peaks 590-610 nm, characteristic to azulenes were also observed in the absorbance spectra of ethanolic 10 min -extracts from the leaf surface, and 24 h - extracts from whole leaves. Among plants studied, the pigments were first observed in 14 terrestrial species (Anthriscus sylvestris, Lolium perenne, Petasites spurius, Phlomis tuberosa, Crambe maritima, Seseli gummiferum, Filipendula ulmaria, Echinocystis lobata, Colutea cilica, Rhus coriaria, Quercus pubescens, Pinus brutia and 2 algae (Chara vulgaris and Spirogyra sp.) use of spectral methods is recommended to search new azulene-containing species for pharmacy, agriculture and ecology. [ABSTRACT FROM AUTHOR]

Lai (Durio kutejensis Hassk. Becc) an endemic plant of Kalimantan-Indonesia leaves contain secondary metabolites as allelochemicals (alkaloids, flavonoids, saponins, phenols, and steroids). We investigated the allelopathic effects of lai leaf extract on the seed germination and early growth of weeds (Ruellia tuberosa L. and Amaranthus spinosus L.) and crops (Oryza sativa L. and Zea mays L.). We conducted two experiments: Germination bioassay and Early growth greenhouse bioassay consisting of 0 (Control), 25, 50 and 75 % leaf extracts. The leaf extracts significantly decreased the germination and early growth of both test weeds and crops: Germination (%) (100 to 26.66 %), shoot length (9.40 to 3.16 cm); germination index (3.30 to 0.36); vigour index (9.40 to 0.84); biomass 1.43 to 0.14 g); and chlorophyll a (0.45 to 0.016 mg/L), b (0.077 to 0.024 mg/L), and total chlorophyll (0.122 to 0.038 mg/L) contents. In contrast, the extract increased the germination time (3.00 to 7.00 h), mortality (0 to 40 %), and phytotoxicity (0 to 2.33 %) of test plants. Higher concentrations of plant extracts were more inhibitory to germination and early growth in all test crops. Therefore, D. kutejensis leaf extract contains a natural compound that can be potentially suitable as an allelopathic-natural herbicide. In future, the results can be used to reduce the use of chemical herbicides in crop production. [ABSTRACT FROM AUTHOR]

Field experiments were carried out at two sites to test the responses of weeds in cowpea crop to soil incorporation and surface mulching of corn residue alone or in combination with 50% rate of trifluralin herbicide. Conventional and zero tillage systems without corn residues, half of label rate and full label rate of trifluralin were included for comparison. Incorporated or mulched corn residues significantly reduced weed density and dry weight compared to conventional tillage treatment (control) at both sites. Residue incorporation and mulching plots in combination with 50% of label rate of trifluralin revealed significantly lower weed numbers and dry weight as compared to their respective controls. Soil incorporation and surface mulching of corn residue in combination with 50% rate of trifluralin achieved similar weed control and cowpea grain yield when compared to the 100% trifluralin treatment. Plots amended with corn residue showed greater levels of phenolics. Also, the periods of maximal suppressive effect against the test weed coincided with periods of maximum phenolic content, indicating the possible involvement of phenolics in weed suppression. Combination of allelopathic residues and a reduced rate of herbicides could reduce herbicide usage in agricultural systems while the weed control is not compromised. [ABSTRACT FROM AUTHOR]

