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An alternative to controlling weeds resistant to conventional herbicides is the isolation of new active principles. Fungi can produce phytotoxic metabolites that may be used in the development of new herbicides. The objectives of this study were: (1) isolate, select, and identify a fungus producer of phytotoxic metabolites and (2) optimize the culture conditions of this fungus in a low-cost culture medium, with the aim of increasing the phytotoxic effects of their metabolites in weeds and commercial plants. Fungi were isolated from the leaves of Conyza sp. with disease symptoms and selected according to the production of phytotoxic metabolites in solid and submerged fermentation in a low-cost culture medium. A Plackett–Burman Design and Central Composite Rotational Design were used to optimize the conditions of temperature, agitation, pH, and concentrations of glucose and yeast extract in submerged fermentation. The phytotoxic metabolites produced under optimal conditions were tested on 10 commercial plants and weeds that are difficult to control. Of the nine fungi isolated, Mycoleptodiscus indicus UFSM54 produced higher leaf lesions. The production of phytotoxic metabolites was optimized when the fungus was cultivated at 35°C, 50 rpm, and 1.5 g L−1 of glucose in submerged fermentation. The metabolites of M. indicus caused severe phytotoxic effects on germination and seedling growth, and enhanced lesion development on detached plant leaves. The present study is the first to report on the production of phytotoxic metabolites by M. indicus, a potential producer of bioherbicides. [ABSTRACT FROM AUTHOR]

Mangrove is a unique marine ecosystem growing in the intertidal zone of tropical and subtropical coast, with the characteristics of hypoxia tolerance, high salinity, and high humidity. In order to discover novel leading compounds with potent phytotoxicity, seven pairs of azaphilones E/Z isomers, isochromophilone H (1a/1b), sclerotiorins A and B (2a/2b and 3a/3b), ochlephilone (4a/4b), isochromophilone IV (5a/5b), isochromophilone J (6a/6b), and isochromophilone I (7a/7b), were isolated from the culture broth of the mangrove-derived fungus, the Penicillium sclerotiorum HY5, by various chromatographic methods. Among them, 1a, 1b, 2a, 3a, 4a, 5a, 6a, and 6b were new compounds. Their chemical structures and absolute configurations were elucidated based on high resolution electrospray ionization mass spectroscopy (HRESIMS), 1D/2D nuclear magnetic resonance (NMR) spectroscopic analysis, and comparisons of electronic circular dichroism (ECD) data. Compounds 3, 4, and 7 exhibited potent phytotoxicity against the growth of radicle and plumule on Amaranthus retroflexus L., with EC50 values ranging from 234.87 to 320.84 μM, compared to the positive control glufosinate-ammonium, with EC50 values of 555.11 μM for radicle, and 656.04 μM for plumule. Compounds 4 and 7 also showed inhibitory effects on the growth of velvetleaf (Abutilon theophrasti Medikus), with EC50 values ranging from 768.97 to 1,201.52 μM. This study provides new leading compounds for the research and development of marine-derived bioherbicides.

The goal of regenerative agriculture is to utilize technologies that build healthy soils and improve the environment. Microbial technologies could play a significant role in reducing reliance on synthetic herbicides for weed control. In the United States, the expenditure on herbicides exceeds $5 billion annually and accounts for 58% of the total pesticide use nationally. This overreliance on chemical weed control has exacerbated herbicide resistance in a multitude of weed species, leading to aggressive cultivation practices that contribute to soil erosion and depletion. The proliferation of microbiome research in agriculture has increased our understanding of the complex interactions between plant species and their microbiota. Microbial technologies offer novel weed management strategies that could reduce the need for herbicides. Some of these strategies could also help rebuild soil and improve environmental quality. Specifically, we propose three emerging areas in microbiome science that can enhance weed management: (1) identifying soil microorganisms that inhibit weed growth; (2) discovering microbial natural products that suppress weeds; and (3) developing field management approaches that promote weed suppression by enhancing soil microbiome function. [ABSTRACT FROM AUTHOR]

BACKGROUND Tea, one of the most important commercial crops on earth, is strongly affected by weeds on productivity and quality. Bioherbicides are shedding new light on weed control in tea gardens in an economical and safe manner. RESULTS: A pathogenic strain SYNJC‐2‐2 was isolated from diseased leaves of a noxious weed, goosegrass (Eleusine indica), from a tea garden in Zhejiang Province, China. It was identified as the fungal species Bipolaris bicolor based on the morphological characteristics and phylogenetic analysis. The potential of the B. bicolor strain SYNJC‐2‐2 as a bioherbicide was assessed by determining its efficacy to control weeds and selectivity to crops, its infection process and the influence of environmental conditions on conidial production and germination. The ED90 (effective dose of conidia resulting in 90 disease index) of SYNJC‐2‐2 on goosegrass was 2 × 104 conidia mL−1. Additionally, three Poaceae weeds, Setaria viridis, Microstegium vimineum and Pennisetum alopecuroides, were also extremely susceptible to SYNJC‐2‐2. SYNJC‐2‐2 was safe to 14 out of 17 crop species in nine families, especially tea plants. Conidial germination, hyphal growth and appressorial formation occurred within 3 to 6 h on goosegrass leaves. Hyphae invaded leaf tissues mainly through epidermal cell junctions and cracks, causing cell death and necrotic lesions within 2 days on inoculated leaves and killing goosegrass plants within 7 days. Furthermore, SYNJC‐2‐2 has a strong adaptability to environmental variables and high conidial production capacity on goosegrass juice agar media. CONCLUSION: Bipolaris bicolor strain SYNJC‐2‐2 has the potential to be developed as a bioherbicide for controlling goosegrass, especially in tea gardens. [ABSTRACT FROM AUTHOR]

Since the increasing prevalence of herbicide-resistant weeds and herbicide bans, the use of biological controls with mycoherbicides become an innovative approach of weed control. In this study, we verified the pathogenicity of Phoma multirostrata TBRC 12769 against the common weed in Thailand, tridax daisy (Tridax procumbens), with its mechanism of infection unveiled by fluorescence microscopy. P. multirostrata directly penetrated through epidermal cells, stomata, and trichomes at 48 h post-inoculation. The hyphae also propagated in the lumen of the trichome, enabling the fungus to grow subcuticular to neighboring weed tissues at the bases of leaf trichomes. The necrotic pattern emerged around the trichome. During necrosis, unicellular chlamydospores were also detected inside the leaf trichomes, suggesting an overwintering stage under stress and nutrient-depleting conditions. Trichomes of weed leaves were found to be key infection sites for pathogenesis. Topical application of conidial suspension on T. procumbens potted plants led to 60–98% and 65 and 87% disease incidence under laboratory and greenhouse conditions, respectively, on days 15–20 post-inoculation. The 16-h dew period incubation results in a sharp increase by 37% in the pathogenicity rate. The greenhouse trials verified that the fungus is non-pathogenic to eight crops. Our LC-MS analysis indicated that norharman, a known bioherbicidal compound, and other compounds were detected in the supernatant fraction of fungal culture, of which resulted in a blight symptom on T. procumbens leaves. This study demonstrated that the P. multirostrata isolate is an effective mycoherbicide for this broadleaf weed. • A Phoma multirostrata isolate is a potential myco-herbicide for controlling Tridax procumbens. • The fungus showed no pathogenicity against eight important crops in Thailand. • The weed pathogenesis is mediated by infection through stomata and trichomes and direct penetration of the epidermis. • Fungal inoculation with a dew period markedly accelerated the infection of the weed. [ABSTRACT FROM AUTHOR]

