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Selected seven allelochemicals from the 14 categories, their sources, and the allelochemicals present in them.
Source publication
Weeds are a serious threat to crop production as they interfere with the crop growth and development and result in significant crop losses. Weeds actually cause yield loss higher than any other pest in crop production. As a result, synthetic herbicides have been widely used for weed management. Heavy usage of synthetic herbicides, however, has resu...
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Weeds are a severe menace to crop cultivation as they interfere with crop growth and development and result in considerable loss in yield of oil seed crops. As a result, farmers have widely used synthetic herbicides for weed management. Using herbicides guides various environmental and health issues, and researchers have been exploring alternative...
Citations
... 4-hydroxyphenyl pyruvate dioxygenase/phytoene desaturase is reported to be inhibited upon treatment with allelochemicals, which is a major intermediate in carotenoid biosynthesis (Romagani et al. 2000). Several reports include such chlorophyll degradation of weeds upon treatment with allelochemicals, e.g., allelochemicals of Arbutus unedo, Medicago minima, and Myrtus communis impact the growth and reproduction of Aegilops geniculata (Scognamiglio and Schneider 2020; Khamare et al. 2022). ...
... Rutin, present in the S. nodiflora extract, as detected from the present investigation, has been earlier detected from Amaranthus spinosus with strong inhibitory activity against Oryza sativa (Pengcheng et al. 2016). Caffeic acid, ferulic acid, and gentisic acid have been reported as potent allelochemicals from different allelopathic plants and exhibit phytotoxicity against some selected plants (Chen et al. 2022;Hussain and Reigosa 2021;Anwar et al. 2023;Li et al. 2010aLi et al. , 2010b. Luteolin-7-O-glucoside, rutin, parthenolide, artemisinic acid, costunolide have been reported as potent allelochemicals by several researchers (Lydon et al. 1997;Macias et al. 1992;Abdelgaleil et al. 2009;Kostina-Bednarz et al. 2023). ...
Weeds are one of the major contaminants of a crop field and seriously hamper agricultural production. The synthetic weedicides used to control weeds affect both ecosystem functioning and human health. Thus, novel techniques, especially nature-based solutions, are in great need as a replacement for the chemical weedicides. The use of phytochemicals obtained from invasive species can be the best sustainable approach. They are known to be allelopathic plants, and their synthesised metabolites, i.e., allelochemicals, exhibit strong selective phytotoxic activity. Invasive taxa synthesise these unique metabolites as a method of niche specialisation or territorial signature that can be exploited biotechnologically for the development of alternative herbicides. The phytochemicals were extracted from leaves of S . nodiflora using different solvents and tested for their allelopathic potentiality on Mimosa pudica seeds. The different germination behaviour and seed biochemical parameters were noted. The allelochemicals were applied to seedlings, and the changes in standard physical and critical biochemical events were reported. The contributing allelochemicals were identified through bioassay-guided fractionation followed by GC–MS-based identification. In the present investigation, phyto-metabolites from methanolic extracts of leaves of S . nodiflora exhibit potent seed germination inhibition activity against mimosa and affect its normal external morphology and internal biochemical machinery. The T 50 (time required for the germination of 50% seeds) value was prolonged, and the reduction in insoluble carbohydrates, nucleic acid, and protein contents, as well as amylase action, was observed. Stress-related antioxidant enzymes- catalase, and peroxidase were drastically reduced. The pigment profiles, i.e., chlorophyll a, b, and carotenoids, were critically lowered, whereas the degree of lipid peroxidation increased. Compared to the control, the common physical parameters related to shoot and root length, dry, and fresh weight were affected in treated seedlings. The major metabolites present in the methanolic extracts responsible for such a promising allelopathic activity were quinic acid, protocatechuic acid, gentisic acid, caffeic acid, and ferulic acid, etc. The allelochemicals of S . nodiflora can be employed for the development of alternative eco-friendly herbicides and also pave the way for the management of alien species.
