Dans le cadre de la promotion de systèmes de culture alternatifs à moindres intrants chimiques, des études sur l'introduction de plantes de service ayant vocation à réduire l'usage des pesticides et engrais azotés mobilisent un effort de recherche considérable. Dans le cadre de la production bananière pour laquelle la nuisibilité causée par les nématodes phytoparasites constitue l'une des principales contraintes, une des principales alternatives à l'utilisation de nématicides chimiques repose sur l'usage raisonné en rotation ou en association culturale de plantes de service à propriétés nématorégulatrices. Parmi les espèces candidates, celles du genre Crota/aria spp. ont largement été étudiées en raison de leur aptitude à contrôler les nématodes phytoparasites. Une méta-analyse révèle cependant que même si de nombreux auteurs s'accordent à reconnaître les propriétés allélopathiques des plantes de cette espèce, ils sont également enclins à reconnaître la forte variabilité d'expression de ces propriétés vis-à-vis du contrôle des nématodes selon les situations expérimentées. L'objectif de ce travail repose sur la compréhension du déterminisme biochimique des exsudats. La stratégie expérimentale mise en oeuvre a consisté à tester en conditions contrôlées le comportement biochimique des exsudats racinaires de deux espèces de crotalaires (C retusa, C spectabilis) et d'une espèce sensible, le bananier dessert (Musa spp.) en fonction i) de conditions biotiques variées -i.e. présence ou non de nématodes (Radopholus similis et Meloidogyne arenariaï, et présence ou non de mycorhizes-, ii) de conditions abiotiques contrastées -i.e. utilisation d'un sol naturel vs. substrat neutre, ajout ou non d'engrais chimique. La méthodologie innovante des «plantes à traire » (Brevet INRA) a été requise pour pouvoir travailler sur les exsudats racinaires des plantes conditionnées plutôt que sur des Iixiviats, comme réalisé dans des expérimentations antérieures.Les résultats obtenus en spectrophométrie visible montrent que la modification des conditions abiotiques affecte de manière importante les profils biochimiques des plantes étudiées. En présence du nématode 1..·1. arenaria les profils biochimiques des deux crotalaires sont également modifiés. Des biotests réalisés à l'aide des exsudats racinaires conditionnés au préalable par les modifications biotiques ont permis de démontrer l'effet nématostatique des crotalaires. Des analyses biochimiques en Ge-MS mettent en évidence de manière plus précise des molécules actives mises en jeu sous différentes modalités biotiques et abiotiques. Ces recherches, de portée générique, permettront de mieux comprendre les conditions de l'environnement qui régulent les profils biochimiques des exsudats racinaires des crotalaires et par extension, seront applicables aux recherches menées sur d'autres plantes de service candidates. Ceci aidera, à terme, à définir les conditions environnementales à réunir, pour orienter de manière optimale les effets allélopathiques dans une perspective de nématorégulation naturelle / As part of the promotion of alternative cropping systems at lower chemical inputs, studies on the introduction of cover crops designed to reduce the use of pesticides and nitrogen fertilizers mobilize a considerable research effort. Under banana production for which the hannfu1ness caused by plant-parasitic-nematodes is one ofthe main constraints, one of the main alternatives to the use ofchemical nematicides is based on the rational use in rotation or intercropping of cover rI crops to proteet crops from plant-parasitic-nematodes, Among the candidate species, the species from the genus of Crota/aria spp. have been widely studied because of their ability to control plant parasitic-nematodes. A meta-analysis reveals that although many authors agree allelopathic properties of these species, they are also likely to recognize the high variability of expression of these properties vis-àvis the control of nematodes according to the situations experieaced.. The objective of this woIk is focnsed on the onderstanding of the biochemical determinism of mot exudates onder environment biotic and abiotic variations. The experimental strategy was 10 test onder controlled conditions the biochemical behavior of mot exudates of two species of crotalarias (C retusa, C. spectabilis) and a