Search

BACKGROUND: 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. RESULTS: 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). CONCLUSION: 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]

As a result of human activities, surface waters worldwide are experiencing increasing levels of eutrophication, leading to more frequent occurrences of microalgae, including harmful algal blooms. We aimed to investigate the impact of decomposing camelina straw on mixed phytoplankton communities from eutrophic water bodies, comparing it to the effects of barley straw. The research was carried out in 15 aquaria (five of each type – containing no straw, camelina straw, and barley straw). The experiment lasted eight weeks, and the water used in the aquaria was sourced from an eutrophic reservoir. Our research revealed that the camelina straw had the most significant inhibitory effect on the growth of specific groups and species of phytoplankton (especially chrysophytes, potentially toxic cyanobacteria, and dinoflagellates). This inhibition was achieved by releasing polyphenols, primarily gallic and caffeic acids and flavonoids. Simultaneously, polyphenols promoted the growth of filamentous green algae. Our findings present novel data on the vulnerability of freshwater species and taxonomic groups of algae to the effects of camelina and barley straw exposure. [ABSTRACT FROM AUTHOR]

We studied the allelopathic effects of mushroom Pholiota (Fr.) P. Kumm. species on seed germination and seedlings growth of Cucumis sativus L. and Lepidium sativum L. The mycelium of Pholiota species suppressed the seed germination, shoot and root length of test plants and also changed the morphology of roots (pubescence, changes in lateral roots). The inhibition in sprout length was 8.6 %-87. 1 % in C. sativus and 42.2 %-91.8 % in L. sativum depending on Pholiota species. Allelopathic effects of Pholiota subochracea (A.H.Sm.) Hesler, drastically decreased the germination to 12.9 % than control. [ABSTRACT FROM AUTHOR]

Weed control is a challenging event during crop cultivation. Natural alternatives to chemical weed control need time and are crucial for sustainable weed control. Chemical weed control is challenging, due to the recent increase in herbicide-resistant biotypes and to the harmful side effects of herbicides on the environment. Integrated management of weeds including the application of bioherbicides, is an emerging method for weed control in sustainable agriculture. Plant extracts, allelochemicals and some microbes are utilized as bioherbicides to control weed populations. Bioherbicides based on plants and microbes inhibit the germination and growth of weeds. One such plant known to have allelopathy property is Alternanthera philoxeroides Mart.) Griseb.]. It is a worldwide obnoxious and invasive weed, causing irreversibly damage in agricultural production especially in Rice and local aquatic ecosystem. Phytotoxic chemicals released by A. philoxeroides into irrigation water and/or directly into rice ecosystems have a significant inhibitory influence on germination, growth and yield of field crops, soil properties and nutrients availability, population and community structure, and weed invasion. Hence, A. philoxeroides can be used as a potential organic alternative to chemical weed-control, due to the higher susceptibility of terrestrial and aquatic weeds to the phytotoxic chemicals released by this weed. [ABSTRACT FROM AUTHOR]

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]

Euphorbia jolkinii dominates the subalpine meadows in Shangri-La (Southwest China) owing to its potent allelopathic effects. However, the effects underlying its allelopathy require further characterization at the physiological and molecular levels. In this study, the physiological, biochemical, and metabolic mechanisms underlying E. jolkinii allelopathy were investigated using Arundinella hookeri as a receptor plant. The treatment of A. hookeri seedlings with E. jolkinii aqueous extract (EJAE) disrupted their growth by inhibiting photosynthesis, disrupting oxidation systems, and increasing soluble sugar accumulation and chlorophyll synthesis. Collectively, this causes severe impairment accompanied by abnormal photosynthesis and reduced biomass accumulation. Moreover, EJAE treatment suppressed gibberellin, indoleacetic acid, zeatin, salicylic acid, and jasmonic acid levels while promoting abscisic acid accumulation. Further metabolomic analyses identified numerous differentially abundant metabolites primarily enriched in the α-linolenic, phenylpropanoid, and flavonoid biosynthesis pathways in EJAE-treated A. hookeri seedlings. This study demonstrated that E. jolkinii exhibits potent and comprehensive allelopathic effects on receptor plants, including a significant disruption of endogenous hormone synthesis, the inhibition of photosynthesis, an impairment of membrane and oxidation systems, and changes in crucial metabolic processes associated with α-linolenic, phenylpropanoid, and flavonoid biosynthesis. Thus, our study provides a solid theoretical foundation for understanding the regulatory mechanisms underlying E. jolkinii allelopathy. [ABSTRACT FROM AUTHOR]

