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By modifying the biotic and abiotic properties of the soil, plants create soil legacies that can affect vegetation dynamics through plant-soil feedbacks (PSF). PSF are generally attributed to reciprocal effects of plants and soil biota, but these interactions can also drive changes in the identity, diversity and abundance of soil metabolites, leading to more or less persistent soil chemical legacies whose role in mediating PSF has rarely been considered. These chemical legacies may interact with microbial or nutrient legacies to affect species coexistence. Given the ecological importance of chemical interactions between plants and other organisms, a better understanding of soil chemical legacies is needed in community ecology. In this Viewpoint, we aim to: highlight the importance of belowground chemical interactions for PSF; define and integrate soil chemical legacies into PSF research by clarifying how the soil metabolome can contribute to PSF; discuss how functional traits can help predict these plant-soil interactions; propose an experimental approach to quantify plant responses to the soil solution metabolome; and describe a testable framework relying on root economics and seed dispersal traits to predict how plant species affect the soil metabolome and how they could respond to soil chemical legacies.

Wheat is often planted directly after maize in fields following the maize harvest, and maize residues decompose in the soil by various biological factors, releasing phenolic compounds that affect the germination and growth of some crops planted with or after it. This research aimed to identify the effect of Zea mays leaf extract on seed germination physiological and anatomical features of Z. mays var. (Drachma, Mahali) and Triticum aestivum var. (Baraka, Abu Ghraib) . The results showed Z. mays leaf extract stimulated some traits germination (100%) in Drachama at control, plumule length (7.8cm) in Abu-Graib, radicle length (11.6cm) in Baraka at 2%, fresh weight of plumule and radical (0.0113, 0.0148gm) respectively in Drachama at control. There was highest reduction germination (60%) in Drachama at 6% extract [plumule length (1.0)cm, radicle length (4.2cm), fresh weight of plumule (0.0052cm) in Mahali at 4%], fresh weight of radical (0.00026gm) in Abu-Graib at 6%. There was a difference in response in greenhouse experiments. Anatomical traits of the two corn cultivars differed at 2% and 4% concentrations. The highest increase in germination (96.7%) was in Baraka at 4%, shoot length (22.1cm) in Drachama at 4%, fresh weight of root (0.254gm) in Abu-Graib at 4%, [root length (44cm), fresh weight of root (0.052 gm) in Abu-Graib at 4%], the highest reduction in germination (80%) in Abu-Graib, dry weight of root (23gm) in Abu-Graib at 2%. Using HPLC, compounds tannic acid, gallic acid, benzoic acid, and salicylic acid were identified from Z. mays L. extracts. The study will help to develop sustainable agricultural practices, such as crop rotation, to increase crop productivity and reduce reliance on chemicals.

This thesis presents the development of a cost-effective and efficient current sensing module designed for monitoring of soil-based Microbial Fuel Cells and the influence plant phenomena has on power production. Soil-based Microbial Fuel Cells has the potential to provide efficient powering of IoT devices in agricultural fields and knowledge behind plant-soil relationships gives insight to optimizing their deployment. The field of study for Microbial Fuel cells falls within multiple disciplines and thus results in inconsistent practices across the varying research groups. This thesis highlights the common practices within each discipline, the avoidable challenges faced during experiments, and the results of plant phenomena Allelopathy and Nitrogen Fixation has on the performance of Microbial Fuel Cells, monitored by the proposed current sensing module.

Following the withdrawal of synthetic pesticides from agro-chemical markets, several extracts from various plants have been tested. Despite this progress, some plant extracts with bio-pesticidal properties have also been documented for their phytotoxic properties. This study was conducted to investigate allelochemical content of Cissus cactiformis plant. Also, to determine its allelopathic effect based on the presence of the phytochemical components on seed germination and seedling growth of lettuce. Phytochemical analysis of C. cactiformis plant extract showed differences in the allelochemical components of different extracts tested. Saponins, terpenoids, flavonoids, tannins, alkaloids, coumarins, phytosterols were detected in plant materials extracted using acetone, methanol and ethanol. With these extracts the presence of phenolic compounds and cardiac glycoside were not detected. However, in distilled water extract terpenoids, flavonoids, tannins, alkaloids, coumarins and phenolic compounds were detected, with saponins and cardiac glycoside being absent. Lettuce seeds in germination bioassay were exposed to four treatments, viz. 0, 0.5, 1.0 and 1.25mg/mℓ of the different extract laid-out in a completely randomised design replicated four times. In all variables measured, treatments were significantly (P ≤ 0.01) different for acetone, ethanol, distilled water and methanol extract of C. cactiformis plant. Mean germination percentage, hypocotyl and radicle length for control were highest when compared to other levels of each extract type. Similarly seedling growth bioassay comprised of six treatments, viz. 0, 0.5, 1.0, 1.25, 2.0 and 2.25 g extracts of C. cactiformis plant per pot, arranged in a randomised complete design, with six replicates in the greenhouse. All measured variables were not significant at P ≤ 0.05 which showed no variation. The results revealed that irrespective of the solvents used, extract of C. cactiformis plant had allelopathic effects on the s, AgriSeta and National Research Foundation (NRF)

The aim of the paper was to examine the allelopathic influence of aqueous extracts of herbs and medicinal plants on the quality parameters of aged soybean seeds. The research was carried out at the Institute of Field and Vegetable Crops in Novi Sad on aged seeds of two soybean varieties, NS simba and NS viseris. The seeds were aged for 20 months. In order to determine the allelopathic effect, the seeds were primed in aqueous plant extracts: geranium (Geranium sinense), dill (Anethum graveolens), andy everlasting (Helichrysum arenarium), creeping thyme (Thymus serpyllum), celery (Apium graveolens), oregano (Origanum vulgare), basil (Ocimum basilicum), lemon balm (Melissa officinalis), rosemary (Rosmarinus officinalis), wormwood (Artemisia absinthium), peppermint (Mentha x piperita), sage (Salvia officinalis), and lavender (Lavandula angustifolia). The results show that it is not possible to talk about the universal application of a particular aqueous extract, because the effect of the allochemicals was significantly influenced by the variety. In the variety NS viseris, all aqueous extracts except Melissa officinalis, significantly reduced GE, GP, and VI. The most negative effect was achieved with the use of Apium graveolens, Thymus serpyllum, and Ocimum basilicum. Apium graveolens and Thymus serpyllum also had the greatest impact on quality reduction in the NS simba variety. However, in the NS simba variety, a significant increase in seed quality was achieved in addition to the reduction. The use of the aqueous extract of Salvia officinalis increased GE and GP by 13.7%, and VI by 10.21%. A positive effect was achieved with the use of Melissa officinalis. All aqueous extracts had a significant effect on T50 in both varieties, even the aqueous extracts that had a negative effect on GE and GP., Cilj rada je bio da se ispita alelopatski uticaj ekstrakta začinskog i lekovitog bilja na kvalitet starog semena soje. Ispitivanje je obavljeno na Institutu za ratarstvo i povrtarstvo u Novom Sadu, na starom semenu dve sorte soje NS Simba i NS Viseris. Seme je bilo staro 20 meseci. Radi utvrđivanja alelopatskog uticaja seme je potapano u biljne vodene ekstrakte: geranijuma (Geranium sinense), mirođije (Anethum graveolens), smilja (Helichrysum arenarium), majčine dušice (Thymus serpyllum), celera (Apium graveolens), origana (Origanum vulgare), bosiljka (Ocimum basilicum), matičnjaka (Melissa officinalis), ruzmarina (Rosmarinus officinalis), pelina (Artemisia absinthium), nane (Mentha x piperita), žalfije (Salvia officinalis), i lavande (Lavandula angustifolia). Rezultati su pokazali da se ne može govoriti o univerzalnoj primeni određenog ekstrakta, jer na efekat alelohemikalija značajan uticaj ima sorta. Kod sorte NS Viseris, svi ekstrakti, osim ekstrakta Melissa officinalis, značajno su smanjili GE, GP i VI. Najnegativniji efekat ostvaren je primenom Apium graveolens, Thymus serpyllum i Ocimum basilicum. Apium graveolens i Thymus serpyllum su najviše uticali na smanjenje kvaliteta i kod sorte NS Simba. Međutim, kod sorte NS Simba, pored smanjenja ostvareno je i značajno povećanje kvaliteta semena. Primenom ekstrakta Salvia officinalis, GE i GP su povećani za 13,7%, a VI je povećana za 10,21%. Dobar efekat je ostvaren i upotrebom Melissa officinalis. Svi ekstrakti, kod obe sorte, imali su značajan uticaj na brzinu klijanja, čak i ekstrakti koji su negativno delovali na GE i GP.

Biotic interactions are a key factor in the development of harmful algal blooms. Recently, a lower abundance of planktonic dinoflagellates has been reported in areas dominated by seagrass beds, suggesting a negative interaction between both groups of organisms. The interaction between planktonic dinoflagellates and marine phanerogams, as well as the way in which bacteria can affect this interaction, was studied in two experiments using a non-axenic culture of the toxic dinoflagellate Alexandrium minutum exposed to increasing additions of eelgrass (Zostera marina) exudates from old and young leaves and to the presence or absence of antibiotics. In these experiments, A. minutum abundance, growth rate and photosynthetic efficiency (Fv/Fm), as well as bacterial abundance, were measured every 48 h. Toxin concentration per cell was determined at the end of both experiments. Our results demonstrated that Z. marina exudates reduced A. minutum growth rate and, in one of the experiments, also the photosynthetic efficiency. These results are not an indirect effect mediated by the bacteria in the culture, although their growth modify the magnitude of the negative impact on the dinoflagellate growth rate. No clear pattern was observed in the variation of toxin production with the treatments

Allelopathy has been considered as a natural method of weed control. Despite the nature of allelochemical compounds has been studied, little is known about the genetic basis underlying allelopathy. However, it is known that rice exhibits diverse allelopathic potentials across varieties, and breeding for rice plants exhibiting allelopathic potential conferring an advantage against weeds in paddy fields would be highly desirable. Knowledge of the gene factors and the identification of the genomic regions responsible for allelopathy would facilitate breeding programs. Taking advantage of the existing genetic diversity in rice, particularly in temperate japonica rice, we conducted a comprehensive investigation into the genetic determinants that contribute to rice allelopathy. Employing Genome-Wide Association Study, we identified four Quantitative Trait Loci, with the most promising loci situated on chromosome 2 and 5. Subsequent inspection of the genes located within these QTLs revealed genes associated with the biosynthesis of secondary metabolites such as Phenylalanine Ammonia Lyase (PAL), a key enzyme in the synthesis of phenolic compounds, and two genes coding for R2R3-type MYB transcription factors. The identification of these two QTLs associated to allelopathy in rice provides a useful tool for further exploration and targeted breeding strategies.