• Thirty-three metabolites were identified by UHPLC-MS/MS analysis. • A possible correlation was observed between flavonoids and allelopathy. • This is the first study for allelopathic activity in Lonchocarpus cultratus. • The phytotoxic effect may occur due to synergistic action. Lonchocarpus cultratus (Vell.) A.M.G. Azevedo & H.C. Lima (Fabaceae) is a native tree species and from which flavonoids, triterpenes, alkaloid were isolated. In addition, potent antiproliferative activity of hexane fraction and chalcone, obtained from this plant, has been described in different cell lines of human tumors. However, no studies were found on the allelopathic and/or bioherbicidal action, using aerial parts of L. cultratus. Thus, the aim of the present work was to evaluate the allelopathic activity of methanol extract, fractions and compounds from aerial parts of L. cultratus. Dried aerial parts were extracted by exhausting extraction with methanol at room temperature, and the solvent was evaporated under reduced pressure providing the crude extract. The crude extract was partitioned in a liquid-liquid extraction and to obtain hexanic (HF), chloroform (CF), ethyl acetate (EAF), and hydromethanolic (HMF) fractions. The compounds were extracted from fractions through chromatographic methods. Crude extract and its fractions inhibited Lactuca sativa germination mean time (GMT) and germination speed índex (GSI), but not the germination percentage (GP) of Lactuca sativa. Crude extract and hexane fraction inhibited the hypocotyl growth of L. sativa seedlings and the other fractions inhibited the primary root of seedlings. Hexane, chloroform, and ethyl acetate fractions inhibited primary root growth of Euphorbia heterophylla. Chalcone 2',4'-dihydroxy-5'-prenylchalcone, flavanone 8-prenylpinocembrin and alkaloid 4-hydroxy-N-methylproline were tested on lettuce early growth. Thirty-three metabolites were identified by UHPLC-MS/MS analysis, with flavonoid derivatives being the most abundant constituents. [ABSTRACT FROM AUTHOR]

Agriculture is affected by the appearance of weeds that reduce crop production. These are controlled with agricultural chemicals that unbalance the environment and human health. For this reason, the need arises to extract the bioactive compounds from these, to produce and apply powerful bioherbicides, which inhibit the spread of weeds that disturb the crops. Recently, the use of biological extracts of plants has been reported, where it is shown that they have phytotoxic bioactive properties that alter cell structure. The objective of this bibliographic review was to report the advances in the development of new biological herbicides, from phytotoxic plant extracts applied in vitro. This review describes the compounds with phytotoxic capacity in plants and their phytotoxic biological activity, such as polyphenols, tannins, alkaloids, quinones, saponins antagonists, and glycosides, to mention some, through the use of the most common experimental methods that include the extraction, determination, and quantification of the metabolites. In addition, the response variables that were considered to evaluate the effect of these biological active substances are mentioned, which include the percentage of inhibition of germination, growth, and root length in plants. [ABSTRACT FROM AUTHOR]

Cirsium arvense is one of the worst weeds in agriculture. As actual herbicides are not very effective and not accepted by organic farming or in order to reduce the cantity of herbicides used, possible biocontrol agents have been investigated since many decades. The work carried out aimed at obtaining and assessing the herbicidal potential of bacterial preparation based on Pseudomonas syringae pv. tagetis (PST) for biological control of Cirsium arvense (L.) Scop. Silibase 2848P, an organosilicone surfactant, was required to facilitate PST penetration into creeping thistle leaves. The experiments were conducted under controlled conditions (growth chamber) to determine the concentration of Silibase 2848P required for the maximum penetration of PST into creeping thistle leaves. As well as to evaluate disease incidence in emerging leaves, and to quantify the effects of inundative foliar application on fresh and dry weights of shoots. In field conditions, efficacy of PST applications was assessed in terms of disease incidence and effect on shoot height, number of flower buds and survival of C. arvense. Maximum disease severity were recorded when PST was applied at a concentration of 10 x 108 cfu/ml + Silibase 0.3%. [ABSTRACT FROM AUTHOR]

Weed control is a critical factor to ensure productivity and quality for food production. Chemical control is the main method used worldwide, but the demand for healthier food and the farmers' health and environment concerns have led to an increase in the search for alternative control methods. In this way, the use of biomolecules produced by microorganisms that present phytotoxic activity against weeds, such as exopolysaccharides, is attracting attention. For this purpose, this work compared two techniques (solid-state and submerged fermentation) for bioherbicide production by Diaporthe schini. Physicochemical characterization of both fermented broth and evaluation of bioherbicidal effect in post-emergence of Amaranthus viridis, Bidens pilosa, Echinocloa crusgalli, and Lollium multiflorum were performed. Fungal broth obtained by submerged fermentation presented better physicochemical characteristics in terms of viscosity, density, and surface tension. Overall, it was more effective than the broth obtained by solid-state fermentation for weed control because it presented an average inhibition of 40% of weed growth and 45% lower surface tension if compared to the control test. Also, reductions of 1.4–4.2 times of root dry mass, 2.9–5.8 times of shoot dry mass and 1.2–3.9 times of weeds heights, if compared to the control test, were achieved. [ABSTRACT FROM AUTHOR]

Alamethicin (AMT) is a linear antimicrobial peptide isolated from fungi Trichoderma viride. To date, the mode of action of AMT in plant cells remains unknown. Our experimental results indicate that AMT causes leaf lesion attributed to its multiple effects on PSII. AMT decreases the O2 evolution rate of PSII. Based on chlorophyll fluorescence data, similar to the classical herbicide diuron, AMT interrupts PSII electron transfer beyond QA at the acceptor side, leading to the inactivation of the PSII reaction centers. Additionally, AMT decreases chlorophyll content and destroys the architecture of PSII pigment assemblies. However, AMT does not affect the oxygen-evolving complex at the donor side of PSII. Thus, it is concluded that AMT is a natural photosynthetic inhibitor with several action sites in PSII.

