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Alfalfa (Medicago sativa) is known to release allelopathic substances to affect the germination and growth of other plants, which have the potential to be applied in controlling weeds. Green foxtail (Setaria viridis) and barnyardgrass (Echinochloa crus-galli), as malignant weeds worldwide, also pose a serious threat to alfalfa in northern China. In this study, the sensitivity of the two weeds to the extracts from the first, second, and third stubbles of six varieties were investigated to further reveal the allelopathic interference of different varieties of alfalfa on notorious weeds. The germination rate, the length and fresh weight of seedlings, the length and fresh weight of roots were measured to elucidate the allelopathy of alfalfa extracts on the two weeds. The results suggested that: (1) The allelopathy of six alfalfa varieties tested showed obvious intraspecific differences, the inhibition of Zhongmu No.3 on green foxtail and barnyardgrass was weaker than other varieties, with the values of synthetical allelopathic effect (SAE) were -0.55 and -0.29, respectively. (2) The inhibitory effect of alfalfa extracts on green foxtail was enhanced with the increase of stubbles, while the differences between three stubbles on barnyardgrass were not clear, especially between the first and second stubbles. (3) Compared with barnyardgrass (SAE = -0.39 ~ -0.29), green foxtail (SAE = -0.65 ~ -0.52) was generally more susceptible to the extracts. (4) The inhibitory effect of alfalfa extracts on root was stronger than seedling in the same weed. For example, the third stubble extracts of Baoding variety inhibited 88.00% of the roots at the concentration of 0.01 g mL-1, but did not affect the seedlings of green foxtail. The study may help to comprehensively reveal the allelopathic effect of different alfalfa varieties in the first three stubbles on green foxtail and barnyardgrass, providing scientific evidence for weed control based on natural plant extracts in the future. [ABSTRACT FROM AUTHOR]

The direction and intensity of plant–soil feedbacks (PSFs) and the reciprocal effects between plants and soils can change over time. PSFs can also affect competition between invasive and native plants. However, most PSF research is conducted in simple experimental settings where temporal changes are not considered. Few studies have assessed the temporal dynamics of PSFs among invasive plants, newly introduced plants and native plants. Here, we conducted a two‐stage PSF experiment to evaluate the temporal dynamics of PSFs among the invasive alien Phytolacca americana, the non‐invasive alien Phytolacca icosandra, and native Phytolacca acinosa. We conducted the experiment with different conditioning time periods. First, we planted the three species individually in pots to condition the soils. Then, each species was grown in a pot conditioned by the same species (‘home soil') or pots conditioned by one of the other two species (‘away soil'). Invasive and native plants produced higher biomass in home soils while non‐invasive alien plants produced higher biomass in away soils. The direction and intensity of PSFs varied with conditioning time among the three species and conditioning time had a significant effect on plant total biomass. Furthermore, sterilizing soils or adding activated carbon altered plant–soil feedbacks, indicating a role for microbes and allelopathic substances in mediating temporal changes. Our study indicates that changes in microbes and allelopathic substances in soils drove temporal changes in PSFs. Invasive alien plants can amplify their competitive advantage through PSFs and also potentially favor establishment of new non‐invasive alien plants. [ABSTRACT FROM AUTHOR]

Coffee beans contain compounds with allelopathic activity, such that some beans that do not meet quality standards might rather be used to obtain a natural herbicide which consequently might be employed to control undesired plants and avoid economic losses. Thus, the objectives of this study were: (1) to investigate the allelopathic effect of different concentrations of green (GC) and roasted (RC) coffee extracts on the inhibition of germination and initial growth of Lactuca sativa L. Bidens pilosa L. and Cyperus rotundus L. and (2) determine the induction of changes in the cell cycle of L. sativa L. and (3) quantify some compounds in the GC and RC extracts with possible allelopathic effects. Seeds and tubers were sown on germination paper, moistened with water or different concentrations of extracts, stored in transparent plastic boxes, and maintained in a germination chamber. Caffeine was found at higher concentrations of 79.768 and 15.532 g/L in GC and RC extracts, respectively. In general, RC extract for L. sativa L. and GC for B. pilosa L. diminished germination parameters. For C. rotundus L. GC extract decreased growth regardless of the concentration. An increased frequency of cell cycle alterations was observed in the root cells of L. sativa L. This study is the first to report that the studied extracts possess allelopathic potential, as they are effective in reducing germination and/or initial growth of weed species and L. sativa L. as well as inducing alterations in the cell cycle of L. sativa L. [ABSTRACT FROM AUTHOR]

One-month-old lettuce seedlings were planted in the field with and without prior hairy vetch (Vicia villosa L.) incorporation (HV and Fallow, respectively). The periods between hairy vetch incorporation and lettuce planting were 1 day, 8 days and 15 days. The inorganic nitrogen concentration in the soil was higher after hairy vetch incorporation, as well as the nitrogen concentration in the lettuce leaves from the HV plot compared to the Fallow plot, at any planting period. When lettuce seedlings were planted 8 days after hairy vetch incorporation, the leaf dry weight in the HV plots was 11% lower than that in the Fallow plots 4 days after planting; however, leaf growth recovered and the dry weight was 24% higher 12 days after planting, which could be due to enhanced leaf growth as the result of additional accumulated nitrogen provided by the hairy vetch. In the incubation experiment, it was suggested that the inhibitory effect of hairy vetch decomposition was not due to allelopathic substances. Therefore, in the hairy-vetch-incorporated field, growth suppression in the lettuce plants occurred early and continued for a short period after hairy vetch incorporation, but the damage due to the growth suppression effect was minor. More importantly, nitrogen supplied from the hairy vetch promoted lettuce growth after the inhibition period. [ABSTRACT FROM AUTHOR]

The allelopathic effect of macrophytes to phytoplankton has been widely formalized and accepted, while, less attention has been paid to aquatic vegetable. Herein, we investigated the inhibitory ability of Ipomoea aquatica (I. aquatica) at different concentrations to Microcystis aeruginosa, and verified the inhibition effect of main allelopathic substances. Results showed that, I. aquatica root secretion solution could effectively inhibit the growth of Microcystis aeruginosa (95%), and exhibited a concentration dependent effect. Seven potential allelopathic substances was both detected in root exudates and secretion solution of I. aquatic, they were succinic acid, salicylic acid, cinnamic acid, 3-(4-hydroxyphenyl) propionic acid, trans-cinnamic aldehyde, coumarin, and isophorone. Exogenous addition experiment further verified the inhibition effect, and the inhibition level varied with the types. Succinic acid, salicylic acid and cinnamic acid showed the tendency of promotion in lower concentration and inhibition in high concentration, with the inhibition threshold of 0.8 mmol/L, which was positively correlated with its concentration. 3-(4-hydroxyphenyl) propionic acid, coumarin and isophorone showed strong inhibition on Microcystis aeruginosa when the concentration was higher than 0.2 mmol/L, which was positively correlated with its concentration and co-culture time. Ipomoea aquatica can continuously release allelopathic substances under natural conditions and is expected to contribute to the restoration of aquatic ecosystems. [ABSTRACT FROM AUTHOR]