... The harmful effects of herbicides on the environment and human health, the ever-increasing number of herbicide-resistant weed populations, the increasing number of invasive alien weed species, the slower development of novel herbicides, the ban on the use of many herbicides, and the intensified focus on organic farming are some of the main factors that have promoted eco-friendly approaches to weed control in recent decades [1][2][3]. In the last two decades, the concept of allelopathy has been employed to reduce our heavy reliance on synthetic herbicides and to find a promising solution to the problems of environmental pollution and herbicide resistance as well as ecological weed management [4,5]. The phytotoxic properties of allelochemicals exuded by allelopathic plants mean they can be a source for the identification and isolation of a wide selection of potential new environmentally acceptable bioherbicides. ...
The use of Artemisia species’ plant extracts and essential oils, which are rich in bioactive compounds (allelochemicals), could support weed management. This study focused on the chemical analysis and evaluation of the allelopathic potential of plant extracts (PEs) and essential oils (EOs) of Artemisia absinthium and A. vulgaris on the germination and early seedling growth of weeds (Amaranthus retroflexus and Setaria viridis) in vitro. The plant extract from A. vulgaris showed higher antioxidant activity (IC50 = 0.171 ± 0.01 mg/mL) and phenolic content than that from A. absinthium (IC50 = 0.263 ± 0.01 mg/mL). Chlorogenic acid was the most abundant phenol in both extracts. However, A. absinthium contained a higher amount (1.694 ± 0.081 mg/g) and exhibited a stronger inhibitory effect on the germination of A. retroflexus (EC50 = 0.54 ± 0.02%) and S. viridis (EC50 = 1.51 ± 0.07%) compared to A. vulgaris. The dominant components of A. absinthium essential oil were β-thujone (18.9%), cis-ocimene epoxide (7.88%), and bicyclogermacrene (7.04%), while the main constituents of A. vulgaris essential oil included gurjunene (10.41%), cis-crysanthenyl acetate (7.17%), and γ-humulene (6.67%). The lowest EC50 values for A. absinthium essential oil regarding seed germination and seedling length were estimated for S. viridis (0.28 ± 0.48% and 0.03 ± 0.00%, respectively), whereas A. retroflexus was the most sensitive to A. vulgaris essential oil (0.11 ± 0.04% and 0.02 ± 0.00%, respectively). All tested extracts showed allelopathic potential; however, the results indicate that the essential oils had a stronger inhibitory effect than the plant extracts.
... About 90% of compounds present in the root exudates (Czarnota et al., 2003). Sorgoleone has been characterized as a potent bioherbicides as it can suppress many weed species (Khamare et al., 2022). Cynodon dactylon foliage contained the following phenolic acids: caffeic, ferulic, coumaric, benzoic, vanelic, chlorogenic and cinnamic. ...
... Also, glyphosate will affect photosynthesis indirectly by inhibit the biosynthesis of carotenoids, chlorophyllus, fatty acid and for amino acids (Fedtke and Duke, 2005). As found that (Khamare et al., 2022) about 90% of compounds present in the root exudates (Czarnota et al., 2003). Sorgoleone has been characterized as a potent bioherbicides as it can suppress many weed species. ...
... In recent years, many scholars have conducted a lot of research on the mechanisms of replacement control, among which allelopathy is a driving factor in the successful replacement control of invasive plants [8]. Allelopathy refers to the effect that plants have on the growth of other plants by releasing specific chemicals into the environment through appropriate pathways (root secretion), and the effect is mostly the inhibition of invasive species [9,10]. Similarly, the alternative plant could gain a competitive advantage and promote it as a dominant single population by producing some allelochemicals that negatively affect the growth of invasive plants. ...
Lolium perenne (Poaceae), a perennial forage, has high economic and nutritional value. It is often used as a replacement control for some invasive plants, as it has achieved good ecological and economic effects. However, its control effects, allelochemicals, allelopathic effects, release pathways, and contents are still unclear in the process of L. perenne replacement control of an invasive plant, Ageratina adenophora (Asteraceae). Therefore, it is necessary to reveal the mechanism of L. perenne replacement control of A. adenophora from the perspective of allelopathy. In this study, L. perenne could effectively inhibit the growth of A. adenophora in the competition assay. In addition, seven norsesquiterpenes (1–7) were isolated and identified from the whole plant of L. perenne, and most of the compounds exhibited potent allelopathic effects on the growth of A. adenophora and one model plant (Lactuca sativa, Asteraceae). Moreover, some active compounds were released into the environment through root secretion and rainwater leaching, and their contents were determined by UPLC-MS/MS (Ultra Performance Liquid Chromatography Tandem Mass Spectrometry). Our results elucidated the allelopathic mechanism of L. perenne’s replacement control, A. adenophora, and provided a theoretical basis for the development of norsesquiterpenes from L. perenne.