2023 Acuerdos transformativos CRUE, Invasive species control management involves a large amount of plant material. The present work evaluated the allelopathic potential of the invasive species Ulex europaeus L. (Fabaceae) or ‘Gorse’ and its possible use as a bioherbicide, taking advantage of the extracted plant material after control measures, particularly needed in invaded areas. Specifically, we investigated the efficacy of dried plant material from U. europaeus in the control of the adventitious plants, Lolium multiflorum Lam. and Lolium rigidum Gaud., using the Avena sativa L. crop as a case study. We only used vegetative plant parts because it is essential to avoid the dispersion of U. europaeus with its use, especially in invaded areas. A greenhouse pot experiment was conducted, using activated carbon (AC). The target species (L. multiflorum, L. rigidum and A. sativa) were subjected to a mixture of organic substrate with U. europaeus mulch applied pre-emergence and a subsequent application of aqueous extracts from the mulch. Emergence, height and biomass of the target species were determined. After 2 months, we also tested a possible legacy effect of the substrate on the germination of the target species. We noticed a negative effect of U. europaeus mulch on the emergence of L. rigidum, which can be attributable to the allelopathic compounds released from U. europaeus mulch because the effect was non-significant in presence of AC. Conversely, no effect on L. multiflorum or A. sativa was produced by mulch treatments. Nevertheless, the combination of U. europaeus mulch and its extracts demonstrated a phytotoxic effect on the biomass of the crop species A. sativa, and a fertilizing effect on the weeds L. multiflorum and L. rigidum, which is why this use is discouraged. With our results we cannot recommend the use of U. europaeus as a bioherbicide in oat crops, but this study emphasizes the capability of U. europaeus to structure plant communities through the chemic- and bio-properties of its tissue, Comunidad de Madrid, Universidad Complutense de Madrid, Banco Santander, Comisión Nacional de Investigación Científica y Tecnológica (Chile), Depto. de Biodiversidad, Ecología y Evolución, Fac. de Ciencias Biológicas, TRUE, pub, APC financiada por la UCM

Lantana camara L., introduced as an ornamental plant in India a century ago, has invaded over 40% forest lands today. It is also actively spreading through Indian states in agricultural farms and interfering with the productivity of several food crops. The detrimental effect of L. camara has been recognised on various plants, however, to the best of our knowledge, published studies have not explored its effect on an important cash crop of India i.e., Arachis hypogea. Hence, in the present study, the allelopathic effect of aqueous extracts of L. camara on germination and chlorophyll, protein profile of peanut seeds was determined. It was observed that 1% L. camara aqueous extracts has negligible effect on seed germination, and chlorophyll a and protein content of germinated A. hypogea seeds, but significantly affected total chlorophyll and chlorophyll b concentration. At higher concentrations (1% and 3%), the allelopathic effect of L. camara aqueous extracts was clearly evident on all three growth parameters of peanuts evaluated in this study. In conclusion, our study reports that L. camara may prove to be a much bigger challenge in management of peanut productivity as compared to other invasive weeds, if proper preventive measures are not recognized immediately.

Many invasive alien species (IAS) produce secondary metabolites that affect how other plants function (allelopathic compounds) and can drive other species invasion, as proposed by the invasional meltdown hypothesis. Acacia melanoxylon and Eucalyptus globulus are two of such species. In this study, we analyzed the germination response of seven IAS (Acacia dealbata, Acacia mearnsii, Acacia melanoxylon, Acacia longifolia, Eucalyptus globulus, Paraserianthes lophantha, Phytolacca americana) and a native biotest species (Lactuca sativa) to the application of two different aqueous extracts at two different concentrations of donor species A. melanoxylon and E. globulus. Extract compounds were identified by UHPLC-ESI-QTOF-MS. Eucalyptus aqueous extracts significantly reduced germination in three species (A. dealbata, E. globulus, P. americana). The germination of all the species tested was reduced with acacia aqueous extracts. Our results support the postulates of the Biochemical Recognition Hypothesis in that seeds gauge establishment potential based on phytochemical release of other plants. Furthermore, A. melanoxylon and E. globulus lowered their own germination, suggesting that these species exhibit intraspecific biochemical recognition. We also found support for the Novel Weapons Hypothesis in the case of L. sativa as a native species. Our research shows that phytochemicals are a component of plant-plant interactions, including the invasion process.

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

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

The experiment aimed to investigate the allelopathic effects of active compounds present in broadleaf weeds Ageratum conyzoides and Borreria alata. The study also sought to assess the viability of various seed varieties grown using allelopathic extracts from these weeds, varying in concentrations of tannins and phenols. The research findings revealed that methanol extracts exhibited potent allelopathic properties, inhibiting germination, radicle and hypocotyl growth, as well as reducing the germination rate of soybean seeds. B. alata weed extracts demonstrated lower allelopathy than A. conyzoides, suggesting a possible alteration in the active compounds (allelochemicals) present due to a reforming process. Extracts from both A. conyzoides and B. alata weeds inhibited root length, hypocotyl growth, and germination across a range of concentrations, from low (10% v/v) to high (30% v/v).

The need to find alternatives to synthetic herbicides has led to the evaluation of the use of allelopathic biomass from different agroforestry species as soil amendments for weed control. Mentha suaveolens Ehrh. (apple mint) could be a suitable candidate as an ecoherbicide due to its availability in the agroecosystem, well-studied biological activities, and known chemical composition. For the present study, two greenhouse pot experiments were conducted by incorporating flowering aerial biomass of apple mint into the soil. In the first one, the potential phytotoxic effects of M. suaveolens at doses 1 and 2% were evaluated on the germination and growth of maize and its accompanying weeds. In a second temporary assay, the duration of phytotoxicity and the effects of apple mint (0.5% dose) on the physicochemical properties of the soil were elucidated. The soluble (phenolics and organic acids) and volatile compounds potentially releasable from the allelopathic biomass were identified. The apple mint exerted adverse effects on the germination and growth of dicotyledonous weed species, especially Amaranthus retroflexus and Solanum nigrum, with almost 100% inhibition, as well as on the growth of monocotyledonous weeds such as Digitaria sanguinalis, with a reduction of more than 95%. On the contrary, maize yield and soil properties pH, CECe, organic matter, and exchangeable cations were improved by the ecoherbicide. Chemical analyses of apple mint aerial biomass revealed the presence of 7 phenolic compounds, 9 organic acids, and 32 volatiles. For this study, the effects of incorporating M. suaveolens aerial biomass into soil were evaluated for the first time, and it was demonstrated that it has potential as an eco-friendly plant-based tool for Integrated Weed Management.

Allelopathy refers to the interaction of plants by the release of chemicals in the environment, interfering positively or negatively and may be present in the seeds of certain species. Thus, the current work sought to analyze the allelopathic potential of the seeds of Ricinus communis L. (castor bean), popularly known for its toxic properties and the oil extracted for industrial use, in addition, morphometry was performed and it was verified whether the storage of these seeds at different temperatures had an influence on the results obtained. The research was conducted in the Biology laboratory of the University Cruzeiro do Sul, São Miguel campus with the preparation of the aqueous extract of castor oil plant seeds, diluted in concentrations of 0% (control), 25%, 50%, 75% and 100%, applied in test seeds (Lactuca sativa L. - lettuce and Solanum lycopersicum L. - tomato), observing the possible allopathic effects during germination on the germination variables and the germination speed index. The seeds of R. communis from both storage periods did not present any variation in their length or width. In the germination tests, the presence of allelopathic substances was proven, capable of inhibiting and reducing the germination of lettuce and tomato seeds. The storage temperature of the specimen under study did not influence the effects achieved in the tests. The seeds of R. communis of both storages, did not present any variation in their length or width. In the germination tests, the presence of allelopathic substances, capable of inhibiting and reducing the germination of lettuce and tomato seeds, was proven. Andthe storage temperature of the specimen under study did not influence the effects obtained in the tests., La alelopatía se refiere a la interacción de las plantas por la liberación de sustancias químicas en el medio ambiente, interfiriendo positiva o negativamente y puede estar presente en las semillas de ciertas especies. Así, el presente trabajo buscó analizar el potencial alelopático de las semillas de Ricinus communis L. (ricino), popularmente conocido por sus propiedades tóxicas y el aceite extraído para uso industrial, además, se realizó morfometría y se verificó si el almacenamiento de estas semillas a diferentes temperaturas influía en los resultados obtenidos. La investigación fue realizada en el laboratorio de Biología de la Universidad Cruzeiro do Sul, campus de São Miguel, con la preparación del extracto acuoso de semillas de ricino, diluido en concentraciones de 0% (control), 25%, 50%, 75% y 100%, aplicado en semillas de prueba (Lactuca sativa L. - lechuga y Solanum lycopersicum L. - tomate), observando los posibles efectos alopáticos durante la germinación sobre las variables de germinación y el índice de velocidad de germinación. Las semillas de R. communis de ambos períodos de almacenamiento no presentaron ninguna variación en su longitud o anchura. En las pruebas de germinación, se comprobó la presencia de sustancias alelopáticas, capaces de inhibir y reducir la germinación de semillas de lechuga y tomate. La temperatura de almacenamiento de la muestra en estudio no influyó en los efectos logrados en las pruebas. Las semillas de R. communis de ambos almacenes, no presentaron variación alguna en su longitud o anchura. En las pruebas de germinación, se comprobó la presencia de sustancias alelopáticas, capaces de inhibir y reducir la germinación de semillas de lechuga y tomate. Y la temperatura de almacenamiento de la muestra en estudio no influyó en los efectos obtenidos en las pruebas., Alelopatia se refere à interação das plantas pela liberação de substâncias químicas no meio ambiente, interferindo positiva ou negativamente e podem estar presentes em sementes de determinadas espécies. Desta forma, este trabalho buscou analisar o potencial alelopático das sementes de Ricinus communis L. (mamona), conhecida popularmente por suas propriedades tóxicas e do óleo extraído para utilidade industrial. Foi realizado a morfometria e verificado se o armazenamento destas sementes em diferentes temperaturas apresentou influência nos resultados obtidos. A pesquisa foi conduzida no Laboratório de Biologia da Universidade Cruzeiro do Sul, campus São Miguel com a preparação do extrato aquoso das sementes de mamona, diluído nas concentrações de 0% (controle), 25%, 50%, 75% e 100%, aplicados em sementes-testes (Lactuca sativa L. - alface e Solanum lycopersicum L. - tomate), observando os possíveis efeitos alopáticos durante a germinação sob as variáveis de germinabilidade e o índice de velocidade de germinação. As sementes de R. communis de ambos os armazenamentos não apresentaram variação em seu comprimento e largura. Nos testes de germinação, foi comprovada a presença de substâncias alelopáticas, capazes de inibir e reduzir a germinação das sementes de alface e tomate. E a temperatura do armazenamento do espécime em estudo, não influenciou nos efeitos alcançados nos testes.