Ageratum conyzoides L. is native to Tropical America, and it has naturalized in many other tropical, subtropical, and temperate countries in South America, Central and Southern Africa, South and East Asia, Eastern Austria, and Europe. The population of the species has increased dramatically as an invasive alien species, and it causes significant problems in agriculture and natural ecosystems. The life history traits of Ageratum conyzoides, such as its short life cycle, early reproductive maturity, prolific seed production, and high adaptive ability to various environmental conditions, may contribute to its naturalization and increasing population. Possible evidence of the molecules involved in the defense of Ageratum conyzoides against its natural enemies, such as herbivore insects and fungal pathogens, and the allelochemicals involved in its competitive ability against neighboring plant species has been accumulated in the literature. The volatiles, essential oils, extracts, residues, and/or rhizosphere soil of Ageratum conyzoides show insecticidal, fungicidal, nematocidal, and allelopathic activity. The pyrrolizidine alkaloids lycopsamine and echinatine, found in the species, are highly toxic and show insecticidal activity. Benzopyran derivatives precocenes I and II show inhibitory activity against insect juvenile hormone biosynthesis and trichothecene mycotoxin biosynthesis. A mixture of volatiles emitted from Ageratum conyzoides, such as β-caryophyllene, β-bisabolene, and β-farnesene, may work as herbivore-induced plant volatiles, which are involved in the indirect defense function against herbivore insects. Flavonoids, such as nobiletin, eupalestin, 5′-methoxynobiletin, 5,6,7,3′,4′,5′-hexamethoxyflavone, and 5,6,8,3,4′,5′-hexamethoxyflavone, show inhibitory activity against the spore germination of pathogenic fungi. The benzoic acid and cinnamic acid derivatives found in the species, such as protocatechuic acid, gallic acid, p-coumaric acid, p-hydroxybenzoic acid, and ferulic acid, may act as allelopathic agents, causing the germination and growth inhibition of competitive plant species. These molecules produced by Ageratum conyzoides may act as defense molecules against its natural enemies and as allelochemicals against neighboring plant species, and they may contribute to the naturalization of the increasing population of Ageratum conyzoides in new habitats as an invasive plant species. This article presents the first review focusing on the defense function and allelopathy of Ageratum conyzoides. [ABSTRACT FROM AUTHOR]

Human population growth constantly requires an increase in the production of food and products from the timber industry. To meet this demand, agriculture and planted forests are advancing over natural areas. In view of this, it is necessary to know the effects of land use for different purposes (grain production, pastures, planted forests, fruit production and among other uses) on the genetic diversity of populations of native species. This knowledge can assist in land use planning as well as in the development of conservation strategies for native species. In this study, we evaluated the effect of land use for agriculture (mainly for cereal production) and planted forests on the genetic diversity of Baccharis crispa Spreng. a herb native to South America. To achieve our goals, we compared population genetic data obtained with three molecular markers (microsatellites, inter-simple sequence repeat and isoenzymes) with data on land use for agriculture and planted forests from 15 different locations. Our results showed that regardless of the molecular marker used, the greater the use of land for agriculture and planted forests, the lower was the genetic diversity of B. crispa populations. Baccharis crispa is a semi-perennial species that needs at least one year to reach its reproductive period, which is prevented in agricultural areas due to the land being turned over or dissected with herbicides every 6 months. In the studied regions, the planted forests are of eucalypt and/or pine, which besides being species with a high production of allelopathic substances, produce strong shading and B. crispa is a species that inhabits open grassland that needs a high incidence of sunlight for development. The data obtained in our study can assist in the decision-making to use land in order to reconcile the production of supplies for humanity and for the conservation of nature. [ABSTRACT FROM AUTHOR]

Digera muricata Mart, a plant having therapeutic characteristics that has been utilised traditionally, belongs to the Amaranthaceae family, and a promising source of specific natural products utilized as antioxidant, prophylactic, antimicrobial, anthelmintic, anti-diabetic, and allelopathic agent. In the present study, a biologically active phytosterol was isolated from Digera muricata Mart. The isolated compound was characterized by 13C, 1H NMR, FTIR, and HRMS. Characterization of the isolate was done by antimicrobial assay, and molecular docking. The antimicrobial potential of the isolated phytosterol (50 µl) against Streptococcus pyogenes was found to be maximum (ZOI-20.0 ± 1.0), followed by Streptococcus agalactiae (ZOI-11.3±1.5), Candida albicans (ZOI-09.0 ± 1.0), Klebsiella pneumonia (ZOI-8.6 ± 1.5) and Escherichia coli (ZOI-8.6 ± 1.5). The molecular docking results indicate that the phytosterol binds to the receptor 1AI9 at the 32th and 58th positions; 1KZN receptor at the 76th position, the 5L3J receptor at the 46th (ASN) and 136th (ARG) position; 7WIJ receptor at the 419th (ARG) and 582th (ASP) and 585th (ASN) positions. [ABSTRACT FROM AUTHOR]

Biological invasions by alien and range-expanding native plant species can suppress native plants through allelopathy. However, the homeland security hypothesis suggests that some native plants can resist invasion by producing allelopathic compounds that inhibit the growth of invasive plants. Most research has focused on allelopathic interactions between individual native and invasive plant species, with less emphasis on how allelopathy helps entire native communities resist invasions. Additionally, limited knowledge exists about allelopathic interactions between range-expanding native species and recipient native communities, and their influence on invasion success. To bridge this knowledge gap, we conducted two greenhouse competition experiments to test reciprocal allelopathic effects between a native woody range-expanding species, Betula fruticosa , and a community of four native herbaceous species (Sanguisorba officinalis , Gentiana manshurica , Sium suave and Deyeuxia angustifolia) in China. We assessed whether B. fruticosa and the native community differed in their competitive effects and responses, and whether these were influenced by activated carbon, which neutralizes allelochemicals in the soil. Activated carbon reduced the suppressive effects of the native community on the above-ground biomass of B. fruticosa , which indicates that the native community exerted a strong allelopathic effect on B. fruticosa. In contrast, activated carbon only marginally enhanced the suppressive effects of B. fruticosa on the native community, which indicates that allelopathy is not the primary mechanism by which B. fruticosa exerts its suppression. Overall, these findings support the homeland security hypothesis and suggest that biotic resistance from the native herbaceous community may limit the invasion success of the woody range-expander B. fruticosa. [ABSTRACT FROM AUTHOR]

The document explores the concept of allelopathy, which involves the release of organic molecules by plants and microorganisms to inhibit or stimulate the growth of neighboring plants and microorganisms. It discusses the potential applications of allelopathy in regenerative agriculture, particularly in integrated weed control in organic farming. The document highlights the need for further research to identify new allelopathic plants, study their effects on crop rotations, and understand the interactions between allelochemicals and pathogens. The special issue compiles research articles on various aspects of allelopathy, emphasizing the importance of sustainable agricultural practices and environmental protection. [Extracted from the article]

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]

Dongmu 70th, a rye (Secale cereale L.) cultivar known for its frost resistance, may potentially be impacted by Ragweed (Ambrosia trifida L.) ambrosin. This study explored the individual and combined effects of freeze-thaw cycles, cadmium (Cd), and ambrosin on Dongmu 70th's physiological responses. Parameters measured included soluble sugars, proteins, malondialdehyde (MDA), catalase (CAT), superoxide dismutase (SOD) activities, and net photosynthetic rate. Our results provide a preliminary understanding of Dongmu 70's resilience to these environmental stressors and guide the development of integrated stress management strategies. [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]

