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Wheat (Triticum aestivum L.) is an important cereal crop in Pakistan which is suffering from major grain production loss because of weed infestations. Control of weeds by herbicides is a primary weed management tool in wheat crop which can be detrimental to the environment and grain produce. Development of an efficient and eco-friendly alternate to the herbicidal weed control, testing the effectiveness of cultural weed control (crop row orientation, selected wheat genotypes and hand weeding) and plants water extracts was undertaken for weed control in wheat. An experiment was run under field conditions in winter season in 2016–2017 and in 2017–2018 in Khyber Pakhtunkhwa Province, Pakistan. The repeated experiment was each time undertaken using a randomized complete block design with a double split plot arrangements at the New Developmental Farm, University of Agriculture, Peshawar, Pakistan. The crop row orientations used were assigned to the main plots. The wheat genotypes used were assigned to the sub-plots. The allelopathic water extracts and hand weeding were assigned to the sub-sub plots. The averaged mean values for row orientations of both the years revealed lowest weed density (95.7 weeds m−2), highest grains per spike (47.3), 1000 grains weight (44.7 g) in north to south row orientation. The averaged mean values of weed density (101.6 weeds m−2), grains per spike (48.2), 1000 grains weight (45.9 g), crude protein content (12.793%), crude fat content (1.533%) and ash content (1.586%) were greater for the wheat genotype Pirsabaq-2013 and Atta-Habib-2010. Water extract of S. halepense, P. hysterophorus, H. annuus and hand weeding showed significantly lower weed density (84.0 to 93.3), grains per spike (50.9 to 48.3), 1000 grains weight (48.3 to 46.2 g), grains protein content (12.280 to 12.209%), grains crude fat content (1.471 to 1.464%) and grains ash content (1.523 to 1.515%). Interaction effect of different tested weed control treatments i.e. N-S × Pirsabaq-2013 and Atta-Habib-2010 × water extract of S. halepense, P. hysterophorus and H. annuus were found to show further reduction in weed density and enhance grains per spike and grains nutrition contributing parameters. Our results show that sowing wheat genotypes Pirsabaq-2013 and Atta-Habib-2010 in north-to-south row orientation, and application of water extract of S. halepense, P. hysterophorus, H. annuus can give an effective weed management and increased quality grain yield of wheat.

The changed phenolic acids (PAs) allelochemicals exuded by the roots induced by interspecific interactions is related to intercropping alleviates soil-borne disease. However, the presence of PAs in roots and root exudations and their rhizodeposition under intercropping are still unclear. Hydroponic and soil experiments of wheat, faba bean, and wheat intercropped with faba bean were conducted, and the major compositions and contents of PAs in roots, root exudations, and rhizospheric soil were determined. The results showed that ρ-hydroxybenzoic, vanillic, and syringic acids were the major components of PAs in roots, root exudations, and rhizospheric soil in a wheat and faba bean intercropping system. The compositions and percentages of PAs in roots of faba bean were altered when faba bean intercropped with wheat. The total exudation rate of PAs in root exudations was decreased by 30%–60% under the wheat and faba bean intercropping (W//F) system as compared to mono-cropped faba bean (MF). ρ-hydroxybenzoic acid was identified in the root exudation of both MF and mono-cropped wheat (MW), but not detected in the intercropping on 60 days after transplanting. Vanillic acid was only detected in the root exudation of MF on 30 days after transplanting. The rhizodepostion of vanillic and cumaric acid were decreased at both branching and pod setting stages in W//F as compared to MF. In conclusion, interspecific interaction changed the compositions and contents of PAs in faba bean roots and root exudations. W//F constrained vanillic acid exuded by roots and decreased vanillic and coumaric acid rhizodeposition by faba bean, which provides insight into root-soil interactions in the intercropping systems.

Weed management is essential for sustainable crop production in all cropping systems. The use of herbicides is causing the problems of herbicide resistant weeds and environmental pollution. Plant-released phytotoxins have ability to promote or inhibit the germination and seedling growth of surrounding crops and weeds. Therefore, it is imperative to identify plant species having the herbicidal potential to use as more safe and sustainable weed management approach. The present study was planned in 2018 to investigate the germination and seedling growth of Daucus carota and Medicago polymorpha influenced by the root extract of Polygonum bistorta and fruit extract of Terminalia chebula. Different concentrations of aqueous extract (0, 2.5, 5, 10, 20, 40 and 80%) significantly reduced the germination and seedling growth of target species. Results of these experiments revealed that thefruit extract of T. chebula was more phytotoxic as compared to root extract of P. bistorta regarding seedling growth of weed. However, fruit extract of T. chebula having 80% concentration fully inhibit the germination of D. carota and M. polymorpha. One the bases of these finding it was concluded that the fruit extract of T. chebula and root extract of P. bistorta have comparatively more active substances with ability to suppress germination and growth of plants which could be exploited as prospective source of bio-herbicides. O manejo de ervas daninhas é essencial para a produção agrícola sustentável em todos os sistemas de cultivo. O uso de herbicidas está causando problemas de ervas daninhas resistentes a herbicidas e poluição ambiental. As fitotoxinas liberadas pelas plantas têm a capacidade de promover ou inibir a germinação e o crescimento das mudas de culturas e ervas daninhas circundantes. Portanto, é imperativo identificar espécies de plantas com potencial herbicida para uso como abordagem de manejo de ervas daninhas mais segura e sustentável. O presente estudo teve como objetivo investigar a germinação e o crescimento de plântulas de Daucus carrota e Medicago polymorphaas influenciados pelo extrato de raiz de Polygonum bistorta e extrato de fruto de Terminalia chebula. Diferentes concentrações de extrato aquoso (0, 2, 5, 5, 10, 20, 40 e 80%) reduziram significativamente a germinação e o crescimento de plântulas das espécies-alvo. Os resultados desses experimentos revelaram que o extrato do fruto de T. chebula foi mais fitotóxico do que o extrato da raiz de P. bistorta em relação ao crescimento de mudas de plantas daninhas. No entanto, o extrato de frutos de T. chebula com concentração de 80% inibe totalmente a germinação de D. carrota e M. polymorpha. Uma das bases deste achado concluiu-se que o extrato do fruto de T. chebula e o extrato da raiz de P. bistorta possuem comparativamente mais substâncias ativas com capacidade de suprimir a germinação e o crescimento das plantas, o que poderia ser explorado como fonte potencial de bio-herbicidas.