Allelopathy refers to the interaction of plants by the release of chemicals in the environment, interfering positively or negatively and may be present in the seeds of certain species. Thus, the current work sought to analyze the allelopathic potential of the seeds of Ricinus communis L. (castor bean), popularly known for its toxic properties and the oil extracted for industrial use, in addition, morphometry was performed and it was verified whether the storage of these seeds at different temperatures had an influence on the results obtained. The research was conducted in the Biology laboratory of the University Cruzeiro do Sul, São Miguel campus with the preparation of the aqueous extract of castor oil plant seeds, diluted in concentrations of 0% (control), 25%, 50%, 75% and 100%, applied in test seeds (Lactuca sativa L. - lettuce and Solanum lycopersicum L. - tomato), observing the possible allopathic effects during germination on the germination variables and the germination speed index. The seeds of R. communis from both storage periods did not present any variation in their length or width. In the germination tests, the presence of allelopathic substances was proven, capable of inhibiting and reducing the germination of lettuce and tomato seeds. The storage temperature of the specimen under study did not influence the effects achieved in the tests. The seeds of R. communis of both storages, did not present any variation in their length or width. In the germination tests, the presence of allelopathic substances, capable of inhibiting and reducing the germination of lettuce and tomato seeds, was proven. Andthe storage temperature of the specimen under study did not influence the effects obtained in the tests., La alelopatía se refiere a la interacción de las plantas por la liberación de sustancias químicas en el medio ambiente, interfiriendo positiva o negativamente y puede estar presente en las semillas de ciertas especies. Así, el presente trabajo buscó analizar el potencial alelopático de las semillas de Ricinus communis L. (ricino), popularmente conocido por sus propiedades tóxicas y el aceite extraído para uso industrial, además, se realizó morfometría y se verificó si el almacenamiento de estas semillas a diferentes temperaturas influía en los resultados obtenidos. La investigación fue realizada en el laboratorio de Biología de la Universidad Cruzeiro do Sul, campus de São Miguel, con la preparación del extracto acuoso de semillas de ricino, diluido en concentraciones de 0% (control), 25%, 50%, 75% y 100%, aplicado en semillas de prueba (Lactuca sativa L. - lechuga y Solanum lycopersicum L. - tomate), observando los posibles efectos alopáticos durante la germinación sobre las variables de germinación y el índice de velocidad de germinación. Las semillas de R. communis de ambos períodos de almacenamiento no presentaron ninguna variación en su longitud o anchura. En las pruebas de germinación, se comprobó la presencia de sustancias alelopáticas, capaces de inhibir y reducir la germinación de semillas de lechuga y tomate. La temperatura de almacenamiento de la muestra en estudio no influyó en los efectos logrados en las pruebas. Las semillas de R. communis de ambos almacenes, no presentaron variación alguna en su longitud o anchura. En las pruebas de germinación, se comprobó la presencia de sustancias alelopáticas, capaces de inhibir y reducir la germinación de semillas de lechuga y tomate. Y la temperatura de almacenamiento de la muestra en estudio no influyó en los efectos obtenidos en las pruebas., Alelopatia se refere à interação das plantas pela liberação de substâncias químicas no meio ambiente, interferindo positiva ou negativamente e podem estar presentes em sementes de determinadas espécies. Desta forma, este trabalho buscou analisar o potencial alelopático das sementes de Ricinus communis L. (mamona), conhecida popularmente por suas propriedades tóxicas e do óleo extraído para utilidade industrial. Foi realizado a morfometria e verificado se o armazenamento destas sementes em diferentes temperaturas apresentou influência nos resultados obtidos. A pesquisa foi conduzida no Laboratório de Biologia da Universidade Cruzeiro do Sul, campus São Miguel com a preparação do extrato aquoso das sementes de mamona, diluído nas concentrações de 0% (controle), 25%, 50%, 75% e 100%, aplicados em sementes-testes (Lactuca sativa L. - alface e Solanum lycopersicum L. - tomate), observando os possíveis efeitos alopáticos durante a germinação sob as variáveis de germinabilidade e o índice de velocidade de germinação. As sementes de R. communis de ambos os armazenamentos não apresentaram variação em seu comprimento e largura. Nos testes de germinação, foi comprovada a presença de substâncias alelopáticas, capazes de inibir e reduzir a germinação das sementes de alface e tomate. E a temperatura do armazenamento do espécime em estudo, não influenciou nos efeitos alcançados nos testes.

The Galician Rías (NW Iberian Peninsula) are an important shellfish aquaculture area periodically affected by toxic episodes often caused by dinoflagellates such as Dinophysis acuminata and Alexandrium minutum, among others. In turn, water discolorations are mostly associated with non-toxic organisms such as the heterotrophic dinoflagellate Noctiluca scintillans, a voracious non-selective predator. The objective of this work was to study the biological interactions among these dinoflagellates and their outcome in terms of survival, growth and toxins content. To that aim, short experiments (4 days) were carried out on mixed cultures with N. scintillans (20 cells mL−1) and (i) one strain of D. acuminata (50, 100 and 500 cells mL−1) and (ii) two strains of A. minutum (100, 500 and 1000 cells mL−1). Cultures of N. scintillans with two A. minutum collapsed by the end of the assays. Both D. acuminata and A. minutum exposed to N. scintillans arrested its growth, though feeding vacuoles in the latter rarely contained any prey. Toxin analyses at the end of the experiment showed an increase in intracellular OA levels in D. acuminata and a significant reduction in PSTs in both A. minutum strains. Neither OA nor PSTs were detected in N. scintillans. Overall, the present study indicated that the interactions among them were ruled by negative allelopathic effects.

Allelopathy is a biological phenomenon in which chemicals released by one plant species directly influence the growth and development of another; therefore, allelopathic species can be a natural source of herbicides. Metopium browneiand Viguiera dentatahave been shown tohave an inhibitory effect on plants and microorganisms.The present work aimedto determine the suppressive effect of different doses of crude extractsof M. browneiand V. dentataon the invitrogermination of a tropical weed (Senna uniflora) and Raphanus sativus, a species highly sensitive to allel ochemicals.It was shown thataqueous extracts of M. brownei fruits applied at doses as low as 0.5% suppressed the germination of the weed S. unifloraby 100%. The ethanolic extracts of both species demonstrated an inhibitory effect onthe germination of S. unifloraseedsat concentrations of 8% or higher. On the other hand, aqueous extracts of V. dentata flowers were themost effective in inhibiting the germination of R. sativus seedswhen applied in doses higher than 15%. According to the results obtained in the present work, it is concluded that V. dentatahas a strong allelopathic effect on S. uniflora when used inethanolic and aqueous extracts, so it can be used as a bioherbicide for the control of theweed in tropical crops, La alelopatía es un fenómeno biológico en el que las substancias químicas liberadas por una especie vegetal influyen directamente sobre el crecimiento y desarrollo de otra; por tanto, las especies alelopáticas pueden ser fuente natural de herbicidas. Se ha demostrado que Metopium brownei y Viguiera dentata tienen un efecto inhibidor sobre plantas y microorganismos. El presente trabajo tuvo como objetivo determinar el efecto supresor de diferentes dosis de extractos crudos de M. brownei y V. dentata sobre la germinación in vitro de una arvense tropical (Senna uniflora) y Raphanus sativus, una especie altamente sensible a aleloquímicos. Se demostró que los extractos acuosos de frutos de M. brownei aplicados a dosis tan bajas como de 0.5% suprimieron la germinación de la arvense S. uniflora al 100%. Los extractos etanólicos de ambas especies demostraron un efecto inhibitorio de la germinación de semillas de S. uniflora en concentraciones de 8% o superiores. Por otra parte, los extractos acuosos de flores de V. dentata fueron los más efectivos en inhibir la germinación de semillas de R. sativus al aplicarse en dosis superiores al 15%. De acuerdo con los resultados obtenidos en el presente trabajo se concluye que V. dentata tiene un fuerte efecto alelopático sobre S. uniflora cuando se emplea en extractos etanólicos y acuosos, por lo que puede emplearse como bioherbicida para el control de la arvense en cultivos tropicales

Abutilon theophrasti Medik. (velvetleaf) is a problematic annual weed in field crops which has invaded many temperate parts of the world. Since the loss of crop yields can be extensive, approaches to manage the weed include not only conventional methods, but also biological methods, for instance by microorganisms releasing phytotoxins and plant-derived allelochemicals. Additionally, benzoxazinoid-rich rye mulches effective in managing common weeds like Amaranthus retroflexus L. have been tested for this purpose. However, recent methods for biological control are still unreliable in terms of intensity and duration. Rye mulches were also ineffective in managing velvetleaf. In this review, we present the attempts to reduce velvetleaf infestation by biological methods and discuss possible reasons for the failure. The resilience of velvetleaf may be due to the extraordinary capacity of the plant to collect, for its own survival, the most suitable microorganisms from a given farming site, genetic and epigenetic adaptations, and a high stress memory. Such properties may have developed together with other advantageous abilities during selection by humans when the plant was used as a crop. Rewilding could be responsible for improving the microbiomes of A. theophrasti.

Lantana camara L., introduced as an ornamental plant in India a century ago, has invaded over 40% forest lands today. It is also actively spreading through Indian states in agricultural farms and interfering with the productivity of several food crops. The detrimental effect of L. camara has been recognised on various plants, however, to the best of our knowledge, published studies have not explored its effect on an important cash crop of India i.e., Arachis hypogea. Hence, in the present study, the allelopathic effect of aqueous extracts of L. camara on germination and chlorophyll, protein profile of peanut seeds was determined. It was observed that 1% L. camara aqueous extracts has negligible effect on seed germination, and chlorophyll a and protein content of germinated A. hypogea seeds, but significantly affected total chlorophyll and chlorophyll b concentration. At higher concentrations (1% and 3%), the allelopathic effect of L. camara aqueous extracts was clearly evident on all three growth parameters of peanuts evaluated in this study. In conclusion, our study reports that L. camara may prove to be a much bigger challenge in management of peanut productivity as compared to other invasive weeds, if proper preventive measures are not recognized immediately.

Implementation of plant extracts that are rich in phytochemicals and have the allelopathic potential for weed management could help reduce the use of chemical herbicides. The present study investigated the herbicidal potential of walnut (Juglans regia L.) leaf extract (WLE) against two weeds, Amaranthus retroflexus L. and Chenopodium album L., by testing in vitro their seed germination and seedling growth, and then evaluated in vivo the oxidative stress of potted plants. The effects of the walnut leaf extract were also tested on maize (Zea mays L.) to eliminate possible negative impacts on a cultivated plant. Total phenolic acids and total flavonoid content in the extract were determined in prior bioassays, followed by separation and analysis of flavonoids and phenolic acids by high-performance liquid chromatography (HPLC). Phytochemical analysis revealed that the obtained extract was notably rich in phenolic compounds, while HPLC analysis confirmed the presence of (+)-catechin, luteolin, myricetin, rutin, (-)-epicatechin, genistin, protocatechuic acid, and caffeic acid as major extract components. The results obtained in bioassays revealed a significant negative impact of the walnut leaf extract on germination and seedling growth of the tested weeds, as well as significant oxidative stress in weeds grown in pots. Although it affected the maize seedling growth in vitro similar to the tested weeds, maize germination was less sensitive to treatment, and the extract did not have a significant negative impact in terms of oxidative stress in maize plants grown in pots. The findings show that walnut leaf extract may have a promising role in replacing chemical herbicides in maize.