The use of allelopathy developed as an alternative practice for weed management in agriculture. Oldenlandia corymbosa is an annual herb and notable for being applied in folk medicine. Its diverse range of pharmacological properties and several bioactive substances have been well reported. Nevertheless, the allelopathic potential of O. corymbosa has not yet been documented. Hence, we aim to explore the allelopathy of O. corymbosa for weed control purposes. The extracts of O. corymbosa were tested to determine their effects on the seedling growth of six tested species. Significant reductions in the growth of seedling were exhibited as the plant extract concentrations increased. The plant extracts of O. corymbosa were separated in several chromatography steps; two active substances isolated and characterized as hedyotiscone A and B. Hedyotiscone A and B significantly restricted the growth of cress seedling at concentrations higher than 0.3 mM. The I50 values of hedyotiscone A and B for the cress seedlings ranged from 0.023 to 0.131 mM and 0.167 to 0.810 mM, respectively. The inhibitory activity against cress seedlings indicates that hedyotiscone A and B contribute to the allelopathic effects and may be responsible for the allelopathic potential of O. corymbosa. [ABSTRACT FROM AUTHOR]

Plantations of exotic trees were proposed as an alternative to restore native forests in degraded lands, because they can attract seed dispersers and modulate the microclimate beneath their canopies. However, the large-scale introduction of exotic tree plantations can negatively affect native species by high competitiveness for soil resources and light, while they can also release allelopathic compounds that inhibit the germination and growth of other plants. In this study, we tested the suitability of Eucalyptus camaldulensis plantations to assist the restoration of degraded lands in central Mexico, which were originally covered with oak forests. For this, we sampled soil seed banks within forest remnants and plantations, which showed that the animal-mediated dispersal of oak propagules from forests inwards plantations is reduced. Additionally, we conducted germination trials that evidenced that the leaves of Eucalyptus trees contain allelopathic compounds that inhibit the germination of oaks seeds, also showing that these compounds accumulate in the soil of plantations. We finally conducted field experiments in which soil form forests and plantations were translocated between these two habitats, and acorns were sowed on both soil types. These field experiments revealed that, besides the accumulation of allelopathic compounds in soils of plantations, oak recruitment in these habitats is also impaired by unfavorable microclimatic conditions. Therefore, we conclude that Eucalyptus plantations are not promoting the recovery of native oak forests in central Mexico and, instead, alternative ecological restoration methods should be applied for reaching this aim. [ABSTRACT FROM AUTHOR]

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This study aimed to determine the effects of Spirogyra extract on plant growth, yields and nutritional and nutraceutical traits of soybean seeds. An experiment was done during 2022- 2023 Soybean seeds of Taqa and Lee 74 cultivars were sown, and the Spirogyra extract (0.5, 1.5, 3 and 6 %) was used to irrigate to 75 % per pot) Field capacity. Biometric traits, seed yield, and seed number were determined. The application of Spirogyra extract decreased the growth and yield of soybean, with no adverse effects on the nutritional value of seeds. Allelopathic compounds present in the algae extract were identified using HPLC, and included hydroquinone and cinnamic acid. [ABSTRACT FROM AUTHOR]

The plant Curcuma longa L. is rich in bioactive compounds. However, there are few available studies that have investigated its allelopathic activity. In this work, we sought to preliminarily investigate the main chemical groups with allelopathic and bioherbicide activity present in the aqueous extract obtained from the rhizomes of C. longa, as well as its effect on the germination and initial growth of lettuce (Lactuca sativa L.) and wheat (Triticum aestivum L.) seedlings. Phytochemical analysis was performed using precipitation and colorimetric techniques. To determine the allelopathic potential of the extract, seven concentrations (1 to 64 g L-1 ) were tested, in addition to two control groups: distilled water (negative control) and glyphosate (positive control). The seeds remained in contact with the different concentrations for 72 hours. The evaluated parameters were: germination percentage (GP), germination speed index (GSI), root and shoot length of the seedlings, and median inhibitory concentration (IC50). Four compounds with allelopathic potential were identified: alkaloids, steroids, flavonoids, and terpenes. The results of the biological assay revealed that the aqueous extract had a limited impact on GP, showing effects only at the highest concentration (64 g L-1 ), causing a reduction of 20.70% in this parameter in both species. Additionally, it was found that the germination speed index (GSI) was significantly influenced by concentrations higher than 4 g L-1 for both species. The length of the root and shoot of the seedlings decreased with increasing doses. Shoot length was the most sensitive parameter, with an IC50 of 3.73 and 7.20 g L-1 required for wheat and lettuce, respectively. The results suggest that the extract of this plant has potential for the production of postemergence bioherbicides. [ABSTRACT FROM AUTHOR]

Allelopathy has a profound impact on the germination and growth of plants, influencing the establishment of plant populations and shaping community ecological patterns. However, the allelopathic potential of many grassland species remains poorly understood. In this study, we prepared aqueous extracts from 17 herbaceous plants to investigate their allelopathic effects on the seed germination and seedling growth of Leymus chinensis, a dominant grassland species. Our results revealed that the response of L. chinensis to allelopathic compounds was dependent on the specific plant species, extract concentration, and target plant organ. Notably, Fabaceae plants exhibited a stronger allelopathic potential than Poaceae, Asteraceae, and other plant families. Moreover, we observed that root growth of L. chinensis was more sensitive to allelopathy than shoot growth, and seed germination was more affected than seedling growth. Generally, the germination of L. chinensis was strongly inhibited as the donor plant extract concentration increased. The leachate of Fabaceae plants inhibited the seedling growth of L. chinensis at concentrations ranging from 0.025 to 0.1 g mL−1. On the other hand, the leachate from other families' plants exhibited either inhibitory or hormetic effects on the early growth of L. chinensis, promoting growth at 0.025 g mL−1 and hindering it at concentrations between 0.05 and 0.1 g mL−1. These findings highlight the significant allelopathic potential of grassland plants, which plays a critical role in establishing plant populations and associated ecological processes. In addition, they shed light on the coexistence of other plants with dominant plants in the community. [ABSTRACT FROM AUTHOR]

Plant extracts with allelopathic activity and their related compounds have been investigated for a long time as an eco-friendly approach to sustainable weed management. Croton oblongifolius (Roxb.) is a traditional medicinal plant valued for its diverse source of bioactive compounds that have been used to treat various diseases. C. oblongifolius leaf extract was previously described to involve a number of allelochemicals. Therefore, we conducted this research to explore more of the allelochemicals in the leaves of C. oblongifolius. The leaf extracts showed significant inhibitory activity against two test plants, Lolium multiflorum (monocot) and Medicago sativa (dicot). The bioassay-directed chromatographic purification of the leaf extracts yielded three compounds, including one novel compound, identified using spectral data, as follows: (1) alpinolide peroxide, (2) 6-hydroxy alpinolide, and (3) 3-hydroxy-5-isopropyl-3-methyl-2,3-dihydro-1H-inden-1-one (a novel sesquiterpene). These compounds considerably limited the growth of L. sativum. The compound concentrations affecting a 50% growth limitation (IC50) of L. sativum varied from 0.16 to 0.34 mM. Therefore, these characterized compounds may be allelopathic agents that cause the allelopathy of C. oblongifolius. [ABSTRACT FROM AUTHOR]

