• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 72
  • 22
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 110
  • 110
  • 50
  • 42
  • 24
  • 21
  • 21
  • 20
  • 16
  • 15
  • 10
  • 9
  • 9
  • 9
  • 8
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Deficiência hídrica e aplicação de ABA sobre as trocas gasosas e o acúmulo de flavonóides em calêndula (Calendula officinalis L.) / Water deficit and ABA application on leaf gas exchange and flavonoid content in marigold (Calendula officinalis L.)

Ana Cláudia Pacheco 14 December 2007 (has links)
Foram estudados os efeitos da deficiência hídrica e da aplicação de ácido abscísico (ABA) sobre alguns aspectos fisiológicos e a produção de flavonóides em plantas de calêndula. Testaramse quatro intervalos de suspensão da irrigação (controle - irrigação diária; 3; 6 e 9 dias sem irrigar) acompanhados por três doses de ABA (0, 10 e 100 µM), resultando em 12 tratamentos. O experimento foi instalado em condições de casa de vegetação com plantas envasadas. Os tratamentos foram aplicados no início do florescimento e seus efeitos foram avaliados pelo conteúdo relativo de água na folha (CRA) e trocas gasosas (A= fotossíntese líquida, gs= condutância estomática, E= transpiração, Ci= concentração intercelular de CO2 e TL= temperatura da folha); por meio de analisador portátil por infra-vermelho. A eficiência do uso da água (EUA) foi calculada como A/E. Aos 3 dias de suspensão da irrigação as plantas de calêndula não apresentaram alterações significativas nas variáveis de trocas gasosas avaliadas. Aos 6 dias de deficiência hídrica as variáveis Ci, CRA e EUA não apresentaram diferença em relação aos tratamentos com suprimento constante de água, acrescidos ou não de ABA. Porém, a imposição de estresse hídrico somada à aplicação de ABA nas plantas resultou em diminuição nos valores de E, gs, A e TL em relação aos tratamentos controle. Aos 9 dias sem irrigar ocorreram mudanças drásticas nas plantas, sendo que todos os parâmetros de trocas gasosas avaliados apresentaram reduções significativas em relação aos tratamentos controle (irrigação diária com ou sem ABA). Concluiu-se que a aplicação exógena de ABA mimetizou as respostas fotossintéticas da planta ao estresse hídrico, sendo que o efeito principal deste biorregulador foi o de causar diminuição na gs. Porém, esta redução na gs só foi acompanhada de uma redução em A quando as plantas estavam submetidas à deficiência hídrica. O efeito residual do ABA nas plantas foi de apenas 7-8 dias e portanto, as variações observadas aos 6 dias de deficiência hídrica foram provavelmente induzidas pelo ABA ; enquanto que as diferenças observadas aos 9 dias foram exclusivamente causadas pela deficiência hídrica. Não houve diferença significativa entre as diferentes intensidades de deficiência hídrica testadas com relação ao acúmulo de flavonóides nas inflorescências de calêndula. Entretanto, a aplicação de ABA provocou uma diminuição de até 50% no teor de flavonóides, tanto nas plantas controle (bem hidratadas) como nas plantas submetidas ao estresse hídrico, para todas as intensidades testadas. Concluiu-se que o ABA restringe a rota biossintética de flavonóides. / It was evaluated the effects of water deficit and abscisic acid (ABA) application on some physiological parameters and flavonoid production in marigold plants. It was tested four intervals of withholding water (control - diary irrigation, 3, 6 and 9 days without irrigation) accomplished of 3 concentrations of ABA (0, 10 e 100 µM), resulting in 12 treatments. The experiment was performed under nursery conditions with plotted plants. The treatments were applied in the beginning of blooming and their effects were evaluated by the relative water content (RWC) and leaf gas exchange (A= net photosynthesis, gs= stomatal conductance, E= evaporation, Ci= CO2 intercellular concentration and TL=leaf temperature); using a portable infrared gas analyzer. The water use efficiency (EUA) was calculated as A?E. At 3 days of water suppression the marigold plants did not showed significant alterations in leaf gas exchange evaluated parameters. At 6 days of water deficit the parameters Ci, RWC and EUA did not showed difference in relation to the treatments with daily irrigation, added or not of ABA. However, the water stress plus ABA application resulted in smaller values of E, gs and A in relation to control plants. At 9 days of water deficit there were drastic changes in the plants, with significant reductions in all leaf gas exchange parameters evaluated in relation to control treatments (daily irrigation with or without ABA). It was concluded that exogenous ABA application mimics the plant photosynthetic responses to water stress, and the main ABA effect was to cause a reduction on gs. However, this gs reduction only was accomplished of a reduction in A when the plants were submitted to the water deficit. The residual effect of ABA in plants was only 7-8 days and so, the differences observed at the 6 days of water deficit were probably inducted by the ABA, yet differences observed at the 9 days were exclusively caused by the water deficit. There was no significant difference among the different levels of water deficit used in relation to total flavonoids content in inflorescences of marigold. However, ABA application resulted in a reduction of almost 50% in flavonoids content, in well watered plant as well as stressed plants, for all levels of water deficit tested. It was concluded that ABA restricts the biosynthetic rote of flavonoids.
52