Profiled metabolites from 5-donor plants; Mucuna pruriens, L. (Mc), Cymbopogon nardus L. (C), Desmodium uncinatum Jacq. DC. (D), (Zea mays, L. (Mz) and New Rice for Africa 1 (NERICA 1) were Terpenoids and Phenols. NERICA 1 (R) is a cross of Oryza sativa and Oryza glaberrima. C produced 10 terpenoids + 1 ester, R and D each released 6 Terpenoids + 3 Phenols. Mc produced 2 Terpenoids + 4 Phenols and 5 Terpenoids + 4 Phenols were profiled from Mz. We adopted a completely randomised block design with 3 replicates and eight combinations of 3 leaf+ stem+root powders namely; Mc+D+C, Mz+Mc+C, RDC, Mc+D+C, Mz+R+Mc, Mz+D+Mc, R+Mc+C and Mz+R+C, mixed with 1.5 kg soil (15, 30 and 45 %, w/w). Controls had no powders. Mixtures were placed in plastic pots and 20 seeds of Biden pilosa L. were sown in each pot. Every 2 days, 200 ml of water was applied to all treatments for 60 days. Mz+Mc controlled B. pilosa and volunteer weeds relative to R+C and C+D. Weed germination and biomass reduced with increased powder doses. Volunteer monocot weeds were more inhibited than dicots. High potential exists for functional allelopathy using allelochemicals in the donor plants to develop bio-herbicides. [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]

The increasing intrusion of weed species into alpine regions is an alarming threat to native floras because their strong and deep root systems cause a scarcity of nutrients to native alpine plant species. Considering the sensitive nature of alpine ecosystems, integrated weed management may be a means of preventing invasive species from going out of control. The present study investigated the allelopathic effect of Elsholtzia strobilifera on the germination and growth characteristics of Himalayan knotweed (Koenigia polystachya, syn. Polygonum polystachyum) under both field and laboratory conditions. The germination of seeds under laboratory conditions was studied by using different dilutions of hydrosol and aqueous extracts derived from E. strobilifera. In our field study, seedlings of K. polystachya were planted together with E. strobilifera in their natural habitat at a nursery. The study indicates that the seed germination and morphological parameters of seedlings were significantly inhibited by different dilutions of hydrosol and extract (reduction by 83–96% and 62–73%, respectively). In field conditions, significant inhibition in the morphological characteristics of K. polystachya was observed when grown in association with E. strobilifera. The results reveal that E. strobilifera has a significant allelopathic effect on K. polystachya. Based on the results of the present study, it can be concluded that growing plants of E. strobilifera around K. polystachya may be a novel approach to curbing the spread of the latter and suppressing the population of this species in ecologically sensitive alpine or other endangered areas. [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]

This paper is the first to propose an allelopathic phytoplankton competition ODE model influenced by the fear effect based on natural biological phenomena. It is shown that the interplay of this fear effect and the allelopathic term cause rich dynamics in the proposed competition model, such as global stability, transcritical bifurcation, pitchfork bifurcation, and saddle-node bifurcation. We also consider the spatially explicit version of the model and prove analogous results. Numerical simulations verify the feasibility of the theoretical analysis. The results demonstrate that the primary cause of the extinction of non-toxic species is the fear of toxic species compared to toxins. Allelopathy only affects the density of non-toxic species. The discussion guides the conservation of species and the maintenance of biodiversity. [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]

Cover cropping is practiced in conservation agriculture to preserve soil and water resources, alleviate soil compaction, sequester organic carbon, and control weeds. Meanwhile, cover cropping is rarely used in forestry, probably due to the lack of awareness of this management practice. In this short essay, we discuss the concept of utilizing cover crops to prepare degraded lands for afforestation or reforestation projects. The benefits of this practice are similar to those in agriculture. The risks of this practice are mostly related to plant-plant interactions, and particularly, to the potential competition for resources with the target trees. As such, this practice should be implemented cautiously, to prevent adverse impacts on the forest system. Also, attention should be paid to ensure the delivery of ecosystem services and functions by the target land. Further, the co-use of complementary practices may be considered to accelerate the success rate of cover cropping in degraded lands designated for afforestation and reforestation. Among these practices, application of soil additives, such as composts, manures, and biochars, may be useful in increasing soil concentrations of organic carbon and nutrients, thus improving soil quality and fertility. Additional complementary active practices may be the direct seeding or planting of nurse shrubs and trees, as well as the inoculation of soil surface with biocrust slurries, aimed to increase ecosystem complexity by forming a multi-story vegetation structure. Recommendations and guidelines for implementing cover crops in forestry should be site-specific and case-dependent, and consider both the desired benefits and potential risks. [ABSTRACT FROM AUTHOR]