Wheat (Triticum aestivum) is grown on more arable acreage than any other food crop and has been well documented to produce allelochemicals. Wheat allelochemicals include numerous benzoxazinoids and their microbially transformed metabolites that actively suppress growth of weed seedlings. Production and subsequent release of these metabolites by commercial wheat cultivars, however, has not yet been targeted by focussed breeding programmes seeking to develop more competitive crops. Recently, the Commonwealth Scientific and Industrial Organisation (CSIRO), through an extensive recurrent selection programme investment, released numerous early-vigour wheat genotypes for commercial use, but the physiological basis for their improved vigour is under investigation. In the current study, we evaluated several early-vigour genotypes alongside common commercial and heritage wheat cultivars to assess the impact of improved early vigour on the production and release of targeted benzoxazinoids by field-grown wheat roots over a two-year period. Using UPLC coupled with triple quadrupole mass spectrometry (LC-MS QQQ), we quantified common wheat benzoxazinoids and their microbially produced metabolites (aminophenoxazinones) in soil collected from the rhizosphere and rhizoplane of wheat plants over two growing seasons in the Riverina region of New South Wales, Australia. The benzoxazolinone MBOA and several aminophenoxazinones were readily detected in soil samples, but actual soil concentrations differed greatly between years and among genotypes. In contrast to 2019, the concentration of aminophenoxazinones in wheat rhizosphere soil was significantly elevated in 2020, a year receiving adequate rainfall for optimal wheat growth. Aminophenoxazinones were detected in the rhizosphere of early-vigour genotypes and also parental lines exhibiting weed suppression, suggesting that improved early vigour and subsequent weed competitiveness may be related to increased root exudation and production of microbial metabolites in addition to changes in canopy architecture or other root-related early-vigour traits. As previously reported, MBOA was detected frequently in both the rhizoplane and rhizosphere of wheat. Depending on the year and genotype, we also observed enhanced biotransformation of these metabolites to several microbially transformed aminophenoxazinones in the rhizosphere of many of the evaluated genotypes. We are now investigating the role of early-vigour traits, including early canopy closure and biomass accumulation upon improved competitive ability of wheat, which will eventually result in more cost-effective weed management. [ABSTRACT FROM AUTHOR]

The evaluation of the wide variety of allelochemicals present in allelopathic plants allows the detection of safer bioherbicides with new mechanisms of action. This study tested two phenolic compounds of Cistus ladanifer essential oil (2-Methoxyphenol and 2,6-Di-tert-butyl-4-methylphenol), which are commercially available. At 0.01 mM, these compounds, both separately and in combination (1/1), inhibited up to over 50% of germination, cotyledon emergence and seedling growth of Lactuca sativa for the tests conducted on paper. Against Allium cepa, cotyledon emergence and seedling growth were inhibited at 0.5 mM. When the tests were carried out in the soil, the mixture of the two study compounds significantly inhibited the germination of L. sativa and A. cepa when applied at 0.5 and 1 mM, respectively, and seedling growth inhibition was greater for the latter in the paper tests. The greatest inhibitions were observed, with the highest concentrations analysed. Although there was no statistically significant difference among treatments, 2-Methoxyphenol seemed to affect germination and cotyledon emergence to a greater extent, whereas 2,6-Di-tert-butyl-4-methylphenol had a greater impact on seedling size. The effect of the mixture was greater than that of both compounds separately. [ABSTRACT FROM AUTHOR]

Rehmannia glutinosa is an important medicinal herb; but its long-term cultivation often leads to continuous cropping problems. The underlying cause can be attributed to the accumulation of and alterations in root exudates; which interact with soil-borne pathogens; particularly Fusarium oxysporum; triggering disease outbreaks that severely affect its yield and quality. It is therefore crucial to elucidate the mechanisms by which root exudates induce F. oxysporum CCS043 outbreaks. In this study; the genome of F. oxysporum CCS043 from R. glutinosa's rhizosphere microbiota was sequenced and assembled de novo; resulting in a 47.67 Mb genome comprising 16,423 protein-coding genes. Evolutionary analysis suggests that different F. oxysporum strains may adapt to the host rhizosphere microecosystem by acquiring varying numbers of specific genes while maintaining a constant number of core genes.The allelopathic effects of ferulic acid; verbascoside; and catalpol on F. oxysporum CCS043 were examined at the physiological and transcriptomic levels. The application of ferulic acid was observed to primarily facilitate the proliferation and growth of F. oxysporum CCS043; whereas verbascoside notably enhanced the biosynthesis of infection-related enzymes such as pectinase and cellulase. Catalpol demonstrated a moderate level of allelopathic effects in comparison to the other two. Furthermore; 10 effectors were identified by combining the genomic data. Meanwhile; it was found that among the effector-protein-coding genes; ChiC; VRDA; csn; and chitinase exhibited upregulated expression across all treatments. The expression patterns of these key genes were validated using qRT-PCR. Transient overexpression of the two effector-encoding genes in detached R. glutinosa leaves provided further confirmation that ChiC (GME8876_g) and csn (GME9251_g) are key effector proteins responsible for the induction of hypersensitive reactions in R. glutinosa leaf cells. This study provides a preliminary indication that the use of allelochemicals by F. oxysporum CCS043 can promote its own growth and proliferation and enhance infection activity. This finding offers a solid theoretical basis and data support for elucidating the fundamental causes of fungal disease outbreaks in continuous cropping of R. glutinosa and for formulating effective mitigation strategies. [ABSTRACT FROM AUTHOR]

Background/Objectives: This study explores the allelopathic effects of volatile organic compounds (VOCs) emitted by the invasive species Ailanthus altissima (Mill.) Swingle on the seed germination of Bidens pilosa. A. altissima is known for releasing allelopathic VOCs that suppress the growth of neighbouring plants, contributing to its invasive potential. Methods: To examine these effects, we exposed B. pilosa seeds to varying concentrations of A. altissima VOCs, assessing germination rates and metabolic changes through untargeted metabolomics. Results: Our findings revealed that VOCs from A. altissima significantly inhibited the germination speed and overall germination rates of B. pilosa in a dose-dependent manner. Metabolomic profiling showed disruptions in energy and amino acid metabolism pathways, specifically involving delayed breakdown of starch and key metabolites, indicating inhibition of critical metabolic processes during early germination stages. This metabolic delay likely impairs B. pilosa's establishment and competitiveness, enhancing A. altissima's ecological dominance. Conclusions: The results underscore the potential of VOC-based allelopathy as a mechanism of plant invasion, offering insights into the role of VOCs in interspecies plant competition and ecosystem dynamics. [ABSTRACT FROM AUTHOR]