Cultivation of cover crops is a valuable practice in sustainable agriculture. In cover crop management, the method of desiccation is an important consideration, and one widely used method for this is the application of glyphosate. With use of glyphosate likely to be banned soon in Europe, the purpose of this study was to evaluate the herbicidal effect of pelargonic acid (PA) as a bio-based substitute for glyphosate. This study presents the results of a two-year field experiment (2019 and 2021) conducted in northeast Germany. The experimental setup included an untreated control, three different dosages (16, 8, and 5 L/ha) of PA, and the active ingredients glyphosate and pyraflufen. A completely randomised block design was established. The effect of the herbicide treatments was assessed by a visual estimate of the percentage of crop vitality and a comparison assessment provided by an Ebee+ drone. Four vegetation indices (VIs) calculated from the drone images were used to verify the credibility of colour (RGB)-based and near-infrared (NIR)-based vegetation indices. The results of both types of assessment indicated that pelargonic acid was reasonably effective in controlling cover crops within a week of application. In both experimental years, the PA (16 L/ha) and PA_2T (double application of 8 L/ha) treatments demonstrated their highest herbicidal effect for up to seven days after application. PA (16 L/ha) vitality loss decreased over time, while PA_2T (double application of 8 L/ha) continued to exhibit an almost constant effect for longer due to the second application one week later. The PA dosage of 5 L/ha, pyraflufen, and a mixture of the two exhibited a smaller vitality loss than the other treatments. However, except for glyphosate, the herbicidal effect of all the other treatments decreased over time. At the end of the experiment, the glyphosate treatment (3 L/ha) demonstrated the lowest estimated vitality. The results of the drone assessments indicated that vegetation indices (VIs) can provide detailed information regarding crop vitality following herbicide application and that RGB-based indices, such as EXG, have the potential to be applied efficiently and cost-effectively utilising drone imagery. The results of this study demonstrate that pelargonic acid has considerable potential for use as an additional tool in integrated crop management.

Weed species many times possess allelochemicals as a part of their survival strategy. These metabolites can be potential targets in search of natural phytotoxins. This study aims to evaluate the phytotoxic ability of fatty aldehyde-rich essential oil from spiny coriander (Eryngium foetidum) leaves, also known as fitweed or spiritweed and to further identify the active phytotoxins. This oil dose-dependently inhibited the wheatgrass coleoptile and radicle growth in multiple bioassays with half maximal inhibitory concentration (IC 50 ) 30.6-56.7 μg/mL, while exhibiting a less pronounced effect on the germination (IC 50 181.8 μg/mL). The phytotoxicity assessment of two oil constituents identified eryngial (trans-2-dodecenal), exclusively major fatty aldehydic constituent as the potent growth inhibitor with IC 50 in the range 20.8-36.2 μg/mL during an early phase of wheatgrass emergence. Eryngial-inspired screening of eleven saturated fatty aldehydes and alcohols did not find a significantly higher phytotoxic potency. In an open vessel, eryngial as the supplementation in agar medium, dose-dependently inhibited the growth of pre-germinated seeds of one monocot (bermudagrass) and one dicot (green amaranth) weed species with IC 50 in the range 23.8-65.4 μg/mL. The current study identified eryngial, an α,β-unsaturated fatty aldehyde of coriander origin to be a promising phytotoxic candidate for weed control., (© 2024 Wiley-VHCA AG, Zurich, Switzerland.)

Vigna mungo L. (black gram) is a summer pulse crop endemic to Central Asia. It is one of Pakistan's top five premium food beans and a highly cost-effective crop. Allelochemicals in Trianthema portulacastrum L. (black pigweed) leaf extract decreased the V. mungo germination rate (34% to 6%), seedling length (10 cm to 3 cm), fresh biomass of seedling (2.4 g to 0.94 g) and dry biomass of seedling (1.2 g to 0.47 g). Biological agent Pseudomonas sp. (PF-097) act as bioherbicide and as plant growth promoter agent to decrease the T. portulacastrum allelopathic stress and to enhance the growth of V. mungo. Amendment of Pseudomonas sp. (PF-097) increase V. mungo percentage of germination (8-42%), seedling length (12-54%), fresh biomass of seedling (8-17%) and dry biomass of seedling (0.47 g to 1.2 g). In vivo pot experiment bioassay revealed that of T. portulaacstrum significantly suppress the shoot length (46 cm to 18 cm), shoot fresh biomass (2.6 g to 0.66 g) and shoot dry biomass of V. mungo (1.31 g to 0.33 g). Pseudomonas sp. (PF-097) PGPR incorporation in vivo experiment significantly increased the shoot length (4% to 12%), shoot fresh biomass (18% to 35%), shoot dry biomass of V. mungo (17% to 35%). Physiological activity of Catalase and peroxidase considerably increased in negative treatments amended with only T. portulacastrum and decreased in positive treatments by using biological agent Pseudomonas sp. (PF-097). Protein content of V. mungo seedling was significantly increased in positive treatments as compared to negative treatments. These results showed that allelochemical stress of T. portulacastrum on the V. mungo can be countered by the herbicidal activity of the Pseudomonas sp. (PF-097). [ABSTRACT FROM AUTHOR]

Copyright of Acta Agriculturae Slovenica is the property of Biotechnical Faculty of the University of Ljubljana 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.)

In the present study the bioherbicidal activity of essential oils hydrodistilled from Nepeta glocephalata Rech.f and N. ispahanica Boiss were investigated on four weed species (barnyard grass (Echinochloa crus-galli (L.) Beauv), redroot pigweed (Amaranthus retroflexus L.), lambsquarters (Chenopodium album L.) and canary grass (Phalaris canariensis L.)). A total of 37 components were identified from the essential oils of N. glocephalata and N. ispahanica constituting approximately 98.61 % and 96.1 % of the oils, respectively. In laboratory bioassay different concentrations (0, 1, 2, 4 and 8 μl ml-1) of two Nepeta essential oils on germination, root and shoot length were studied. Results showed by increasing the concentration of oils, all studied traits of the weeds were decreased compared with control. In a glass house bioassay post-emergence application of Nepeta essential oils (1.25 %, 2.5 %, 5 % and 10 %, v/v) on 3-week-old weed plants caused visible injury (7-days after spray) ranging from chlorosis to necrosis of plant weeds. In foliar application under glasshouse conditions, both Nepeta essential oils reduced the seedling dry mass and concentrations of chlorophyll a chlorophyll b. The study concludes that Nepeta essential oils have phytotoxic effects and could be used as bioherbicides but the selectivity of these compounds should be considered also.