Ecofisiologia em poliploides de Lippia alba sob diferentes regimes hídricos

Freitas, Jober Condé Evangelista January 2018 (has links)
Submitted by Geandra Rodrigues (geandrar@gmail.com) on 2018-06-14T15:15:46Z No. of bitstreams: 1 jobercondeevangelistafreitas.pdf: 1552019 bytes, checksum: 9ee88d5723251c6df682f9f3445a6163 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2018-06-27T14:37:53Z (GMT) No. of bitstreams: 1 jobercondeevangelistafreitas.pdf: 1552019 bytes, checksum: 9ee88d5723251c6df682f9f3445a6163 (MD5) / Made available in DSpace on 2018-06-27T14:37:53Z (GMT). No. of bitstreams: 1 jobercondeevangelistafreitas.pdf: 1552019 bytes, checksum: 9ee88d5723251c6df682f9f3445a6163 (MD5) Previous issue date: 2018 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Lippia alba (Mill.) N. E. Br ex Britton & P. Wilson é uma planta arbustiva muito utilizada na medicina tradicional como analgésica e calmante, estando amplamente distribuída pela América do Sul. Há, também, o interesse comercial pela espécie, pois alguns cosméticos e chás industrializados utilizam-na em sua composição. Assim, torna-se clara a necessidade de se estudar como essa espécie responde a diferentes condições de cultivo, principalmente em relação à água, recurso escasso em muitas regiões e diretamente impactado pelas mudanças climáticas globais. O objetivo deste trabalho foi verificar como acessos autopoliploides diploide, tetraploide e hexaploide de L. alba respondem fisiologicamente à desidratação. Para tanto, em dois experimentos, foram avaliados parâmetros bioquímicos e metabólicos da fisiologia de plantas de L. alba cultivadas sob diferentes condições de irrigação. Em ambos os experimentos ficou demonstrado que o nível de poliploidia não influenciou na resposta fisiológica das plantas de L. alba ao estresse hídrico. O Experimento 1 contou com quatro tempos de desidratação contínua do solo após a suspensão da irrigação: 0; 5; 10 ou 15 dias. Os resultados dessa etapa indicaram que o quadro de estresse hídrico ocorreu apenas no tratamento de 15 dias sem irrigação. Além disso, a condutância estomática e a transpiração destacaram-se como as variáveis mais sensíveis e responsivas ao estresse, sendo a queda nas taxas fotossintéticas atribuída principalmente ao fechamento estomático. O Experimento 2 foi planejado e conduzido de acordo com os resultados do Experimento 1. Nesta etapa, plantas das mesmas ploidias do experimento anterior foram submetidas a 0 ou 15 dias de suspensão total da irrigação e reidratadas após o período de déficit hídrico. Passadas 24 horas da reidratação, as mesmas foram reavaliadas. Em adição, mais parâmetros fisiológicos foram avaliados durante o período de desidratação do Experimento 2. Os resultados demonstraram que os parâmetros de trocas gasosas possuem um alto poder de explicação da variação total dos dados em relação aos demais. Sobre a reidratação, ficou apurado que apenas 24 horas não foram o suficiente para que plantas de L. alba recuperassem o seu status hídrico e fisiológico ideais, embora algumas mudanças positivas, em menores escalas, começaram a serem percebidas. As análises de óleos permitiram inferir que o estresse hídrico não influencia no perfil qualitativo da produção destes compostos, que é fortemente regulado por fatores genéticos. Os resultados encontrados indicam que L. alba é uma espécie tolerante ao estresse hídrico, o que, provavelmente, é um dos principais fatores que contribuem para a sua alta dispersão em diferentes regiões. / Lippia alba (Mill.) N. E. Br ex Britton & P. Wilson is a shrub widely used in traditional medicine as an analgesic and soothing, with wide distribution throughout South America. There is also commercial interest in this species because some cosmetics and industrialized teas use it in its composition. Thus, it becomes clear the need to study how this species responds to different growing conditions, mainly in relation to water, a scarce resource in many regions and directly impacted by global climate change. This work aimed to verify how diploid, tetraploid and hexaploid autopolyloid accessions of L. alba respond physiologically to dehydration. For that, biochemical and metabolic parameters were evaluated in L. alba plants cultivated under different irrigation conditions in two experiments. In both it was shown that polyploidy level does not influence the physiological response of L. alba under water stress. Experiment 1 had four continuous soil dewatering times after watering suspension: 0; 5; 10 or 15 days. The results of this step indicated that the water stress situation occurred only in the 15 days treatment without irrigation. In addition, stomatal conductance and transpiration were the most sensitive and stress-responsive variables, and loss in photosynthetic rates was attributed mainly to stomatal closure. Experiment 2 was planned and conducted according to the results of Experiment 1. At this stage, plants of the same ploidy from previous experiment were submitted to 0 or 15 days of total irrigation suspension and rehydrated after the period of water deficit. After 24 hours of rehydration, they were reevaluated. Furthermore, more physiological parameters were evaluated during the dehydration period in Experiment 2. The results showed that parameters of gas exchange have a high power of explanation of the total data variation in relation to the others. On rehydration, it was found that only 24 hours are not enough for L. alba plants to irrigaçãoin their water and physiological status, although some positive changes, on smaller scales, could begin to be perceived. The analysis of essential oils allowed us to infer that water stress does not influence qualitative profile production of these compounds, which is strongly regulated by genetic factors. The results indicate that L. alba is a tolerant species to water stress, which is probably one of the main factors that contribute to its high dispersion in different regions.
53