Using allelochemicals produced by submerged plants to inhibit algal growth is an environmentally friendly approach to controlling harmful algal blooms in eutrophic lakes. This study aimed to evaluate the inhibition of cyanobacterial growth by allelochemicals accumulated by the aquatic plant Vallisneria natans, with enhancement through blue and red light-emitting diode (LED) supplementation. We conducted a laboratory experiment to assess the fluorescence parameters, enzyme activities, and phycocyanin contents of cyanobacteria Microcystis aeruginosa grown in different V. natans cultivation media. The fluorescence parameters in the BG-11 medium remained stable, but sharply decreased in both LED treatments, with nearly 100% inhibition observed after 12 h of incubation. Superoxide dismutase (SOD) and peroxidase activities were stable in the BG-11 treatment, but enhanced in both LED treatments, reaching maximum values within 48 h. Higher SOD activities were observed with blue LED compared with red LED, suggesting better performance with blue light. A constant high phycocyanin fluorescence intensity was observed in the BG-11 treatment, while both LED treatments showed lower intensities. These results provided strong evidence that LED supplementation enhances the inhibitory effects of V. natans on M. aeruginosa growth. The combination of aquatic plant growth with underwater LED light supplementation offers a promising approach to controlling cyanobacterial blooms. [ABSTRACT FROM AUTHOR]

In subtropical coastal dune ecosystems, biotic interactions can play a pivotal role in shaping species distribution patterns and community dynamics. We evaluated the influence of three dominant shrub species on plant species richness, plant abundance, and community composition, assessing their interaction roles (facilitation, neutrality, interference) in plant communities in southern Brazil. We selected 15 isolated individuals of each of the three most common shrub species in this environment, Guapira opposita, Dodonaea viscosa and Vitex megapotamica. We sampled all woody plants and bromeliads both under the canopy of each individual of the three shrub species and in a paired open site near each shrub. We compared species richness, plant abundance, and interaction strength between the two microhabitats (under the canopy and open area). Plant abundance and richness were higher under the canopy of G. opposita, indicating its role as a facilitator. V. megapotamica exhibited mild facilitation, with a small effect on abundance and no effect on richness, while Dodonaea viscosa acted as an interferer, with lower pant abundance under its canopy than in open sites. Community composition differed among shrub species and open sites, as well as across different shrubs. Our study reveals a wide spectrum of plant-plant interactions influencing plant community structure and dynamics. [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]

Litter decomposition is essential for nutrient and chemical cycling in terrestrial ecosystems. Previous research on in situ litter decomposition has often underestimated its impact on soil nutrient dynamics and allelopathy. To address this gap, we conducted a comprehensive study involving both field and greenhouse experiments to examine the decomposition and allelopathic effects of the invasive Solidago canadensis L. in comparison with the native Phalaris arundinacea L. In the field, a 6-month litter bag experiment using leaf litter from S. canadensis and P. arundinacea was conducted across three community types: invasive, native, and mixed. Seed germination tests were also performed to investigate the allelopathic effects of decomposing litter. In the greenhouse, a pot experiment with lettuce as a bioindicator was performed to examine the allelochemical inputs from litter decomposition over various time intervals (0, 30, 60, 120, and 180 days). Subsequently, a soil–plant feedback experiment was carried out to further evaluate the effects of decomposing litter on soil biochemistry and plant dynamics. The findings of this study revealed that S. canadensis litter decomposed more rapidly and exhibited greater nitrogen (N) remaining mass compared with P. arundinacea in both single and mixed communities. After 180 days, the values for litter mass remaining for S. canadensis and P. arundinacea were 36% and 43%, respectively, when grown separately and were 32% and 44%, respectively, in mixed communities. At the invasive site, the soil ammonia and nitrate for S. canadensis increased gradually, reaching 0.89 and 14.93 mg/kg by day 120, compared with the native site with P. arundinacea. The soil organic carbon for S. canadensis at the invasive site also increased from 10.6 mg/kg on day 0 to 15.82 mg/kg on day 120, showing a higher increase than that at the native site with P. arundinacea. During the initial decomposition stages, all litters released almost all of their allelochemicals. However, at the later stages, litters continued to input nutrients into the soil, but had no significant impact on the soil carbon (C) and N cycling. Notably, litter-mediated plant–soil feedback facilitated the invasion of S. canadensis. In conclusion, this study highlights the significance of litter decomposition as a driver of transforming soil biochemistry, influencing the success of invasive S. canadensis. [ABSTRACT FROM AUTHOR]