... The Tree of Heaven is a perennial woody plant that can produce various allelochemicals including quassinoids, terpenoids, and alkaloids [10]. The widespread distribution and invasive nature of this plant in many regions around the world have been well documented, making it a problematic weed in these areas [11]. ...
The Tree of Heaven (Ailanthus altissima (Mill.) Swingle), originally from Southeast Asia, is considered an invasive alien plant in many countries. It produces a strong allelochemical called ailanthone, and this phytotoxic quassinoid inhibits the germination of seeds and/or suppresses the growth of other plants. This study aimed to determine the applicability of plant biomass of the Ailanthus as a raw material to prepare various compost types. The compost treatments were composed of the biomass of A. altissima alone, the biomass of A. altissima+chicken manure, and the biomass of A. altissima+cattle manure. Weed seeds in the mixtures were kept for 7, 14, 21, and 28 days in the composts during the summer and autumn seasons, and the effect of these durations on the viability of the weed seeds was determined by a 28-day petri experiment. The percentage of decayed weed seeds (DSP) placed in the compost increased over time. The decayed seed percentage for Sorghum halepense (L.) Pers. (Johnson grass) in summer-prepared compost was higher than that in autumn-prepared composts, whereas seasonal differences were insignificant for Convolvulus arvensis L. (Field bindweed). Additionally, increasing mulch thickness reduced weed emergence, indicating that a mulch layer of at least 5 cm is necessary for effective weed control.
... These chemicals can be released through root exudation, leaf leachates, or the decomposition of plant residues. Rye (Secale cereale) and mustard (Brassica spp.) produce allelopathic compounds that suppress weeds (Kelton et al., 2012;Khamare et al., 2022). Cover crop's biomass also acts as a physical barrier, preventing weed seeds from accessing the soil surface and germinating, enhancing weed suppression (Gerhards et al., 2024). ...
This paper explores the multifaceted role of cover crops in enhancing soil health, improving sustainability, and supporting regenerative agriculture systems. It critically evaluates their agronomic benefits, including nitrogen fixation and weed suppression, alongside practical challenges such as species selection and labor intensity. Future directions for research and policy are also discussed to promote broader adoption
... The ability of producing allelochemicals as phenolic compounds and terpenes has been largely described for the Asteraceae botanical family in general (Chon et al., 2003;Chon and Nelson, 2010;La Iacona et al., 2024) and the genus Baccharis in particular (Dias et al., 2017;Ibañez and Zoppolo, 2011;Miranda-Araḿbula et al., 2021). Research on secondary metabolites with allelopathic action is critical to the improvement of sustainable weed management tools, such as the selection and breeding of allelopathic cover crops and the development of natural herbicides (Khamare et al., 2022). ...
... Large experimental variability in magnitude of phytotoxicity, e.g. reduction of treated plant biomass, leading to unsatisfactory weed control from a practical perspective, were often observed in studies testing plant-derived natural products as herbicides (Loddo et al., 2023;Torres-Pagań et al., 2024;Khamare et al., 2022). Biomass of weeds treated with the different doses of roots (BR) and leaves (BL) extracts of B. halimifolia in the Post-emergence trial. ...