This study was conducted to evaluates the allelopathic potential of Peganum harmala L. (Zygophyllaceae) on the growth of Cynodon dactylon L. (Poaceae). Seeds, stems, and a mixture of (seeds and stems) aqueous extracts of P. harmala plants were applied as a foliar application to three weeks old seedlings of Cynodon dactylon weeds. The result indicated that the application of aqueous extracts of different plant parts of P. harmala caused a significant reduction in growth traits of Cynodon dactylon including plant height, number of branches, number of leaves, and plant weight. Moreover, the result revealed that the Inhibitory effect of P. harmala aqueous extract on Cynodon dactylon L was more pronounced in plant height and number of leave plant-1 traits. In addition, the results illustrated that among the different P. harmala plant parts used in this study, seeds extract was the most toxic and caused the greatest negative effect on growth traits of Cynodon dactylon. According to the results, the degree of toxicity of different P. harmala plant parts can be arranged in the following order: seeds > mixture > stems. The results of this study concluded that the use of Peganum harmala L plant has the potential to be developed further as a bio-herbicide system to control weed such as Cynodon dactylon L.

Background: Roadside grass cuttings are currently considered a waste product due to their association with road sweepings as contaminated waste, therefore, their potential as a biofertilizer is understudied. Aim: This study aimed to determine whether grass liquid fraction (GLF) collected from a roadside verge in Maldegem, Belgium, and pressed using a screw press was suitable as a biofertilizer. Methods: The characterization of the heavy metal content of the GLF was conducted using an ICP-OES. From May to September 2019, a pot experiment was set up using a randomized block design to compare tomato plant growth, yield, and nutrition for GLF-treated plants to two commercial fertilizers and tap water as a control. Results: The heavy metal content of the GLF was below the maximum permissible concentrations (MPCs) for organic fertilizers as set out by the European Comission fertilizer regulation 1069/2009 and 1107/2009 (European Comission, 2019). However, despite having a fairly well-balanced nutrient content (0.1% N, 0.04% P2O5, and 0.2% K2O), GLF had a negative effect on the growth, root weight, and yield of the tomato plants, killing six out of ten plants. GLF also promoted mold growth in the soil of some plants. Since the GLF was uncontaminated, heavy metal toxicity did not cause the negative effect. Conclusions: Previous research showed that liquid fractions from some plants negatively affect the growth of others due to allelopathic chemicals; this, together with the stimulation of fungal growth, could have caused the negative effects observed. Future experiments will investigate the herbicidal property of GLF and possible treatments to potentially recover the nutrients contained within the GLF for application as a biofertilizer.

Allelopathy, i.e. plant-plant inhibition via the release of secondary metabolites into the environment, has potential for the management of weeds by circumventing herbicide resistance. However, mechanisms underpinning allelopathy are notoriously difficult to elucidate, hindering real-world application either in the form of commercial bioherbicides or allelopathic crops. Such limited application is exemplified by evidence of limited knowledge of the potential benefits of allelopathy among end-users. Here, we examine potential applications of this phenomenon, paying attention to novel approaches and influential factors requiring greater consideration, with the intention of improving the reputation and uptake of allelopathy. Avenues to facilitate more effective allelochemical discovery are also considered, with a view to stimulating the identification of new compounds and allelopathic species. Synthesis and Applications: We conclude that tackling increasing weed pressure on agricultural productivity would benefit from greater integration of the phenomenon of allelopathy, which in turn would be greatly served by a multi-disciplinary and exhaustive approach, not just through more effective isolation of the interactions involved, but through greater consideration of factors which may influence them in the field, facilitating optimisation of their benefits for weed management.

Murray-Darling Freshwater Research CentreMDFRC item.1. The hypothesis is tested that large daphnids are able to suppress their own and other species' feeding and reproduction by means of excreting an inhibitory chemical (or chemicals).2. In laboratory experiments with an Australian species, Daphnia carinata, water preconditioned with 3–67 daphnids 1-−1 for 30 h had the effect of reducing feeding rates of D. carinata and D. lumholtzi provided with Selenastrum capricornutum.3. For the two Daphnia species, there were highly significant negative correlations between feeding rate and the preconditioning density of D. carinata.4. Water preconditioned with 20–30 daphnids 1-−1 for 1–2 weeks reduced the grazing rates of Daphnia, Moina, and Diaphanosoma 2–3-fold.5. Moina kept in such water for 2 days stopped feeding. Conditioned water kept for 3 days without animals still inhibited grazing by Moina. Hearing to 100°C removed the inhibitory effect.6. Given excess food, and in non-renewed water, a gradient of D. carinata densities developed a strong negative correlation between clutch size and daphnid density after a 6-day time lag. This result may help explain the direct density-dependent regulation of cladoceran reproduction observed earlier in a subtropical lake.

The congeneric approach assesses the relative role of exotic invasive plants compared to native plants on associated species. However, most studies on seed germination have been conducted in Petri dishes that do not reflect natural soil conditions. Here, we compared the effects of different litter extracts of the exotics Prosopis juliflora (Sw.) DC. and Prosopis pallida (Willd.) Kunth, as well as native Prosopis cineraria (L.) Druce, on seed germination and seedling dry weight of two weedy plants (Amaranthus graecizans L. and Sisymbrium irio L.) and the native Senecio flavus (Decne.) Sch.Bip. in both Petri dishes and potted soil experiments. The results indicate that non-treated seeds (control) of the three species attained more than 95% germination in the Petri dishes (in vitro). The increase in the litter concentrations of both invasive Prosopis species inhibited the native Senecio flavus germination and significantly reduced germination and seedling weight of the weedy A. graecizans and Sisymbrium irio. Nevertheless, the native P. cineraria extracts had significant depressive effects on seed germination and seedling growth of the native Senecio flavus but limited effects on the weedy A. graecizans and Sisymbrium irio. The results support a greater impact of exotic than native congener on native plants. To better assess allelopathic effects, it is recommended to not rely on germination in Petri dishes.