Harmful algal blooms (HABs) have always been a worldwide environmental issue. The methods based on the principle of allelopathy provide a novel direction for controlling HABs; however, there are a few studies on the application of allelopathic algaecides to control harmful algae in marine environments. Here we examined the algicidal capacity of 15 fruit peel extracts with biological activity on Alexandrium catenella. The results displayed that the mango peel extracts (MPE) showed efficient inhibition on species growth. The algicidal rate reached 93.32 ± 0.56% at 96 h after adding 5 g/L MPE to the culture medium of A. catenella. Furthermore, we found that the expression of key genes involved in PSII and PSI was downregulated as well as obstructed the electron transportation in the light reaction process and the synthesis of organic matter. The blocked photosynthetic chain induced the accumulation of substantial reactive oxygen species, resulting in severe peroxidation of the membrane lipids. Simultaneously, the expression pattern of key genes involved in the fatty acid, amino acid, and peroxisome breakdown pathways was upregulated, which suggested that the synthesis and decomposition of intracellular organic matter may be in an imbalanced state. The results above indicated that oxidative damage and energy metabolism disequilibrium are two key pathways by which MPE induced algal cell death. Furthermore, several kinds of active substances and their proportion in MPE had been identified by liquid chromatography quadrupole time-of-flight mass spectrometry. It is speculated that esters may be the important component playing an algicidal effect. However, the specific substance that plays a key role in inhibiting the growth of A. catenella and the algicidal mechanism remain to be further studied. This study might provide a new direction in the management of HABs in the future. [ABSTRACT FROM AUTHOR]

Many species of the dinoflagellate genus Karenia produce neurotoxins and often cause harmful algal blooms. Heterotrophic dinoflagellates are major grazers of bloom-forming dinoflagellates. Therefore, to understand the population dynamics of Karenia species, it is necessary to investigate the interactions between Karenia species and their potential heterotrophic dinoflagellate predators. We examined the interactions between the bloom-forming dinoflagellates Karenia bicuneiformis and Karenia selliformis and eight common heterotrophic dinoflagellates. Gyrodinium dominans, Gyrodinium moestrupii, Oxyrrhis marina, Oblea rotunda, and Protoperidinium pellucidum fed on K. bicuneiformis, whereas Gyrodiniellum shiwhaense, Pfiesteria piscicida, and Noctiluca scintillans did not. Furthermore, K. bicuneiformis supported the positive growth of G. dominans, G. moestrupii, O. marina, and P. pellucidum, but K. bicuneiformis did not support the growth of O. rotunda. With increasing prey concentration, the growth and ingestion rates of P. pellucidum on K. bicuneiformis increased and then became saturated. Maximum growth and ingestion rates of P. pellucidum on K. bicuneiformis were 0.19 d-1 and 0.86 ng C predator-1 d-1 (1.26 cells predator-1 d-1), respectively. However, all eight heterotrophic dinoflagellates tested were lysed by K. selliformis. At a K. selliformis concentration of 100 cells mL-1 within 48 h, the survival of G. dominans and G. moestrupii was only 0 and 13%, respectively. Therefore, K. bicuneiformis can be prey for the heterotrophic dinoflagellates, whereas K. selliformis kills them. These differential interactions may have resulted in different ecological niches for these two Karenia species. [ABSTRACT FROM AUTHOR]

Crop protection from algal grazers is a key area of concern, as grazing zooplankton and flagellates can decimate microalgae crops and impede economic viability of cultivation for biofuels and bioproducts. Inhibition of grazing by chemical and physical interference is one promising solution; however, there have been few empirical tests of this approach that use defense traits innate to algal crop species. Botryococcus braunii is of particular interest because a) it excretes high levels of hydrocarbons and exopolysaccharides and b) forms colonies and possesses chemical defenses. Here we conduct a controlled laboratory experiment to test whether B. braunii can mitigate losses to grazing by two distinct grazers, Daphnia magna and Poterioochromonas malhamensis, due to both chemical inhibition and physical interference linked to large/inedible colonies. We show that chemical and physical defenses interactively reduce the total effect of grazing, thus significantly increasing the biomass and growth rates of cultures of B. braunii and Nannochloropsis limnetica when either grazer is present. We also find that B. braunii medium enhances the growth of N. limnetica. Our study demonstrates how community engineering can identify synergies arising from algal co-cultivation (e.g., by using industrially relevant strains for crop protection). While our lab study serves as a proof-of-concept, future research should test this strategy at pilot scale; if successful, such ecological discoveries may help to reduce the costs of large-scale deployment of algal cultivation for sustainable foods, fuels, bioproducts (e.g., bioplastics), and carbon capture. [ABSTRACT FROM AUTHOR]

This study investigates the effects of substrate composition on root architecture, plant growth, and allelopathic secondary metabolites, specifically benzoxazinoids (BXs), in the rhizospheres of rye (Secale cereale L.) and redroot pigweed (Amaranthus retroflexus L.). Given the complexities of root exudate analysis, including the influence of substrate on root morphology and exudation, the experiment compared plant growth and BX release in two substrates: glass microbeads and a mixture of clay beads and attapulgite. Rye, pigweed, and co-cultures of the two were grown under controlled conditions, with root and shoot parameters measured to assess substrate suitability. Additionally, UPLC-QTOF-MS was used to analyze BXs in rye and rye–pigweed co-cultures. The results demonstrated that the clay bead and attapulgite mixture provided better growth conditions and was effective for BX extraction, making it a suitable substrate for studying allelopathy in controlled environments. The findings highlight the critical role of substrate composition in both plant development and the study of root exudates, with implications for better understanding of crop–weed interactions and allelopathy. [ABSTRACT FROM AUTHOR]