susceptible species, the dessert banana crop (Musa spp.) with i) modification ofbiotic conditions -ie presence or absence of nematodes iMeloidogyne arenaria and Radopho/us similis), and presence or absence of mycorrhiza-ii) contrasting abiotic conditions -ie using a natural soil vs. neutral substrate, whether to add fertilizer. The innovative methodology of "milking plants" (patent INRA) was required in order to work on the root exudates of plants packed rather thanleachate, as done in previous experiments. The results obtained show that 'visible spectrophotometry changing abiotic conditions affect significantly the biochemical profiles of the studied plants. In the presence of nematode M. arenaria biochemical profiles of both crotalarias are also changed. Bioassays conducted using mot exudates conditioned in advance by biotic changes have demonstrated the effect of nématostatique crotalarias. Biochemical Ge-MS demonstrate more clearly active molecules that are involved in varions biotic and abiotic conditions. This research, generic scope, to better understand the environmental conditions that regulate biochemical profiles of mot exudates crotalarias and by extension, will apply to research on other plants service candidates. This will ultimately define the environmental conditions to meet, to guide optimal allelopathic effects from the perspective ofnatural nématorégulation

The impacts of two strains of the dinoflagellate Alexandrium tamarense, differing in lytic activity, on the abundance and the composition of microbial communities (<150 μm) were studied in North Sea water during spring with Phaeocystis globosa as a dominant species. Cell-free suspensions (supernatant) of exponentially growing lytic and non-lytic Alexandrium culture were added at different concentrations to natural microbial communities under nutrient rich conditions. The non-lytic strain had a positive impact on diatoms whereas the lytic strain suppressed phytoplankton growth in comparison to the control. P. globosa, present as single cells in the initial community, increased in abundance and formed colonies in all treatments. However, total abundance and number of colonies was low with lytic Alexandriumadditions, whereas shape of the colonies, but not abundance of cells, was affected by non-lytic Alexandrium additions. During the 4-day experiment, bacterial abundance was constantly higher with high lytic additions (highest concentration equivalent to 1000 cells ml−1) whereas nanoflagellate abundance in the same treatments was found to be lower at the end of the experiment. Initial bacterial community composition differed significantly among lytic Alexandrium, non-lyticAlexandrium and North Sea water. However, neither bacterial activity nor composition was significantly affected by the supernatants after 96 h. Our results indicated that Alexandrium allelochemicals do not inhibit growth and production of bacteria in seawater collected during spring in the North Sea. / Allelopathy among phytoplankton - a structuring force among phytoplankton

Magistrantūros baigiamasis darbas atliktas 2011–2013 m. Aleksandro Stulginskio universiteto Bandymų stotyje ir Agroekosistemų ir dirvožemio mokslų instituto laboratorijoje. Tyrimų objektas – žieminis rapsas (Brassica napus L.) ir jo atskirų morfologinių dalių liekanos dirvoje. Taip pat, piktžolės: baltoji balanda, dirvinė pienė, kibusis lipikas. Tyrimų tikslas – nustatyti ir įvertinti atskirų žieminių rapsų morfologinių dalių liekanų – kūlenų, ražienojų ir šaknų (po derliaus nuėmimo, dirvoje irusių tris, septynis ir keturiolika mėnesių) – vandeninių ištraukų alelopatinę įtaką piktžolių (baltosios balandos, dirvinės pienės ir kibiojo lipiko) dygimui ir augimui. Tyrimų schema – A veiksnys – rapsų liekanos: 1) žieminių rapsų kūlenos; 2) žieminių rapsų ražienojai; 3) žieminių rapsų šaknys; B veiksnys – vandeninių ištraukų koncentracijos: 1) distiliuotas vanduo; 2) 1:6250 (rapsų liekanų ir vandens santykis); 3) 1:1250; 4) 1:250; 5) 1:50; 6) 1:10. Darbo rezultatai. Vertinant žieminių rapsų liekanų morfologinių dalių ir skaidymosi trukmės įtaką piktžolių sudygimui nustatyta, kad po derliaus nuėmimo labiausiai variavo dirvinės pienės sudygimo duomenys. Skirtingose žieminių rapsų šaknų ištraukose sudygo 94–100 % mažiau dirvinės pienės sėklų, nei distiliuotame vandenyje. Po trijų mėnesių skaidymosi