Natural herbicide is considered as a sustainable approach for weed management in agriculture. Here, allelopathic activities of Piper betle L. extract (BE) and known allelochemical eugenol (EU) were studied against rice and associated weeds in terms of germination and seedling growth. Five plant species including a rice crop (Oryza sativa L.); a dicot weed, false daisy (Eclipta prostrata (L.) L.); and three monocot weeds, barnyard grass (Echinochloa crus-galli (L.) P. Beauv.), swollen fingergrass (Chloris barbata Sw.), and weedy rice (Oryza sativa f. spontanea Roshev.) were studied. The paper-based results demonstrated that BE and EU had inhibitory effects on seed germination and seedling growth. The IC50 values of BE and EU for seed germination were ranked from swollen fingergrass, to false daisy, barnyard grass, rice, and weedy rice, respectively. The ratio of root to shoot length of the seedlings indicated that the roots were more affected by the treatments than the shoots. In addition, the gel-based results showed the reduction of the rice seedling root system, especially on lateral root length and the numbers upon the treatments. Taken together, BE had an allelopathic activity similar to that of EU. Interestingly, the major paddy weed, barnyard grass, was more sensitive to BE than rice, underlining BE as a natural herbicide in rice agriculture.

Biological herbicides have received much attention due to their abundant resources, low development cost, unique targets and environmental friendliness. This study reveals some interesting effects of mycotoxin cytochalasin A (CA) on photosystem II (PSII). Our results suggested that CA causes leaf lesions on Ageratina adenophora due to its multiple effects on PSII. At a half-inhibitory concentration of 58.5 μΜ (I50, 58.5 μΜ), the rate of O2 evolution of PSII was significantly inhibited by CA. This indicates that CA possesses excellent phytotoxicity and exhibits potential herbicidal activity. Based on the increase in the J-step of the chlorophyll fluorescence rise OJIP curve and the analysis of some JIP-test parameters, similar to the classical herbicide diuron, CA interrupted PSII electron transfer beyond QA at the acceptor side, leading to damage to the PSII antenna structure and inactivation of reaction centers. Molecular docking model of CA and D1 protein of A. adenophora further suggests that CA directly targets the QB site of D1 protein. The potential hydrogen bonds are formed between CA and residues D1-His215, D1-Ala263 and D1-Ser264, respectively. The binding of CA to residue D1-Ala263 is novel. Thus, CA is a new natural PSII inhibitor. These results clarify the mode of action of CA in photosynthesis, providing valuable information and potential implications for the design of novel bioherbicides.

The fungal genus Myrothecium was once polyphyletic but a recent reconsideration of the family Stachybotryaceae spilt it into several genera. The ex-neotype specimen of the species Myrothecium verrucaria is now recognized as Albifimbria verrucaria. The well-studied plant pathogen and candidate bioherbicide CABI-IMI 368023, previously identified as M. verrucaria, was analyzed morphologically and genetically and found to be most consistently aligned with the other representatives of A. verrucaria. [ABSTRACT FROM AUTHOR]

Copyright of Revista Ciencia y Tecnología Agropecuaria is the property of Agrosavia 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.)

Although cover crops are widely used for weed suppression in the agroecosystem, little research is available regarding the possibility that the decomposed weed solution may control weeds. In this study, we tested the allelopathic effect of decomposed weed solution on barnyardgrass (Echinochloa crus‐galli). In two separate tests, we found that the solution of decomposed Myosoton aquaticum completely suppressed the germination of barnyardgrass seeds at a concentration of 20 g l‐1. We then isolated and identified the predominant inhibitory substance in the decomposed M. aquaticum solution. The solution was subjected to organic solvent extraction and then separated on a silica gel column before the final identification of its components by high‐performance liquid chromatography‐tandem mass spectrometry (HPLC‐MS/MS). Dihydrocoumarin was isolated from the M2 and M3 fractions using a bioassay‐guided method and was found to be the most active of eleven candidate allelochemical compounds. Dihydrocoumarin is typically used as a food additive. In this study, barnyardgrass germination was completely inhibited when treated with dihydrocoumarin at 1 g l‐1, and its root and shoot growth were significantly inhibited at an application rate of 0.005 g l‐1. Dihydrocoumarin showed highly efficient inhibition of root and shoot growth in barnyardgrass at low concentrations compared with coumarin. These findings show that weeds may be used as cover crops to provide allelochemicals for weed suppression and that dihydrocoumarin has the potential to be used as a bioherbicide. [ABSTRACT FROM AUTHOR]

Abstract Due to increased number of herbicide resistant weeds, it is needed to explore the allelopathic potential of plants as an alternative. The research was conducted to investigate allelopathic effects of Carica papaya L. leaf powder and aqueous extract on seeds as well as pre-germinated seeds of Avena fatua L., Helianthus annuus L., Rumex dentatus L., Zea mays L. and Triticum aestivum L. on filter paper and soil in Weed Management Program Laboratory, Department of Plant and Environmental Protection at PARC Institute of Advanced Studies in Agriculture, National Agriculture Research Centre, Islamabad, Pakistan. Germination percentage (%), radicle length (cm) and plumule length (cm) were parameters observed for ‘Plant leaf powder bioassay’ and ‘Aqueous extract method’. Most significant growth inhibition was observed in A. fatua seedlings in filter paper method. A. fatua radicle length was reduced by C. papaya aqueous extract (80%) and leaf powder (89%) bioassays. Plumule length was reduced under the influence of aqueous extract (57-73%) and powdered material (59-77%). The inhibitory effects on other test species were in sequence of H. annuus followed by Z. mays and R. dentatus. The aqueous extract showed non-significant effect on wheat seed germination, radicle and plumule growth. It is suggested that C. papaya aqueous extract can be used as source of weed management in wheat crop.

Burcucumber (Sicyos angluatus) is a representative ecosystem-disturbing plant in Korea and currently widely spread throughout the country. A sclerotia-forming fungus with moderate host selectivity, Sclerotinia trifoliorum BWC98-105, was tested in the laboratory, green house and natural habitat for its pathogenicity to burcucumber. When mycelial culture fragment was inoculated to burcucumber seedlings under the green house condition, mycelial growth was observed in the following day, and then resulted in the onset of wilting from 5 days after inoculation (DAI). Its characteristic sclerotia as a sign was observed from 7 DAI, and thus plants turned into dark-brown color at the bottom of stem of burcucumber that was eventually blighted at 14 DAI. Similar visible symptoms were observed in natural habitat. Based on the results of showing typical blight symptom to burcucumber and the sign of sclerotia, we report S. trifoliorum BWC98-105 causing stem blight against burcucumber. Its globular pellet was considered of having quite potential as a bioherbicide to control burcucumber in Korea.