Ambrosia trifida L. is native to North America, has been introduced into many countries in Europe and East Asia, and is also expanding its habitat in its native ranges. Ambrosia trifida grows in sunny and humid environments, such as grasslands, riverbanks, floodplains, abandoned places, and agricultural fields, as an invasive plant species. Ambrosia trifida has a strong adaptive ability to adverse conditions and shows great variation in seed germination phenology and plant morphology in response to environmental conditions. Effective natural enemies have not been found in its native or introduced ranges. The species is allelopathic and contains several allelochemicals. These characteristics may contribute to the competitive ability and invasiveness of this species. Ambrosia trifida significantly reduces species diversity and plant abundance in its infested plant communities. The species also causes significant yield loss in summer crop production, such as in maize, soybean, sunflower, and cotton production. Ambrosia trifida is capable of rapid evolution against herbicide pressure. Populations of Ambrosia trifida resistant to glyphosate, ALS-inhibiting herbicides, and PPO-inhibiting herbicides, as well as cross-resistant populations, have already appeared. An integrated weed management protocol with a more diverse combination of herbicide sites of action and other practices, such as tillage, the use of different crop species, crop rotation, smart decision tools, and innovative equipment, would be essential to mitigate herbicide-dependent weed control practices and may be one sustainable system for Ambrosia trifida management. [ABSTRACT FROM AUTHOR]

Allelopathic interactions between crops in an intercropping system can directly affect crop yields. Faba beans may release allelochemicals to the cropping system. However, the allelopathic effects in the faba bean–maize relay intercropping system are still unclear. Maize seeds and seedlings were treated with a 50 mL of 100 g L−1 faba bean leaf extract (L1), 150 g L−1 faba bean leaf extract (L2), 100 g L−1 faba bean stem extract (S1), or 150 g L−1 faba bean stem extract (S2) and sterile water (CK) to study the allelopathic effects of faba bean extracts on maize seed germination and seedling growth. The α-amylase activities, antioxidant enzyme activities, phytohormones and allelochemical content in maize seeds were determined to evaluate the allelopathic effects of faba bean extracts on maize seed germination. The agronomic traits, photosynthetic parameters and nutrient absorption characteristics of maize seedlings were determined to explore the allelopathic effects of faba bean extracts on maize seedling growth. High-concentration (150 g L−1) faba bean stem extracts released allelochemicals, such as 4-hydroxybenzoic acid, hydrocinnamic acid, trans-cinnamic acid, and benzoic acid. These allelochemicals entered the interior of maize seeds and increased the abscisic acid, salicylic acid and indole-3-acetic acid content in maize seeds but decreased the aminocyclopropane carboxylic acid in maize seeds. High-concentration (150 g L−1) faba bean stem extracts increased the superoxide dismutase and peroxidase activity and decreased the α-amylase activity in maize seeds at germination (36 h). Faba bean extracts released nitrogen, potassium and phosphorus and increased nitrogen content, phosphorus content, potassium content and photosynthesis of maize seedling. In summary, faba bean extracts released allelochemicals that inhibited the germination of maize seeds but released nutrients and promoted the growth and development of maize seedlings. The research results provide a basis for improving the Faba bean–maize relay strip intercropping. [ABSTRACT FROM AUTHOR]

Allelopathy plays a crucial role in shaping phytoplankton community dynamics and diversity. It influences competition between photoautotrophs for resources and affects species succession in aquatic ecosystems. This article evaluates the allelopathic activity of cyanobacteria isolated from Lake Tuzkol, Kazakhstan. The allelopathic effects, including growth inhibition or stimulation, were assessed by adding cell‐free filtrates of the cyanobacteria Oscillatoria sp. SS‐9, Nostoc sp. CZS 2205, Synechococcus sp. SS‐5, or Anabaena sp. SS‐8 to the tested microalgae. The most pronounced effect was observed with Nostoc sp. CZS 2205, which reduced the cell counts of Chlorella vulgaris SP BB‐2 and Chlamydomonas reinhardtii CC‐124 by 60% and 57%, respectively, and Scenedesmus quadricauda CC‐1 and Ankistrodesmus falcatus CB‐2 by 55% and 53%, respectively. Synechococcus sp. SS‐5, in contrast, stimulated the growth of Chlorella vulgaris SP BB‐2 and Scenedesmus quadricauda CC‐1 by 11% and 8.8%, respectively. Filtrates from Oscillatoria sp. SS‐9 and Anabaena sp. SS‐8 had no significant impact on microalgal growth. Considering the significant allelopathic activity of Nostoc sp. CZS 2205, an agar diffusion test using biomass extracts confirmed a significant inhibitory effect, with the biomass extracts showing stronger activity than cell‐free filtrates. A detailed analysis of the cell‐free filtrates revealed eight compounds, including methyl heptadecanoate, methyl eicosanoate, tricosane, methyl octadeca‐9,12‐dienoate, methyl 13,16‐octadecadienoate, and 2,2‐dimethoxybutane. Additionally, nostocyclamide, a cyclic peptide, was identified in the biomass extract. The detection of nostocyclamide emphasizes its ecological importance and potential evolutionary role. These results enhance our understanding of the role of cyanobacteria in aquatic ecosystems and lay the groundwork for future research into their ecological applications. [ABSTRACT FROM AUTHOR]

