Submitted by Eunice Novais (enovais@uepg.br) on 2018-05-07T19:38:50Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Gizele Baldo.pdf: 5751948 bytes, checksum: df4e7c4c9be199c089c189cbe28764f0 (MD5) / Made available in DSpace on 2018-05-07T19:38:50Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Gizele Baldo.pdf: 5751948 bytes, checksum: df4e7c4c9be199c089c189cbe28764f0 (MD5) Previous issue date: 2018-02-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Os vírus de poliedrose nuclear são importantes agentes de controle microbiano de larvas de lepidópteros. No entanto, sua atividade pode ser comprometida durante a interação com suas plantas hospedeiras. Entender como ocorre a interação do vírus da lagarta Chrysodeixis includens, ChinNPV, com dois de seus hospedeiros, soja e algodão, pode auxiliar a expandir o uso de pesticidas biológicos amenizando suas limitações. A interação planta/vírus foi estudada a fim de verificar a influência da planta sobre o processo de infecção, alterando a forma e o momento em que as larvas se alimentam desses substratos. Os tratamentos foram: disco de folha, incorporação de folha (liofilizada e seca em estufa) em dieta, alimentação com substrato foliar antes da inoculação viral, persistência e exposição do vírus sobre a planta. As avaliações foram realizadas até o 10º ou 12º dias após a inoculação, quando foram determinados o peso e o estágio de desenvolvimento de cada sobrevivente. Os dados de mortalidade foram submetidos à análise de sobrevivência com riscos competitivos e os demais dados à ANOVA. Alterações histopatológicas no intestino médio das lagartas alimentadas com folhas de soja e algodão e inoculadas com o ChinNPV foram analisadas por microscopia de luz. A fixação das partículas virais foi avaliada através da extração da cera epicuticular com cinco solventes, seguida de aplicação, lavagem e contagem do vírus remanescentes. Fixação, morfologia e persistência dos poliedros sobre folhas de soja e algodão, em ambiente controlado e campo, foram avaliadas por MEV em diferentes períodos. A mortalidade das lagartas foi comprometida pelo algodão em quase todos os bioensaios realizados. A inoculação do NPV sobre discos de folha de soja resultou em mortalidades semelhantes à dieta. No entanto, quando tecidos liofilizados foram incorporados à dieta, os folíolos de soja reduziram a mortalidade de C. includens por NPV, com mortalidade análoga à provocada pelo algodão e, quando secos em estufa, a mortalidade larval foi intermediária, entre o apresentado pela dieta artificial e as folhas de algodão. Quando o vírus foi exposto na superfície da soja e posteriormente recuperado, o tempo de contato com a folha (72h) reduziu a atividade do vírus, o mesmo não foi válido para o algodão. A análise histopatológica mostrou desestruturação das células epiteliais no tratamento de alimentação prévia com folha, entretanto este fenômeno não alterou a mortalidade das lagartas. Enquanto em campo, a distribuição dos poliedros foi uniforme no filoplano das duas culturas, no laboratório, os poliedros formaram agregados sobre a superfície da soja. Já quando a cera epicuticular foi removida, a interação da folha com o vírus foi afetada. A atividade do ChinNPV foi comprometida tanto por folhas de soja quanto algodão, sendo que a persistência do vírus começa a reduzir após o terceiro dia de contato com o filoplano. Foi possível observar que a inativação do vírus somente ocorre quando folha de algodão e vírus são fornecidos em conjunto, enquanto na soja, o tempo de contato do vírus com a folha parece influenciar reduzindo a mortalidade das lagartas. Assim, seria interessante estudar formulações e doses para compensar a perda de atividade viral provocada pelos tecidos foliares. / Nucleopolyhedrovirus are important microbial control agents of lepidopteran larvae. However, their activity may be compromised during interaction with their host plants. Understanding the interaction process of the caterpillar virus Chrysodeixis includens, ChinNPV, with two of its hosts, soybean and cotton, may help to expand the use of biological pesticides by alleviating their limitations. The plant/virus interaction was studied in order to verify the influence of the plant on the infection process, changing the form and the moment in which the larvae feed on these substrates. The treatments were: leaf disc, incorporation of leaf (lyophilized and oven-dried) in diet, feeding with leaf substrate before viral inoculation, persistence, and virus exposure on the plant. Evaluations were carried out until the 10th or 12th days after inoculation, when the weight and stage of development of each survivor were determined. Mortality data were submitted to survival analysis with competitive risks