The present study was designed to assess the allelopathic potential of invasive weed Ageratina adenophora leaf extracts on seed germination and seedling development efficiency of native tree [viz. Quercus leucotrichophora A. Camus (Oak) and Pinus roxburghii Sarg. (Pine)] and crop [(Triticum aestivum L. (Wheat) and Lens culinaris Medik. (Lentil)] species of Kumaun Himalaya. Pot experiments were conducted in the glasshouse of the Botany Department, D.S.B. Campus, Kumaun University Nainital, following a Completely Randomized Block Design (CRBD) with three treatments (C1-25%, C2-50%, and C3-100% of aqueous leaf extract) and one control, each with five replicates. The experiment lasted one year for tree species and continued until the seed maturation phase for crop species. Parameters such as seed germination proportion, root and shoot measurements, biomass, and crop productivity traits were recorded accordingly. Our bioassay results indicated that the inhibitory effect of leaf extracts on the measured traits of the selected native species was proportional to the applied extract concentrations of A. adenophora. Overall, lentil among crops and oak among tree species exhibited more inhibition compared to wheat and pine, respectively. At the highest concentration, reductions of 44%, 34%, 36%, and 24% in biomass production capacity were recorded for wheat, lentil, pine, and oak, respectively, while wheat and lentil productivity decreased by up to 33% and 45%, respectively. These results suggest that water-soluble allelochemicals produced by A. adenophora may impede the establishment of selected crop and tree species in agroecosystems and forest ecosystems invaded by this weed species. However, further studies on the characterization of phytochemicals and their specific role in seed germination and growth are warranted. Furthermore, the allelopathic potential of A. adenophora can be explored for the preparation of biopesticides and nature-friendly option to improve soil health, crop productivity, and reduce environmental pollution and management of this invasive weed. [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]

Weed management through herbicide is costing economically and environmentally. Developing of improved weed-suppressive rice genotypes is one of the ultimate goals of rice breeders for sustainable cultivation. In the current investigation, we evaluated the weed-suppressive potential of different rice genotypes and the genetic behind transmitting this ability to their progeny. To achieve this goal, a half diallel mating system was designed and conducted to generate F1 hybrids from six genotypes. Among these genotypes a previously developed allelopathic-resistant pre-breeding advanced lines, the F1 crosses along with their parents were cultivated under weed stress and normal field condition during the 2022 summer growing season. Several vegetative, allelopathic, yield and physio-biochemical traits were studied. The results indicate that the crosses AL1/Sakha Super 300 and AL2/Sakha Super 300 have the highest yield under weed stress condition. AL1, AL2 and Sakha Super 300 have the highest general combining ability for yield and allelopathic characters under weed stress. Furthermore, the cross AL2/Sakha Super 300 ranked the highest based on the stress tolerance indices. High positive correlation was detected between grain yield and the most studied physio-biochemical characteristics. This investigation provides evidence of the potential of enhancing the allelopathic activity of rice crop through precise selection of parental genotypes. [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.