Synergistic effects of mixtures of fungicides and medicinal plant extracts against Botrytis cinerea

Vries, Filicity Ann January 2008 (has links)
Philosophiae Doctor - PhD / We hypothesize that South African medicinal plants contain compounds that can act in synergism with synthetic antifungal compounds. Four fungicides - Sporekill™, Rovral™, Terminator™ and Teldor™ at doses 0.1, 0.2, 0.4 and 0.8 mL L-1 and plant species Galenia africana, Elytropappus rhinocerotis and Tulbaghia violacea were tested aloneand in different combinations for their potency (efficacy) on radial growth inhibition of Botrytis cinerea strains on potato dextrose plates. Four doses of plant extract for each of the respective plant species were used. A total of 48 combinations were tested for each strain. Mixtures of plant extracts were far more effective in controlling strains compared to the individual components alone, representing significant levels of in vitro synergistic interactions. Combinations of these components represent an attractive future prospect for the development of new management strategies for controlling B. cinerea. Since the in vitro tests of these mixtures showed inhibitory activity, the mixtures were tested for activity in assays on Granny Smith apples. In vitro tests can be used to screen mixtures to obtain information on their inhibitory activity on a pathogen, however, the environmental conditions of the fruit and the ability of the pathogen to grow into the fruit cannot be simulated in vivo. A series of two-fold doses of medicinal plant extracts were combined with fungicides to conduct decay inhibition studies. The incidence of gray mold was significantly reduced by mixtures of plant extracts and fungicides. Under conditions similar to those in commercial storage, a drench treatment with G. africana and Rovral™ significantly (p=0.05) inhibit gray mold on the apples and was more effective than the plant extract and fungicide alone. The treatments exerted synergistic effects and were markedly better than the components applied alone. The wound colonization assay was used for optimal decay control. In a drench, much higher volumes of the treatments are used to ensure that the components of the suspension are deposited evenly over the entire fruit surface. Drenching of fruit to apply other chemicals is an established practise in the pome (fleshy) fruit industry, and simplifies the commercial application of the mixtures, as no additional infrastructure at commercial packing houses will be required. This approach not only makes it possible to reduce fungicide concentrations while maintaining adequate decay control, but also ensures a reduction of the chemical residue on the fruit. / South Africa
54