Objectives: The objective of this study was to test the alleopathic effects of E. globulus leaves and litter fall aqueous extracts on germination and growth of Winter Wheat (Triticale hexaploide), Barley (Hordeum vulgare), and Maize (Zea mays) crops. Methods: Allelopathic potential of Eucalyptus globulus on germination and seedling growth of Maize (Zea mays), Winter Wheat (Triticale hexaploide), and Barley (Hordeum vulgare) was studied under laboratory conditions. Aqueous extracts of young tree leaves, old tree leaves, and litter fall of E. globulus were prepared. Filtered extracts were used to treat germinating seeds of test crops. Open and undercanopy soils collected from different depths were also tested for allelopathic effects. ANOVA was used to analyze data in SAS software. Means were compared using Tukey's HSD test at the 5% level of significance. Results: The result indicated that the extracts of E. globulus had a significant inhibitory effect on germination and seedling growth of the test crops. The highest effect of extracts was observed from old tree leaves, followed by young tree leaves, and the least from litter fall. Among the three crops, Z. mays found to be more sensitive than others. However, the undercanopy soils did not show any allelopathic effect on test crops. Conclusion: We concluded that E. globulus allelochemicals do not accumulate in soils and the crops can develop adaptation through time. Thus, use of E. globulus for agro-forestry with removal of fallen leaves before cultivation is recommended. [ABSTRACT FROM AUTHOR]

Marigold (Tagetes spp.) is one of the most popular flower crop commercially exploited for multipurpose use. Apart from great demand of marigold flowers, the plants use in phytoremediation and allelopathic effect has been greatly exploited. Marigolds can be used against plant parasitic nematodes as a cover crop in rotation, as an intercrop, or as a crop residue amendment. Successful use of marigold as trap crop is well on record whereas its use as potential natural herbicide needs to be explored. Essential oils obtained from marigold possess antibacterial and antifungal properties and are widely used in perfumery industries, as insect repellent and as flavor component. Its extracts can be explored as alternative natural insecticides towards the stored products. Use of marigold for its medicinal value for curing various diseases has been well documented. Carotenoids extracted from flowers are being used commercially in pharmaceuticals. Marigold extract also finds application in coloring foods and various dairy products. Marigold petals are used as additives for poultry feed, as they provide bright colors in egg yolks, skin and fatty tissues and also as emulsifying gum. Silver and gold nanoparticles have been synthesized from marigold for antimicrobial activity. This review paper discusses the research undertaken for various uses of marigold plant worldwide. [ABSTRACT FROM AUTHOR]

Setaria viridis (green foxtail) is an invasive weed species in various agricultural systems, prompting the search for effective compounds to control its germination. The species has primary and secondary dormancy depending on the time elapsed since post-harvesting, making management strategies more difficult. Several weed plants, such as Lantana camara L., can be a source of allelochemicals with herbicidal effects, being a potential candidate for the control of S. viridis. We investigated the effects of L. camara extracts on the germination and initial growth of S. viridis seeds with different degrees of dormancy and revealed a dose-dependent bioherbicide effect. Aqueous extracts of L. camara were analyzed by HPLC-DAD and applied (0.1 to 5.0 mg/mL) to 12- and 110-day post-harvest S. viridis seeds. Seeds were evaluated daily and germination percentage (GP), speed germination index (SGI), and radicle length (RL) were calculated. Phenolic acids and flavonoids were major components of the extract. Lower concentrations (0.1 and 0.5 mg/mL) stimulated and accelerated the germination of S. viridis, breaking its dormancy. Both 1.0 and 5.0 mg/mL concentrations hindered germination, especially in 12 dph seeds. The 1.0 mg/mL concentration resulted in longer roots, whereas 5.0 mg/mL inhibited root development. Lantana camara extracts potentially stimulate germination and radicle growth of S. viridis at low concentrations while inhibiting these parameters at higher doses. These results may open new possibilities for using L. camara in weed-control strategies. [ABSTRACT FROM AUTHOR]

The effect of secondary metabolites secreted by plants on the growth and development of other plants that come after them or in the same environment, positively or negatively, is called allelopathy. This study aimed to determine the allelopathic effect of extracts obtained from forage turnips (Brassica rapa L.) on the germination and seedling development of the grass pea (Lathyrus sativus L.) plant. 500 g of forage turnip harvested during the flowering period was weighed, placed in 3 liters of pure water, and waited for 7 hours. Four different doses (100%, 75%, 50%, and 25%) were obtained from this extract. The 100% pure water was used as a control. The study, which was carried out as a petri study, was established according to the Randomized Plot Trial Design with 4 repetitions. Germination rate (GR), seed viability index (SVI), root and stem length, root and stem fresh-dry weight, root (RB), and stem biomass (SB) were determined in the grass pea irrigated with forage turnips. In the study, GR and SVI were between 72.00-96.00% and 24.98-49.38%, respectively. The highest root (61.83 kg/ha) and stem (1780.84 kg/ha) biomass weight was obtained from the treatment irrigated with 25% forage turnip extract. As a result, it was determined that 25% of the forage turnip extract had a positive effect on germination and seedling development of the grass pea, and after this dose, it had an inhibitory effect. This situation is also an indication that fodder turnip has a negative allelopathic effect on grass pea due to its rich bioactive component content. Accordingly, lower doses should be tested to understand more clearly the effect of fodder turnip on the development of the grass pea. [ABSTRACT FROM AUTHOR]