For invasion biologists, the key question as to why only some alien species emerge as successful invaders as against a majority of other alien introduced species is still unclear. One of the best ways to resolve this question is to compare phylogenetically related alien invasive vs alien non-invasive species. Here we compared the allelopathic potential and phytochemical profiling of two congeneric species of Amaranthus (Amaranthus caudatus—invasive alien and non-invasive alien Amaranthus blitum. Petri dish bioassay followed by a pot experiment was used to evaluate the allelopathic effects of aqueous leaf and root extracts (1:10 w/v) of the said alien congeners on the germination and shoot length of Raphanus sativus. Petri dish bioassay results revealed that both species exhibited comparable levels of allelopathic activity; however, leaf extracts of both species showed significantly stronger inhibitory effects than root extracts, a trend corroborated by phenolic content assessments. However, no allelopathic effects on seed germination were observed in the pot culture bioassay. Comparative phytochemical profiling of these Amaranthus species, utilizing Gas Chromatography–Mass Spectrometry (GC–MS) and High-resolution liquid chromatography and mass spectrometry (HR-LC-MS) identified diverse array of compounds including methyl 8,9-octadecadienoate, n-hexadecanoic acid, phytol, loliolide, stigmasta-7,16-dien-3-ol, catechol borane, ellagic acid etc. which are known for their role in allelopathic interactions and invasiveness of the alien plants. Phytochemical analysis unveiled comparable levels of phytochemicals in both the invasive alien and non-invasive alien species of Amaranthus. In conclusion, our study revealed that while allelopathy may contribute to the invasiveness of the Amaranthus species, it does not seem to be a unique characteristic feature for the invasiveness of invasive alien species (Amaranthus caudatus) in comparison with its non-invasive alien congener. The present study recommends that more congeneric comparisons are needed to understand the role of high chemical diversity in alien plant invasions, and whether it is linked to the origin of the plant species. [ABSTRACT FROM AUTHOR]

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]

• All four extracts had a negative effect on the germination of species tested. • The A. grandiflora extract inhibited the germination more effectively in all species except V. unguiculata. • A 50 % dilution of the A. grandiflora extract made it less potent. • Extracts had a stronger effect when used to irrigate the seeds rather than a pre-germination soak. Many unpopular species are useful for medicinal and food security use. However, their extracts can be used to improve seed germination and can remove unwanted vegetation by acting as herbicides. Often, such use is based on a history of traditional practices. For example, Vhavenda villages in the Limpopo province (South Africa) use Anthocleista grandiflora leaves to cover maize and millet grains during malting to stimulate germination, but few studies have tested their efficacy or even formulated extracts out of them. This study tested the allelopathic effect of aqueous leaf extracts of Aloe ferox, Aloe marlothii, Anthocleista grandiflora and shoot extracts of Pollichia campestris. The extracts were applied at a 100 or 50 % concentration through irrigating or soaking seeds of Strychnos spinosa and common vegetable seeds of Pisum sativum, Vigna unguiculata and Zea mays were used as benchmark species. The results showed that the extracts had a significant effect (P < 0.001, P < 0.002 and P < 0.010) on the germination of three species and suppressed germination instead of enhancing it. The exception was Vigna unguiculata , where extracts had a non-significant effect (P = 0.784). The highest inhibition was observed in the crude extract of Anthocleista grandiflora (100 %), which inhibited Pisum sativum germination with a percentage inhibition of 76 %. All extracts inhibited the seed germination of Zea mays and the highest germination of 52 % was achieved compared to 87 % germination in the control (no extracts applied). None of the different extract concentrations (100 or 50 %) or application methods (irrigation and soaking) improved the seed germination of species. These results suggest the tested extracts could be useful as growth suppressors (especially Anthocleista grandiflora) of Strychnos spinosa but more research is required. [ABSTRACT FROM AUTHOR]

Background and aims: Nitrogen (N) deposition and native allelopathic plants may affect seed germination and growth of species through their effects on soil microbes and soil nutrient availability. However, our understanding of the interactions between N addition and allelopathic plants on the regeneration of alpine grasslands remains limited. Methods: Here, we investigated the effects of N addition and the presence of the allelopathic plant Ligularia virgaurea (Maxim.) Mattf. on seed germination, survival, and growth of native herbaceous species (Elymus nutans, Delphinium kamaonense and Tibetia himalaica) on the Qinghai-Tibet Plateau. We used piecewise structural equation modelling to assess both the direct effects of N addition, allelopathic plants, and their interactions and indirect effects mediated by soil properties, soil microbial richness and diversity, and soil enzyme activity. Results: We found that (1) L. virgaurea directly increased seed germination and early plant survival, and reduced plant root-to-shoot ratio; N addition directly increased early plant survival and biomass, (2) L. virgaurea indirectly increased plant biomass via bacterial richness, (3) N addition offsets the increase in seed germination promoted by the presence of L. virgaurea via soil acid phosphatase. Conclusion: Our study suggests the importance of direct and indirect roles of allelopathic plants, N addition and their interaction on seed germination, survival and plant growth. Our results highlight the need to consider the interactions between environmental and biological factors as well as their direct and indirect effects to obtain reliable predictions and mechanistic understanding of the response of alpine plants to future climate change. [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]