Synergistic effects of mixtures of fungicides and medicinal plant extracts against Botrytis cinerea

Vries, Filicity Ann January 2008 (has links)
Philosophiae Doctor - PhD / We hypothesize that South African medicinal plants contain compounds that can act in synergism with synthetic antifungal compounds. Four fungicides - Sporekill™, Rovral™, Terminator™ and Teldor™ at doses 0.1, 0.2, 0.4 and 0.8 mL L-1 and plant species Galenia africana, Elytropappus rhinocerotis and Tulbaghia violacea were tested alone and in different combinations for their potency (efficacy) on radial growth inhibition of Botrytis cinerea strains on potato dextrose plates. Four doses of plant extract for each of the respective plant species were used. A total of 48 combinations were tested for each strain. Mixtures of plant extracts were far more effective in controlling strains compared to the individual components alone, representing significant levels of in vitro synergistic interactions. Combinations of these components represent an attractive future prospect for the development of new management strategies for controlling B. cinerea. Since the in vitro tests of these mixtures showed inhibitory activity, the mixtures were tested for activity in assays on Granny Smith apples. In vitro tests can be used to screen mixtures to obtain information on their inhibitory activity on a pathogen, however, the environmental conditions of the fruit and the ability of the pathogen to grow into the fruit cannot be simulated in vivo. A series of two-fold doses of medicinal plant extracts were combined with fungicides to conduct decay inhibition studies. The incidence of gray mold was significantly reduced by mixtures of plant extracts and fungicides. Under conditions similar to those in commercial storage, a drench treatment with G. Africana and Rovral™ significantly (p=0.05) inhibit gray mold on the apples and was more effective than the plant extract and fungicide alone. The treatments exerted synergistic effects and were markedly better than the components applied alone. The wound colonization assay was used for optimal decay control. In a drench, much higher volumes of the treatments are used to ensure that the components of the suspension are deposited evenly over the entire fruit surface
55

Comportamento fotossintético, anatômico e produtivo de Melissa officinalis L. cultivada sob malhas coloridas / Photosynthetic, anatomical and productive behaviors of Melissa officinalis L. grounded under colored nets

Oliveira, Graziele Cristina de 02 April 2014 (has links)
Made available in DSpace on 2016-01-26T18:56:30Z (GMT). No. of bitstreams: 1 Graziele Cristina de Oliviera.pdf: 394148 bytes, checksum: 62431a9e3875b8437fc76808bdfa964c (MD5) Previous issue date: 2014-04-02 / Studies related to the pursuit of a favorable environment for the production of medicinal plants with a focus on optimizing the synthesis of active substances are necessary in view of the economic and social importance of these species. This study aimed to evaluate the effect of quantitative and qualitative control of the spectrum of light transmitted through the shading nets on growth and essential oil production in plants of Melissa officinalis L. The experiment was conducted in Presidente Prudente / SP. Plants were potted and subjected to shading treatments offered by black net (retention of 50 %), Chromatinet ® red and blue shading nets (50 %) and full sun for a period of 120 days after transplanting (DAT) , in which two cuts were performed. It was determined the global solar radiation, the photosynthetic photon flux density, the chlorophyll content , the plants gas exchange, biometric and anatomical parameters and content and yield of essential oil in leaves . The experiment was performed in a completely randomized design with 4 treatments and 5 replications. Based on the results, it was found that despite melissa be considered as a plant with better development in shaded environments, this specie has adapted to the condition of full sun, in which the photosynthetic data were more significant , indicating no damage to the photosynthetic apparatus. However, the use of the blue net resulted in higher biomass production and essential oil content in plants, and therefore its utilization is indicated for Melissa production. No anatomical changes were observed as a result of the cultivation of Melissa under different quantity and quality of light. / Estudos relacionados à busca de um ambiente favorável de produção de plantas medicinais com foco na otimização da síntese de substâncias ativas se fazem necessários tendo em vista a importância econômica e social destas espécies. O presente trabalho teve o objetivo de avaliar o efeito do controle quantitativo e qualitativo do espectro de luz transmitidas através das malhas fotoconversoras sobre o crescimento e a produção de óleo essencial em plantas de Melissa officinalis L. O experimento foi conduzido em Presidente Prudente/SP. As plantas foram conduzidas em vasos e submetidas aos tratamentos de sombreamento proporcionados por malha preta de retenção de 50%, malhas fotoconversoras Chromatinet® vermelha (50%) e azul (50%) e pleno sol, por um período de 120 dias após o transplantio (DAT), no qual foram realizados dois cortes. Determinou-se a radiação solar global, a densidade de fluxo de fótons fotossintéticos, o índice de teor de clorofila, as trocas gasosas, os parâmetros biométricos e anatômicos e o teor e o rendimento de óleo essencial das folhas. O experimento foi conduzido seguindo delineamento inteiramente casualizado com 4 tratamentos e 5 repetições. Diante dos resultados obtidos, verificou-se que apesar da melissa ser considerada uma planta de com melhor desenvolvimento em meio sombreado, esta espécie se adaptou à condição de pleno sol, na qual os dados fotossintéticos foram mais expressivos, indicando a ausência de danos ao aparato fotossintético. No entanto, a utilização de malha azul resultou maior produção de biomassa e teor de óleo essencial nas plantas, sendo, portanto indicada sua utilização para o cultivo de melissa. Não foram observadas modificações anatômicas em decorrência do cultivo da melissa sob alteração da quantidade e qualidade da luz.
56