Alelopatski efekti aktinobakterija na klijanje semena i rani porast klijanaca Teofrastove lipice (Abutilon theophrasti Medik.) REZIME Cilj ovog rada je bio da se ispitaju alelopatski efekti aktinobakterijskih izolata u in vitro uslovima na klijavost semena i rani porast klijanaca semena Abutilon theophrasti. Iz zemlje i komposta u različitim fazama kompostiranja dobijeno je 35 izolata aktinobakterija. Takođe, u ogled je uključen i tretman herbicidom (mezotrion) u preporučenoj količini primene, kao referentni standard. Na osnovu dobijenih rezultata može se utvrditi da postoji statistički značajna razlika (p lt 0,05) između kontrole (neinokulisana tečna skrobno-kazeinska podloga) i svih tretmana sa aktinobakterijskim izolatima na klijavost semena, dužinu korenka i stabaoceta. Najveća inhibicija (100%) klijanja semena i dužine korenka zabeležena je u tretmanima sa izolatima A10 i NOV2. Pokazalo se da je dužina stabaoceta osetljiviji parametar, jer je zabeležena inhibicija od 100% u većini tretmana A010, NOV2, NOV3, NOV4 i NOV5. Izolati aktinobakterija su pokazali veći inhibitorni efekat na klijanje semena u odnosu na tretman herbicidom mezotrionom., This study aimed to examine in vitro allelopathic effects of actinobacterial isolates on seed germination and early seedling growth of velvetleaf (Abutilon theophrasti). Thirty-five actinobacterial isolates were obtained from soil and compost in different phases of composting. Also, an experiment variant involving the herbicide mesotrione was set in the recommended amount of application, as a reference standard. The experimental results indicate statistically significant differences (p lt 0.05) between controls and all treatments with actinobacterial isolates regarding seed germination, and radical and shoot length. The highest inhibition (100%) was observed in seed germination and radical length in treatments with the isolates A10 and NOV2, compared to uninoculated starch casein broth (SCB) as control. Shoot length was shown to be the most sensitive parameter, where 100% inhibition was observed in the following treatments with actinobacteria: A010, A017, NOV2, NOV3, NOV4 and NOV5. Actinobacterial isolates showed a higher inhibitory effect on seed germination than treatment with the reference herbicide mesotrione.

Cilj ovog rada je bio da se ispita alelopatski potencijal biljnog ekstrakta izolovanog iz zelenih plodova oraha na klijanje i rani porast semena dve korovske vrste (Amaranthus retroflexus i Chenopodium album), kao i fitotoksični efekat na klijanje i rani porast semena kukuruza Zea mays. Pored toga, cilj je bio i da se uradi analiza biljnog ekstrakta i procena njegove antioksidativne aktivnosti. Antioksidativna aktivnost biljnog ekstrakta određivana je kroz sposobnost neutralizacije DPPH (2,2-difenil-1-pikrilhidrazil) radikala i ispitivanjem sposobnosti redukcije gvožđa FRAP metodom. Inhibicija merenih parametara (ukupna klijavost i dužina klijanaca) se proporcionalno smanjivala sa smanjenjem koncentracije rastvora biljnog ekstrakta izolovanog iz zelenih plodova oraha. Takođe, parametar dužina klijanaca je ispoljio veću osetljivost u odnosu na parametar ukupne klijavosti semena kod obe korovske vrste. Iako, dobijeni rezultati iz biotesta sa semenima pokazuju visok inhibitorni efekat na klijanje i rani porast obe korovske vrste, ujedno ukazuju i na fitotoksične efekte kod ranog porasta semena gajene vrste Z. mays. Buduća istraživanja će se fokusirati na HPLC analizu biljnog ekstrakta izolovanog iz zelenih plodova oraha i njegovog alelopatskog svojstva na rani porast biljaka testiranih vrsta., 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.

Secondary plant metabolites with allelopathic activity or phytotoxicity could be biotechnologically important, serving as a source of allelochemicals, and thus contributing to the agro-industrial sector. The objective of this study was to use the obtained common walnut (Juglans regia L.) and bitter dock (Rumex obtusifolius L.) leaves extracts rich in phenolic compounds, i.e. with high antioxidant potential, and to identify their phytotoxicity to Setaria glauca (L.) P. Beauv. and Sorghum halepense (L.) Pers. weed seedlings grown in vitro. The obtained plant extracts had remarkably high affinity for scavenging free radicals, having DPPH IC 50 values of 0. 127 mg/ml for common walnut leaf extract and 0.194 mg/ml for bitter dock leaf extract. Ferric reducing antioxidant power of the extracts was also high, FRAP value of the common walnut leaf extract was 384.4 ± 8. 1 mmol Fe 2+ /g dry mass, and of the bitter dock leaf extract 321.6 ± 2.5 mmol Fe 2+ /g dry mass. At the highest used concentration, common walnut leaf extract reduced germination of S. glauca by 67.3%, while bitter dock leaf extract reduced germination of that weed by 54.5%. Shoot length of S. glauca was inhibited 80.7% when subjected to common walnut leaf extract, and 78.2% under the influence of bitter dock leaf extract, and its root length was inhibited 96.4% and 93. 1% respectively. Germination of S. halepense was inhibited 100% under the influence of the obtained common walnut leaf extract at its highest test concentration, and 79.2% when subjected to bitter dock leaf extract at the same concentration. Shoot length of this weed was reduced 100% after treatment with common walnut leaf extract, and 93.7% when subjected to bitter dock leaf extract. Root length was reduced 100% and 99.3%, respectively. Overall, the extracts demonstrated pronounced antioxidant activity and remarkable allelopathic potential., Alelopatski potencijal i fitotoksičnost sekundarnih metabolita biljaka značajni su sa aspekta biotehnologije imajući u vidu da ove fitohemikalije u svojstvu alelohemikalija mogu značajno da doprinesu razvoju agroindustrijskog sektora. Cilj rada bio je da se dobiju ekstrakti lista oraha (Juglans regia L.) i štavelja (Rumex obtusifolius L.) bogati fenolnim jedinjenjima odnosno sa visokim antioksidativnim potencijalom i da se ispita njihova fitotoksičnost prema korovskim vrstama Setaria glauca i Sorghum halepense kroz inhibiciju klijanja i rasta klijanaca. Dobijeni biljni ekstrakti pokazali su izražen potencijal u neutralisanju DPPH radikala, sa IC 50 vrednostima od 0,127 mg/ml za ekstrakt lista oraha i 0,194 mg/ml za ekstrakt lista štavelja. Redukciona sposobnost jona metala dobijenih biljnih ekstrakata takođe je bila veoma visoka, FRAP vrednost za ekstrakt lista oraha iznosila je 384,4 ± 8.1 mmol Fe 2+ /g suvog ekstrakta, dok je za ekstrakt lista štavelje iznosila 321,6 ± 2.5 mmol Fe 2+ /g suvog ekstrakta. Pri najvećoj korištenoj koncentraciji ekstrakt lista oraha inhibirao je klijanje semena S. glauca za 67,3%, dok je ekstrakt lista štavelja inhibirao klijanje ovog korova za 54,5%. Porast stabaoceta S. glauca inhibiran je 80,7% nakon tretmana ekstraktom lista oraha, a 78,2% pod uticajem ekstrakta lista štavelja, dok je porast korenka inhibiran 96,4%, odnosno 93,1%. Klijanje semena S. halepense potpuno je inhibirano (100%) pod uticajem ekstrakta lista oraha, dok je ekstrakt lista štavelja pri najvećoj korišćenoj koncentraciji prouzrokovao 79,2% inhibicije. Porast stabaoceta ovog korova potpuno je redukovan (100%) nakon tretmana ekstraktom lista oraha, a ekstrakt lista štavelja prouzrokovao je 93,7% inhibicije ovog parametra. Porast korenka inhibiran je 100% odnosno 99.3% nakon tretmana ovim ekstraktima. Dobijeni rezultati ukazuju na postojanje značajne antioksidativne aktivnosti i izraženog alelopatskog potencijala dobijenih ekstrakata lista oraha i lista štavelja.

U laboratorijskim uslovima ispitivan je uticaj 10 sojeva aktinobakterija na klijanje semena i porast klijanaca kukuruza i divljeg sirka. Primarni inokulumi sojeva aktinobakterija su zasejani na tečnu skrobno-kazeinsku podlogu i stavljeni su na mućkanje na tresilicu 7 dana. U sterilne Petri kutije odbrojano je po 10 semena obe biljne vrste i dodato po 5ml filtrirane suspenzije aktinobakterija koje su odložene u termostat (26°C). Posle 7 dana mereni su dužina korenka i stabaoca, kao i broj isklijalih semena. Suspenzije svih 10 ispitivanih sojeva aktinobakterija imale su uticaja na klijanje semena i porast klijanaca kukuruza i sirka. Soj A18 pokazao se kao najbolji kandidat za dalja ispitivanja jer su utvrđene inhibicije za kukuruz bile manje od 35%, dok su za sirak bile veće od 90%., In laboratory conditions 10 actinobacteria strains were screened for germination and seedling growth of maize and Johnson grass. Primary inoculum of actiobacteria were grown in starch casein broth for 7 days in a shaking incubator. Ten seeds from both species, were placed inside sterile Petri dishes and moinsted with 5ml of the culture filtrate of actinobacteria and incubated at 26°C. After the period of 7 days, the percentage of germination was calculated and coleoptile and radicle length were measured. Suspensions of all 10 actinobacteria strains had an effect on seed germination and early seedling growth of maize and Johnson grass. The A18 strain proved to be the best candidate for further testing because the inhibitions for maize were less than 35% and for Johnson grass they were higher than 90%.