The search for new tools appear to be crucial to ensure sustainable weed management and the study of allelochemicals in plants plays a strategic role in the eco-friendly agrochemical development. This study aims, for the first time, to identify and quantify allelopathic substances in aqueous extracts from leaves (BL) and roots (BR) of the invasive species Baccharis halimifolia L. (Asteraceae) and to assess their phytotoxic activity at different dilutions in both germination tests and greenhouse pot trials for the weed species Abutilon theophrasti Medik., Solanum nigrum L., Lolium rigidum Gaudin and Setaria pumila Roem. & Schult. HPLC-DAD-(ESI)-MS analysis revealed the presence of several saponins and phenolics (e.g. Apigenin and Protocatechuic acid), possibly implicated in the observed phytotoxic action. The most relevant effects were observed in the germination test, where BR was more effective than BL and at 20% v/v dilution caused a 50-75% reduction in root length of all weed species. Maximum reduction (>85%) in root length occurred at 100% v/v dilution of both extracts for all species. Pre- and post-emergence greenhouse trials showed unstable and variable herbicidal activity among the tested species and extract doses. Effects were observed mainly on the grasses S. pumila and L. rigidum , where BR application in post-emergence reduced plant biomass by 42% and 34%. This study suggests that B. halimifolia could be a potential source of natural herbicides; however, it also showed the difficulties in reproducing, under the field-like conditions of pot trials, the phytotoxic effects observed in germination tests due to radical differences in applied doses and exposure conditions. This highlights the importance of studies that consider field application and the need of green extraction methodologies that improve active substances concentration in extract.
... Allelopathy is a phenomenon of plant interference, which consists in the production, accumulation and/or release of specialized compounds, known as allelochemicals, either by exudation through the roots, leaching, decomposition of the tissues or volatilization, which can affect the development of surrounding plant species [9]. Of course, this phenomenon is also present in the agroecosystems among crop and weed species [2,10,11]. Agroecology and organic agriculture benefit from this phenomenon in different ways. For example, intercropping takes advantage of allelopathy when allelopathic plants are cultivated simultaneously or alternatively in a field for a certain period of time, so that they exude or release natural compounds with allelopathic capacity, allowing the sustainable management of weeds once the crop is rotated to a non-allelopathic one [1]. ...
... The observed effects on weeds are probably due to the presence of these compounds in the medium, as wheat has been repeatedly reported as an allelopathic crop [38][39][40]. DIMBOA, the main hydroxamic acid present in wheat [11,41] has previously found to suppress the growth of different weeds. For example, Li et al. [42] found a correlation between an increase of DIMBOA in the medium and the inhibition of several weeds as Abutilon theophrasti Medik, Aegilops tauschii Coss, Amaranthus retroflexus L., Avena fatua L., and Digitaria sanguinalis (L.) Scop. ...
Background
Weeds cause low crop productivity and increasing costs, and therefore, different solutions, such as manual weeding or synthetic herbicides, have been suggested to solve this problem. These methods involve high efforts and costs, in addition to being harmful to the environment in the case of herbicides, which also result in increasing resistance mechanisms in weeds. Therefore, this work addresses the use of in vivo allelopathic crops to control surrounding weeds. To carry out the experiments, co-cultivation of wheat, rice and barley with the monocot weed annual ryegrass (Lolium rigidum Gaud.) and the dicot weed common purslane (Portulaca oleracea L.) was conducted without physical contact among crop and weed plants. Germination and growth parameters of weeds, and growth parameters and chemical profile of crops, were analysed after the end of the experiment.
Results
The three crops tested caused inhibitory effects on the two target weeds, and significant concentrations of benzoxazinoids were found in the plant tissues and/or root exudates of the different crops in response to the presence of weeds. All the crops showed different responses to the treatments. While the growth of rice was stimulated, barley was not affected, and wheat growth experienced inhibition due to the presence of weeds.
Conclusions
This study demonstrates the capacity of wheat, rice and barley to inhibit both growth and germination of L. rigidum and P. oleracea. The effects observed could be due to the accumulation and/or exudation of benzoxazinoids such as DIMBOA, DIBOA, BOA or HBOA. Barley and rice are able to sustainably manage both target weeds without disrupting their development, while growth of wheat was affected by the presence of weeds. Based on our results, rice would be the most promising crop, since it has the ability to control weeds, while stimulating the development of rice plants. Nevertheless, more research should be carried out to fully confirm this fact, especially under non-controlled conditions.