and the other data to ANOVA. Histopathological changes in the midgut of caterpillars fed with soybean and cotton leaves and inoculated with ChinNPV were analyzed by light microscopy. Fixation of the virus particles was evaluated by extracting the epicuticular wax with five solvents followed by the application, washing and counting of the remaining virus. Fixation, morphology and persistence of the polyhedra on soybean and cotton leaves, under controlled environment and field, were evaluated by SEM on different periods. The mortality of caterpillars was compromised by cotton in almost all bioassays performed. NPV inoculation on soybean leaf discs resulted in diet-like mortalities. However, when lyophilized tissues were incorporated into the diet, soybean leaflets reduced the mortality of C. includens by NPV, with mortality similar to that caused by cotton, and when drying in oven, the larval mortality was intermediate between that presented by artificial diet and cotton leaves. When the virus was exposed on the soybean surface and later recovered, the time of contact with the leaf (72h) reduced the activity of the virus; the same was not true for cotton. The histopathological analysis showed disruption of epithelial cells in treatments of previous leaf feeding; however, this phenomenon did not change the mortality of caterpillars. While in the field, the polyhedra distribution was uniform on the phylloplane of the two cultures, in the laboratory, the polyhedra formed aggregates on the surface of the soybean. Already when the epicuticular wax was removed, the interaction of the leaf with the virus was affected. The activity of ChinNPV was compromised by both soybean and cotton leaves, and the persistence of the virus begins to decrease after the third day of contact with the phylloplane. It was possible to observe that the inactivation of the virus only occurs when cotton leaf and virus are supplied together, while in soybean, the time of contact of the virus with the leaf seems to influence, reducing the mortality of the caterpillars. Thus, it would be interesting to study formulations and doses to compensate for the loss of viral activity caused by foliar tissues.

<p> Previous work on the ultrastructure of leaf surfaces has been confined to commercial terrestrial plants. Until recently there was a conflicting overlap of definitions of surface structures. Lately, studies have concentrated on the role of the epicuticular wax layer in surface phenomena such as water permeability, transpiration, and herbicide susceptibility. The initiating factors in surface wax formation and the mode of extrusion still remain unresolved. </p> <p> An emergent hydrophyte, Zizania aquatica L., was selected to attempt to clarify the initiation and extrusion of epicuticular wax. The first appearance of epicuticular wax occurs while the whole plant is submerged. The wax platelet shape is probably controlled by an endogenous circadian rhythm with very little environmental control. The significance of water depth, temperature, continous light, physical and chemical abrasion are discussed in terms of the surface morphology of the three types of leaves. </p> / Thesis / Master of Science (MSc)

Dans le cadre de la pulvérisation agricole, la diminution de la quantité des intrants est devenue une étape cruciale, et ce notamment en viticulture. La pulvérisation de précision en viticulture implique cependant une maitrise conjointe du matériel utilisé, des produits et de la répartition de ces produits sur le feuillage. Dans ce contexte, nombreuses sont les recherches menées sur l’optimisation d’utilisation des produits phytosanitaires, leur objectif final étant de réduire de manière significative la quantité d’intrants dans la culture. Cependant, peu de travaux ont été effectués sur l’étude du comportement des produits directement sur le feuillage, ce qui constitue donc l’objectif de cette thèse. La première partie de ce travail est consacrée particulièrement à l’analyse de l’état de la surface foliaire, en se focalisant spécifiquement sur l’étude de la rugosité de surface de la feuille qui constitue un paramètre essentiel dans le processus d’adhésion du produit pulvérisé sur la feuille. L’analyse de la surface de la feuille est réalisée en déterminant les caractéristiques texturales extraites d’images microscopiques. Un nouvel indicateur de rugosité est proposé ainsi que, des paramètres spatiaux et fréquentiels sont utilisés pour estimer et la rugosité de la feuille. Ces paramètres permettent ensuite la caractérisation de l’homogénéité de la surface et la détection des nervures/poils au niveau de la surface de la feuille. Cette partie représente une base fondamentale pour mieux comprendre le comportement