Parthenium hysterophorus L. is a noxious herb with pharmaceutical properties and has allelopathic potentiality to retards the growth of many species. Hence, research was undertaken with the aim to identified phytotoxic compounds and determine the possibility of using aerial parts (leaf, stem and flower) of P. hysterophorus as a potential bioherbicide to control weed in Bambara groundnut field. The experiment was conducted in laboratory and glasshouse condition at University Putra Malaysia (UPM) using complete randomize design (CRD) and randomize complete block design (RCBD) accordingly. Germination of seeds and seedling growth of selected crops and weed species were tested with six concentrations of methanol, hexane, acetone, and water extracts (25, 50, 75, 100, and 150 g L-1) and distilled water as the control. The results showed that the phytotoxicity effects were significantly higher by leaf extract and methanol solvent compared to other treatments. The methanol extract of P. hysterophorus leaf sprayed as post-emergence applications on bambara groundnut (V. subterranean L.), maize (Z. mays), D. sanguinalis, E. indica, A. conyzoides, C. iria, E. hirta, C. difformis showed that the efficacy of the treatments were in the following trend; leaf>flower>stem and methanol>acetone>water>hexane. The liquid chromatography-mass spectrometry (LC-MS) analysis exposed the presence of 67 and 196 compounds in methanol, 60 and 191 in hexane, 75 and 77 in acetone, and 52 and 184 from water in both positive and negative polarity analysis. Seven phytotoxic derivatives were identified from the methanol solvents of leaf and flower but two and three compounds in acetone, hexane, and water extract respectively. On the other hand, high-performance liquid chromatography (HPLC) analysis confirmed methanol with leaf extracts contained a higher number and amount of chemical compounds than did those of the other solvent extracts. Caffeic acid, chlorogenic acid, and parthenin (highest allelopat

To evaluate the allelopathic effects of leaf (LEC) and stem extract concentrations (SEC) of Elephant grass (Pennisetum purpureum) on germination (G) root length (RL), shoot length (SL) and water absorption (WA) of Stylosanthes hamata (Stylo) and Lablab purpureus (Lablab). In the first experiment twenty seeds (20) of Stylo and Lablab were set on three filter papers that were placed in Petri dishe`s. The filter papers were moistened with LEC ranging from 0, 0.5, 1, 1.5 and 2% (w/v). The same methodology was followed in the second experiment except that SEC of Elephant grass was used instead.  The design of the experiments was a 2 x 5 factorial in a completely randomized design. The factors were two legume seeds species and five leaf/stem extract concentrations (0, 0.5, 1, 1.5 and 2%). The results of the study indicated significant differences between seeds of Stylo and Lablab treated with LEC. Lablab seeds had significantly higher (P<0.05) percentage G, RL and SL than Stylo. Concentrations were not significantly different except in the case of WA. G and RL were observed to decline with increase in LEC. In the second experiment, seeds of Stylo and Lablab were significantly different (P<0.05) in terms of all parameters measured. Lablab had consistently higher (P<0.05) values for G, RL, SL and WA. SEC did not significantly affect G, RL and SL except WA that was found to be the highest at 2% SEC. Overall LEC were observed to have decreased G and RL while SEC enhanced the two parameters.

NRPs were involved in growth responses of both cyanobacteria and algae; however, the primary driver of the growth trajectories was high pH induced by N. spumigena. Thus, the pH-mediated inhibition of eukaryotic phytoplankton may be involved in the bloom formation of N. spumigena. Nodularia spumigena is a bloom-forming cyanobacterium that produces several classes of nonribosomal peptides (NRPs) that are biologically active; however, the ecological roles of specific NRPs remain largely unknown. Here, we explored the involvement of NRPs produced by N. spumigena in interspecific interactions by coculturing the cyanobacterium and its algal competitors, the diatom Phaeodactylum tricornutum and the cryptomonad Rhodomonas salina, and measuring NRP levels and growth responses in all three species. Contrary to the expected growth suppression in the algae, it was N. spumigena that was adversely affected by the diatom, while the cryptomonad had no effect. Reciprocal effects of N. spumigena on the algae were manifested as the prolonged lag phase in R. salina and growth stimulation in P. tricornutum; however, these responses were largely attributed to elevated pH and not to specific NRPs. Nevertheless, the NRP levels in the cocultures were significantly higher than in the monocultures, with an up to 5-fold upregulation of cell-bound nodularins and exudation of nodularin and anabaenopeptin. Thus, chemically mediated interspecific interactions can promote NRP production and release by cyanobacteria, resulting in increased input of these compounds into the water.

An important aspect of understanding how plants effect their environmentis the study of volatile compounds and how these influence interactions between plants and other living organisms. The study of these secondary metabolites from plants can be used in practical applications, such as behaviour control of insects, and is an important part in the search for novel compounds that can be used to influence the behaviour of disease spreading vectors. The study of secondary metabolites can also be used as tools for introducing and teaching chemical ecology and analytical chemistry. The proper use of sample preparation methods and analysis has a key role in both these applications. In this thesis, different sample collection methods are combined with gas chromatography-mass spectrometry to investigate the diversity of secondary metabolites emitted from plants. In paper I, two different sample collection methods, ultrasound assisted extraction and solid-phase microextraction, were used as a basis to collect six metabolites as a metric of comparison of the methods. The work compares the ultrasound assisted extraction and solid-phase microextraction of stored Cyperus rotundus, and also compares solid-phase microextraction collections from stored and live plant samples. The static headspace solid-phase microextraction method used in paper I was then used to analyse the headspace samples of three other graminoid plants, namely Cynodon dactylon, Cyperus exaltatus and Panicum repens. In paper III, the identification of the headspace volatiles of the graminoid plants were determined, and the relative peak area percentages were analysed using one-way ANOVA. The result of this work allowed for a comparison between the three different plants to determine significant differences between the compounds detected based on relative peak area percentages. Adding to the results of paper I and III, the results from paper II offers more insight into the chemicals present in the gas phase above, En viktig aspekt för förståelsen av hur växter påverkar sin omgivning är studien av flyktiga ämnen och hur dessa påverkar interaktionen mellan växter och andra levande organismer. Studier av sekundära metaboliter från växter kan användas i praktiska applikationer, så som beetendekontroll av insekter, till exempel myggor, där denna kunskap är en viktig del i sökandet efter nya ämnen som kan användas för att påverka beteendet hos smittbärande insekter. Studier av sekundära metaboliter kan också användas som ett redskap för att introducera och undervisa i kemisk ekologi och analytisk kemi. God användning av provpreparering och provanalys har en viktig roll i båda applikationerna. I denna avhandling så används olika provberedningsmetoder, i kombination med gaskromatografi-masspektometri, för att undersöka den mångfald av sekundära metaboliter som utsöndras från växter. I paper I används två olika provuppsamlingsmetoder, ultraljudsassisterad extraktion och fastfas-mikroextraktion, som grunden för uppsamling av sex metaboliter som mått för jämförelse mellan metoderna. Detta arbete jämför provuppsamling med ultraljudsassisterad extraktion och fastfasmikroextraktion på gräs som har förvarats en tid innan analys, men jämför även fastfas-mikroextraktion uppsamlingar från levande gräs med det som legat på förvaring. Den statiska gasfas fastfas-mikroextraktionsmetod som användes i paper I, användes sedan också för att analysera den kemiska gasfasen för tre andra gräs-liknande växter, nämligen Cynodon dactylon, Cyperus exaltatus och Panicum repens. I paper III så utförs identifiering av flyktiga ämnen från de gräs-liknande växternas gasfas, och deras relativa toppareaprocent analyseras med one-way ANOVA. Resultaten från detta arbete möjliggör en jämförelse mellan de tre växter för att avgöra om man kan se signifikanta skillnader för de ämnen som detekteras baserat på den relativa toppareaprocenten. Vidare, tillför arbetet från paper II mer insikt om de kemiska föreningar som kan, QC 2022-03-03

An important aspect of understanding how plants effect their environmentis the study of volatile compounds and how these influence interactions between plants and other living organisms. The study of these secondary metabolites from plants can be used in practical applications, such as behaviour control of insects, and is an important part in the search for novel compounds that can be used to influence the behaviour of disease spreading vectors. The study of secondary metabolites can also be used as tools for introducing and teaching chemical ecology and analytical chemistry. The proper use of sample preparation methods and analysis has a key role in both these applications. In this thesis, different sample collection methods are combined with gas chromatography-mass spectrometry to investigate the diversity of secondary metabolites emitted from plants. In paper I, two different sample collection methods, ultrasound assisted extraction and solid-phase microextraction, were used as a basis to collect six metabolites as a metric of comparison of the methods. The work compares the ultrasound assisted extraction and solid-phase microextraction of stored Cyperus rotundus, and also compares solid-phase microextraction collections from stored and live plant samples. The static headspace solid-phase microextraction method used in paper I was then used to analyse the headspace samples of three other graminoid plants, namely Cynodon dactylon, Cyperus exaltatus and Panicum repens. In paper III, the identification of the headspace volatiles of the graminoid plants were determined, and the relative peak area percentages were analysed using one-way ANOVA. The result of this work allowed for a comparison between the three different plants to determine significant differences between the compounds detected based on relative peak area percentages. Adding to the results of paper I and III, the results from paper II offers more insight into the chemicals present in the gas phase above, En viktig aspekt för förståelsen av hur växter påverkar sin omgivning är studien av flyktiga ämnen och hur dessa påverkar interaktionen mellan växter och andra levande organismer. Studier av sekundära metaboliter från växter kan användas i praktiska applikationer, så som beetendekontroll av insekter, till exempel myggor, där denna kunskap är en viktig del i sökandet efter nya ämnen som kan användas för att påverka beteendet hos smittbärande insekter. Studier av sekundära metaboliter kan också användas som ett redskap för att introducera och undervisa i kemisk ekologi och analytisk kemi. God användning av provpreparering och provanalys har en viktig roll i båda applikationerna. I denna avhandling så används olika provberedningsmetoder, i kombination med gaskromatografi-masspektometri, för att undersöka den mångfald av sekundära metaboliter som utsöndras från växter. I paper I används två olika provuppsamlingsmetoder, ultraljudsassisterad extraktion och fastfas-mikroextraktion, som grunden för uppsamling av sex metaboliter som mått för jämförelse mellan metoderna. Detta arbete jämför provuppsamling med ultraljudsassisterad extraktion och fastfasmikroextraktion på gräs som har förvarats en tid innan analys, men jämför även fastfas-mikroextraktion uppsamlingar från levande gräs med det som legat på förvaring. Den statiska gasfas fastfas-mikroextraktionsmetod som användes i paper I, användes sedan också för att analysera den kemiska gasfasen för tre andra gräs-liknande växter, nämligen Cynodon dactylon, Cyperus exaltatus och Panicum repens. I paper III så utförs identifiering av flyktiga ämnen från de gräs-liknande växternas gasfas, och deras relativa toppareaprocent analyseras med one-way ANOVA. Resultaten från detta arbete möjliggör en jämförelse mellan de tre växter för att avgöra om man kan se signifikanta skillnader för de ämnen som detekteras baserat på den relativa toppareaprocenten. Vidare, tillför arbetet från paper II mer insikt om de kemiska föreningar som kan, QC 2022-03-03