Comportamento fotossintético, anatômico e produtivo de Melissa officinalis L. cultivada sob malhas coloridas / Photosynthetic, anatomical and productive behaviors of Melissa officinalis L. grounded under colored nets

Oliveira, Graziele Cristina de 02 April 2014 (has links)
Made available in DSpace on 2016-07-18T17:51:13Z (GMT). No. of bitstreams: 1 Graziele Cristina de Oliviera.pdf: 394148 bytes, checksum: 62431a9e3875b8437fc76808bdfa964c (MD5) Previous issue date: 2014-04-02 / Studies related to the pursuit of a favorable environment for the production of medicinal plants with a focus on optimizing the synthesis of active substances are necessary in view of the economic and social importance of these species. This study aimed to evaluate the effect of quantitative and qualitative control of the spectrum of light transmitted through the shading nets on growth and essential oil production in plants of Melissa officinalis L. The experiment was conducted in Presidente Prudente / SP. Plants were potted and subjected to shading treatments offered by black net (retention of 50 %), Chromatinet ® red and blue shading nets (50 %) and full sun for a period of 120 days after transplanting (DAT) , in which two cuts were performed. It was determined the global solar radiation, the photosynthetic photon flux density, the chlorophyll content , the plants gas exchange, biometric and anatomical parameters and content and yield of essential oil in leaves . The experiment was performed in a completely randomized design with 4 treatments and 5 replications. Based on the results, it was found that despite melissa be considered as a plant with better development in shaded environments, this specie has adapted to the condition of full sun, in which the photosynthetic data were more significant , indicating no damage to the photosynthetic apparatus. However, the use of the blue net resulted in higher biomass production and essential oil content in plants, and therefore its utilization is indicated for Melissa production. No anatomical changes were observed as a result of the cultivation of Melissa under different quantity and quality of light. / Estudos relacionados à busca de um ambiente favorável de produção de plantas medicinais com foco na otimização da síntese de substâncias ativas se fazem necessários tendo em vista a importância econômica e social destas espécies. O presente trabalho teve o objetivo de avaliar o efeito do controle quantitativo e qualitativo do espectro de luz transmitidas através das malhas fotoconversoras sobre o crescimento e a produção de óleo essencial em plantas de Melissa officinalis L. O experimento foi conduzido em Presidente Prudente/SP. As plantas foram conduzidas em vasos e submetidas aos tratamentos de sombreamento proporcionados por malha preta de retenção de 50%, malhas fotoconversoras Chromatinet® vermelha (50%) e azul (50%) e pleno sol, por um período de 120 dias após o transplantio (DAT), no qual foram realizados dois cortes. Determinou-se a radiação solar global, a densidade de fluxo de fótons fotossintéticos, o índice de teor de clorofila, as trocas gasosas, os parâmetros biométricos e anatômicos e o teor e o rendimento de óleo essencial das folhas. O experimento foi conduzido seguindo delineamento inteiramente casualizado com 4 tratamentos e 5 repetições. Diante dos resultados obtidos, verificou-se que apesar da melissa ser considerada uma planta de com melhor desenvolvimento em meio sombreado, esta espécie se adaptou à condição de pleno sol, na qual os dados fotossintéticos foram mais expressivos, indicando a ausência de danos ao aparato fotossintético. No entanto, a utilização de malha azul resultou maior produção de biomassa e teor de óleo essencial nas plantas, sendo, portanto indicada sua utilização para o cultivo de melissa. Não foram observadas modificações anatômicas em decorrência do cultivo da melissa sob alteração da quantidade e qualidade da luz.
57