Phytotoxic substances in plants that may serve as alternative natural herbicides for controlling weeds are required for sustainable agriculture. We explored the phytotoxic activities of aqueous methanol extracts of Senna garrettiana (Craib) Irwin & Barneby leaves and the active substances they contain. The results revealed that the S. garrettiana leaf extracts had significant phytotoxic effects on three dicotyledons (Lepidium sativum L., Lactuca sativa L., and Medicago sativa L.) and two monocotyledons (Phleum pratense L. and Lolium multiflorum Lam.). An bioassay-guided isolation process yielded three active substances; caffeic acid, methyl caffeate, and (S)-6-hydroxymellein inhibited the seed germination, seedling growth, and biomass accumulation of L. sativum in a concentration-dependent manner. Based on the concentration required for 50% growth inhibition (IC50), (S)-6-hydroxymellein had the highest inhibitory effects on L. sativum in all test parameters, followed by methyl caffeate and caffeic acid. The L. sativum roots were the most susceptible to (S)-6-hydroxymellein (IC50 = 383 µM) and caffeic acid (IC50 = 2627 µM), whereas methyl caffeate (IC50 = 1361 µM) had the greatest effect on the L. sativum shoots. Thus, three isolated compounds may explain the phytotoxic effects of the S. garrettiana extracts. Consequently, caffeic acid, methyl caffeate, and (S)-6-hydroxymellein could be potential candidates for the future production of bioherbicides.

Exposure to invasive weeds in pasturelands may result in significant losses and toxicity in forage crops. These species may also contain a compound that may be toxic as well as beneficial depending upon the effect induced. The Ministry of Environment of the Republic of Korea has now recognized Solanum carolinense (Horsenettle)—an invasive weed species—as a potential threat to forage crops in pasturelands and to the entire agro-ecosystem. As a forage crop, Festuca arundinacea (Tall fescue) is one of the major economical crops and diets of livestock; in this study, the competition patterns of Solanum carolinense and Festuca arundinacea were examined with respect to their seeding ratios and growth periods. In addition, an extract from the root of Solanum carolinense (SCE) was prepared and treated at 2500 ppm and 5000 ppm in a Festuca arundinacea plant to observe its effect. The experimental results showed that as the growth period of the Horsenettle and the SCE treatment increased, the germination rate, plant height, root length, fresh weight, and dry weight of the tall fescue were significantly decreased. Moreover, the SCE treatment significantly increased the quantities of reactive oxygen species (O2− and H2O2), antioxidants (Catalase and Peroxidase), and endogenous phytohormones (Abscisic acid and Salicylic acid), and simultaneously decreased the superoxide dismutase content in the tall fescue shoots. Furthermore, we identified several glycoalkaloids from the SCE extract, among which Solanidan-3-ol, (3β,5α)’ possessed a higher number (52%). Based on these results, we predicted that the Solanidan-3-ol, (3β,5α)’ present in horsenettle has a major role in imposing phytotoxicity on agricultural crops. The glycoalkaloids in the Solanum species have been reported to possess both phytotoxic and therapeutic uses. Based on this concept, we believe that the compound available in Solanum carolinense could be used in developing crop protection or medicinal products through broader research. Conversely, our findings also showed the probable risk of horsenettle to the agro-ecosystem, especially in terms of forage production.

Background: The application of synthetic pesticides to the tomato crop (Solanum lycopersicum -Solanaceae-) increases fruit production, but also carries risks for the environment, human and animal health. Hypothesis: local ruderal plant extracts could be an alternative for weed control, with potential applications in agroecology and organic agriculture. Methods: Organic and aqueous extracts (1 and 10% w/v) were prepared with the fresh (FAE) and dry (DAE) aerial parts of five ruderal species from Tlaxcala, Mexico: Argemone mexicana L. (Papaveraceae), Baccharis salicifolia Pers. (Asteraceae), Lepidium virginicum L. (Brassicaceae), Leucena leucocephala S. Zárate (Fabaceae) and Reseda luteola L. (Resedaceae). Their phytotoxic activity was evaluated in vitro with the seeds of three model plants (amaranth, lettuce, and tomato). Results: DAE of B. salicifolia and L. virginicum (1 % w/v) showed the highest potential as natural herbicides. These inhibited 100 % seed germination and radicle elongation in the three model plants but did not affect the growth of tomato seedlings of 8 and 12 weeks in greenhouse conditions. Both extracts analyzed by HPLC-ESI-QTOF-MS showed two major peaks. Bacharis salicifolia with m/z 432.9 and 725.4. Lepidium virginicum with m/z 532.9 and 527.1. Conclusions:DAE of local ruderal plants B. salicifolia and L. virginicum (1 % w/v) are potential natural herbicides, without harmful effects on tomato cultivated seedlings, awaiting the precise identification of their active compounds.

Modern agriculture has been facing new challenges and fostering innovations to establish sustainable plant production. An integral part of these strategies is implementing new eco-friendly technologies in plant protection for better human health and a safer environment by minimizing the use of hazardous chemicals and also encouraging innovations such as the use of bio-based strategies for weed control. This specific strategy addresses the need to reduce the use and risk of pesticides, replacing conventional chemical herbicides with new bio-based solutions. In response to these issues, biocontrol strategies are gaining increased attention from stakeholders such as farmers, seed companies, agronomists, breeders, and consumers. Among these, bioherbicides have huge potential for the management of harmful weeds without affecting the natural quality of the environment and human health. In this context, this review is devoted to present an overview of the mycoherbicidal potential of Phoma sensu lato group of fungi, examining the advances in this field, including technological and scientific challenges and outcomes achieved in recent years. The mycoherbicides are eco-friendly and economically viable. Key points: • Some Phoma species have demonstrated herbicide activity. • These species secrete secondary metabolites responsible for the control of weeds. • They can be used as non-chemical, cost-effective, and eco-friendly bioherbicides. [ABSTRACT FROM AUTHOR]