The cucurbitaceae family comprises of economically important vegetable crops grown for food and medicine. Most cucurbit crops produce cucurbitacins in leaves, flowers, fruit, seed and roots which possess various pharmacological and pharmaceutical values. Cucurbitacins are toxic to pests and diseases, and allelopathic to noxious weeds thus providing opportunities for improving tolerance to biotic stresses. Further, cucurbitacins are responsive to environmental stimuli and can therefore enhance tolerance to abiotic stress. The objective of this review was to highlight the breeding value of cucurbitacins to develop cucurbitacins-enriched genotypes for food and medicine, and for management of biotic and abiotic stresses. The following themes were discussed: a comparative analysis of cucurbitacin concentrations in edible and non-edible plant parts; genetic control and associated quantitative trait loci and molecular markers associated with cucurbitacins; pharmacological and pharmaceutical values of cucurbitacins, and potential applications for management of biotic and abiotic stresses. Results of the present study will guide genetic improvement of cucurbitacins for use as food and medicine, and in the development of genotypes tolerant to biotic and abiotic stresses.

A pot experiment was conducted at Alzaiem Alazhari University during 2020/2021 to study the effect ofAmaranthus viridispowder incorporated into the soil on germination and growth of garden rocket (Eruca sativa). The experiment was arranged in completely randomized design (CRD) with four replicates. Five concentrations (0, 0.5, 1.0, 1.5 and 2.0% w/w) on basis ofAmaranthus viridispowder incorporated in the soil. Results indicated thatAmaranthus viridispowder decreased germination, shoot length, leaf area, shoot and root fresh and dry weight as well as chlorophyll content and some chemical elements (P, Ca, Mg, Fe).

A pot experiment was conducted at Faculty of Education, Alzaiem Alazhari University, Sudan, during 2019/2020 to evaluate the effect ofAmaranthus viridispowder on the emergence and growth of Swiss chard (Beta vulgarisvar. cicla). The experiment was set as a completely randomized design (CRD) with four replicates. In the treatments the powder ofAmaranthus viridiswas incorporated into the soil at rate of (0, 0.5, 1.0. 1.5 and 2.0% w/w) representing T1(control), T2, T3, T4and T5respectively. Results indicated thatAmaranthus viridispowder decrease germination, plant height, number of leaves, leaf area, shoot and root fresh and dry weight, chlorophyll content (a, b) and some chemical elements (P, Ca, Mg, Fe) of Swiss chard (Beta vulgarisvar. cicla).

Allelopathy is a plant-plant interaction in which one plant releases biologically active compounds that have negative effects on the fitness of the target plant. The most pronounced effects are inhibition of seed germination and growth of neighboring plants. The roots of these plants are in contact with the allelochemicals released into the soil, as the primary target of the allelopathic action. To date, the best documented allelopathic activities relate to some weeds and invasive alien plants that show rapid spread and successful growth. A better understanding of the mechanisms of allelopathy will help to improve crop production and to manage and prevent plant invasions. At the cellular level, allelochemicals induce a burst of reactive oxygen species in the target plants, which leads to oxidative stress, and can promote programmed cell death. Lipid peroxidation and cell membrane changes, protein modifications, and increased protease activities are the early signs of cell damage. When enzymatic and nonenzymatic antioxidants cannot scavenge reactive oxidants, this can result in hydrolytic or necrotic degradation of the protoplast. Cell organelles then lose their integrity and function. In roots, the structure and activity of the apical meristem are changed, which affects root growth and water absorption. Such allelopathically active compounds might thus be applied to control and manage weeds and invasive plants in a more sustainable way, to reduce chemical pollution.

The aim of this study was to test the allelopathic effects of the plant extracts isolated from immature walnut fruits on the germination and early seedling growth of two weed species (Amaranthus retroflexus and Chenopodium album), and its phytotoxic effects on the germination and early seed growth of maize, Zea mays. Additionally, the goals was to also conduct an analysis of the plant extracts and determine its antioxidant properties. Antioxidant activity of the plant extracts were determined via its ability to neutralize DPPH (2,2-diphenyl-1-picrylhydrazyl) radicals and by testing their potential for iron reduction using the FRAP method. The inhibition of the measured parameters (total germination and seedling length) decreased proportionally, with the reduction of concentrations of plant extracts isolated from immature walnut fruits. Also, the seedling length parameter has shown greater sensitivity when compared with the parameters of total seed germination in both weed species. Even though the results of both biotests with seeds show a high inhibitory effect on the germination and early growth of the tested weed species, they also point to phytotoxicity in early growth of Z. mays seeds. Future research will be focused on the HPLC analysis of the plant extracts isolated from immature walnut fruits and their allelopathic effects on the early growth of plants of the tested species.