Robinia pseudoacacia is native to North America and has been introduced into many other countries in Europe, South and South East Asia, South America, Africa, and Oceania. The species has been planted intensively in a large area of these countries because of its ornamental and economic values. However, R. pseudoacacia often infests unintended places, including protected areas, and causes significant ecological impacts. The species is now listed as one of the harmful invasive plant species. The characteristics of its life-history, such as the high growth and reproduction rate and adaptive ability to various environmental conditions, may contribute to the invasiveness of the species. The defense ability against natural enemies such as pathogenic fungi and herbivores and its allelopathic potential against the competitive plant species may also contribute to its invasiveness. The R. pseudoacacia infestation alters the ecological functions of the plant community, including the soil microbe community, and reduces the abundance and diversity of the native plant species, including vertebrates and invertebrates in the introduced ranges. R. pseudoacacia is a shade intolerant and early successional tree species and is replaced by larger and more shade tolerant tree species in the native ranges, while plant succession seems not to occur always in the introduced ranges across the different ages of R. pseudoacacia stands. Several other review articles have summarized the afforestation, utilization, biology, and management of the species, but this is the first review focusing on the invasive mechanism of R. pseudoacacia and its impacts on species diversity. [ABSTRACT FROM AUTHOR]

The release of allelochemicals is one of the contributing factors to the success of invasive plants in their non-native ranges. It has been hypothesised that the impact of chemicals released by a plant on its neighbours is shaped by shared coevolutionary history, making natives more susceptible to "new" chemicals released by introduced plant species (novel weapons hypothesis). We explored this hypothesis in a New Zealand system where the two invasive plants of European origin, Cytisus scoparius (Scotch broom) and Calluna vulgaris (heather) cooccur with natives like Chionochloa rubra (red tussock) and Leptospermum scoparium (mānuka). We characterised the chemical composition of root extracts of broom, heather, red tussock and mānuka using gas chromatography–mass spectrometry and then investigated the influence of aqueous root extracts at different concentrations (0.1%, 1%, 5%, 50% and 100% v/v) on mānuka seed germination and seedling growth (root and shoot length and biomass), using deionised water as control. The results show clear distinctions in the chemical composition of the four plants' root extracts, with 4-O-methylmannose dominating the broom extract and (E)-pinocarveol the heather extract, while 16-kaurene and methyl palmitate were abundant in both mānuka and tussock extracts. We found a significant effect of invasive plant (heather and broom) root extracts on mānuka germination at all concentrations tested, and adverse effects on seedling growth and biomass only at higher concentrations (≥ 5%). Broom displayed stronger allelopathic effects than heather at the highest concentration (100%). For extracts of conspecific and other native species (mānuka and red tussock) allelopathic effects were only observed at very high concentrations (50 and 100%) and were generally weaker than those observed for invasive plants. These results show that while both native and invasive plants produce chemicals with allelopathic potential, native species are likely to be more vulnerable to the allelopathic effects of species they did not co-evolve with, supporting the novel weapons hypothesis. However, this study also highlights differences in allelopathic potential between invasive species. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Kirkuk University for Agricultural Sciences 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 excessive intake of biogenic elements into water bodies leads to the active development of planktonic algae, water bloom pathogens, which mostly include cyanobacteria. In vitro studies have allowed us to test a working hypothesis on the absence of any inhibitory effect of metabolites of the Chlorella vulgaris BIN strain on the CALU 799 Dolichospermumspiroides (Klebhan) Wacklin, L. Hoffmann & Komárek and CALU 1749 Planktothrix agardhii (Gomont) Anagnostidis & Komárek cyanobacterial cultures in working concentrations of 1 : 1, 10 : 1, 100 : 1, and 1000 : 1 (cyanobacteria : chlorella). In a series of experiments, no effect of chlorella culture on the viability of cells of the studied cyanobacteria has been detected. However, high cyanobacteria densities (concentrations of 1 : 1, 10 : 1, 100 : 1, and 1000 : 1) are associated with an increase in the number of dead chlorella cells. The toxic effect of the CALU 799 D. spiroides strain is more pronounced in comparison with that of CALU 1749 Planktothrix agardhii. [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]

Limited phytodiversity and regeneration rates occur in some of the southern Brazilian formations known as the Myrtacean Woodlands. Data on phytotoxicity, chemical composition, and allelopathic potential of Myrciaria cuspidata O. Berg, a dominant species in such woodlands, is missing. In this study, both the chemical composition and phytotoxic activity of an aqueous extract (AE) from M. cuspidata leaves were investigated. Target plants were the model species Lactuca sativa L. and the weed Bidens pilosa L. Germination rates, seedling growth, and phenotypic responses of target species were assessed following AE application to determine the inhibitory capacity of M. cuspidata leaf extract. Germination of L. sativa was reduced and delayed in the presence of AE. Strong inhibition of germination was recorded in B. pilosa achenes under the same treatment. Pre-germinated seedlings of L. sativa were essentially not affected by AE, whereas those of the weed showed some negative developmental responses. Overall, inhibitory responses were consistent both in vitro and in soil substrate. Detrimental effects were most apparent in roots and included tip darkening and growth anomalies often preceded by loss of mitochondrial viability. AE proved rich in phytotoxic phenolic compounds including quercetin, gallic and tannic acid. To sum up, AE shows potential as an environmentally friendly pre-emergence bioherbicide of low residual effect and minor environmental impact. Experimental data in laboratory conditions were consistent with potential allelopathic activity of this tree, as inferred from field observations of dominance in the Myrtaceae Woodlands. [ABSTRACT FROM AUTHOR]