geriausias sudygimo procentas (76,0 %) buvo kibiojo lipiko sėklų. Visos, septynis mėnesius skaidytos, žieminių rapsų liekanų ištraukos 46–82 % slopino dirvinės pienės sudygimą lyginant su... [toliau žr. visą tekstą] / The master wokr were conducted at Experimental Station and Laboratory of Agroecosystems and Soil Science Institute of the Aleksandras Stulginskis University in 2011–2013. Research object - winter oilseed rape (Brassica napus L.) and its various morphological parts of the residues in the soil. Also, weeds: Chenopodium album L., Galium aparine L., Sonchus arvensis L. The aim of investigations was to evaluate the allelopathic effect of aqueous extracts of winter oilseed rape residues (threshing remains, stubble and roots) on Chenopodium album L., Galium aparine L., Sonchus arvensis L. germination and early growth. Treatments of the investigations: Factor A – winter oilseed rape residues: 1) threshing remains, 2) stubble, 3) roots; Factor B – concentrations of aqueous extracts: 1) distilled water, 2) 1:6250 (ratio of oilseed rape residues and water), 3) 1:1250, 4) 1:250, 5) 1:50, 6) 1:10. The results of work. Evaluation of winter oilseed rape residues morphological parts and decomposition duration on weed emergence showed that after harvesting the most variavo Sonchus arvensis L germination data. Winter oilseed rape roots extracts germinated 94-100% units less Sonchus arvensis L seeds than in distilled water. All seven months biodegradable, winter oilseed rape residues extracts 46–82% units suppressed Sonchus arvensis L germination compared with distilled water. And after fourteen months of division all winter oilseed rape residues extracts stimulated (6,5 to 43%) Sonchus... [to full text]

Phytoplankton produce allelochemicals; excreted chemical substances that are affecting other microorganisms in their direct environment. In my thesis, I investigated strain specific variability in the expression of allelochemicals of the harmful flagellate Prymnesium parvum, that is euryhaline but mainly bloom forming in brackish water. I found a large variation among strains, but further showed that all strains of P. parvum were more allelopathic in brackish water compared to marine water. In a marine microbial community, allelochemicals can affect prey, competitors and grazers both, directly and indirectly. For instance, in a food web where grazing controls prey abundance, the negative direct effect of allelochemicals on grazers will positive affect their prey. During my thesis, I investigated how marine microbial communities respond to the addition of allelochemicals. I performed field experiments with microbial communities from seawater collected from different places over Europe, and tested how this communities respond to the addition of allelochemicals from the dinoflagellate Alexandrium tamarense. Before I incubated the microbial communities for several days with A. tamarense algal filtrate, I evaluated the allelopathic efficiency of the algal filtrates with an algal monoculture of Rhodomonas spp. This allowed me to compare the effect of A. tamarense filtrate between the different microbial communities. In general, bacteria reached higher abundances when allelochemicals were present. As allelochemicals also inhibited nanoflagellates and ciliates, we concluded, that allelochemicals indirectly benefit bacteria by reducing grazing pressure. In microbial food webs with many heterotrophic grazers, allelochemicals further benefitted other phytoplankton by inhibiting grazers. It was also shown that bioavailable DOM is released from a microbial community when allelochemicals are present. As most DOM was released from the seawater fraction > 60 μm, we concluded, that larger microorganisms are more affected by allelochemicals than smaller microorganisms. The results can be explained by the surface to volume ratio of microorganisms: Larger organisms provide more contact surface for allelochemicals, and therefore, are probably more vulnerable towards allelochemicals. In conclusion, the effect of allelochemicals on a microbial community depends among others on the structure of the microbial food web, the amount of available DOM, the particle density in the seawater and the composition of the phytoplankton community.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2000. / Härtill 4 uppsatser.