Florações de cianoabactérias são consideradas um dos maiores desafios na preservação de fontes hídricas, especialmente quando estão presentes espécies como Microcystis aeruginosa. A descoberta de alternativas de remediação faz-se necessária, e uma delas é o uso de macrófitas aquáticas, como as espécies do gênero Myriophyllum, que apresentam atividades alelopáticas para o controle fitoplanctônico. Diante disso, este trabalho teve como objetivos avaliar a inibição do crescimento de células de M. aeruginosa em uma coexposição com Myriophyllum aquaticum e avaliar a remoção de microcistina-LR. Os experimentos foram conduzidos com cultivos de M. aeruginosa (1x106células mL-1) em coexposição com M. aquaticum por sete dias. Os efeitos inibitórios foram investigados por contagem celular. Os efeitos nos pigmentos fotossintéticos foram mensurados, além da quantificação de microcistina-LR no último dia experimental. Para avaliar possíveis efeitos de competição por nutrientes e espaço, realizou-se a quantificação da concentração de ortofosfato total e utilizou-se um tratamento com planta de plástico. Os experimentos com M. aquaticum apresentaram inibição total do crescimento de M. aeruginosa e redução significativa na concentração dos pigmentos fotossintéticos (> 98%). Além disso, foi constatada redução na concentração de microcistina-LR (79%) nos testes com macrófitas quando comparadas ao grupo controle. Não foi observada competição por espaço e nutrientes, o que demonstra que os efeitos sobre M. aeruginosa foram causados pela presença da macrófita aquática. Dessa forma, estes resultados podem demonstrar que M. aquaticum gerou a inibição no crescimento de cianobactérias por efeitos alelopáticos, além de remover a microcistina-LR das águas. Harmful algal blooms are one of the greatest challenges when preserving water sources, especially when involving cyanobacteria such as Microcystis aeruginosa. Finding remediation possibilities is needed, and one of them has been the use of macrophytes such as the species Myriophyllum, which have presented allelopathic mechanisms of phytoplankton control. Thus, this work aimed to evaluate the inhibition of M. aeruginosa cell growth in a co-exposure with Myriophyllum aquaticum and the influence on microcystin-LR concentration. The experiments were carried out using a culture of M. aeruginosa (1x106 cells mL-1) in a co-exposure with M. aquaticum for seven days. The inhibitory effects were investigated by counting the cells; the effects on photosynthetic pigments were measured and microcystin-LR was quantified in the culture medium on the last experimental day. To evaluate the possible effects of competition for nutrients and space, the concentration of total orthophosphate was quantified and treatment with plastic plants was used. The experiments with Myriophyllum aquaticum achieved the total inhibition of M. aeruginosa growth and a significant reduction of the photosynthetic pigments (> 98%). Additionally, we observed a reduction of microcystin-LR concentration (79%) in the tests with macrophytes when compared to the control. Competition for space and nutrients was not observed, demonstrating that the effects on M. aeruginosa were caused by aquatic macrophyte presence. These results may indicate that M. aquaticum causes inhibitory effects on cyanobacteria growth by allelopathic effects and removes microcystin-LR.

Premise of research. The gametophytes of ferns are nutritionally independent of the sporophytes and are potentially hermaphroditic. The sexual expression of fern gametophytes is based on environmen...

A comprehensive understanding of mechanisms of allelopathy and resource availability is critical for protecting rare and endangered species, biodiversity, and ecosystems. We treated 20 major plant species with three concentrations of an aqueous extract of Dacrydium pierrei Hickel litter and different irrigation and nutrients to compare the relative importance of allelopathy and resource availability on roots, stem growth, and seed germination, using bioassays. The results showed that the height, ground diameter, and aboveground biomass of individuals increased more quickly in the early stage, and the rate of increase tended to slow down in the later stages. The allelopathy was species specific (inhibitory, neutral, or promotive), and the survival rate and growth rate of saplings changed significantly along a resource treatment gradient (P < 0.05), indicating that the native species diversity was reduced by lower or higher resource availability in natural forests. The effect of allelopathy on trees was relatively weak during the treatments, and that of resource availability was relatively strong. Resource availability is relatively more important than allelopathy in mediating the reduction in plant biodiversity. Therefore, water and nutrient availability and the species and number of allelochemicals released by plants have substantial influences on the survival and growth of plant species in a natural Dacrydium forest.

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 index (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.

One new eudesmane sesquiterpene 1 and one new chromolaevane sesquiterpene 2, along with 19 known compounds, have been isolated from the invasive plant Solidago canadensis. Their structures were established by spectroscopic means, including 1D/2D-NMR and HR-ESIMS analyses. Compounds 10 and 12, in combination with fluconazole, showed significant activity in an in vitro synergistic antifungal assay against Candida albicans, with FIC values of

Cilj istraživanja bio je utvrditi alelopatski potencijal lucerne (Medicago sativa L.) na klijavost sjemena i rast klijanaca rotkvice (Raphanus sativus L.), radiča (Cichorium intybus L. var. foliosum) i rajčice (Lycopersicon esculentum Mill.). Vodeni ekstrakti pripremljeni od suhe nadzemne mase lucerne u tri koncentracije (1 %, 2,5 % i 5 %) testirani su u laboratorijskim uvjetima. Alelopatski potencijal lucerne ovisio je o test vrsti, koncentraciji vodenog ekstrakta te mjerenom parametru. Najslabije djelovanje zabilježeno je na klijavost te rast klijanaca rajčice. Povećanjem koncentracije vodenog ekstrakta povećavao se i negativni alelopatski potencijal. Najmanji utjecaj vodenih ekstrakata zabilježen je na suhu masu klijanaca test vrsta., The aim of the study was to determine the allelopathic potential of alfalfa (Medicago sativa L.) on seed germination and seedling growth of radish (Raphanus sativus L.), radicchio (Cichorium intybus L. var. foliosum) and tomato (Lycopersicon esculentum Mill.). Water extracts prepared from dry alfalfa biomass in three concentrations (1%, 2.5% and 5%) were tested under laboratory conditions. The allelopathic potential of alfalfa depended on the test species, the water extract concentration, and the measured parameter. The weakest effect was recorded on germination and growth of tomato seedlings. As the concentration of the water extract increased, the negative allelopathic potential also increased. Dry weight of seedlings of test species was the least affected.

Sicklepod is an important weed in Brazil pastures, but control measures are not yet effective. Thus, allelopathy can be an alternative, due to its ecological importance and for being able to provide new structures sources for agrochemicals production. This research aimed to verify the allelopathic potential of sesame (Sesamum indicum L.) on germination and seedling development of sicklepod (Senna occidentalis L.) and brachiaria (Brachiaria brizantha). The treatments were root and leaf extract of sesame, and control (distilled water). Germination percentage, speed of germination, hypocotyl and radicle length were evaluated. Speed of germination, germination percentage and radicle length had no interference from the aqueous extracts. However, in brachiaria these traits had lower values than sicklepod. Hypocotyl length was not influenced by the extracts, however, the leaf extract showed lower growth of this feature. Allelopathy did not affect germination and speed of germination in both species, but interfered in brachiaria development.