A key question in plant invasion biology is why invasive plants are more competitive in their introduced habitat than in their native habitat. Studies show that invasive species exhibit allelopathy, influencing other plants by releasing chemicals. Research on allelopathy uses in vitro tests, investigating effects on seed germination and seedling development. Although soil plays a role in modifying allelopathic effects, observations with soil are rare and almost nothing is known about the root development of test plants developing in soil and the effects of allelopathic compounds on root architecture. Our study evaluates the allelopathic effects of false indigo-bush (Amorpha fruticosa L.) and common milkweed (Asclepias syriaca L.) on oilseed rape growth as a model plant. The rhizotron system was used to study the effect of morphology and root architecture. Leaf–soil mixtures at 0.5%, 1%, and 5% concentrations were used. Shoot and root development was strongly inhibited at 5%. But there was no difference between the allelopathy of the two species, and the application of lower concentrations did not show any effect, demonstrating that soil has a significant modifying effect on their allelopathy. Our results highlight that the development of roots growing in the soil is also worth investigating in connection with allelopathy, which can strengthen the ecological importance of allelochemicals during successful invasions. [ABSTRACT FROM AUTHOR]

This study investigates the allelopathic effects of root exudate extracts from Chromolaena odorata on the germination and growth of six crop species. The results reveal variable sensitivity among the species, with the control treatment consistently exhibiting superior germination percentages. Initially, some species, including Abelmoschus esculentus (okra), Solanum lycopersicum (tomato), and Cicer arietinum (chickpea), experienced a substantial decline in germination, indicating a potential inhibitory effect of the exudates, although partial recovery was observed in subsequent treatments. Phaseolus vulgaris (common bean) displayed a moderate decrease, while Zea mays (corn) exhibited the most significant drop in germination rates, albeit with slight recovery at higher concentrations of exudates. Conversely, Cucumis sativus (cucumber) appeared least affected by the exudates. Moreover, all species demonstrated reductions in shoot and root lengths with increasing concentrations of exudates. Chlorophyll content analysis revealed a significant reduction across most treatments, highlighting concerns regarding photosynthetic efficiency and overall plant health. The species-specific response to root exudates suggests varying metabolic or adaptive mechanisms among crops. Additionally, malondialdehyde (MDA) levels, indicative of oxidative stress, varied among species, with A. esculentus and P. vulgaris showing a dose-dependent increase, while S. lycopersicum displayed a peak at intermediate treatment levels. Z. mays exhibited marginal elevation in MDA content, potentially indicating the presence of protective compounds within the exudates. Conversely, C. arietinum and C. sativus showed a steady increase in MDA, suggesting limited mitigation of allelopathic effects. These findings feature the complexity of allelopathic interactions and highlight the need for further research into active compounds and their modes of action to develop sustainable weed management strategies while safeguarding crop health. Understanding these dynamics is crucial for maximizing the potential benefits of allelopathy in agriculture. [ABSTRACT FROM AUTHOR]

When facilitating other species and sustaining plant community structures and biodiversity, alpine cushion plants simultaneously experience negative feedback effects from surrounding vegetation. However, the impact of surrounding vegetation on cushion dynamics remains poorly understood, particularly in terms of allelopathic potentials. To investigate the allelopathic potentials of surrounding vegetation on seedling establishment of the typical cushion plant Arenaria polytrichoides Edgew. along an elevational gradient, we extracted potential allelopathic compounds and tested their impacts on seed germination and seedling growth of A. polytrichoides. In addition, exclusion experiments using activated carbon were conducted to further elucidate these effects. Our results demonstrate that surrounding vegetation exhibits certain allelopathic potentials on A. polytrichoides seedling establishment, with variations observed based on elevation, source and concentration of allelopathy compounds, as well as growing season. Specifically, low-elevation vegetation exerts pronounced suppression on seedling establishment. Conversely, higher-elevation vegetation generally shows no effect on seed germination but stimulates seedling growth through allelopathy mechanisms. Moreover, aboveground vegetation predominantly inhibits both seed germination and seedling growth in low-elevation communities; however, the effects of belowground vegetation depend on elevation and extract concentration levels. The identified allelopathic potentials of surrounding vegetation significantly influence the population dynamics of cushion A. polytrichoides by potentially accelerating population degeneration in lower-elevation communities while ensuring consistent population recruitment and expansion in higher-elevation communities. [ABSTRACT FROM AUTHOR]

Introduction: Continuous cropping challenges have gradually emerged as pivotal factors limiting the sustainable development of agricultural production. Allelopathicals are considered to be the primary obstacles. However, there is limited information on allelopathic accumulation across various continuous cropping years and its correlation with the associated challenges. Methods: Tobacco was subjected to varying planting durations: 1 year (CR), 5 years (CC5), 10 years (CC10), and 15 years (CC15). Results: Our findings unveiled discernible disparities in tobacco growth patterns across diverse continuous cropping periods. Notably, the most pronounced challenges were observed in the CC5 category, characterized by yield reduction, tobacco black shank outbreaks, and a decline in beneficial flora. Conversely, CC15 exhibited a substantial reduction in challenges as the continuous cropping persisted with no significant differences when compared to CR. Within the tobacco rhizosphere, we identified 14 distinct allelopathic compounds, with 10 of these compounds displaying noteworthy variations among the four treatments. Redundancy analysis (RDA) revealed that eight allelopathic compounds exhibited autotoxic effects on tobacco growth, with MA, heptadecanoic acid, and VA ranking as the most potent inhibitors. Interaction network highlighted the pivotal roles of VA and EA in promoting pathogen proliferation and impeding the enrichment of 13 beneficial bacterial genera. Furthermore, a structural equation model elucidated that MA and EA primarily exert direct toxic effects on tobacco, whereas VA fosters pathogen proliferation, inhibits the enrichment of beneficial bacteria, and synergistically exacerbates the challenges associated with continuous cropping alongside EA. Discussion: These findings suggested discernible disparities in tobacco growth patterns across the various continuous cropping periods. The most pronounced challenges were observed in CC5, whereas CC15 exhibited a substantial reduction in challenges as continuous cropping persisted. VA may play a pivotal role in this phenomenon by interacting with pathogens, beneficial bacterial genera, and EA. [ABSTRACT FROM AUTHOR]

Majority of cash crops have the problem of continuous cropping in the planting process, especially the genus Panax. A series of diseases occur in the process of ginseng planting, which will aggravate the obstacle of continuous cropping, directly lead to the significant decline of ginseng yield and quality, and seriously affect the development of ginseng planting industry. Taking two main species of Panax plants, namely Panax ginseng C. A. Mey and Panax notoginseng (Burkill)F.H. Chen ex C.H., this paper explains the three main factors affecting their continuous cropping, namely (i). Allelopathic autotoxic substances, (ii). Soil microbial community and (iii). Soil physico-chemical properties. The main methods to overcome continuous cropping obstacles were listed, including (i). Biological breeding, (ii). Soil sterilization, (iii). Establishment of reasonable farming system, (iv). Use of microbial fertilizer and (v). The directions of future research were discussed to provide scientific reference for the cultivation and management of alleviating or overcoming the obstacle of continuous cropping of ginseng. [ABSTRACT FROM AUTHOR]

Due to the aging of trees, aged apple and cherry orchards need to be rebuilt urgently. However, due to the limitation of land resources, it is inevitable to rebuild the apple orchard by taking the aged cherry orchard as a replacement, which will lead to replant disease and seriously affect the sustainable development of the horticulture industry. This study investigated the effect of aged cherry orchard soil on the growth of M. hupehensis seedlings grown in pots, and it was further verified that allelochemicals in soil were one of the reasons for this effect. Three treatments were implemented: aged apple orchard soil (ppl), aged cherry orchard soil (pyl), and aged cherry orchard soil after fumigation with methyl bromide (pyz). Compared with pyz, pyl treatment significantly decreased the biomass, root growth, and antioxidant enzyme activity of M. hupehensis seedlings, and increased the content of MDA. Compared with ppl, pyl contains a smaller number of fungi and bacteria, but the abundance of the four disease-causing Fusarium remained high. In addition, the levels of allelochemicals found in the soil of aged cherry orchards can inhibit the normal growth and development of M. hupehensis seedlings. Amygdalin most strongly inhibited these seedlings. In summary, directly planting M. hupehensis seedlings in the soil of the aged cherry orchards still inhibits their normal growth and development, although the seedlings grow better than in aged apple orchard soil. Therefore, it is not feasible to directly plant M. hupehensis seedlings in the soil of aged cherry orchards, and measures should be taken to eliminate allelochemicals such as amygdalin and harmful microorganisms. [ABSTRACT FROM AUTHOR]