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Coral–algal interactions are pivotal in reef ecosystems globally as they can scale up ecosystem levels and lead to dominance shifts. In this study, we conducted a systematic review of global coral–algal interactions, identifying the most studied locations, species, and types of interactions. We then assessed how these interactions may be impacted by consumers and climate change. Over the past 20 years (2001–2020), coral and algae interactions were mostly explored in the Pacific, and the Caribbean and US East Coast, where branching and massive corals were the focus, while other coral growth forms received less attention, and effects on algae were often overlooked. Adult corals were generally reported to be damaged when directly interacting with algae through physical abrasion or allelopathy. Conversely, algae interactions were found to have a positive impact on juvenile corals by facilitating larval recruitment and settlement. As expected, coral–algal interactions and the type of coral–algal relationships vary globally, most likely due to differences in abiotic conditions, community composition and the number of studies performed in a region. Despite the large emphasis on the role of consumers in controlling coral–algal interactions, few studies directly explored the effects of herbivory on coral–algal interactions. Given the growing evidence that ocean warming and acidification can reduce the competitive ability of corals, understanding the dynamic relationships between coral, algae, and consumers under future climate change conditions is crucial in predicting future coral recruitment potential and reef composition patterns. Here, we highlight the main findings from coral–algal interaction studies performed in the last 20 year and point to future directions, such as: 1) diversifying location, coral species, growth forms and life phases; 2) considering effects on both sides of interaction, not neglecting effects on algae; and 3) taking a closer look into the role of consumers and microbiomes. Advancing our understanding of coral–algal interactions, as well as how these interactions shift under changing conditions, is critical in predicting how coral reef ecosystems may operate in the future. [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]

Just as plants attack heterospecific competitors with allelopathic phytotoxins, they also attack conspecifics with phytotoxins to inhibit seedling germination and growth (autotoxicity). As a result, for many plant species, autotoxicity limits offspring germination and growth proximate to parental plants—consequently reducing deleterious density dependent effects. Autotoxicity appears to vary across species, but it also may vary within species. We tested autotoxicity and variability in six ecotypes of the model plant, Arabidopsis thaliana, using allelopathy bioassays. We found that autotoxic impacts varied across the Eurasian and African ecotypes, and the negative effects on conspecific root growth were greater from above-than belowground exudate. In half the ecotypes, root growth decreased 71% in seedlings treated with exudate from the same ecotype than when treated with exudate from other ecotypes. That the ecotypes limited themselves more than they did other ecotypes is consistent with coexistence theory, which assumes species limit themselves more than others. Moreover, it is consistent with negative density dependent theories that suggest seedling mortality is highest near conspecific adults. Finally, the variation in autotoxicity across ecotypes suggests that intraspecific genetic variability and/or local habitat influence autotoxic intensity. It is well recognized that phytotoxic effect (allelopathy and autotoxicity) varies interspecifically but ecotype-level effects suggests that plants may exhibit greater intraspecific variation in autotoxicity than currently recognized. [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]

Goat weed (Ageratum conyzoides L.) possesses several phytochemicals, which can be used environment friendly alternatives to synthetic chemical pesticides and herbicides. The major chemicals can serve as natural herbicides and pesticides to expand the range of the green biosphere. This paper: (i) overviews A. conyzoides L.; (ii) classification of A. conyzoides L.; (iii) botanical characteristics; (iv) invasiveness of A. conyzoides. (v) bioactivity of major compounds identified in Ageratum conyzoides L. and (vi) effects of A. conyzoides on different pathogens as biopesticide. [ABSTRACT FROM AUTHOR]