Plant interference is a key factor influencing plant coexistence and species composition. The two primary forms of plant interference—allelopathy and resource competition—are often difficult to separate. This study conducted an outdoor pot experiment to quantify the distinct contributions of resource competition and allelopathy of Artemisia frigida on seedling growth of three species: Leymus chinensis, Cleistogenes squarrosa, and Potentilla acaulis. The index of relative neighbor effect (RNE) was used to quantify the overall effect of plant interference, while the inhibition rates (IRs) of resource competition and allelopathy were utilized to determine the specific contributions of allelopathy and resource competition from A. frigida on the growth of target plant species. The interference effect of A. frigida was found to be species-specific. The allelopathic effect of A. frigida played a major role in inhibiting the belowground biomass of L. chinensis (23.97%) and C. squarrosa (58.27%), while allelopathy and resource competition from A. frigida promoted the belowground biomass (45.12%) and aboveground biomass (46.63%) of P. acaulis, respectively. The combined effect of allelopathy and resource competition from A. frigida significantly affected the aboveground biomass of C. squarrosa and P. acaulis, as well as the belowground biomass of L. chinensis and C. squarrosa. These findings contribute to a better understanding of the patterns and mechanisms of plant species composition and its relationship with grazing intensity in this grassland ecosystem. [ABSTRACT FROM AUTHOR]

Many phenolics are known to possess allelopathic activity, but the allelopathic effect of pyrogallol has not been previously reported. Here, the present experiment was conducted to investigate the effects of commercially obtained pyrogallol at different concentrations on the seed germination and seedling growth of L. perenne. The results showed that (1) Pyrogallol treatment inhibited L. perenne seed germination, as evidenced by a decrease in the final germination rate and a delay in germination peaks. (2) Pyrogallol treatment reduced L. perenne plumule length, radicle length, fine root length, and fine root surface area, higher pyrogallol concentrations reduced the proportion of fine roots. (3) Higher concentrations (2.00 g/L) of pyrogallol resulted in decreased protein content and increased membrane lipid peroxidation. (4) Spraying pyrogallol inhibited the growth of L. perenne seedlings, as manifested by a decrease in plant height and biomass. Overall, our findings indicate that pyrogallol is one of the allelochemicals present in aqueous extracts of K. integrifoliola leaves that inhibits the seed germination and seedling growth of L. perenne. [ABSTRACT FROM AUTHOR]

The escalating global demand for food, propelled by population growth, necessitates increased use of plant protection products. However, heavy reliance on chemical pesticides poses sustainability challenges due to their persistence in the environment and potential toxicity to humans and wildlife. To address these concerns, there is a growing shift towards sustainable and eco-friendly plant protection measures, notably biological preparations. This paper explores the potential of alternative methods, particularly biological preparations, for plant protection. It delves into three main categories: plant extracts, compost extracts, and tree bark-based preparations. Plant extracts, derived from sources like nettle, brown algae, and horsetail, exhibit promising antifungal and antibacterial properties, bolstering plant resistance against pathogens. Compost extracts, rich in diverse microbial populations, offer soil enhancement and disease suppression benefits. Additionally, preparations based on tree bark, abundant in phenolic compounds, demonstrate antimicrobial effects against various pathogens. Although some biological preparations are more effective than chemically produced ones, continued research and development of these alternatives are needed to ensure their effectiveness and availability.

Allelopathy can be a viable approach to address the issues of environmental degradation by reducing the use of herbicides and herbicide-resistant weeds. Allelopathic crop residues have a lot of potential for improving soil quality and suppressing weed growth. A field experiment at an agronomic research farm, Lovely Professional University in Phagwara, Punjab, examined the effects of water extracts and crop residues from sorghum on the population of weeds, indices of weed management, and the productivity of field peas. The experiment during the year 2022-2023 comprised in randomized block design with 2 levels of Sorghum water extract (1:10, 1:20 w/v), 3 levels of Sorghum stalk soil incorporation @ 2, 4, 6 Mg.ha-1, Sorghum surface mulching at 10tonnes ha-1, Field pea and rabi sorghum intercropping at 2:1, Weedy check and hand weeding. The findings showed that the sorghum surface mulching, addition of sorghum water extract, and sorghum stalk incorporation significantly altered the dynamics of weeds which was comparable with hand weeding. In the case of weed density (9.17 no.m-2), weed fresh (7.66g), and dry weight (3.0g) hand weeding gave the best result which was followed by sorghum surface mulching with 10.77 weeds no.m-2, 10.11 g weed fresh weight and 4.26gm weed dry weight. The highest weed control efficiency (80.9%) was recorded in hand weeding which was followed by sorghum water extract (1:10) and sorghum stalk incorporation (4 Mg.ha-1). The weed management index, weed persistence index, and agronomic management index showed an inverse relationship with weed control efficiency. Hand weeding (20, 40, 60 DAS) gave the highest grain yield (2897 kg.ha-1) of field pea followed by Sorghum surface mulching. Yield attributes were calculated which prescribed that all the treatments significantly reduced the weed infestation and increased the yield attributes over a weedy check. Hand weeding gave the best result, but it is not economical due to the intensive labor requirement. Initiating sustainable weed control and significantly improving the nutrient content of field peas can be achieved through sorghum surface mulching, sorghum stalk incorporation at 4 Mg.ha-1, and sorghum water extract (1:10). These practices can contribute to environmentally friendly and sustainable agriculture. [ABSTRACT FROM AUTHOR]