An ecological evaluation of the sustainability of bark harvesting of medicinal plant species in the Venda region, Limpopo province, South Africa

Tshisikhawe, Milingoni Peter 01 May 2013 (has links)
The study evaluated the extent and threat of bark harvesting of plant species for medicinal purposes in the Venda region and investigated possibilities of the sustainability of these practices. Approximately 30% of the woody plant species in Venda were found to have medicinal properties in their bark, but only about 12% of these species are commonly traded in muthi shops in the region. Fifty-eight medicinal plant species are commonly harvested for medicinal properties in their bark and found in muthi shops in the region. These 58 species were scored for the possible threat of bark harvesting to the species’ survival using 20 ecologically relevant plant population traits. The most vulnerable species were Adansonia digitata, Adenia spinosa, Albizia adianthifolia, Albizia versicolor, Brackenridgea zanguebarica, Croton megalobotrys, and Warburgia salutaris. Of these species Brackenridgea zanguebarica and Warburgia salutaris are amongst the ten most traded medicinal plant species in Venda region. Elaeodendron transvaalense and Brackenridgea zanguebarica, the two species investigated in detail in this study, were amongst the most commonly traded medicinal plant species in Venda region. Analysis of size class distributions showed that both species had growing and healthy populations, exhibiting J-shaped population curves, centroids left-skewed from the midpoint of the size class distribution, and a fine-grained status. However, size-class distributions in both species revealed certain classes that needed monitoring since they were negatively affected by bark harvesting. Adult individuals of B. zanguebarica showed a high degree of bark regeneration as a response to bark removal from medicine men. The crown health status of E. transvaalense was generally good although some individuals, contributing 9% of the sample, had dead crowns. A linear relationship was noticed between areas harvested and stem circumference, which is understandable considering the large surface area of harvestable bark on bigger individuals. Matrix modeling of E. transvaalense revealed that the vegetative stage should be targeted for management action. An assessment of the adequacy of the Brackenridgea Nature Reserve, an initiative aimed at protecting Brackenridgea zanguebarica, revealed that the reserve size is not enough for conservation of a viable population. The method flagged out potential growth habitat for B. zanguebarica around the current reserve, which could be incorporated to enlarge the conservation area, which could be incorporated to enlarge the conservation area. Four different scenarios were analysed on how best to conserve the species. Assuming a 50% reduction in human-related activities, such as cultivation, harvesting and livestock grazing, it is recommended that the reserve be enlarged from its current 110 ha to 366 ha to maintain a viable population into the future. Finally, the study recommended the adoption of an integrated approach to achieve sustainability of bark harvesting in the Venda region. Only by selecting best practices from both indigenous and conventional conservation techniques will the conservation of natural resources that are of important to local communities, be successful. An action plan that will involve the formation of an association by all stakeholders interested in the sustainable utilization of natural resources must be developed. The association must be governed by a constitution with a clear mission statement and the harvesting of natural resources should be done in line with a collection policy. / Thesis (PhD)--University of Pretoria, 2012. / Plant Science / unrestricted
58

Influence of spacing and drying methods on concentration of artemisinin in artemisia annua