O capim annoni-2, Eragrostis plana Nees, é uma espécie vegetal africana conhecida por sua capacidade invasora e, por este motivo, classificada como planta daninha, sendo considerada a mais agressiva e de mais difícil controle nos campos sulinos. Esta espécie ativa mecanismos de inibição de crescimento e germinação de outras espécies vizinhas no fenômeno denominado alelopatia. O estudo fitoquímico de E. plana Nees, justifica-se por se tratar de uma espécie com suposta atividade alelopática, bem como, em função de suas características e do impacto biológico e econômico causado por ela. Com o objetivo de identificar e caracterizar moléculas bioativas e avaliar seus efeitos alelopáticos, foram realizados os experimentos. As folhas de E. plana Nees, foram coletadas no inverno e verão, para análise fitoquímica, e a obtenção do óleo essencial das amostras foi feita por hidrodestilação e, posteriormente, filtrados e refrigerados até a análise cromatográfica gasosa acoplada a espectrometria de massas. Para os metabólitos secundários não voláteis, o material botânico foi submetido a extração exaustiva a frio, com éter de petróleo e acetato de etila. Os extratos foram submetidos à técnica de Infravermelho. Na identificação alelopática foram utilizadas sementes da espécie Ipomoea grandifolia em dois bioensaios comumente realizados em estudos alelopáticos. Os testes, de germinação e alongamento de radícula e hipocótilo foram monitorados diariamente por 7 dias, em condições controladas e realizados em câmaras BOD (Demanda Bioquímica de Oxigênio). Para os dois testes foram empregados 5 doses com diferentes concentrações de cada extrato em volume de 5 mL em cada placa de Petri. O delineamento utilizado foi o inteiramente casualizado com 4 repetições, sendo água destilada e Tween 80 + solvente extratores como testemunhas. Os dados foram submetidos ao teste de homogeneidade de variâncias, pelo teste de Cochran C e à análise de normalidade pelo teste de Shapiro–Wilk, com posterior análise de variância, ANOVA e teste de Tukey a 5% de significância para as variáveis homogêneas. O efeito alelopático apresentado pelas folhas de E. plana Nees, pode estar relacionado com os teores de terpenos observados na análise do óleo essencial, uma vez que os mesmos, possuem propriedades alelopáticas, conforme relatos da literatura. Os extratos brutos expressaram o potencial alelopático da E. plana Nees, interferindo no desenvolvimento da espécie receptora. A utilização destes extratos de forma direta ou como fonte de moléculas químicas, pode colaborar no desenvolvimento de novos bio-herbicidas. / The grass - 2 lovegrass , Eragrostis plana Nees , is an African plant species known for its invasive capacity and , therefore , classified as a weed , and is considered the most aggressive and more difficult to control in the southern fields . This species active mechanisms of inhibition of germination and growth of neighboring species in the phenomenon called allelopathy . The phytochemical study of E. plana Nees , is justified because it is a species with alleged allelopathic activity and, depending on its characteristics and the biological and economic impact caused by it . In order to identify and characterize bioactive molecules and evaluate their allelopathic effects , the experiments were performed . The leaves of E. plana Nees were collected in winter and summer , for phytochemical analysis , and obtain the essential oil sample was taken by hydrodistillation and subsequently filtered and chilled to the gas chromatographic analysis coupled with mass spectrometry . For non- volatile secondary metabolites , the plant material was subjected to exhaustive cold extraction with petroleum ether and ethyl acetate . The extracts were subjected to IR technique . In allelopathic identification seeds of Ipomoea grandifolia species commonly performed in two bioassays in allelopathic studies were used . The tests , germination and radicle and hypocotyl elongation were monitored daily for 7 days under controlled and conducted in chambers BOD ( Biochemical Oxygen Demand ) conditions . For both tests 5 doses with different concentrations of each extract volume of 5 mL in each Petri dish were used. The experimental design was completely randomized with 4 replications, with distilled water and Tween 80 + solvent extractors as witnesses . The data were submitted to variance homogeneity test, the Cochran C and analysis of normality by the Shapiro - Wilk test, with subsequent analysis of variance , ANOVA and Tukey test at 5 % significance level for the homogeneous variables. The allelopathic effect exhibited by the leaves of E. Nees plane can be related to the levels observed in the analysis of terpenes of essential oil , since they possess allelopathic effects , as reported in the literature. The extracts expressed the allelopathic potential of E. plana Nees , interfering with the development of the receiving species . The use of these extracts directly or as a source of chemical molecules , can collaborate in developing new bio - herbicides.