Sekundarni metaboliti jabuke (Malus × domestica Borkh.) florizin i floretin su dihidrohalkoni visoko specifični za vrste roda Malus. Autoalelopatski potencijal ovih fenolnih jedinjenja se ogleda u suzbijanju rasta klijanca i sadnica zasađenih na mestu prvobitnih voćnjaka jabuke. U osnovi njihove fitotoksičnosti su ultrastrukturne i molekularne promene koje se ogledaju u povećanju sadržaja malondialdehida, prolina i aktivnosti antioksidativnih enzima: superoksid-dismutaze, peroksidaza i katalaza, kao i nivoa ekspresije proteina uključenih u odbrambene mehanizme ćelije. Najnovija istraživanja ukazuju na fitotoksičnost ovih dihidrohalkona i prema drugim biljnim vrstama, kao npr. korovskoj model biljci Arabidopsis thaliana. Tretman floretinom izaziva značajnu inhibiciju rastenja i razvića klijanaca A. thaliana, poremećaj gravitropskog odgovora i pojavu morfoloških i ultrastrukturnih malformacija u čijoj osnovi leži promena ekspresije CDKA1;1, CDKB2;1, CYCA3;1 i CYCB2;4 gena ćelijskog ciklusa, kao i gena uključenih u održanje homeostaze auksina (PINs, AUX1, LAX3, ABCBs, TAA1 i YUCs) i biosinteze giberelina (GA20ox2 i GA3ox1). Ovo otvara mogućnost za dalja istraživanja njihovog alelopatskog delovanja ali i potencijalnu primenu kao ekološki bezbednih bioherbicida., Phloridzin and phloretin are dihydrochalcones highly specific to domestic apple (Malus × domestica Borkh.) and other species from genus Malus. Auto-allelopathic potential of these phenolics was recognized in ‘Apple Replant Disease’ (ARD) characterized by stunted growth, reduced root system and low yields in apple trees replanted on lands that previously supported apple orchards. Physiological basis of phloridzin and phloretin autotoxicity are ultrastructural and molecular alterations that include increased catalase, peroxidases and superoxide dismutase activities, raised malondialdehyde and proline contents, and high expression of genes involved in cell defence system. The latest research on model plant Arabidopsis thaliana indicates phytotoxicity of these dihydrochalcones towards other plant species. Phloretin inhibits A. thaliana seedlings growth and development inducing agravitropic phenotype and morphological and ultrastructural malformations in treated seedlings. Altered expression of CDKA1;1, CDKB2;1, CYCA3;1 and CYCB2;4 cell cycle genes and genes involved in auxin homeostasis (PINs, AUX1, LAX3, ABCBs, TAA1 and YUCs) and gibberellin biosynthesis (GA20ox2 and GA3ox1) are in the physiological bases of phloretin phytotoxicity. This mechanism makes phloretin a prospective candidate for an eco-friendly bioherbicide and paves the way for further research of phloretin role in ARD.

La alelopatía es descrita como el efecto positivo o negativo que puede causar una planta en el crecimiento y desarrollo de otra, a través de la liberación de componentes químicos al ambiente. El tarwi, Lupinus mutabilis Sweet., es una leguminosa originaria de la zona andina cuyos granos contienen un alto porcentaje de proteínas. Sin embargo, tiene un sabor amargo debido a la presencia de alcaloides. Estos son metabolitos que han sido reportados como potenciales componentes aleloquímicos, cuyos usos en agricultura se están investigando. Se realizaron experimentos en laboratorio para determinar el efecto de 5 concentraciones (0; 1,55; 3,10; 4,65 y 6,20 mg mL–1) de extracto acuoso de alcaloides del tarwi sobre la germinación y crecimiento de las plántulas in vitro de tres especies de malezas: Amaranthus dubius, Bidens pilosa y Medicago polymorpha. Se evaluó el porcentaje de germinación y las longitudes de radícula e hipocótilo de las plántulas. Se observó una relación inversamente proporcional entre las dosis y ambas longitudes evaluadas para todas las especies, siendo A. dubius la más afectada en germinación y M. polymorpha en crecimiento de plántula. La mayor reducción en germinación y crecimiento de plántulas se obtuvo en concentraciones mayores de 4,65 mg mL–1 de extracto., Allelopathy is described as the positive or negative effect that one plant causes on the growing of another, which occurs through the release of chemical components to the environment. The ‘tarwi’, Lupinus mutabilis Sweet., is a native legume from the Andean region whose seeds have a high protein content, however, these have a bitter taste due to the presence of alkaloids, metabolites that have been reported as allelochemical components, whose uses in agriculture are being investigated. Laboratory experiments were conducted to determine the effect of 5 concentrations (0, 1.55, 3.10, 4.65 and 6.20 mg mL–1) of aqueous extract of tarwi alkaloids on the germination and growth of in vitro seedlings of three species of weeds; Amaranthus dubius, Bidens pilosa and Medicago polymorpha, in which the germination percentage, radicle and hypocotyl lengths of the seedlings were evaluated. An inversely proportional relationship between the concentrations and lengths evaluated for all species was considered, having A. dubius germination and M. polymorpha seedling growth as the most affected. The most significant reduction in germination and plant growth occurred at concentrations above 4.65 mg mL–1.

Orobanche cumana is an obligate holoparasitic plant with noxious effects in sunflower crops. Bellardia trixago is a facultative hemiparasitic plant that infects ruderal plants without noxious significance in agriculture and is known to produce a wide spectrum of bioactive metabolites. The objective of this study was to evaluate the allelopathic effects of B. trixago on the growth of O. cumana seedlings. Three different extracts using solvents of increasing polarity (n-hexane, dichloromethane and ethyl acetate) were prepared from the flowers, aerial green organs and roots of two populations, a white-flowered and a yellow-flowered population of B. trixago, both collected in southern Spain. Each extract was studied using allelopathic screenings on O. cumana which resulted in the identification of allelopathic activity of the ethyl acetate extracts against Orobanche radicles. Five iridoid glycosides were isolated together with benzoic acid from the ethyl acetate extract of aerial green organs by bio-guided purification. These compounds were identified as bartsioside, melampyroside, mussaenoside, gardoside methyl ester and aucubin. Among them, melampyroside was found to be the most abundant constituent in the extract (44.3% w/w), as well as the most phytotoxic iridoid on O. cumana radicle, showing a 72.6% inhibition of radicle growth. This activity of melampyroside was significantly high when compared with the inhibitory activity of benzoic acid (25.9%), a phenolic acid with known allelopathic activity against weeds. The ecotoxicological profile of melampyroside was evaluated using organisms representing different trophic levels of the aquatic and terrestrial ecosystems, namely producers (green freshwater algae Raphidocelis subcapitata and macrophyte Lepidium sativum), consumers (water flea Daphnia magna and nematode Caenorhabditis elegans) and decomposers (bacterium Aliivibrio fischeri). The ecotoxicity of melampyroside differed significantly depending on the test organ

Broomrape weeds (Orobanche and Phelipanche spp.) are noxious parasites that infect crops using haustoria formed at the tip of their radicles. Dichloromethane extract obtained from the roots of Convolvulus arvensis strongly inhibits the radicle growth of broomrape weeds. A complex mixture of arvensic acids was isolated as the metabolites responsible of the inhibitory activity of C. arvensis extract against broomrape radicle growth via activity-guided fractionation and 1H NMR and ESI MS data. We showed that the exposure of broomrape seedlings to this arvensic acids mixture results in a strong phytotoxic effect on their radicles in four broomrape species infecting a wide range of crops worldwide. This discovery paves the way for the synthesis of new bioherbicides and could contribute to the development of efficient and sustainable management strategies for broomrape weeds, for which control in many crops is limited or non-existing.

To evaluate the allelopathic effects of leaf (LEC) and stem extract concentrations (SEC) of Elephant grass (Pennisetum purpureum) on germination (G) root length (RL), shoot length (SL) and water absorption (WA) of Stylosanthes hamata (Stylo) and Lablab purpureus (Lablab). In the first experiment twenty seeds (20) of Stylo and Lablab were set on three filter papers that were placed in Petri dishe`s. The filter papers were moistened with LEC ranging from 0, 0.5, 1, 1.5 and 2% (w/v). The same methodology was followed in the second experiment except that SEC of Elephant grass was used instead.  The design of the experiments was a 2 x 5 factorial in a completely randomized design. The factors were two legume seeds species and five leaf/stem extract concentrations (0, 0.5, 1, 1.5 and 2%). The results of the study indicated significant differences between seeds of Stylo and Lablab treated with LEC. Lablab seeds had significantly higher (P<0.05) percentage G, RL and SL than Stylo. Concentrations were not significantly different except in the case of WA. G and RL were observed to decline with increase in LEC. In the second experiment, seeds of Stylo and Lablab were significantly different (P<0.05) in terms of all parameters measured. Lablab had consistently higher (P<0.05) values for G, RL, SL and WA. SEC did not significantly affect G, RL and SL except WA that was found to be the highest at 2% SEC. Overall LEC were observed to have decreased G and RL while SEC enhanced the two parameters.

An important aspect of understanding how plants effect their environmentis the study of volatile compounds and how these influence interactions between plants and other living organisms. The study of these secondary metabolites from plants can be used in practical applications, such as behaviour control of insects, and is an important part in the search for novel compounds that can be used to influence the behaviour of disease spreading vectors. The study of secondary metabolites can also be used as tools for introducing and teaching chemical ecology and analytical chemistry. The proper use of sample preparation methods and analysis has a key role in both these applications. In this thesis, different sample collection methods are combined with gas chromatography-mass spectrometry to investigate the diversity of secondary metabolites emitted from plants. In paper I, two different sample collection methods, ultrasound assisted extraction and solid-phase microextraction, were used as a basis to collect six metabolites as a metric of comparison of the methods. The work compares the ultrasound assisted extraction and solid-phase microextraction of stored Cyperus rotundus, and also compares solid-phase microextraction collections from stored and live plant samples. The static headspace solid-phase microextraction method used in paper I was then used to analyse the headspace samples of three other graminoid plants, namely Cynodon dactylon, Cyperus exaltatus and Panicum repens. In paper III, the identification of the headspace volatiles of the graminoid plants were determined, and the relative peak area percentages were analysed using one-way ANOVA. The result of this work allowed for a comparison between the three different plants to determine significant differences between the compounds detected based on relative peak area percentages. Adding to the results of paper I and III, the results from paper II offers more insight into the chemicals present in the gas phase above, En viktig aspekt för förståelsen av hur växter påverkar sin omgivning är studien av flyktiga ämnen och hur dessa påverkar interaktionen mellan växter och andra levande organismer. Studier av sekundära metaboliter från växter kan användas i praktiska applikationer, så som beetendekontroll av insekter, till exempel myggor, där denna kunskap är en viktig del i sökandet efter nya ämnen som kan användas för att påverka beteendet hos smittbärande insekter. Studier av sekundära metaboliter kan också användas som ett redskap för att introducera och undervisa i kemisk ekologi och analytisk kemi. God användning av provpreparering och provanalys har en viktig roll i båda applikationerna. I denna avhandling så används olika provberedningsmetoder, i kombination med gaskromatografi-masspektometri, för att undersöka den mångfald av sekundära metaboliter som utsöndras från växter. I paper I används två olika provuppsamlingsmetoder, ultraljudsassisterad extraktion och fastfas-mikroextraktion, som grunden för uppsamling av sex metaboliter som mått för jämförelse mellan metoderna. Detta arbete jämför provuppsamling med ultraljudsassisterad extraktion och fastfasmikroextraktion på gräs som har förvarats en tid innan analys, men jämför även fastfas-mikroextraktion uppsamlingar från levande gräs med det som legat på förvaring. Den statiska gasfas fastfas-mikroextraktionsmetod som användes i paper I, användes sedan också för att analysera den kemiska gasfasen för tre andra gräs-liknande växter, nämligen Cynodon dactylon, Cyperus exaltatus och Panicum repens. I paper III så utförs identifiering av flyktiga ämnen från de gräs-liknande växternas gasfas, och deras relativa toppareaprocent analyseras med one-way ANOVA. Resultaten från detta arbete möjliggör en jämförelse mellan de tre växter för att avgöra om man kan se signifikanta skillnader för de ämnen som detekteras baserat på den relativa toppareaprocenten. Vidare, tillför arbetet från paper II mer insikt om de kemiska föreningar som kan, QC 2022-03-03