Phytotoxic substances released from plants are considered eco-friendly alternatives for controlling weeds in agricultural production. In this study, the leaves of Afzelia xylocarpa (Kurz) Craib. were investigated for biological activity, and their active substances were determined. Extracts of A. xylocarpa leaf exhibited concentration-dependent phytotoxic activity against the seedling length of Lepidium sativum L., Medicago sativa L., Phleum pratense L., and Echinochloa crus-galli (L.) P. Beauv. Bioassay-guided fractionation of the A. xylocarpa leaf extracts led to isolating and identifying two compounds: vanillic acid and trans-ferulic acid. Both compounds were applied to four model plants using different concentrations. The results showed both compounds significantly inhibited the model plants' seedling length in a species-dependent manner (p < 0.05). The phytotoxic effects of trans-ferulic acid (IC50 = 0.42 to 2.43 mM) on the model plants were much greater than that of vanillic acid (IC50 = 0.73 to 3.17 mM) and P. pratense was the most sensitive to both compounds. In addition, the application of an equimolar (0.3 mM) mixture of vanillic acid and trans-ferulic acid showed the synergistic effects of the phytotoxic activity against the root length of P. pratense and L. sativum. These results suggest that the leaves of A. xylocarpa and its phytotoxic compounds could be used as a natural source of herbicides. [ABSTRACT FROM AUTHOR]

BACKGROUND The organic extracts (OEs) of Dittrichia viscosa, a ruderal plant common in the Mediterranean regions, proved to have herbicidal properties. In order to improve OE effectiveness and to develop novel eco‐friendly bioherbicidal products, different amounts of OE were included in poly(butylene succinate)‐ and polycaprolactone‐based films (PBS and PCL, respectively). Particular attention was given to the study of interactions between the polymers and OEs, with a deep spotlight concerning the influence of OEs on structural, morphological and thermal properties of both polymers, in order to assess the OE releasing kinetics from the matrices and its tuned herbicidal action against seeds. RESULTS: The bioassays carried out on Lepidium sativum and Phelipanche ramosa seeds evidenced a more controlled and effective OE release by PBS than PCL, and a longer lasting efficacy by the polymers with a higher OE content. The chemical–physical analyses were performed on films before and after biological assays. The thermogravimetric analysis confirmed that OE was a thermal stabilizer of the polymer; the presence of OE and polymer separated degradative kinetics suggested that only a partial and functional miscibility between polymers and OE occurred. The morphological analysis confirmed the good OE dispersion between PBS and PCL molecular chains. Infrared spectroscopy highlighted the enhanced hydrolysed structure of the doped polymers after the bioassays. These outcomes well matched the quantitative information outlined by release kinetics. DISCUSSION The use of biodegradable polymers allows the effectiveness and tuning of the release of the formulated bioactive compounds to be improved. The easy‐to‐obtain and easy‐to‐formulate OE could become a suitable and environmentally friendly instrument in weed management programmes. [ABSTRACT FROM AUTHOR]

Weed control in sustainable agriculture requires new bioherbicidal molecules to replace synthetic herbicides that have damaged the environment and generated resistance in weeds. This study was conducted to investigate the chemical composition of Eucalyptus globulus essential oil and to explore its bioherbicidal potential on the germination and radicle growth inhibition. The phytotoxic effects of E. globulus essential oil (1, 10 and 20 μL mL-1) were tested in comparison to those of the synthetic herbicide Glyphosate (1, 10 and 20 μL mL-1) in bioassays of germination and radicle growth of Lactuca sativa and the resistant weeds Avena fatua and Amaranthus hybridus. Gas Chromatography with Flame Ionization Detector and Gas Chromatography-Mass Spectroscopy analysis showed that major monoterpenes comprised 1,8-Cineole (86.94%), α-pinene (7.71%), d-limonene (2.65%), and p-cymene (1.48%). The seed germination and radicle length exhibited different degrees of inhibition in response to the concentration of E. globulus essential oil. At some concentrations, both the Glyphosate herbicide and the E. globulus essential oil demonstrated the same phytotoxicity against the resistant weeds A. fatua and A. hybridus. Essential oil bioactivity Lethal Concentration (LC50) in the majority of cases was lowest for A. hybridus, followed by A. fatua and L. sativa. Based on the results, it can be concluded that E. globulus essential oil possesses phytotoxic potential and could be explored as a bioherbicide for resistant weeds management programs. [ABSTRACT FROM AUTHOR]

Copyright of Acta Scientiarum Polonorum. Formatio Circumiectus is the property of Wydawnictwo Uniwersytetu Rolniczego im. Hugona Kollataja w Krakowie 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 good phytotoxicity and selectivity against weeds versus tomato or cress make saponin-rich fractions from Agave macroacantha , A. colorata , A. parryi , and A. parrasana attractive candidates as bioherbicides. The saponin contents have only previously been reported for A. macroacantha , and as a consequence, simultaneous dereplication has been performed on saponin-rich fractions from the other plants by mass spectrometry (MS) and nuclear magnetic resonance (NMR) spectroscopy. This strategy enables the identification of a total of 26 saponins, 14 of which have been described previously and 12 of which are proposed as new saponins. They include isomers and a new sugar chain with a β-d-apiofuranose unit. The method is corroborated by the isolation of eight dereplicated saponins from A. colorata .

In recent years, synthetic herbicides' intense and disordered use has triggered severe contamination of soils and water bodies, causing damage to living organisms, including vegetal herbicide-resistance. In-part, biological herbicides, offer promise in addressing these problems, especially for sustainable weed management in both agricultural and natural resource management contexts. The search for culture media to serve as alternatives to the existing conventional synthetic media has focused on microalgae biomass. The natural properties of these organisms make them ideal raw materials for fermentative processes. Therefore, this study aimed to integrate bioprocesses producing bioherbicidal extract using a submerged fermentation process. For this, a substrate of microalgae recycled biomass to replace commercially used media for fungal growth for relatively cheap biomass obtained from wastewater phycoremediation after anaerobic treatment (UASB). We also verified its potential for weed control. Preliminary tests of microalgae fermentation were conducted in the raw and lyophilized form, using the fungus Trichoderma koningiopsis. To evaluate their phytotoxic potential, the biocompounds were applied to Bidens pilosa, Conyza bonariensis, Urochloa plantaginea, and Euphorbia heterophylla weeds. A central composite rotatable design (CCRD) was used to evaluate the influence of temperature (20–45°C), agitation (0–200 RPM), and pH (3–14) on the improvement of enzyme activities, fungal growth and the effects on Cucumis sativus germination tests. We found that microalgae could be used as a substrate for obtaining bioherbicides. The biocompounds produced in this study were relevant for pre- and post-emergence control of model plants (Cucumis sativus), with vigor indexes of up to 8.05% and herbicide-resistant plants (Conyza bonariensis) with phytotoxic damage of up to 100% after 15 days. From the experiments' design, we found that agitation was the variable that had the most significant effect on enzyme and biomass production, followed by pH and temperature. The enzymes also showed synergistic action when acting together with microalgae and fungi, potentiating the control effect on weeds. Finally, the system integrated bioprocesses through agro-industrial effluent recovery and reuse, considered one of the essential economic viability mechanisms by enhancing the development of more sustainable technologies that embrace the principles of a circular economy.