The fruit of Forsythia suspensa (Thunb.) Vahl has been used in traditional Chinese medicine as "Forsythiae fructus". The species is also grown in parks and gardens, and on streets and building lots, as an ornamental plant, but it requires pruning. In this study, the allelopathic activity and allelopathic substances in the leaves of pruned branches of F. suspensa were investigated to determine any potential application. The leaf extracts of F. suspensa showed growth inhibitory activity against three weed species; Echinochloa crus-galli, Lolium multiflorum, and Vulpia myuros. Two allelopathic substances in the extracts were isolated through the bioassay-guided purification process, and identified as (-)-matairesinol and (-)-arctigenin. (-)-Matairesinol and (-)-arctigenin, which showed significant growth inhibitory activity at concentrations greater than 0.3 mM in vitro. The inhibitory activity of (-)-arctigenin was greater than that of (-)-matairesinol. However, both compounds were more active than (+)-pinolesinol which is their precursor in the biosynthetic pathway. The investigation suggests that F. suspensa leaves are allelopathic, and (-)-matairesinol and (-)-arctigenin may contribute to the growth inhibitory activities. Therefore, the leaves of the pruned branches can be applied as a weed management strategy in some agricultural practices such as using the leaf extracts in a foliar spray and the leaves in a soil mixture, thereby reducing the dependency on synthetic herbicides in the crop cultivation and contributing to developing eco-friendly agriculture. [ABSTRACT FROM AUTHOR]

Platycodon is a medicinal plant of considerable pharmacological and dietary value. With the growing demand, agricultural production is increasing. However, the continuous cropping significantly causes negative impacts on its yield and quality. In this study, in order to solve the problem of continuous cropping, we evaluated the allelopathic activity of Platycodon and investigated the potential use of activated carbon for mitigating the negative impacts of allelopathic chemicals produced by Platycodon. The sandwich method (method for assaying the allelopathic activity of each part of a plant) was employed to evaluate the allelopathic activity of different parts (leaves, stems, and roots) of Platycodon. The inhibitory effects of various Platycodon plant parts were assessed based on their effects on lettuce seedling growth. At a concentration of 10 mg parts/10 mL agar, the average inhibition rates of Platycodon leaves on the radicle and hypocotyl growth of lettuce were 79.4% and 61.8%, stems 58.0% and 45.7%, and roots 53.4% and 49.3%, respectively. At a concentration of 50 mg parts/10 mL agar, the inhibitory effects were as follows: leaves (91.9%, 72.2%), stems (79.5%, 60.3%), and roots (71.4%, 65.2%). The effect of activated carbon on the adsorption of allelopathic substances was investigated, and the results of the sandwich method with a concentration of 10 mg parts/10 mL agar showed the following growth-inhibitory effects on lettuce seedlings and hypocotyls—roots (27.8%, 25.7%), leaves (13.3%, 25.7%), and stems (9.1%, 13.6%)—in each case showing a significant decrease in the inhibitory activity. The plant box method (method for assaying the allelopathic activity of plant root exudates) was employed to evaluate the activity of Platycodon root exudate. The growth inhibition rates of lettuce radicle and hypocotyls were 45.5% and 18.9%, respectively. The plant box method with addition of activated carbon revealed average rates of promotion of 16.7% and 4.7% on the growth of lettuce seedlings and hypocotyls, respectively. The results of this study demonstrated that activated carbon has a mitigating effect on allelopathic inhibition associated with the different plant parts and root exudation of Platycodon and provide a potential solution for overcoming problems associated with the continuous cropping of Platycodon. [ABSTRACT FROM AUTHOR]

Screening different plant species for herbicidal activity and identifying new allelochemicals with novel structures and phytochemical activity could be promising candidates for reducing the negative consequences of chemical herbicides. Our study aims to investigate the allelopathic substance(s) and herbicidal efficacy of Cleome rutidosperma DC. on rice filed weeds in the lab and glasshouse. The phytochemical constituents of the methanol extract of Cleome rutidosperma were analyzed by high-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight mass spectrometry (HPLCESI-QTOF-MS). The allelopathic effect of C. rutidosperma has been further studied on the germination and early development of five common rice field weeds: Echinochloa crus-galli (L.) P. Beauv., Fimbristylis miliacea (L.) Vahl, Oryza sativa f. spontanea Roshev., Leptochloa chinensis (L.) Nees, and Cyperus iria L. The seed germination and growth of tested weeds under lab and glasshouse conditions were compared to three concentrations of C. rutidosperma methanol extract at 2.5, 5, and 10% with the control (only distilled water). The results indicated the presence of 64 and 10 known chemicals using positive and negative ionization techniques, the majority of which were toxic. The inhibitory effect of C. rutidosperma was stronger in the lab than in the glasshouse. No seed germination of the tested species was observed when 10% C. rutidosperma extract was applied. The photosynthesis rate of C. iria exhibited a higher reduction (70.56%) compared to other species at higher doses (10%) of C. rutidosperma. These findings demonstrated that C. rutidosperma is a significant source of phytotoxic components and can be used to develop future bio-herbicides. The outcome of this study can be employed in the organic management of weeds and reduce our heavy reliance on synthetic herbicides. [ABSTRACT FROM AUTHOR]

Weeds present a significant challenge to high crop yield and quality. In our study, we investigated the phytotoxic activity of β-caryophyllene (BCP) and eugenol, which are natural allelopathic chemical compounds, on Arabidopsis seedlings. We found that these compounds inhibited the growth of Arabidopsis thaliana plants. When either BCP or eugenol was applied, it led to decrease in the content of cell wall components such as lignin, cellulose, hemicellulose, and pectin; and increase in the levels of endogenous hormones like ETH, ABA, SA, and JA in the seedlings. Through transcriptome profiling, we identified 7181 differentially expressed genes (DEGs) in the roots and shoots that were induced by BCP or eugenol. The genes involved in the synthesis of lignin, cellulose, hemicellulose, and pectin were down-regulated, whereas genes related to synthesis and signal transduction of ABA, ETH, SA, and JA were up-regulated. However, genes related to IAA synthesis and signal transduction were found to be down-regulated. Furthermore, we characterized 24 hub genes using Weighted Correlation Network Analysis (WGCNA). Among them, the identified 16 genes in response to BCP was primarily associated with hypoxia stress, while 8 genes induced by eugenol were linked to inhibition of cell division. Our results suggested that BCP and eugenol had ability to target multiple genes to inhibit growth and development of Arabidopsis plants. Therefore, they can serve as excellent candidates for natural biological herbicides. [ABSTRACT FROM AUTHOR]