In aquatic ecosystems, allelopathic activity depends on the production and secretion of allelopathic compounds and their effective dispersal in the environment. In addition, macroalgae have been found to produce active metabolites that affect other organisms that compete with them for nutrients. However, the allelopathic activity of Baltic red and brown macroalgae on filamentous cyanobacteria is still insufficiently understood. Therefore, the main objective of this study was to demonstrate and compare the allelopathic effects of macroalgae Fucus vesiculosus L. and Coccotylus brodiei (Turner) Kütz. on the growth and photosynthetic activity of two Baltic cyanobacteria Aphanizomenon sp. and Nostoc sp. It was found a stimulating effect of different concentrations (5, 25, and 50 µL mL–1) of the aqueous extract obtained from C. brodiei on the number of cells of Nostoc sp. which constituted 108%, 140%, and 147%, respectively, relative to the control treatment. On the other hand, extracts obtained from F. vesiculosus had no statistically significant effect on the number of cells of the cyanobacteria Aphanizomenon sp. and Nostoc sp. Moreover, the C. brodiei extracts had no significant impact on the growth of Aphanizomenon sp. Furthermore, Baltic macroalgae F. vesiculosus and C. brodiei was able to exert allelopathic effects on photosynthesis performance of Nostoc sp. and Aphanizomenon sp. and compounds produced by them had inhibitory, stimulatory, or no significant effect on the maximum PSII quantum efficiency (Fv/Fm) and the effective quantum yield of PSII photochemistry (ΦPSII). The results obtained in this work constitute an important contribution to the knowledge on the allelopathic activity of Baltic red and brown algae on certain bloom-forming species of filamentous cyanobacteria.

Summary Allelopathic effects of different plant allelochemicals have become the focus of studies that aim to determine new pesticidal compounds. Plant extracts with different chemical compositions can be obtained using different methods of extraction, whereas studies dealing with allelopathic properties use biotests to obtain fast and precise results. Such studies were undertaken after noticing the allelopathic effects of industrial hemp (Cannabis sativa L.) on the surrounding crops. Trials that involve the application of hemp extracts obtained by different methods resulted in determining the hemp allelopathic effects on Stellaria media (L.)Scop., Beta vulgaris ssp. vulgaris var. vulgaris, Lupinus albus L., corn (Zea mays L.), Cyperus rotundus L., Matricaria recutita L., Lepidium sativum L., lettuce (Lactuca sativa L.), rapeseed (Brassica napus L.), wheat (Triticum aestivum L.), rye (Secale cereal M. Bieb.), Ambrosia artemisiifolia L., Chenopodium album L., and Sorghum halepense L..

Alfalfa (Medicago sativa L.) establishment failure is often attributed to autotoxicity when alfalfa is reseeded shortly after termination of the previous alfalfa stand, but renovation/rotation strategies for irrigated semiarid, subtropical environments have not been studied. Two identical studies were initiated at the New Mexico State University Rex E. Kirksey Agricultural Science Center at Tucumcari, NM, USA to compare continuous alfalfa (ALF), a single year of rotation to sorghum-sudangrass (SS1, Sorghum bicolor × S. sudanense (Piper) Stapf), two years of rotation with sorghum-sudangrass (SS2), and winter wheat forage (Triticum aestivum L.) followed by a single season of sorghum-sudangrass (WW/SS). Soil type and renovation/rotation strategy may influence soil fertility prior to replanting alfalfa, but soil fertility did not appear to influence alfalfa re-establishment or first production year yields. With a Test x Rotation interaction due to differences between tests for WW/SS for first production year yield after September alfalfa replanting, the main effect of Rotation was significant for yield (6.43AB, 5.3B0, 6.92A, and 3.54C Mg ha−1 for ALF, SS1, SS2, and WW/SS, respectively, 5% LSD = 1.22). Alfalfa stand destruction and replanting with no intervening crop rotation may be feasible in sandy soils with irrigation in the semiarid, subtropical southwestern USA and similar environments.

The application of biochar and plant‐growth‐promoting bacteria (PGPBs) in biocontrol soil‐borne pathogens has garnered worldwide interest recently. However, how agricultural replanting disease is alleviated by a combination of biochar and PGPBs treatment (SYBB) remains largely unexplored. In this study, we investigated the beneficial effects of single biochar addition and the combination of biochar and PGPBs on alleviating replanting disease by altering the rhizosphere microbiome and metabolites. Our field experiment showed that the SYBB treatment had a better alleviating effect on replanting disease than the single biochar addition. The study indicated the dominant effect of deterministic processes on the bacterial community and of stochastic processes on the fungal community under biochar and PGPBs treatment. The combination of biochar and PGPBs tended to convert the stochastic processes of fungal community assembly into deterministic processes. We found SYBB treatment increased the abundance of potentially beneficial Pseudomonas, Lysobacter, Gemmatimonadetes and Nitrospira, and decreasing the abundance of potentially pathogenic Fusarium, Talaromyces and Fusarium oxysporum. Moreover, the SYBB treatment increased the abundances of carbohydrates, fatty acids and plant hormones, and decreased the abundances of amino acids in the rhizosphere soil. Co‐occurrence network analysis indicated that SYBB treatment increased the connections within the microbial communities and drove the alteration of co‐occurrence network among the microbial communities and metabolites, which increased positive correlations in bacteria‐metabolite networks and decreased positive correlations in fungi‐metabolite networks. Spearman correlation analysis showed the abundances of beneficial Streptomyces, Pseudomonas and Lysobacter were significantly and positively correlated to the metabolites most increased under SYBB treatment. The combination of biochar and PGPBs alleviated replanting disease by mediating the change of rhizosphere soil metabolites, and stimulating the proliferation of indigenous and beneficial soil microbes. The research results are intended to provide the basis for new strategies for green and sustainable remediation of soil‐borne pathogens.