Graphical Abstract
... Plant extracts may delay seed germination, inhibit plant growth, or cause other adverse effects due to the presence of allelochemicals Wang et al., 2024). Numerous studies have examined the allelopathic behavior and extract potential of certain graminoid species for weed control (Khamare et al., 2022;Mohamed Salman et al., 2024). The herbicidal potential of semi-arid plants such as Rhazya stricta, Citrullus colocynthis, Crotalaria burhia, and Calligonum polygonoides against Lathyrus aphaca, a common weed in wheat fields, has shown suppression rates ranging from 9% to 91% across various growth parameters, offering a sustainable alternative to synthetic herbicides (Iqbal et al., 2020). ...
This study explores the potential of ten arid dryland plant species as novel bioherbicides for the sustainable suppression of purple nutsedge (Cyperus rotundus L.), a troublesome weed in many ecosystems. We investigated the allelopathic effects of Calotropis procera, Alhagi maurorum, Tamarix aphylla, Aerva javanica, Capparis decidua, Withania coagulans, Leptadenia pyrotechnica, Haloxylon salicornicum, Fagonia indica, and Rhazya stricta using a factorial experiment arranged in a completely randomized design with four replications. Three treatments were compared: a control (C1), a crude aqueous extract (C2), and a 20-fold concentrated extract (C3). The concentrated extracts (C3) of all species completely inhibited the sprouting and growth of purple nutsedge. Notably, F. indica (P9 × C2) achieved 100% suppression even at the crude extract level, performing comparably to the concentrated extracts of the other species. H. salicornicum (P8 × C2) and L. pyrotechnica (P7 × C2) showed statistically similar suppression to F. indica. Other crude extracts significantly reduced sprouting percentage, sprouting energy, vigor index, shoot and root length, biomass, and chlorophyll index compared to the control, except for A. maurorum and W. coagulans. These findings underscore the potential of dryland plant extracts, especially F. indica, as promising natural herbicide sources for managing purple nutsedge. Incorporating these bioherbicides into integrated weed management strategies offers a sustainable and eco-friendly alternative to synthetic herbicides, reducing their usage and enhancing ecological health.
... The vacant space helps weeds grow, resulting in nutrient depletion through weeds (Kaur et al. 2018). Besides, the allelopathic effect of weeds on the growth of the main crop has also been recorded (Yuvraj et al. 2022). Thus, intercrop provides shelter/ cover to the soil, suppresses weed growth, provides greater below-ground productivity than sole crops, and sequesters more soil carbon over time due to more significant root litter input (Cong et al. 2015). ...
Autumn sugarcane planting provides ample scope for intercropping of ‘rabi’ season crops in available space between sugarcane rows. The component crops can grow with sugarcane because of the lesser tillering in winter. The intercrop affects the overall productivity and soil quality parameters. Thus, a field experiment was conducted from 2020–2021 to 2023–2024 for four consecutive years with the objectives (1) to assess the effect of different intercrops/ intercropping systems on soil quality parameters, (2) to assess the effect on system productivity, (3) to work out the economics of different intercropping systems, and (4) to suggest the most remunerative cropping systems for subtropical India. Nine treatments viz., T1: Sugarcane Sole, T2: Sugarcane + Mustard, T3: Sugarcane + Garlic, T4: Sugarcane + Onion, T5: Sugarcane + Carrot, T6: Sugarcane + Maize (green cobs purpose), T7: Sugarcane + Coriander (green leaf), T8: Sugarcane + Linseed, T9: Sugarcane + Lentil in different row arrangements were applied in field experiment conducted in randomized block design under three replications. Results briefly indicated that intercropping compatible crops with autumn-planted sugarcane improved soil quality parameters, viz., soil organic carbon, soil microbial biomass carbon, soil respiration, and available nutrient contents after harvesting the sugarcane crop. During 2020–2021 to 2023–2024, various intercrops reduced the mean sugarcane yield by 3.17% (sugarcane + garlic) to 20.05% (sugarcane + maize). However, system productivity could be improved up to 141.1% over the mean yield of sole cane (103.1 t/ha). Intercropping coriander (leaf purpose), garlic, and maize (cobs purpose) with autumn sugarcane was most remunerative compared to other intercrops. Sugarcane + coriander intercropping recorded the highest B:C ratio (2.69); however, the mean B:C of intercrops was 1.91 versus 1.52 with sole cane planting over the four years, indicating the intercropping systems' profitability.