An important aspect of understanding how plants effect their environmentis the study of volatile compounds and how these influence interactions between plants and other living organisms. The study of these secondary metabolites from plants can be used in practical applications, such as behaviour control of insects, and is an important part in the search for novel compounds that can be used to influence the behaviour of disease spreading vectors. The study of secondary metabolites can also be used as tools for introducing and teaching chemical ecology and analytical chemistry. The proper use of sample preparation methods and analysis has a key role in both these applications. In this thesis, different sample collection methods are combined with gas chromatography-mass spectrometry to investigate the diversity of secondary metabolites emitted from plants. In paper I, two different sample collection methods, ultrasound assisted extraction and solid-phase microextraction, were used as a basis to collect six metabolites as a metric of comparison of the methods. The work compares the ultrasound assisted extraction and solid-phase microextraction of stored Cyperus rotundus, and also compares solid-phase microextraction collections from stored and live plant samples. The static headspace solid-phase microextraction method used in paper I was then used to analyse the headspace samples of three other graminoid plants, namely Cynodon dactylon, Cyperus exaltatus and Panicum repens. In paper III, the identification of the headspace volatiles of the graminoid plants were determined, and the relative peak area percentages were analysed using one-way ANOVA. The result of this work allowed for a comparison between the three different plants to determine significant differences between the compounds detected based on relative peak area percentages. Adding to the results of paper I and III, the results from paper II offers more insight into the chemicals present in the gas phase above, En viktig aspekt för förståelsen av hur växter påverkar sin omgivning är studien av flyktiga ämnen och hur dessa påverkar interaktionen mellan växter och andra levande organismer. Studier av sekundära metaboliter från växter kan användas i praktiska applikationer, så som beetendekontroll av insekter, till exempel myggor, där denna kunskap är en viktig del i sökandet efter nya ämnen som kan användas för att påverka beteendet hos smittbärande insekter. Studier av sekundära metaboliter kan också användas som ett redskap för att introducera och undervisa i kemisk ekologi och analytisk kemi. God användning av provpreparering och provanalys har en viktig roll i båda applikationerna. I denna avhandling så används olika provberedningsmetoder, i kombination med gaskromatografi-masspektometri, för att undersöka den mångfald av sekundära metaboliter som utsöndras från växter. I paper I används två olika provuppsamlingsmetoder, ultraljudsassisterad extraktion och fastfas-mikroextraktion, som grunden för uppsamling av sex metaboliter som mått för jämförelse mellan metoderna. Detta arbete jämför provuppsamling med ultraljudsassisterad extraktion och fastfasmikroextraktion på gräs som har förvarats en tid innan analys, men jämför även fastfas-mikroextraktion uppsamlingar från levande gräs med det som legat på förvaring. Den statiska gasfas fastfas-mikroextraktionsmetod som användes i paper I, användes sedan också för att analysera den kemiska gasfasen för tre andra gräs-liknande växter, nämligen Cynodon dactylon, Cyperus exaltatus och Panicum repens. I paper III så utförs identifiering av flyktiga ämnen från de gräs-liknande växternas gasfas, och deras relativa toppareaprocent analyseras med one-way ANOVA. Resultaten från detta arbete möjliggör en jämförelse mellan de tre växter för att avgöra om man kan se signifikanta skillnader för de ämnen som detekteras baserat på den relativa toppareaprocenten. Vidare, tillför arbetet från paper II mer insikt om de kemiska föreningar som kan, QC 2022-03-03

An important aspect of understanding how plants effect their environmentis the study of volatile compounds and how these influence interactions between plants and other living organisms. The study of these secondary metabolites from plants can be used in practical applications, such as behaviour control of insects, and is an important part in the search for novel compounds that can be used to influence the behaviour of disease spreading vectors. The study of secondary metabolites can also be used as tools for introducing and teaching chemical ecology and analytical chemistry. The proper use of sample preparation methods and analysis has a key role in both these applications. In this thesis, different sample collection methods are combined with gas chromatography-mass spectrometry to investigate the diversity of secondary metabolites emitted from plants. In paper I, two different sample collection methods, ultrasound assisted extraction and solid-phase microextraction, were used as a basis to collect six metabolites as a metric of comparison of the methods. The work compares the ultrasound assisted extraction and solid-phase microextraction of stored Cyperus rotundus, and also compares solid-phase microextraction collections from stored and live plant samples. The static headspace solid-phase microextraction method used in paper I was then used to analyse the headspace samples of three other graminoid plants, namely Cynodon dactylon, Cyperus exaltatus and Panicum repens. In paper III, the identification of the headspace volatiles of the graminoid plants were determined, and the relative peak area percentages were analysed using one-way ANOVA. The result of this work allowed for a comparison between the three different plants to determine significant differences between the compounds detected based on relative peak area percentages. Adding to the results of paper I and III, the results from paper II offers more insight into the chemicals present in the gas phase above, En viktig aspekt för förståelsen av hur växter påverkar sin omgivning är studien av flyktiga ämnen och hur dessa påverkar interaktionen mellan växter och andra levande organismer. Studier av sekundära metaboliter från växter kan användas i praktiska applikationer, så som beetendekontroll av insekter, till exempel myggor, där denna kunskap är en viktig del i sökandet efter nya ämnen som kan användas för att påverka beteendet hos smittbärande insekter. Studier av sekundära metaboliter kan också användas som ett redskap för att introducera och undervisa i kemisk ekologi och analytisk kemi. God användning av provpreparering och provanalys har en viktig roll i båda applikationerna. I denna avhandling så används olika provberedningsmetoder, i kombination med gaskromatografi-masspektometri, för att undersöka den mångfald av sekundära metaboliter som utsöndras från växter. I paper I används två olika provuppsamlingsmetoder, ultraljudsassisterad extraktion och fastfas-mikroextraktion, som grunden för uppsamling av sex metaboliter som mått för jämförelse mellan metoderna. Detta arbete jämför provuppsamling med ultraljudsassisterad extraktion och fastfasmikroextraktion på gräs som har förvarats en tid innan analys, men jämför även fastfas-mikroextraktion uppsamlingar från levande gräs med det som legat på förvaring. Den statiska gasfas fastfas-mikroextraktionsmetod som användes i paper I, användes sedan också för att analysera den kemiska gasfasen för tre andra gräs-liknande växter, nämligen Cynodon dactylon, Cyperus exaltatus och Panicum repens. I paper III så utförs identifiering av flyktiga ämnen från de gräs-liknande växternas gasfas, och deras relativa toppareaprocent analyseras med one-way ANOVA. Resultaten från detta arbete möjliggör en jämförelse mellan de tre växter för att avgöra om man kan se signifikanta skillnader för de ämnen som detekteras baserat på den relativa toppareaprocenten. Vidare, tillför arbetet från paper II mer insikt om de kemiska föreningar som kan, QC 2022-03-03

To evaluate the allelopathic effects of leaf (LEC) and stem extract concentrations (SEC) of Elephant grass (Pennisetum purpureum) on germination (G) root length (RL), shoot length (SL) and water absorption (WA) of Stylosanthes hamata (Stylo) and Lablab purpureus (Lablab). In the first experiment twenty seeds (20) of Stylo and Lablab were set on three filter papers that were placed in Petri dishe`s. The filter papers were moistened with LEC ranging from 0, 0.5, 1, 1.5 and 2% (w/v). The same methodology was followed in the second experiment except that SEC of Elephant grass was used instead.  The design of the experiments was a 2 x 5 factorial in a completely randomized design. The factors were two legume seeds species and five leaf/stem extract concentrations (0, 0.5, 1, 1.5 and 2%). The results of the study indicated significant differences between seeds of Stylo and Lablab treated with LEC. Lablab seeds had significantly higher (P<0.05) percentage G, RL and SL than Stylo. Concentrations were not significantly different except in the case of WA. G and RL were observed to decline with increase in LEC. In the second experiment, seeds of Stylo and Lablab were significantly different (P<0.05) in terms of all parameters measured. Lablab had consistently higher (P<0.05) values for G, RL, SL and WA. SEC did not significantly affect G, RL and SL except WA that was found to be the highest at 2% SEC. Overall LEC were observed to have decreased G and RL while SEC enhanced the two parameters.

Allelopathy is an efficient strategy by which some microalgae can outcompete other species. Allelochemicals from the toxic dinoflagellate Alexandrium minutum have deleterious effects on diatoms, inhibiting metabolism and photosynthesis and therefore give a competitive advantage to the dinoflagellate. The precise mechanisms of allelochemical interactions and the molecular target of allelochemicals remain however unknown. To understand the mechanisms, the short-term effects of A. minutum allelochemicals on the physiology of the diatom Chaetoceros muelleri were investigated. The effects of a culture filtrate were measured on the diatom cytoplasmic membrane integrity (polarity and permeability) using flow-cytometry and on the photosynthetic performance using fluorescence and absorption spectroscopy. Within 10 min, the unknown allelochemicals induced a depolarization of the cytoplasmic membranes and an impairment of photosynthesis through the inhibition of the plastoquinone-mediated electron transfer between photosystem II and cytochrome b6f. At longer time of exposure, the cytoplasmic membranes were permeable and the integrity of photosystems I, II and cytochrome b6f was compromised. Our demonstration of the essential role of membranes in this allelochemical interaction provides new insights for the elucidation of the nature of the allelochemicals. The relationship between cytoplasmic membranes and the inhibition of the photosynthetic electron transfer remains however unclear and warrants further investigation.

Allelopathy is an efficient strategy by which some microalgae can outcompete other species. Allelochemicals from the toxic dinoflagellate Alexandrium minutum have deleterious effects on diatoms, inhibiting metabolism and photosynthesis and therefore give a competitive advantage to the dinoflagellate. The precise mechanisms of allelochemical interactions and the molecular target of allelochemicals remain however unknown. To understand the mechanisms, the short-term effects of A. minutum allelochemicals on the physiology of the diatom Chaetoceros muelleri were investigated. The effects of a culture filtrate were measured on the diatom cytoplasmic membrane integrity (polarity and permeability) using flow-cytometry and on the photosynthetic performance using fluorescence and absorption spectroscopy. Within 10 min, the unknown allelochemicals induced a depolarization of the cytoplasmic membranes and an impairment of photosynthesis through the inhibition of the plastoquinone-mediated electron transfer between photosystem II and cytochrome b6f. At longer time of exposure, the cytoplasmic membranes were permeable and the integrity of photosystems I, II and cytochrome b6f was compromised. Our demonstration of the essential role of membranes in this allelochemical interaction provides new insights for the elucidation of the nature of the allelochemicals. The relationship between cytoplasmic membranes and the inhibition of the photosynthetic electron transfer remains however unclear and warrants further investigation.