Over the decades the presence of aquatic weeds has caused immense biodiversity loss to the ecosystem. The use of herbicides has arisen emergence of herbicide-resistant weeds and loss of inherent flora and fauna due to the recalcitrant nature of the chemicals used. Hence, there is a need to use nontoxic, ecosustainable, low-cost, and efficient biological molecules that are analogous to chemical herbicides. Various plants, bacteria, fungi as well a few viruses are reported to secrete allelopathic biomolecules that inhibit the growth and development of weeds. However, majorly fungal pathogens and their metabolites are found to be effective biocontrol agents for the water hyacinth. The present review puts forward major findings and interventions in the biological control of the weed, water hyacinth. The biosynthesis, mechanism of action and factors regulating the activity of bioherbicides are discussed. In addition, the issues associated with the in situ application of these bioherbicides are also conferred focusing on the available mode of applications and formulation used. The major factors include the type and concentration of allelopathic biomolecules, age, type, and morphology of targeted weed, formulation type, mode of application and other physiological and environmental factors. Among various modes for the application of bioherbicides, emulsions are found to be most effective for the control of water hyacinth. Most of the toxicity studies indicated no toxicity of this fungal pathogen to other ecological plant species except water hyacinth. Yet, in-depth investigations are needed of these allelochemicals and toxins before field applications. Overall, lab-scale studies have shown promising results and highlighted a few potential fungi that need to be further explored for optimizing their bioherbicidal activity.

Allelopathy (i.e., chemical interaction among species) was originally conceived as inclusive of positive and negative effects of plants on other plants, and we adopt this view. Most studies of allelopathy have been phenomenological, but we focus on studies that have explored the ecological significance of this interaction. The literature suggests that studies of allelopathy have been particularly important for three foci in ecology: species distribution, conditionality of interactions, and maintenance of species diversity. There is evidence that allelopathy influences local distributions of plant species around the world. Allelopathic conditionality appears to arise through coevolution, and this is a mechanism for plant invasions. Finally, allelopathy promotes species coexistence via intransitive competition, modifications of direct interactions, and (co)evolution. Recent advances additionally suggest that coexistence might be favored through biochemical recognition. The preponderance of phenomenological studies notwithstanding, allelopathy has broad ecological consequences.

Azadirachta indica have allelopathic potential, attributed to the presence of allelochemicals capable of altering plant diversity in surrounding areas. This work aimed to evaluate if the decomposed leaves of A. indica can affect the germination and growth of Myracrodruon urundeuva. A. indica leaves were collected at the end of senescence and mixed with soil in different concentrations and decomposed for 90 and 180 days. Through phytochemical analysis, it was found the presence of diterpenes and triterpenes, such as margocinolide, epoxyazadiradione and salimuzzalin. Leaf decomposition negatively affected germinability, emergence speed and the germination synchrony index of M. urundeuva, especially during the first decomposition period. The residues of the leaves of A. indica also negatively affected the length of the young plants of M. urundeuva, since the lengths of the stem and root were reduced, and the treatment of lower concentration a reduction in root length was observed only in the first decomposition period (T1). Leaf residues in the first decomposition time also negatively influenced the total biomass of M. urundeuva, in all treatments evaluated. The decomposition were also able to change the amount of photosynthetic pigments in the first decomposition period, since the total chlorophyll content had a reduction from the average value of 3.23 to 2.40 g/kg, corresponding to a 25.71 inhibition. The observed results suggest that the compounds present in the litter of A. indica have an allelopathic action, being necessary to limit the use of the former in areas that need ecological restoration and in preserved natural environments.

Prymnesium parvum is a toxin-producing harmful alga that has caused ecological and economic damage worldwide. Effective methods to control blooms of this species in the field, however, are unavailable. This study examined five natural compounds present in the invasive plant Arundo donax and one synthetic derivative (5,6-dichlorogramine) for their effect on P. parvum growth. All compounds except one inhibited growth in the following order of potency: ellipticine > > 5,6-dichlorogramine > 1 H-indole = 2,4,6-trimethyl-benzonitrile > gramine. Ellipticine was by far the most potent inhibitor, with full algicidal activity at concentrations as low as 0.04 mg L−1 and 3- and 9-day IC50 values of 0.012 and 0.007 mg L−1, respectively. A reduction in chlorophyll content and swimming activity and an increase in length and volume (swelling) were documented in algal cells exposed to 0.01–0.02 mg ellipticine L−1. These results show that ellipticine is among the most potent natural algicides identified to date. The sixth compound tested, oleamide, unexpectedly stimulated algal growth above control levels. Overall, these observations confirm the existence of highly potent anti-P. parvum allelochemicals in giant reed and demonstrate potential for using products derived from this plant in the development of natural, environmentally friendly methods to control harmful algal blooms.

Tectona grandis L.f. (Teak) is a highly cultivated forest species in Brazil. When industrially processed, it generates a large amount of sawdust, a waste that has limited reuse and accumulates in the industrial yards. The aim of this study was to evaluate the effect of fresh teakwood sawdust on the development of Urochloa brizantha (Hochst. ex A.Rich.) R.D.Webster cv. Xaraés in a nursery. The treatments consisted of concentrations of 0, 5, 10, 20, 33 and 50% of sawdust, arranged in four randomized blocks in split-plots. At 45, 75 and 120 days, plant heigh (h), average tillers diameter (d), number of live (nll) and dead leaves per plant, fresh and dry mass of shoots and roots, and Dickson's quality index (dqi) were measured. There was a decrease in h growth, d, nll, fresh and dry mass of shoots and roots and in the dqi of the cv. Xaraés as it increased to concentration of wood sawdust in the substrate. This negative effect can be attributed to the high C/N ratio of sawdust (196/1), which influences the decomposition of organic matter. In addition, the possible Teak allelopathic effects, which are the subject of other studies, should be considered. Unlike the other variables, number of live leaves was not influenced by the treatment with 5% sawdust. Teakwood sawdust has negative effects on the U. brizantha cv. Xaraés development.