Senna garrettiana (Craib) Irwin & Barneby (Fabaceae) is a medicinal plant known to be rich in biologically active compounds that could be exploited to produce bioherbicides. The present study was conducted to explore the allelopathic potential and phytotoxic substances of S. garrettiana. Extracts of S. garrettiana leaves were found to significantly inhibit the growth of Lepidium sativum L. and Echinochloa crus-galli (L.) P. Beauv. (p ≤ 0.05). The phytotoxic substances were isolated and identified as vanillic acid and ferulic acid by bioassay-directed fractionation and spectral data analysis. The two compounds were shown to significantly inhibit the seed germination, seedling growth, and dry biomass of L. sativum. Based on the concentration required for 50% growth inhibition (defined as IC50), the roots of L. sativum were the most sensitive to the compounds, and the inhibitory effect of ferulic acid (IC50 = 0.62 mM) was >1.3 times more potent than that of vanillic acid (IC50 = 0.82 mM). In addition, a mixture of the two compounds (0.3 mM) resulted in synergistic inhibitory activity against the L. sativum roots compared with the individual compounds. These results suggest that the extracts of S. garrettiana leaves and their phytotoxic compounds have potential as candidate natural herbicides.

This work describes efforts to encapsulate savory (Satureja hortensis L.) essential oil (EO) with different natural polymers (i.e., Arabic gum/gelatin (AGG), apple pectin (AP), gelatin (G)) and, as a separate set of experiments, with bio cross-linkers (i.e., citric acid and transglutaminase enzyme). The phytotoxic activity of encapsulated savory EO on tomato (Lycopersicon esculentum Mill.) and amaranth weed (Amaranthus retroflexus L.) was investigated. The micro-capsules were evaluated in terms of size, polydispersity, stability, encapsulation efficiency, morphology, and release properties. The Korsmeyer–Peppas model operated when EO was being released from the micro-capsules. Carvacrol (52.5%) and γ-terpinene (30.2%) comprised the main constituents of the savory EO. Based on the results, encapsulating the EO with cross-linked biopolymers increased the stability and herbicidal activity of EO, as compared to simple EO emulsions. Maximum toxicity injuries (MTI) were caused by encapsulations of apple pectin, cross-linked with APe enzyme (15 ml/L) on both plant species. MTI were observed 2 days after using the micro-encapsulated herbicides (MCHs). However, the injury caused by MCHs on tomato was not significant. The lowest values of fresh weight (2.80 g), chlorophyll a (0.194 mg/g Fw), and total chlorophyll content (0.219 mg/g Fw) of amaranth occurred in response to APe (15 ml/L). Moreover, using AP(e) (10 ml/L) caused the lowest values of starch (0.444 mg/g Fw) and flavonoid contents (4.18 mg Cat/g Fw) in amaranth which measured as 59% and 90% reductions, respectively, in comparison with the control. The highest values of MDA (0.0109 nmol/g Fw) and H2O2 (0.0432 μmol/g Fw) were observed in amaranth plants treated with AP(e) (10 ml/L). In summary, cross-linked apple pectin can perform well in slow release delivery systems of agrochemicals. It can be recommended for use in the production of commercial, EO-based natural herbicides. [ABSTRACT FROM AUTHOR]

The phytotoxic potential of the leaves and twigs of Schumannianthus dichotomus, discarded in the mat-making industry against four test plants (lettuce (Lactuca sativa L.), rapeseed (Brassica napus L.), foxtail fescue (Vulpia myuros (L.) C.C. Gmel.) and timothy (Phleum pratense L.)) was investigated and found strong phytotoxic activity. An assay-guided fractionation of S. dichotomus extarcts against cress (Lepidium sativum L.) through a series of column chromatography steps yielded two compounds, 8-(5-oxo-2,5-dihydrofuran-2-yl) octanoic acid (ODFO) and (E)-6-hydroxy-2,6-dimethylocta-2,7-dienoic acid (8-carboxylinalool). ODFO and 8-carboxylinalool showed strong phytotoxic activity against cress and timothy. The concentrations required for 50% growth inhibition (I50 value) of the seedlings of cress and timothy were 111.94–128.01 and 36.30–91.75 µM, respectively, for ODFO, but the values were much higher at 315.98–379.13 and 107.92–148.41 µM, respectively, for 8-carboxylinalool, indicating the stronger phytotoxic activity of ODFO. This study is the first to isolate ODFO and 8-carboxylinalool from S. dichotomus and their phytotoxic potential while ODFO is firstly encountered from any natural source. The growth inhibitory activity of the identified compounds may explain their role in the phytotoxic activity of S. dichotomus, which suggests the possible use of its leaves and twigs or its active constituents as natural bioherbicides. [ABSTRACT FROM AUTHOR]

Agricultural pesticides can become persistent environmental pollutants and their use is destined to be reduced. Consequently, weed control is shifting to green products and strategies. A combined approach, made of pelargonic acid based herbicide spraying and interspecific competition (i.e. seeding of plants species competing for growth against weeds) could boost the weeding effect. In case of the contemporary seeding and spraying, needed to reduce costs, seed coating is necessary as barrier to herbicide toxic effects but, at the same time, the coating has to be endowed with the right features to allow germination. This work aims to verify the feasibility of using cellulose acetate/cardanol (CA/Card) as seed coating polymer–plasticizer blend and to identify possible relationship between material features and germination rate. For these purposes, untreated and pelargonic acid herbicide treated coated seeds coated through solvent evaporation methods (CA/Card ratios from 0/0 to 100/0) were subjected to germination test. Coatings were characterized through SEM, EDX, media uptake, DSC and mechanical analysis with and without conditioning in seeding conditions. Germination test showed that 70/30 seeds, treated and untreated with herbicide, presented the best germination rate. Germination assays showed that coating presence reduced and slowed (without stopping) seeds germination equally with and without herbicide treatment. Consequently, was possible to conclude that CA/Card coatings allowed germination and presented a barrier effect against herbicide. Thus coating resulted suitable for seed coating in herbicide spraying/interspecific combined applications. No strong correlations were found between material features and germination, but it is plausible to hypothesize that both water absorption and mechanical properties of the coating play an important role and have to be optimized to improve germination rate avoiding difficulty in sprouting. Finally, the study opened a new perspective in the use of cellulose acetate for seed coating from waste sources such as cigarette filters. [ABSTRACT FROM AUTHOR]

Plant allelochemical is very potential to be developed as an effective and environmentally friendly bioherbicide for controll weeds. Each part of Tetracera indica has potential as an allelochemical compounds bioherbicide. The purpose of this research was to identify the allelochemical content of each part of Tetracera indica (L.) Merr. Allelochemical compounds were analyzed using GC-MS (Gas Chromatography-Mass Spectrometer) method. The result of the analysis showed an extract of each part Tetracera indica had different type of compounds. Potential allelochemical bioherbicide compounds were fatty acids, flavonoids, and steroids. Flower extract has the highest compound of fatty acids and steroids compared to other parts. [ABSTRACT FROM AUTHOR]

Copyright of Brazilian Journal of Biology is the property of Instituto Internacional de Ecologia 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.)