Made available in DSpace on 2016-06-02T19:32:12Z (GMT). No. of bitstreams: 1 DissABG.pdf: 2489261 bytes, checksum: 65c0d87f1aabe3f9693bdb8719c132fb (MD5) Previous issue date: 2003-09-11 / Universidade Federal de Sao Carlos / The objective of this work was analyze the effects of aqueous extracts of Aristolochia esperanzae organs in the germination and early growth of lettuce and radish. All the prepared extracts obeyed the ratio of 100g of plant material + 300 mL of distilled water to produce an extract 100% concentrated. This extract was diluted with distilled water to produce final concentrations of 75, 50 and 25%. In the germination tests the extracts of leaf, stem, root, fruit and flower, with concentration of 100, 75, 50, 25% were evaluated. In the seedlings growth, extracts of leaf, stem and root were used in the concentration of 100 and 50%. In the germination tests, four replicates of 30 seeds were distributed in Petri dishes with two filter paper moistened with 5 mL of the extracts, dried during 12 hours and moistened again with 4,5 mL of distilled water. In the first test, the rate and germination percentage was evaluated. In the growth test, the seeds were previously germinated (2-4mm root length) and transferred to plastic boxes containing the filter paper or coconut fiber, moistened with the extracts. The aerial part height, root length, dry mass and the presence of abnormalities in the seedlings were evaluated. Both tests were maintained at constant temperature (27ºC). The obtained results showed that the leaf extracts affected strongly the germination percentage and all the extracts, in different concentrations, delayed the germination of lettuce and radish seeds. In the growth test could be verified that the stem and root extracts caused abnormalities in the seedlings. The seedlings grown in filter paper presented bigger growth inhibition in relation to seedlings from coconut fiber. The extract concentration was the main responsible for the incentive or inhibition caused on lettuce and radish seedlings growth. / O objetivo deste trabalho foi analisar os efeitos de extratos aquosos de diferentes órgãos de Aristolochia esperanzae na germinação e crescimento de alface e rabanete. Todos os extratos preparados obedeceram à proporção de 100g de material vegetal para 300 mL de água destilada, que produziu o extrato considerado 100% concentrado. A partir deste, foram feitas diluições com água destilada para 75, 50 e 25%. Nos testes de germinação foram avaliados os efeitos dos extratos obtidos de folha, caule, raiz, fruto e flor a 100, 75, 50 e 25% Para o teste de crescimento foram utilizados extratos de folha, caule e raiz na concentração de 100 e 50%. Nos testes de germinação foram utilizadas quatro repetições de 30 sementes distribuídas em placas de Petri forradas com duas folhas de papel de filtro umedecidas com 5 mL dos referidos extratos, secas durante 12 horas e reumedecidas com 4,5 mL de água destilada. No primeiro teste avaliou-se a porcentagem e velocidade de germinação das sementes. No teste de crescimento, as sementes foram previamente germinadas (2-4 mm de radícula) e depois transferidas para caixas plásticas contendo os substratos papel de filtro e fibra de coco umedecidos com os respectivos extratos. Avaliou-se a altura das plântulas, o comprimento radicular, a massa seca das plântulas, e a presença de anormalidades nas plântulas. Os testes foram mantidos a temperatura constante de 27ºC. Através dos resultados obtidos pode-se concluir que os extratos de folha foram os que mais afetaram a porcentagem de germinação e que todos os extratos e as diferentes concentrações retardaram a germinação de sementes de alface e de rabanete. Quanto ao teste de crescimento pode-se verificar que os extratos de caule e raiz causaram anormalidades nas plântulas. As plântulas crescidas no substrato papel de filtro apresentaram maior inibição do crescimento, em relação àquelas crescidas no substrato fibra de coco. A concentração dos extratos foi a principal responsável pelo estímulo ou inibição causada no crescimento das plântulas de alface e rabanete.

Species Lupinus polyphyllus is one of the most hazardous invasive species in the Czech Republic and its increasing occurence represents a threat of native biodiversity not only in the flora of conservation areas. Influence of management experiments on invaded communities was studied on permanent plots founded on three localities in the Šumava National Park. The role of nitrogen fixed in this invasion was explored by analyzing of soil samples. Influence of allelopathic inhibition of invasive species on some coexisting native species was tested in the laboratory experiment.

Field observation and manipulative experiments were carried out to describe and test important processes affecting the plant succession on Sokolov post-mining sites. Examined was mainly effect of dominant tree species (which are planted or spontaneously established) on understory plants, litter decomposability and effect of earthworms (Lumbricidae) on late successional plant species.