Maphoto, Mary Leann January 2017 (has links)
Thesis (M.Sc. Agriculture (Horticulture)) -- University of Limpopo, 2017 / Artemisia annua L. from the family Asteraceae is an annual medicinal plant and has been used to make herbal remedies in Asia for thousands of years. Artemisinin is a sesquiterpene lactone, isolated from aerial parts of Artemisia annua, with the highest concentrations being in flowers and leaves. In addition to potent anti-malarial activity, artemisinin possesses anti-cancer, anti-schistosomiatic, anti-hepatitis B, anti-HIV, anti-leishmanial and herbicidal activities. Low artemisinin production (0.01-2%) from A. annua is a major constraint in commercialisation of the drug for control of malaria. Worldwide, efforts have been underway to improve the concentration of artemisinin using conventional breeding, biochemical, physiological, molecular and hairy-root culture techniques, however all these methods are not economical. Cultural practices like spacing and pruning have limitation in improving artemisinin concentration and these may help in increasing the concentrations of artemisinin. Study was conducted at the experimental farm of the Agricultural Research Council – Vegetable and Ornamental Plants, Roodeplaat Pretoria. The objective of this study was to determine whether spacing, pruning and their interactions would have any effect on the concentrations of artemisinin, growth and yield of A. annua and whether drying methods would have an effect on the concentrations of artemisinin in A. annua. Since there was only one field trial, all sub-objectives were addressed at once (Chapter 3). Fresh seeds of A. annua were obtained from the ARC-VOP gene bank and sown in seedling trays in September 2014. Uniform eight-week-old seedlings were hardened-off, transplanted in November 2014 in 10 cm deep holes and then pruned ten weeks after transplanting. Treatments for Experiment 1, viz., 3 × 4 factorial experiment were laid out in a randomised complete block design, with four replications (n = 48). The two factors of the experiment were (a) spacing [0.5 × 1 m2 (standard: 0.50 m2), 0.5 × 0.7 m2 (small: 0.35 m2) 0.5 × 0.5 m2 (smaller: 0.25 m2) and 0.3 × 0.7 m2 (smallest: 0.21 m2)] and (b) pruning [no pruning (control), removing the apical bud and removing shoots three nodes from the bottom]. The plants were irrigated using overhead sprinklers system for two hours three times per week. Four readings for growth variables (plant height, stem diameter and chlorophyll content) were collected with one week interval. Plants were harvested after 180 days from planting, and leaves, stems and roots were separated weighed and oven dried at 40 ºC for 72 h. In Experiment 2 (drying methods), treatments, namely, 100% sun, 100% shade, 50% shade, freeze and oven drying were arranged in completely randomised design with four replicates (n = 20). The treatments were exposed for a week, to full sunlight, 50% shade-drying under a shade net that allows 50% light penetration, 100% shade under enclosed room at ambient (24-25 ºC) temperature, oven drying for 24 h at 40 ºC, and freeze-drying for three days. Freeze-drying had significant effect on artemisinin concentration of 1.941%. It was followed by oven (1.738%) and 100% shade drying (1.657%) and the lowest artemisinin concentration (1.412%) was obtained from 50% shade drying. The smaller spacing of 0.25 m2 in combination with apical bud removal had a significant effect on artemisinin concentration, producing artemisinin concentration of 0.193%. Spacing had a significant effect on stem diameter, fresh leaf mass and dry leaf mass but had no effect on plant height and chlorophyll content. Pruning had a significant effect on plant height and chlorophyll content and had no effect on stem diameter. The small spacing of 0.35 m2 had the highest fresh and dry leaf mass of 17.99 and 9.62 t/ha. The interaction of spacing and pruning had no significant effect on the growth and yield of A. annua. The results from this study suggested that cultural and processing practices may have direct effects in the concentration of artemisinin, growth and yield of A. annua. The results xiv provided some understanding on how agronomic and processing practices can be used to increase artemisinin content in A. annua and understand the interaction between different agronomic practices and thereby allowing the development of economic methods for A. annua post-harvest handling. Future work should focus on implementing various pruning techniques to trigger stress and indirectly secondary metabolites
59

Traditional pharmacopoeias and medicines among Albanians and Italians in southern Italy: a comparison.

Pieroni, Andrea, Quave, C.L. January 2005 (has links)
No / A cross-cultural comparison of traditional household remedies in primary health care and ritual healing practices in two economically and socio-demographically similar communities in Lucania (inland southern Italy) was considered: Ginestra/Zhurë, inhabited by ethnic Albanians, who migrated to the area during the 15th century, and Castelmezzano, inhabited by autochthonous South-Italians. In Ginestra/Zhurë, the number of traditional natural remedies (mainly derived from local medicinal plants) was only half of that in the local folk pharmacopoeia quoted in Castelmezzano. However, ritual magic-healing practices still play a central role among the Albanians in Ginestra/Zhurë, while they do not in Castelmezzano. Reasons for this shift, as well as components that have affected cultural adaptation phenomena and transitions among the Albanians are discussed.
60