Phytotoxic substances released by invasive plants have been reported to have anti‐pathogen, anti‐herbivore, and allelopathic activity. The aim of this study was to determine the allelopathic influence of the Ambrosia trifida L. on oxidative stress parameters (the lipid peroxidation process; reduced glutathione (GSH) content; and activity of antioxidant enzymes catalase (CAT), superoxide dismutase (SOD), and peroxidase (PX)) and phenolic compounds (total phenolic and tannin content) in maize (Zea mays L.), soybean (Glycine max L.), and sunflower (Helianthus annuus L.) crops to explore the effect of released allelochemicals through A. trifida root on crops. An analysis by HPLC confirmed the presence of protocatechuic acid, p‐hydroxybenzoic acid, vanillic acid, and syringic acid as major components in the A. trifida. Based on the obtained results for oxidative stress parameters, it can be concluded that the sunflower was the most sensitive species to A. trifida allelochemicals among the tested crops. The other two crops tested showed a different sensitivity to A. trifida. The soybean did not show sensitivity, while the maize showed sensitivity only 10 days after the sowing.

Given the cultural and economic importance for Mexico of maize cultivation, and the effects on germination and initial development caused by weeds, phytopathogens and adverse environmental conditions, the objective of this research was to evaluate the effect of osmoconditioning of maize seeds on germination and initial development. Two tests were carried out; in the first one, the effect of three plant extracts was studied: Cinnamomum zeylanicum, Azadirachta indica and Zingiber officinale; sodium bicarbonate and lean biofertilizer. The first with eleven treatments in a completely randomized design, in which the emergence speed and the germination percentage were quantified. In the second test, nine treatments were studied, which consisted of the concentrations that allowed germination in the first test; as variables, height, weight of total fresh and dry matter, and root volume were quantified. Local seeds from Chiapas were used. Sowing was carried out in a green house in sterile sand. The seeds treated with sodium bicarbonate and C. zeylanicum 10% (V:V) had higher emergence speed; the sodium bicarbonate treatment (30 g/L) favored germination and together with the treatments C. zeylanicum at 10% (V:V) A. indica at 20% (V:V) and Z. officinale at 30% (V:V) registered the highest values of fresh root weight, fresh and dry weight of aerial biomass, also stimulated aerial growth 56% with respect to the control treatment (p <0.05). The plant extracts of C. zeylanicum, A. indica and Z. officinale at low concentrations stimulate root and aerial growth, and inhibit the growth of phytopathogenic fungi on seeds and roots when sowing, while at concentrations of 100% they inhibit the germination of Z. mayz seeds., Dada la importancia cultural y económica para México del cultivo del maíz, y los efectos sobre la germinación y el desarrollo inicial provocado por malezas, fitopatógenos y condiciones ambientales adversas, el objetivo de esta investigación fue evaluar el efecto del osmoacondicionamiento de semillas de maíz sobre la germinación y el desarrollo inicial. Se realizaron dos ensayos; en el primero se estudiaron los resultados de tres extractos vegetales: Cinnamomum zeylanicum, Azadirachta indica y Zingiber officinale; bicarbonato de sodio y el biofertilizante magro. El primero con once tratamientos en un diseño completamente al azar, en el cual se cuantificó la velocidad de emergencia y el porcentaje de germinación. En el segundo ensayo se estudiaron nueve tratamientos, los cuales consistieron en las concentraciones que permitieron la germinación en el primer ensayo; como variables se cuantificaron altura, peso de materia fresca y seca total, y volumen de raíz. Se utilizaron semillas locales de Chiapas, la siembra se realizó en vivero, utilizando arena de río estéril como sustrato. Las semillas que fueron tratadas con bicarbonato de sodio y C. zeylanicum 10 % (V:V) presentaron mayor velocidad de emergencia; el tratamiento bicarbonato de sodio (30 g/L) favoreció la germinación y junto a los tratamientos C. zeylanicum al 10 % (V:V) A. indica al 20 % (V:V) y Z. officinale al 30 % (V:V) registraron los valores más altos de peso fresco de raíz, peso fresco y seco de biomasa aérea, además estimularon el crecimiento aéreo en un 56 % con respecto al tratamiento control (p<0.05). Los extractos vegetales de C. zeylanicum, A. indica y Z. officinale a concentraciones bajas estimulan el crecimiento radicular y aéreo, e inhiben el crecimiento de hongos fitopatógenos sobre las semillas y raíces al momento de la siembra, mientras que a concentraciones del 100 % inhiben la germinación de las semillas de Z. mayz.

Scotch broom (Cytisus scoparius (L.) Link) is a highly competitive, nonnative, leguminous shrub species of major concern in coast Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. menziesii) forests of the Pacific Northwest that has potential to impact long-term soil productivity. We conducted a bioassay to assess the potential for legacy effects on soils (e.g., soil nutrient effects, soil seedbank, etc.) following Scotch broom removal and the potential for recovery over time. The bioassay was conducted using glacial-outwash soils from an existing Long-Term Soil Productivity study near Matlock, WA, USA, where Scotch broom had been removed or kept out for 0 (broom present), 4, 10, or 14 years. Soils from each broom removal duration were combined with fertilizer treatments to assess mechanisms of response of three native plant species: yarrow (Achillea millefolium L.), Roemer's fescue (Festuca idahoensis Elmer ssp. Roemeri), and coast Douglas-fir. There was evidence for negative soil legacy effects on Douglas-fir growth and biomass, which decreased with time since broom removal. Responses to the fertilizer treatments indicated the effect was not associated with reduced nutrient availability. In contrast, both yarrow and Roemer's fescue had significantly greater biomass in soil from where broom was recently present, which decreased with time since broom removal. Responses to the fertilizer treatments indicated that this positive legacy effect is associated with nutrient availability, likely increased N. Soils from 0 and 4 years since broom removal were estimated as having the potential to produce over 578,500 Scotch broom germinants ha(-1) . Our results demonstrate the potential for both negative and positive soil legacy effects of broom depending on the responding plant species. Combined effects of negative soil legacies and a large and viable seed bank from Scotch broom create growing conditions likely to hinder long-term productivity of Douglas-fir.

This research is concerned with the Allelopathy research literature published from 1995 to 2019 obtained from SCOPUS and studied to identify the trends in research publication in terms of various document types, annual growth, the share of publication, citation growth, average citation per paper, most productive country, authors, journals, highly cited articles during this period. These factors were identified and compared for their research impact over a period of 25 years.

Various species of Alexandrium can produce a number of bioactive compounds, e.g., paralytic shellfish toxins (PSTs), spirolides, gymnodimines, goniodomins, and also uncharacterised bioactive extracellular compounds (BECs). The latter metabolites are released into the environment and affect a large range of organisms (from protists to fishes and mammalian cell lines). These compounds mediate allelochemical interactions, have anti-grazing and anti-parasitic activities, and have a potentially strong structuring role for the dynamic of Alexandrium blooms. In many studies evaluating the effects of Alexandrium on marine organisms, only the classical toxins were reported and the involvement of BECs was not considered. A lack of information on the presence/absence of BECs in experimental strains is likely the cause of contrasting results in the literature that render impossible a distinction between PSTs and BECs effects. We review the knowledge on Alexandrium BEC, (i.e., producing species, target cells, physiological effects, detection methods and molecular candidates). Overall, we highlight the need to identify the nature of Alexandrium BECs and urge further research on the chemical interactions according to their ecological importance in the planktonic chemical warfare and due to their potential collateral damage to a wide range of organisms

Allelopathy is an efficient strategy by which some microalgae can outcompete other species. Allelochemicals from the toxic dinoflagellate Alexandrium minutum have deleterious effects on diatoms, inhibiting metabolism and photosynthesis and therefore give a competitive advantage to the dinoflagellate. The precise mechanisms of allelochemical interactions and the molecular target of allelochemicals remain however unknown. To understand the mechanisms, the short-term effects of A. minutum allelochemicals on the physiology of the diatom Chaetoceros muelleri were investigated. The effects of a culture filtrate were measured on the diatom cytoplasmic membrane integrity (polarity and permeability) using flow-cytometry and on the photosynthetic performance using fluorescence and absorption spectroscopy. Within 10 min, the unknown allelochemicals induced a depolarization of the cytoplasmic membranes and an impairment of photosynthesis through the inhibition of the plastoquinone-mediated electron transfer between photosystem II and cytochrome b6f. At longer time of exposure, the cytoplasmic membranes were permeable and the integrity of photosystems I, II and cytochrome b6f was compromised. Our demonstration of the essential role of membranes in this allelochemical interaction provides new insights for the elucidation of the nature of the allelochemicals. The relationship between cytoplasmic membranes and the inhibition of the photosynthetic electron transfer remains however unclear and warrants further investigation.

Various species of Alexandrium can produce a number of bioactive compounds, e.g., paralytic shellfish toxins (PSTs), spirolides, gymnodimines, goniodomins, and also uncharacterised bioactive extracellular compounds (BECs). The latter metabolites are released into the environment and affect a large range of organisms (from protists to fishes and mammalian cell lines). These compounds mediate allelochemical interactions, have anti-grazing and anti-parasitic activities, and have a potentially strong structuring role for the dynamic of Alexandrium blooms. In many studies evaluating the effects of Alexandrium on marine organisms, only the classical toxins were reported and the involvement of BECs was not considered. A lack of information on the presence/absence of BECs in experimental strains is likely the cause of contrasting results in the literature that render impossible a distinction between PSTs and BECs effects. We review the knowledge on Alexandrium BEC, (i.e., producing species, target cells, physiological effects, detection methods and molecular candidates). Overall, we highlight the need to identify the nature of Alexandrium BECs and urge further research on the chemical interactions according to their ecological importance in the planktonic chemical warfare and due to their potential collateral damage to a wide range of organisms

Allelopathy is an efficient strategy by which some microalgae can outcompete other species. Allelochemicals from the toxic dinoflagellate Alexandrium minutum have deleterious effects on diatoms, inhibiting metabolism and photosynthesis and therefore give a competitive advantage to the dinoflagellate. The precise mechanisms of allelochemical interactions and the molecular target of allelochemicals remain however unknown. To understand the mechanisms, the short-term effects of A. minutum allelochemicals on the physiology of the diatom Chaetoceros muelleri were investigated. The effects of a culture filtrate were measured on the diatom cytoplasmic membrane integrity (polarity and permeability) using flow-cytometry and on the photosynthetic performance using fluorescence and absorption spectroscopy. Within 10 min, the unknown allelochemicals induced a depolarization of the cytoplasmic membranes and an impairment of photosynthesis through the inhibition of the plastoquinone-mediated electron transfer between photosystem II and cytochrome b6f. At longer time of exposure, the cytoplasmic membranes were permeable and the integrity of photosystems I, II and cytochrome b6f was compromised. Our demonstration of the essential role of membranes in this allelochemical interaction provides new insights for the elucidation of the nature of the allelochemicals. The relationship between cytoplasmic membranes and the inhibition of the photosynthetic electron transfer remains however unclear and warrants further investigation.