Iris pallida Lam., also known as Sweetie Iris, is a perennial ornamental and medicinal plant that produces a wide range of secondary metabolites. The Sweetie Iris was recently reported to have high allelopathic properties with the potential to be explored in sustainable weed management. This study aimed to identify and evaluate the contributions of compounds involved in the inhibitory effects of the rhizome of Sweetie Iris. High-performance liquid chromatography (HPLC) analysis was used to determine the content of β-ionone in the rhizome of Sweetie Iris. The phytotoxicity of β-ionone was evaluated on lettuce (Lactuca sativa L.) and other test plants. The content of β-ionone in the crude extract of Sweetie Iris rhizome was found to be 20.0 mg g−1 by HPLC analysis. The phytotoxicity bioassay showed that β-ionone had strong inhibitory activity on the growth of lettuce (Lactuca sativa L.) and the other test plants, including Taraxacum officinale, Stellaria media, Eleusine indica, Amaranthus hybridus, Vicia villosa, and Brassica napus. At a concentration of 23.0 µg mL−1, β-ionone inhibited the growth of all test plant species treated. Therefore, β-ionone is an active compound among the other allelopathic substances contained in the rhizome of Sweetie Iris. [ABSTRACT FROM AUTHOR]

Among the factors that affect potato productivity, the interference caused by weeds stands out as they may compete with the crop, release allelopathic substances to soil and host insects and diseases. Therefore, the objective of this work was to assess the competitive ability of white (Aghata) and pink (Asterix) potato cultivars when infested by Alexandergrass (Urochloa plantaginea) or wild poinsettia (Euphorbia heteroplylla). The experiment was carried out into greenhouse in randomized blocks design, with four replications. A single potato plant faced competition by either Alexandergrass or wild poinsettia, ranging from 0 to 64 plants per plot. Fifty days after seedling transplanting, variables related to the morphophysiology of potato cultivars and weeds were assessed. Potatoes have low competitive ability with both weed species, with wild poinsettia being the most aggressive in reducing the accumulation rates of leaf area and aboveground dry mass. Potato photosynthetic rate is negatively influenced by the presence of both weeds. Internal CO2 concentration, stomatal conductance, carboxylation efficiency and transpiration rates of potato varied depending on weed species and density. Morphological parameters are reduced when potato competed with Alexandergrass or wild poinsettia; however the physiological parameters are most sharply affected when under competition with wild poinsettia. [ABSTRACT FROM AUTHOR]

In the framework of benthic harmful algal bloom monitoring, the most common sampling strategy is based on the collection of macroalgae, and the abundance of epiphytic microalgae are mainly expressed as cells g−1 macroalgal fresh weight (fw). However, this methodology has some inherent problems, due to (i) the thallus-specific weights that markedly differ among algal species, (ii) the thallus architecture, and (iii) the production of allelopathic compounds that affects the epiphyte abundances among macroalgae, irrespective of the available colonizable surface. This study proposes a method to compare the abundances of Ostreopsis cf. ovata cells on different substrata, using a conversion factor that converts the abundances expressed as cells g−1 fw (or dry weight) to cells cm−2. Expressing abundances in terms of cells cm−2, the abundances can be compared (i) among different macroalgal species and (ii) between macroalgae and other substrata (such as rocks, pebbles, or shellfish shells). We also propose to normalize abundances when different macroalgae are sampled throughout the bloom period, considering the different epiphyte loads of different macroalgal species regardless of the available surface area. [ABSTRACT FROM AUTHOR]

Copyright of Acta Biologica Slovenica is the property of Drustvo Biologov Slovenije and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Root exudates of the invasive Solidago canadensis and the cereal crop Sorghum bicolor (L.) Moench cv. 'Hybridsorgo' were tested for allelopathic interactions against native and invasive plant species in a controlled environment. After the surface was sterilized, the seeds of two invasive species (Bromus sterilis and Veronica persica) and two native species (Youngia japonica and Rumex acetosa) were germinated and transplanted into the soil (1:1 mixture of coco peat and sand) that had been conditioned for one month by the cultivation of Solidago canadensis and Sorghum bicolor, both in combination or as unplanted controls. After an additional eight weeks of growth, morphometric measurements of the shoot and root, including foliar characteristics and above- and below-ground biomass accumulation, were performed. The results revealed significant inhibitory effects of root exudates released by Sorghum bicolor and Solidago canadensis on native species' productivity and physiology. The invasive species exhibited variable growth responses, with Veronica persica showing reduced shoot and root expansion, but Bromus sterilis revealed increased shoot and root biomass allocation and nutrition under the exudate treatments. Exudates from Solidago canadensis and Sorghum bicolor together showed synergistic negative effects on native species, while they promoted growth and nutrition in Veronica persica. Taken together, the differential species responses indicate that the tested native species were more sensitive to the allelopathic compounds than the invasive species, which is in line with the theory of novel weapons. The legacy effects of root exudates of both Sorghum bicolor and Solidago canadensis could promote invasive establishment through imposing allelochemical interference competition against native plant species. Understanding the specific allelopathic mechanisms may help with the development of integrated strategies for managing invasive species. [ABSTRACT FROM AUTHOR]

Copyright of Iraqi Journal of Desert Studies is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The present study was conducted in Department of Botany, Institute of Science, Nagpur, to investigate the allelopathic effects of Mexican poppy (Argemone mexicana L.) on wheat. Wheat is the most important edible cereal crop. Wheat can grow in a wide variety of soils and temperatures, but thrives in humid regions with 30-90 cm of precipitation. Argemone mexicana L. is a rapidly expanding weed and an important competitor of wheat (in terms of allelochemicals). Weed is one of major cause of crop production loss. The entire plants of Argemone mexicana L. were harvested, rinse with tap water to remove soil debris, roots are dried in shade which kept at 25 degrees celcius (±2) for 72 hours. To demonstrate the germination of seeds of two locally grown wheat varieties (Sharabati and Lokwan), five concentrations of different ratios of root aqueous extract were obtained. A bioassay of a petri dish was carried out to assess the allelopathic potential of Argemone mexicana L. on the germination of Triticum aestivum L. seeds. The water based root extracts of weeds were used for treatment. The differential inhibitory effect of Argemone mexicana L. on Sharbati and Lokwan variety of wheat was observed. [ABSTRACT FROM AUTHOR]

The secondary metabolites of indigenous plants have significant allelopathic inhibitory effects on the growth and development of invasive alien plants. Methyl palmitate (MP) and methyl linolenate (ML) were used as exogenous allelopathic substances. The research investigated the differences of inhibitory effects of MP and ML on the growth of seedlings of Alternantheraphiloxeroides, and calculated their morphological characteristics, biomass, physiological indicators and the response index (RI). The synthetical allelopathic index (SE) of 1 mmol/L MP was the smallest (− 0.26) and the allelopathic inhibition was the strongest; therefore, it was selected as a 13C-labeled allelochemical. The distribution of 1 mmol/L MP in different parts of A.philoxeroides and the correlation between the biomass ratios of roots, stems and leaves and the 13C content were studied by 13C stable isotope tracing experiments. Atom percent excess (APE) between roots, stems and leaves of A.philoxeroides treated with 1 mmol/L MP were significantly different in terms of magnitude, with leaves (0.17%) > roots (0.12%) > stems (0.07%). The root, stem and leaf biomass ratios of invasive weeds had great significant positive correlation with 13C content (p < 0.01, R2 between 0.96 and 0.99). This current research provides a new idea and method for the control of A.philoxeroides, but large-scale popularization remains to be studied. [ABSTRACT FROM AUTHOR]