A central pillar of modern weed control is the discovery of new herbicides which are nontoxic to humans and the environment and which have low application dosage. The natural products found in plants and microorganisms are well suited in this context because they are generally nontoxic and have a wide variety of biological activities. In this work, Diaporthe phaseolorum (Dp), Penicillium simplicissimum (Ps) and Trichoderma spirale (Ts) (methanolic extracts) were evaluated as photosynthesis and plant growth inhibitors in Senna occidentalis and Ipomoea grandifolia. The most significant results were observed for Ts and Dp in S. occidentalis and I. grandifolia, respectively. Ts reduced PI(abs), ET0/CS0, PHI(E0) and PSI0 parameters by 64, 28, 40 and 38%, respectively, indicating a reduction on electron transport efficiency. Additionally, Ts decreased shoot length by 9%, affecting the plant growth. Dp reduced PI(abs), ET0/CS0 and PHI(E0) parameters by 50, 20, 26 and 22%, respectively, revealing the inhibition competency on PSII acceptor site. Furthermore, Dp decreased by 50% the shoot length on germination assay. Thus, the phytotoxic behaviors based on endophytic fungal extracts may serve as a valuable tool in the further development of a bioherbicide since natural products represent an interesting alternative to replace commercial herbicides. [ABSTRACT FROM AUTHOR]

Lovegrass (Eragrostis plana) is the most important invasive plant in pastures of southern Brazil. The research evaluated the potential of Ruta graveolens (rue) and Schinus terebinthifolius (Brazilian peppertree) essential oils (EOs) to inhibit germination and initial development of lovegrass. The in vitro treatments tested were control (distilled water), alcohol control, 0.001, 0.005, 0.01, 0.05 and 0.1% (v/v) of both EOs. Higher concentrations of these EOs were applied to germinated plants under greenhouse conditions. The EOs of both species were effective in reducing lovegrass germination, with emphasis on rue. Height and shoot dry mass, at greenhouse conditions, were significantly reduced by both EOs, especially when applied at a concentration of 1%. The results point to the potential of rue and Brazilian peppertree EOs for the formulation of natural herbicides. [ABSTRACT FROM AUTHOR]

BACKGROUND: Ludwigia hyssopifolia (G. Don) Exell, one of the problem weeds in some rice‐producing countries, was studied to determine its allelopathic potential based on the effects of aqueous extracts of its tissues (leaves, roots and stem) on seedling growth of selected weeds and rice. The major phenolic compound of its leaves was also isolated and characterized. RESULTS: L. hyssopifolia aqueous leaf extract showed significant inhibition of shoot growth and biomass accumulation of weeds (Amaranthus spinosus L., Dactyloctenium aegyptium L., Cyperus iria L.) while maintaining less adverse effects on rice (crop) compared to other aqueous extracts of roots and stem. Phytochemical screening showed that phenols, tannins, flavonoids, terpenoids, saponins and coumarins are found in its leaf aqueous extract. The Folin–Ciocalteu method revealed that its leaves contain 26.66 ± 0.30 mg GAE g−1 leaf. The extract was then acid‐hydrolyzed to liberate the phenolics (25 mg phenolics g−1 leaf). The major compound was isolated via preparative thin‐layer chromatography using formic acid–ethyl acetate–n‐hexane (0.05:4:6) solvent system. It had maximum UV absorption at 272 nm while its Fourier transform infrared spectrum revealed phenol, carboxylic acid and ether functionalities. This also had similar chromatographic mobility when run together with syringic acid in two‐dimensional paper chromatography and thin‐layer chromatography. CONCLUSIONS: L. hyssopifolia has potential allelopathic activity and its leaf aqueous extract showed the highest phytotoxic activity (P ≤ 0.05) indicating its potential as a bioherbicide. The most probable identity of the major phenolic compound is syringic acid. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The need to reduce the use of chemical pesticides currently fosters great interest in eco-friendly biological control agents. In addition, the isolation of plant allelopathic substances and the evaluation of their phytotoxic effects can lead to the discovery of new natural herbicides. In this context, our study aimed to assess the herbicidal activity of ten crude extracts obtained from aerial parts of Tunisian spontaneous plants against Trifolium incarnatum, Silybum marianum and Phalaris minor. It confirmed that the Cynara cardunculus methanolic extract best inhibited weed germination and seedling growth, and caused necrosis or chlorosis. Following a bioassay-guided fractionation, five main phenolic compounds, (1) syringic acid, (2) p -coumaric acid, (3) myricitrin, (4) quercetin and (5) naringenin were identified in the most active crude methanolic extract. Then, only 3 of the flavonoids contained in the most active fraction were tested on Trifolium incarnatum. The 3 compounds had a significant phytotoxic effect and therefore could be employed in a new composition of botanical herbicides to control crop weeds. Besides, a novel herbicide composition was designed to improve the post-emergence activity of the methanolic extract. The formulation containing the C. cardunculus crude methanolic extract showed the same herbicidal activity as the standard industrial bioherbicide containing pelargonic acid. These results make C. cardunculus a suitable source of natural compounds potentially usable as natural herbicides. Image, graphical abstract • C. cardunculus extract had the best herbicidal activity among 10 plant extracts. • Five phenolic compounds were identified in C. cardunculus. • Myricitrin, naringenin and quercetin were the main active compounds in C. cardunculus. • Fraction 2 of C. cardunculus had the same herbicidal effect as biological herbicide. [ABSTRACT FROM AUTHOR]

Alamethicin (AMT) is a linear antimicrobial peptide isolated from fungi Trichoderma viride. To date, the mode of action of AMT in plant cells remains unknown. Our experimental results indicate that AMT causes leaf lesion attributed to its multiple effects on PSII. AMT decreases the O2 evolution rate of PSII. Based on chlorophyll fluorescence data, similar to the classical herbicide diuron, AMT interrupts PSII electron transfer beyond QA at the acceptor side, leading to the inactivation of the PSII reaction centers. Additionally, AMT decreases chlorophyll content and destroys the architecture of PSII pigment assemblies. However, AMT does not affect the oxygen-evolving complex at the donor side of PSII. Thus, it is concluded that AMT is a natural photosynthetic inhibitor with several action sites in PSII. [ABSTRACT FROM AUTHOR]