Nematicidal properties of crude extracts obtained from medicinal plants against rootlesion nematode Pratylenchus coffeae / Đặc tính kháng tuyến trùng của các hợp chất chiết xuất từ cây thuốc phòng trừ Pratylenchus coffeae gây hại rễ cà phê

Nguyen, Dang Minh Chanh, Jung, Woo Jin 09 December 2015 (has links) (PDF)
To investigate nematicidal activity against the root-lesion nematode, Pratylenchus coffeae, the methanolic extracts were obtained from 5 medicinal plants in Vietnam. Methanol extracts of the 5 samples were screened for nematicidal activity against Pratylenchus coffeae in vitro. Of the plant extracts tested, a 5 mg/ml concentration of Terminalia nigrovenulosa extract showed the highest level (95.0%) of nematicidal activity against Pratylenchus coffeae at 9 h after treatment. The remainder of the plant extracts was followed by Cinnamomum camphora (66.7%), Jasminum suptriplinerve (30.8%), Premna integrifolia (6.7%), and Treptocaulon juventas (5.8%). A 2.0 mg/ml concentration of T. nigrovenulosa resulted in 13.3, 42.5, 62.5 and 86.7% at 1, 3, 5 and 7 h after treatment, respectively against Pratylenchus coffeae. Concentration of 0.1, 0.5, 1.0 and 2.0 mg/ml of T. nigrovenulosa resulted in 26.7, 71.7, 78.3 and 86.7% effectiveness respectively, at 7 h after treatment. Also, at 3 days after exposure to T. nigrovenulosa, hatch was inhibited by 60.0, 45.8, 17.5 and 5.8% at 0.1, 0.5, 1.0 and 2.0 mg/ml, respectively. Hatch was inhibited by 65.0, 50.8, 21.7 and 6.7% at 0.1, 0.5, 1.0 and 2.0 mg/ml respectvely, at 6 days after exposure to T. nigrovenulosa. The mortality rate and hatch inhibition increased with increasing incubation time for crude extract of T. nigrovenulosa. / Trong nghiên cứu này, 5 cây thuốc (Cinnamomum camphora, Jasminum suptriplinerve, Premna integrifolia, Terminalia nigrovenulosa, Treptocaulon juventas) đã được sử dụng làm nguyên liệu chiết xuất bằng methanol để thử hoạt tính kháng tuyến trùng Pratylenchus coffeae. Kết quả cho thấy chiết xuất từ cây Terminalia nigrovenulosa biểu hiện hoạt tính kháng tuyến trùng cao nhất (95,0%) sau 9 giờ xử lý với nồng độ 5 mg/ml. Hoạt tính kháng tuyến trùng của các chất chiết xuất được biểu hiện theo thứ tự giảm dần lần lượt là C. camphora (66,7%), J. suptriplinerve (30,8%), P. integrifolia (6,7%) và T. juventas (5,8%). Với nồng độ 2 mg/ml của chất chiết xuất từ T. nigrovenulossa biểu hiện hoạt tính gây chết tuyến trùng Pratylenchuss coffeae là 13,3; 42,5; 62,5 và 86,7% sau 1, 3, 5 và 7 giờ xử lý theo thứ tự. Ở cùng thời điểm sau xử lý 7 giờ, các nồng độ 0,1; 0,5; 1,0 và 2,0 mg/ml chiết xuất của T. nigrovenulossa có hoạt tính gây chết tuyến trùng Pratylenchus coffeae lần lượt là 26,7; 71,7; 78,3 và 86,7%. Bên cạnh đó, chất chiết xuất của T. nigrovenulossa cũng cho thấy tỷ lệ ức chế trứng nở cao. Cụ thể là sau 3 ngày xử lý với chất chiết xuất của T. nigrovenulossa, tỷ lệ ức chế trứng không nở là 60,0; 45,8; 17,5 và 5,8% at 0,1; 0,5; 1,0 và 2,0 mg/ml theo thứ tự. Sau 6 ngày xử lý với chất chiết xuất của T. nigrovenulossa, tỷ lệ ức chế trứng nở là 65,0; 50,8; 21,7 và 6,7% tại nồng độ 0,1; 0,5; 1,0 và 2,0 mg/ml theo thứ tự. Tỷ lệ gây chết và tỷ lệ ức chế của chất chiết xuất phụ thuộc vào cả thời gian và nồng độ xử lý.

Page generated in 0.0917 seconds