Casparian strip membrane domain protein-like (CASPL) genes are key genes for the formation and regulation of the Casparian strip and play an important role in plant abiotic stress. However, little research has focused on the members, characteristics, and biological functions of the patchouli PatCASPL gene family. In this study, 156 PatCASPL genes were identified at the whole-genome level. Subcellular localization predicted that 75.6% of PatCASPL proteins reside on the cell membrane. A phylogenetic analysis categorized PatCASPL genes into five subclusters alongside Arabidopsis CASPL genes. In a cis-acting element analysis, a total of 16 different cis-elements were identified, among which the photo-responsive element was the most common in the CASPL gene family. A transcriptome analysis showed that p-hydroxybenzoic acid, an allelopathic autotoxic substance, affected the expression pattern of PatCASPLs, including a total of 27 upregulated genes and 30 down-regulated genes, suggesting that these PatCASPLs may play an important role in the regulation of patchouli continuous cropping obstacles by affecting the formation and integrity of Casparian strip bands. These results provided a theoretical basis for exploring and verifying the function of the patchouli PatCASPL gene family and its role in continuous cropping obstacles. [ABSTRACT FROM AUTHOR]

Over the past few decades, nearly 300 known cyanotoxins and more than 2000 cyanobacterial secondary metabolites have been reported from the environment. Traditional studies have focused on the toxic cyanotoxins produced by harmful cyanobacteria, which pose a risk to both human beings and wildlife, causing acute and chronic poisoning, resulting in diarrhea, nerve paralysis, and proliferation of cancer cells. Actually, the biotechnological potential of cyanotoxins is underestimated, as increasing studies have demonstrated their roles as valuable products, including allelopathic agents, insecticides and biomedicines. To promote a comprehensive understanding of cyanotoxins, a critical review is in demand. This review aims to discuss the classifications; biosynthetic pathways, especially heterogenous production; and potential applications of cyanotoxins. In detail, we first discuss the representative cyanotoxins and their toxic effects, followed by an exploration of three representative biosynthetic pathways (non-ribosomal peptide synthetases, polyketide synthetases, and their combinations). In particular, advances toward the heterologous biosynthesis of cyanotoxins in vitro and in vivo are summarized and compared. Finally, we indicate the potential applications and solutions to bottlenecks for cyanotoxins. We believe that this review will promote a comprehensive understanding, synthetic biology studies, and potential applications of cyanotoxins in the future. [ABSTRACT FROM AUTHOR]

Investigation of allelopathic substances from herbal plants may lead to the development of allelochemical-based natural herbicides. Croton oblongifolius (Roxb.) is a well-known herbal plant with a long history of being used for traditional medicines and for being the source of a diverse range of bioactive compounds. This plant has been reported to have allelopathic potential; however, its allelopathic-related substances have not yet been described. Therefore, we conducted this investigation to explore the allelopathic substances from the leaves of C. oblongifolius. Aqueous methanol extracts of C. oblongifolius leaves exhibited significant growth inhibitory potential against four test plants (monocot barnyard grass and timothy, and dicot cress and lettuce). The leaf extracts were purified in various chromatographic steps and yielded four active compounds identified as (3R,6R,7E)-3-hydroxy-4-7-megastigmadien-9-one (I), 2-hydroxy alpinolide (a novel compound) (II), alpinolide (III), and epialpinolide (IV) via an analysis of the spectral data. These identified compounds significantly restricted the seedling growth of cress. The concentration necessary for 50% growth reduction of the cress seedlings varied from 0.15 to 0.24 mM for (3R,6R,7E)-3-hydroxy-4-7-megastigmadien-9-one, 0.04 to 0.11 mM for 2-hydroxy alpinolide, 0.07 to 0.12 mM for alpinolide, and 0.09 to 0.16 mM for epialpinolide. Therefore, the leaf extracts of C. oblongifolius and the characterized compounds have the potential to be used as weed-suppressive resources for natural weed control. [ABSTRACT FROM AUTHOR]

Representative species of the Taxus genus, known since antiquity for their toxicity, have been an essential plant resource for the production of plant extracts with medicinal properties (antiinflammatory, antifungal, and antibacterial) and, more recently, for the study of their allelopathic properties with significant implications in organic agriculture (bioherbicidal potential). With a view to the development of this new direction of research, the present work aims: to present a qualitative evaluation of two types of plant extracts (aqueous and alcoholic) of different concentrations (1% and 5%) obtained from various organs (bark, leaves, arils, and seeds) belonging to three Taxus taxa: a spontaneous taxa - Taxus baccata L. (T1) and two cultivated taxa - Taxus baccata (T2) and Taxus baccata 'Robusta' (T3) at different times of the phenological cycle by determining their absorption spectra (of both types of extracts), total amounts of polyphenols and flavonoids, and by evaluating their antioxidant capacity (alcoholic extracts); to investigate, under experimental conditions of cultivation the possible allelopathic effects induced by the aqueous extracts on the germination, growth, and development of the seedlings in two test plant species: Amaranthus retroflexus L. (ruderal species) and Lycopersicon esculentum Mill, variety Silvia (crop species). The data indicates the presence of phenolic and compounds, alkaloids, and carotenoid pigments in the alcoholic extracts prepared from the different organs of the studied yew taxa, showing higher amounts of polyphenols and flavonoids in the extracts obtained from the leaves of taxon T2 compared to taxon T1. The effect of 1% and 5% aqueous extracts obtained from the bark of the three investigated yew taxa, as well as 1% aqueous extracts prepared from the leaves of taxon T3 on seed germination, seedling growth, and development was more pronounced in the crop species Lycopersicon esculentum Mill, variety Silvia, compared to the ruderal broadleaf weed Amaranthus retroflexus L., both species having rapid germination stimulated by ambient light. Aqueous extracts of 5% concentration obtained from the arils of plants belonging to the three yew taxa stimulated the elongation of the seedlings' hypocotyls of both test species. [ABSTRACT FROM AUTHOR]

Polygonum chinense Linn., belonging to the Polygonaceae family, is distributed mostly in northern temperate climates. This species is a high-risk invasive plant and is thought to possess allelopathic potential. This study aimed to isolate and identify the allelopathic substances from P. chinense. Aqueous methanol extracts of P. chinense significantly inhibited the growth of alfalfa and Italian ryegrass seedlings in a species- and concentration-dependent manner. Activity-guided fractionation led to the isolation of two active compounds: dehydrovomifoliol and loliolide. A cress bioassay was used to determine the biological activity of dehydrovomifoliol, and cress, alfalfa, and Italian ryegrass were used to determine loliolide. Dehydrovomifoliol significantly suppressed the seedling growth of cress at the concentration of 1 mM, and the concentrations necessary for 50% growth inhibition (I50 values) of the roots and shoots were 1.2 and 2 mM, respectively. Loliolide significantly suppressed the shoot growth of cress, alfalfa, and Italian ryegrass at the concentration of 1 mM, and the concentrations necessary for I50 values of the shoots and roots were 0.15 to 2.33 and 0.33 to 2.23 mM, respectively. The findings of our study suggest the extracts of P. chinense might have growth-inhibitory potential and that dehydrovomifoliol and loliolide might contribute as allelopathic agents. [ABSTRACT FROM AUTHOR]