Blooms of freshwater toxic cyanobacteria are a growing environmental health problem, enhanced by anthropogenic eutrophication and climate change. A variety of techniques were tested for their remediation, from physical methods using artificial mixing or flocculation, to chemical methods employing synthetic and natural compounds, as well as constructed wetlands. In this work, we conducted an evaluation at microcosm scale of the usefulness of the allelochemicals produced by a strain of the filamentous cyanobacteria Phormidium sp. for the bioremediation of proliferations of four strains of toxic freshwater cyanobacteria (Cylindrospermopsis raciborskii, Chrysosporum ovalisporum, Anabaena sp. and Nodularia sp.). Allelochemicals produced by this strain of Phormidium sp. belong to the portoamides compounds family. Their effect was tested in bioassays using cell-free filtrate, the results showing that all the four strains were sensitive. In addition, we performed phosphate-limited long-term competition experiments in continuous cultures, in which Phormidium sp. was co-cultured with each of the toxic cyanobacterial strains. The purpose of these later experiments was to demonstrate that allelopathy and not resource competition was responsible for the ecological exclusion of the toxic cyanobacteria strains, and also to employ higher population abundances to test the effectiveness of the allelochemicals. Before that, we needed to estimate the competitive ability of each species to limit the resource that we employed (phosphate). Phormidium sp. were clearly a better competitor for phosphate than Anabaena sp., worse than Nodularia sp., and very similar to C. raciborskii and C. ovalisporum. Only in the case of Nodularia sp. could we demonstrate that the ecological exclusion of the toxic cyanobacteria was caused by allelopathy. However, the rapid exclusion shown in our experiments suggests that allelopathy was the main cause in all cases. An inter-specific competition model including only competition for phosphate and an allelopathic interaction was able to accurately describe the patterns of population dynamics observed in our experiments.

Allelopathy can have an important applicaiton in areas of agriculture, especially in integrated protection from weeds, by using of allelopathic crops in different ways. In this research allelopathic effects of invasive species acacia (Robinia pseudoacacia L.) and white goosefood (Chenopodium album L.) are explored on germination of tomato (Solanum lycopersicum L.). Water extracts of dry leaves of white goosefoot and acacia are prepared according tothe method : Norsworthy (2003). Experiment has been made in controlled laboratory conditions. Results of this research show that acacia and white goosefood have negative allelopathy potential and they act inhibitory on germination of tomatoes. Research of allelopathy and allelopathic relationships of weed species and agricultural cultures represents a big challenge for those people who are working in food production, and at the same time can be an instrument of ecologically sustainable agriculture.

Pruning Ficus trees in urban green spaces may lead to the accumulation and spread of their leaf litter on the understory vegetation. This study was conducted to evaluate the allelopathic effect of Ficus retusa L. leaf litter on the understory species in urban gardens. A field study showed that the plant cover and species richness of litter-affected plots were lower than those of litter-free areas. The litter-affected soils had substantially lower pH and higher electrical conductivity. In a greenhouse experiment, litter-affected soil significantly inhibited the emergence and growth of understory species selected for the purpose of this study: Melilotus indicus (L.) All., Trifolium resupinatum L. and Amaranthus viridis L. Osmotic potentials equivalent to those of the litter-affected soils did not affect emergence or growth of these species. A spectrophotometric analysis indicated that the litter-affected soils contained larger amounts of phenolics and flavonoids. An HPLC analysis revealed that the litter-affected soils contained higher concentrations of free phenolic and flavonoid allelochemicals. These results demonstrate that F. retusa leaf litter may reduce plant cover and species richness. The significant inhibition in both field and greenhouse experiments could be attributed to phenolic and flavonoid allelochemicals released from the tree litter, as the osmotic potential of the litter had no effect on the understory species. The allelopathic potential of F. retusa leaf litter plays at least a partial role in reducing urban vegetation.

Allelopathy is the effect of one plant species by reducing the germination and growth of the neighbouring plants of another species through releasing chemical compounds. It has been reported by many researchers that weeds are major hazard in reducing crop yield but it can be managed effectively through phytotoxic properties of plants. A field study was conducted at Students Experimental Farm, Agronomy Department, Crop Production Faculty, Sindh Agriculture University Tandojam, Pakistan during spring 2019 and repeated during 2020 to validate the previous results. The research conducted to evaluate the allelopathic potential of sunflower and Bermuda grass extracts under various irrigation levels on weeds density and yield of mungbean cultivar ‘AEM-96’. Split plot design having four replications was managed. The experiment consisted of weed control practices: Weedy check, various levels of sunflower and bermuda grass extracts as sole and in combination with each other, different levels of herbicides as alone and in integration with allelopathic plant extracts as well as hand weeding under three irrigation frequencies (2, 3 and 4 watering applications). The analysis variance of results showed that various levels of sunflower and bermuda grass extracts as sole and in combination with each other, different levels of herbicides as alone and in integration with allelopathic plant extracts as well as hand weeding caused significant suppression of weeds and increased in seed yield as compared to weedy check. The combined treatment Atlantis: 0.1 Ltr ha-1 + Puma Super: 0.156 Ltr ha-1 + Sunflower extract: 15 L ha-1 resulted in less weed density (51.6 m-2) and produced maximum seed yield of 2404.4 kgs ha-1. Bermuda grass extract: 15 Ltr ha-1 integration with low dose of herbicides Atlantis: 0.1 Ltr ha-1+ Puma Super: 0.156 Ltr ha-1 showed weed density of 61.3 m-2 resulted seed yield of 2282.1 kgs ha-1. The application of herbicides treatment Atlantis: 0.2 Ltr ha-1 + Puma Super: 0.312 Ltr ha-1 suppressed weed density of 70.9 m-2 and produced seed yield of 2162.5 kgs ha-1. It is noted that Hand weeding: 30 days after sowing showed weed density of 76.1 m-2 and seed yield 2042.5 kgs ha-1. The combined allelopathic plant applications of Sunflower +Bermuda grass extract each: 15 Ltr ha-1 reduced weed density 80.7 m-2 and obtained seed yield of 1923.2 kgs ha-1. Sole application of sunflower extract: 30 Ltr ha-1 resulted weed density 91.0 m-2 and recorded seed yield of 1804.2 kgs ha-1. Alone allelopathy application of Bermuda grass extract: 30 Ltr ha-1 noticed weed density 103.3 m-2 and produced seed yield of 1684.8 kgs ha-1. The highest weed density 140.9 m-2 and lowest seed yield 1343.1 kgs ha-1 noticed in weedy check treatment where no any application applied for weed reduction. According to irrigation frequencies the 4 watering applications resulted less weed density 82.2 m-2 and obtained maximum seed yield 1996.3 kgs ha-1 followed by 3 watering applications noted weed density 84.5 m-2 and achieved seed yield 1955.5 kgs ha-1. The maximum weed density 86.7 m-2 and lowest seed yield recorded in 2 watering application. The analysis of variance of pooled data revealed that Atlantis: 0.1 Ltr ha-1 + Puma Super: 0.156 Ltr ha-1 + Sunflower extract: 15 Ltr ha-1 integrated treatment under 4 watering applications (15, 30, 45 and 60 DAS) caused significant impact on weed inhabitation and yield enrichment