Made available in DSpace on 2016-06-02T18:57:32Z (GMT). No. of bitstreams: 1 3268.pdf: 7396436 bytes, checksum: f0d498a6504b05a66b1bd7df25a69f3b (MD5) Previous issue date: 2010-05-31 / With the recent advent of biodiesel in Brazil, there has been a significant increase in the number of research on the potential of utilizing oleaginous as raw material, especially in physic nut (Jatropha curcas L.), due to its superior oil technical characteristics, as well as the plant s hardiness and productivity. However, since the production of physic nut only becomes economically viable from the third year, there is a need to consider planting in intercropping manner. The aim of this study was to evaluate the interaction and the technical and economical feasibility of intercropping of jatropha and sunflower (Helianthus annuus L.), which is also an excellent source of oil for biodiesel production. The project was implemented at UFSCar / CCA in Araras, São Paulo. The jatropha seedlings were planted in May 1998, spaced 2 meters between plants and 4 meters between rows. The sowing of sunflower variety IAC Iarama was done in November 2008, between physic nut lines, with four rows spaced at fifty centimeters, with an estimated 50,000 seeds per hectare. We evaluated the sunflower plant yield, the development of physic nut and the possible allelopathic interactions between cultures. Allelopathic effects between sunflower and weeds were also investigated. We adopted the split-plot design with four replications and four combinations of consortia, whereas T1: growing sunflowers on both sides of the physic nut planting, T2: growing sunflowers west of the physic nut planting with the east side being reserved for the germination of weeds, T3: growing sunflowers to the east line of physic nut with the west side being reserved for the germination of weeds; T4: both sides of the line of physic nut were reserved for the germination of weeds. It was concluded that there was no influence on the development of jatropha vi ii plantations in intercropped with sunflower and sunflower production was not affected by physic nut. There was also a suppression of spontaneous plants in areas with sunflower. The alternative of this consortium demonstrates a good choice for the national biodiesel program. / Com o recente advento do Biodiesel, no Brasil, houve um aumento significativo no número de pesquisas com as oleaginosas potenciais como matériaprima, destacando-se o Pinhão-Manso (Jatropha curcas L.), tanto devido às excelentes características técnicas do óleo, bem como a rusticidade e produtividade da planta. Contudo, como a produção econômica do pinhão-manso inicia-se a partir do terceiro ano, há possibilidade de estudar o plantio em sistema de consórcio. O objetivo deste trabalho foi avaliar as interações e a viabilidade técnica e econômica do consórcio de pinhão-manso e o girassol (Helianthus annuus L.), também excelente fonte de óleo para produção de biodiesel. O projeto foi implantado na UFSCar/CCA, em Araras, São Paulo. As mudas de pinhão-manso foram plantadas em maio de 1998, no espaçamento de 2 metros entre as plantas e de 4 metros entre as linhas de plantio. A semeadura do girassol, da variedade IAC-Iarama, foi realizada em novembro de 2008, nas entrelinhas do pinhão-manso, com quatro linhas de plantio, espaçadas em cinqüenta centímetros, com média de 2,5 sementes por metro linear, o equivalente a 50.000 sementes por hectare. Foram avaliados, a produtividade da cultura do girassol, o desenvolvimento das plantas do pinhãomanso e, as possíveis interações aleloáticas entre as culturas do girassol e do pinhão-manso. Possíveis efeitos alélopaticos entre o girassol e plantas espontâneas também foram investigados. Adotou-se o delineamento de parcelas subdivididas, com quatro repetições e quatro combinações de consórcios, sendo, T1: plantio de girassol em ambos os lados da linha de plantio de pinhão-manso; T2: plantio de vi girassol a oeste da linha de pinhão-manso, o lado leste foi reservado para germinação de plantas espontâneas; T3: plantio de girassol a leste da linha de pinhão-manso, o lado oeste foi reservado para germinação de plantas espontâneas; T4: em ambos os lados da linha de pinhão manso foram reservados para a germinação de plantas espontâneas. Foi concluído que não houve influência no desenvolvimento do pinhão-manso em plantio consorciado com girassol. Conclui-se que a produção do girassol também não foi influenciada pelo pinhão-manso. Observou-se também, uma inibição e redução, estatisticamente significativa, de plantas espontâneas nas áreas de cultivo com girassol. A alternativa deste consórcio demonstra ser uma boa opção para o programa nacional de biodiesel.