• Types of bioactive metabolites and their role in plant growth and stress tolerance. • Plants terpenes are the largest group of secondary metabolites that play an important role in defense mechanisms against the herbivores and pathogens. • Impacts and role of secondary metabolites during biotic and abiotic stresses. • Role of microorganisms in altering plant metabolome under various environmental stresses. Primary metabolites are ubiquitous in nature and actively involved in growth while secondary metabolites (SMs) are involved in interaction with the environment. In plants terpenes are the largest group of secondary metabolites that play an important role in defense mechanisms against the herbivores and pathogens. Plant secondary metabolites such as alkaloids, phenolics and diterpenes have a great potential against many carcinogens. Carotenoids provide photoprotection and act as a pigment to absorb light during photosynthesis. Carotenoids are also efficient in the interaction with other organisms as they are phagostimulant and allelopathic agent. Flavonoids from the higher plants play a significant role in ultra-violet (UV) filtration, nitrogen fixation, floral pigmentation, and defense mechanisms against many diseases. These secondary metabolites provide protection to plants in a different type of biotic and abiotic stresses. Microorganisms also contain a high number of bioactive metabolites but not all of them. Marine microorganisms are a rich source of secondary metabolites such as alkaloids, terpenoids, polyketides, isoprenoids and non-isoprenoid and quinones amongst others. These metabolites are anti-inflammatory, anti-bacterial and anti-tumor in action. Secondary metabolites from fungi have a great therapeutic value as they have antifungal and antibacterial activity against many pathogens. Plant growth promoting rhizobacteria (PGPR) and Plant growth regulators (PGR) are the key biological entities to enhance the production of bioactive secondary metabolites in plants and can change the plant metabolome in response to various environmental stresses. This review paper will provide a new insight about the role of secondary metabolites in plant defense and the role of microorganisms in modulating the plant metabolome under various environmental stresses and their interactions with other microorganisms and plant growth regulators. [ABSTRACT FROM AUTHOR]

The present study investigated the antibacterial, antifungal and allelopathic activities of Pistacia lentiscus essential oils (EOs) isolated at the vegetative, flowering and fructification stages. The chemical composition of EOs varied according to both the phenological stages and the used mix plant parts. The main chemical class was sesquiterpene hydrocarbons with the predominance of germacrene D, δ-cadinene and β-caryophyllene. The antibacterial activity was evaluated against five collection strains. At the vegetative stage, P. lentiscus EO was the most effective against Listeria monocytogenes and Echerchia coli as compared to the other stages. P. lentiscus EO also exhibited significant antifungal activity against the phytopathogenic strain Botrytis cinerea. Microscopic observation showed that EO induced swelling and crumbling of B. cinerea conidia. Moreover, P. lentiscus EO at the vegetative stage possessed significant allelopathic activity by inhibiting low concentration the germination and radical elongation of Raphanus sativus and radical elongation of Lepidium sativum. [ABSTRACT FROM AUTHOR]

BACKGROUND: Cover crops can suppress soilborne nematodes and fungal pathogens by serving as a poor host to pathogens and producing allelopathic compounds. Yet, cultural practices can influence their effectiveness. Cover crop and weedy fallow rotations and their interactions with deep tillage were evaluated from 2019 to 2021 in a three‐season vegetable cropping system (spring tomato, fall squash, and winter cabbage) for their suppressive effects on soilborne diseases. Experimental plots were arranged in a split‐plot 2 × 4 factorial design in randomized complete blocks. Whole‐plot tillage treatments were shallow‐tilled or deep‐tilled. Subplots had two factors of crop rotations: rotation type (cover crop [spring or fall sunn hemp or winter rye] or weedy fallow) and rotation season. RESULTS: Independent of tillage practice, sunn hemp and weedy fallow reduced population density and root galling severity of root‐knot nematode (Meloidogyne incognita) for the first subsequent vegetable compared to the all‐vegetable rotation (P < 0.05) but had little effect on fungal pathogens. Fall sunn hemp had higher plant biomass and reduced gall severity for the second subsequent vegetable. Spring and fall sunn hemp improved vegetable yields. Winter rye only reduced ring nematodes (Mesocriconema spp.) population density in the first subsequent vegetable. Deep tillage reduced incidence of fungal pathogens of Rhizoctonia solani and Sclerotinia sclerotiorum, and population density of stubby‐root nematode (Nanidorus minor). CONCLUSION: Sunn hemp is effective in suppressing M. incognita, whereas deep tillage can be used to suppress R. solani, S. sclerotiorum, and N. minor in vegetable production systems. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Trewia nudiflora Linn. is a valuable forest resource due to its economic, ethnomedicinal, and ecological properties; however, its allelopathic potential is undocumented. Therefore, this research was designed to investigate the allelopathic impacts of T. nudiflora leaf extracts on alfalfa (Medicago sativa L.) and barnyard grass (Echinochloa crus-galli (L.) P. Beauv.) growth, as well as to isolate and to identify the active allelopathic substances responsible for these effects. A bioassay experiment with eight different treatments (0.1, 0.3, 1, 3, 10, 30, 100, and 300 mg dry weight (DW) equivalents of T. nudiflora extracts in mL−1) was carried out. The results showed that the growth of both plants decreased with increasing contents of T. nudiflora extracts, with the effect depending on the plant species and reaching its peak at a concentration of a 300 mg DW equivalent of T. nudiflora extract in mL−1. Active substances were isolated and identified using an HPLC system, which revealed the presences of methyl gallate and pinoresinol in aqueous methanol extracts of T. nudiflora. The shoot and root lengths of the alfalfa and the barnyard grass decreased significantly when they were treated with the methyl gallate and the pinoresinol. The allelopathic inhibition increased with increasing compound concentrations, with the root growth being more sensitive to the pinoresinol than to the methyl gallate, and it was significantly higher at the concentration of 10 mM. These results indicated that the T. nudiflora leaf extracts limited the growth of the treated plants, and the methyl gallate and pinoresinol in the extracts may have caused the inhibition of the T. nudiflora extracts. Thus, the leaf extracts of T. nudiflora and the substances methyl gallate and pinoresinol could be incorporated into sustainable agricultural practices or used to develop bioherbicides that would promote sustainable weed management practices. [ABSTRACT FROM AUTHOR]

The article focuses on investigating the efficacy of the new herbicide clodinafop propargil+ metribuzin for weed control in wheat fields in Fars province, Iran. It study aims to determine the most appropriate dose, compare the effectiveness of the new herbicide with existing ones, and assess the reaction of wheat to the herbicide.

The current review was aimed at investigating the potential of Lantana camara extract as an effective alternative for synthetic herbicides to control weeds and also establishing the effects of allelochemicals in the extract on the germination and growth of cultivated crops. The researchers assessed abstracts and articles published from 2011 to 2022. The review has established that although L. camara extract has allelopathic properties to suppress the germination and growth of weeds in the fields. However, the extract is not entirely selective for the plants it inhibits; as a result, it also suppresses the growth of cultivated crops. Therefore, the review recommends that the extract should only be used on crops whose germination and growth cannot be suppressed by it. There is a need to establish the proper timing of the application of the extract to avoid the suppression of germination and early seedling growth in cultivated crops. More studies have been done on the effects of extract on plants in the Poaceae, Fabaceae, and Brassicaceae families. Therefore, more research has to be done to evaluate the allelopathic effects of L. camara extract on agronomic crops under Onagraceae, Solanaceae, Asteraceae, Convolvulaceae, Euphorbiaceae, Malvaceae, and Amaranthaceae families.There is limited information on the effects of the L. camara extract on the yields of the crops; as such, this review recommends that further research be conducted to evaluate the effects of the allelochemicals of L. camara on the yields of the cultivated crops in the fields where the extract has been applied. [ABSTRACT FROM AUTHOR]