Crop plants release biochemicals into surrounding environment that help in obtaining maximum yield of crop by acting bioherbicide at high concentration and plant growth hormone at low concentration. Therefore, this study was planned at Department of Agronomy in Weed Science Laboratory, University of Agriculture Faisalabad during Winter 2018 to evaluate the hermetic effects of Althaea officinalis L. (khatami) on vegetable crop Radish (Raphanus sativus) The experiments were laid out under completely randomized design (CRD) having three replications. The aqueous extracts of A. officinalis L. were used on radish different concentrations (2.5%, 5%, 10%, 20%, 40% and 80%). Data regarding seed germination and seedling growth (shoot length, root length, shoot fresh weight, root dry weigh) of radish were recorded using standard procedures. Results Reveals that the aqueous extract of A. officinalis at higher concentration (80%) act as bioherbicide and produced inhibitory effects on R. sativus result in Maximum time to 50% germination (4.68 days) and mean germination time (9.05 days) while minimum germination index (3.60), germination percentage (85.00%), shoot length (42.4 cm), root length (25.90 cm), shoot fresh weight (53.30 g) and root fresh weight (13.30 g). While at lower concentration (10%) it shows hermetic effect and produce maximum germination percentage (100.00%), shoot length (58.2 cm), root length (52.0 cm), shoot fresh weight (90.00g), root fresh weight (26.30 g) minimum time to complete 50% germination (3.36 days), germination index (6.00%) and mean germination time (5.73 days) growth. In A. officinalis among different phenolic compound minimum Syringic acid (0.60%) and maximum Quercetion (12.3%) compound was found. Therefore, it was concluded from this study that aqueous extract of officinalis can be used as growth promoter at lower concentration while at higher concentration for environmentally friendly control of weeds.

Leptospira interrogans spirochetes belong to a group of pathogens of particularly dangerous infections that cause leptospirosis in many species of wild, farm and domestic animals, as well as humans. Significant economic damage caused by this disease to livestock around the world, numerous cases of death from leptospirosis, and mainly waterborne transmission of the infection determine the topicality of studying all the aspects of the existence of L. interrogans in freshwater ecosystems. The objective of our study was to determine the nature of ecological relationships between L. interrogans and green algae. We used green algae of the Desmodesmus brasiliensis species as a model object. In the experiments, sterile algae culture filtrates were added to L. interrogans containers grown at 27–28 °C. Comparison of the content of spirochete cells in the experiment and control samples, conducted 24 hours after exposure, showed that the reproduction of L. interrogans is markedly inhibited in the samples containing algae secretions at the dilutions of 1:10 and 1:100. In order to reduce resistance to the allelopathic influence of D. brasiliensis algae, leptospira strains were located as follows: Pomona, Australis, Hebdomadis, Canicola, Sejroe, Icterohaemorrhagiae, Grippotyphosa, Tarassovi. The obtained results indicate a complex intraspecific structure of L. interrogans and their high ecological plasticity. In addition, experimental data indicate that, due to the release of biologically active substances into the aquatic environment, green algae have the potential to affect the dynamics of a number of leptospirosis pathogens in situ. Given the important epidemiological and epizootic significance of pathogenic leptospira, further research is necessary to determine the patterns of their interactions and existence in the environment.

Non-native plant species can disrupt plant–pollinator interactions by altering pollinator foraging behavior, which can in turn affect levels of interspecific pollen transfer between native and non-native plant species. These processes may be amplified in cases where introduced plant species act as magnet taxa that enhance pollinator visitation to other plant species. We investigated these interactions on Santa Cruz Island (Santa Barbara Co., California) between non-native fennel (Foeniculum vulgare), a widespread and abundant invader, and the endemic Santa Cruz Island buckwheat (Eriogonum arborescens), which broadly overlaps fennel in its local distribution and blooming phenology. A fennel flower removal experiment revealed that this invader acts as a magnet species by increasing insect visitation to adjacent buckwheat flowers. Analysis of the amount of pollen carried on the bodies of insect pollinators (i.e., pollen transport) revealed that 96% of visitors to buckwheat flowers carried fennel pollen and 72% of visitors to fennel flowers carried buckwheat pollen. Pollen transport analyses and visitation rate data further suggest that members of three bee genera (primarily Augochlorella) may be responsible for the majority of fennel pollen deposited on the stigmas of buckwheat flowers (i.e., pollen transfer) and vice versa. Lastly, fennel pollen transport appeared to occur at a larger spatial scale than the magnet effect that fennel plants exert on floral visitors to neighboring buckwheat plants. The ability of fennel to act as a magnet species, coupled with the fact that it is widespread invader with known allelopathic capacities, suggests that future studies could evaluate if the transfer of fennel pollen adversely affects native plant reproduction in areas where fennel is introduced.