des gouttelettes pulvérisées sur la feuille de vigne. La deuxième partie de ce travail de thèse est consacrée à des études expérimentales, qui ont pour but de définir et construire des modèles statistiques permettant d’estimer la quantité de produit restant sur la feuille ou la surface occupée par les gouttes. Ces modèles prennent en considération différents paramètres de pulvérisation, tels que la taille de la goutte et sa vitesse, la tension superficielle du produit, l’angle d’inclinaison et la rugosité de la surface de la feuille. Ces modèlespourraient être vus comme des outils de décision communs pour optimiser la quantité du produit pulvérisé et l’estimation du produit restant sur la feuille, et comme un outil d’aide pour optimiser les bancs d’essais et de tests de la qualité de la pulvérisation. / In the context of agricultural spraying, reducing the amount of input became a crucial step particularly in viticulture. The development of spraying precision in this domain needs the mastery of the use of spray equipment, product and distribution of these products on the foliage. In this area, many research have been done, their main goal being to optimize the use of plant product protection and to reduce significantly the input quantity inside the culture. However, few research has been done on the behavior of the product directly on the foliage which constitutes finally the main goal of this thesis. The first part of this report deals particularly with the analysis of leaf surface state by focusing precisely on the leaf surface roughness, one of the main parameters in product adhesion process. A leaf surface analysis is performed by determining the textural features extracted from microscopic images. A new roughness indicator is proposed and, spatial and frequency parameters were used to estimate and characterize the leaf roughness. These parameters allow both the characterization of surface homogeneity and the detection of the presence of rib/hair on the leaf surface. Indeed, this part represents a fundamental basis for understanding the spray droplet behavior on the vine leaf. The second part of this thesis deals with experimental studies which aim to define and to create statistical models to estimate the amount of product remaining on the leaf surface or the surface occupied by droplets. These models consider different spray parameters, such as droplet size and velocity, surface tension of the product, slope angle and roughness of the leaf. These models could be seen as aid-decision tools to optimize the amount of spray and the estimated product remaining on the leaf.

Orientador: Gustavo Habermann / Banca: José Pires de Lemos Filho / Banca: Rafael Vasconcelos Ribeiro / Resumo: As folhas são órgãos adaptados para a captação de energia luminosa e sua transformação em energia bioquímica. Entretanto, a irradiância interceptada pelas folhas é maior do que a irradiância que é de fato absorvida e aproveitada de forma eficiente, o que torna os mecanismos de fotoproteção essenciais. Esses mecanismos podem minimizar a absorção da irradiância ou ativar respostas metabólicas responsáveis pela proteção do sistema fotoquímico. Styrax camporum é uma espécie com ampla distribuição no cerrado sensu lato. Suas folhas possuem orientação horizontal ou vertical, mas também podem apresentar ângulos intermediários. Com a finalidade de observar a influência que a orientação foliar exerce sobre o desempenho fotossintético, foram avaliadas as curvas das taxas fotossintéticas em resposta ao aumento da disponibilidade de luz para ambas as faces (adaxial e abaxial) de folhas horizontais e verticais. Além disso, foi realizado um experimento de deficiência hídrica no qual as trocas gasosas, a fluorescência da clorofila a e as relações hídricas foram acompanhadas em ambas as faces dos dois tipos foliares. Os resultados mostraram que, em S. camporum, a orientação vertical de parte das folhas não está relacionada à fotoproteção estrutural e que, nessa espécie, o posicionamento vertical das folhas poderia estar relacionado à otimização da assimilação de CO2 em decorrência da potencial exposição de ambas as faces foliares à radiação direta / Abstract: Leaves are organs adapted to sunlight interception and conversion of light energy into biochemical energy. However, the irradiance that is intercepted by leaves is greater than the absorbed irradiance that is effectively used in photosynthesis, making photoprotective mechanisms essential. Such mechanisms may reduce the amount of absorbed irradiance or may activate metabolic activities that are responsible for protecting the photochemical system. Styrax camporum is a woody species that is widely distributed in the cerrado sensu lato areas. S. camporum leaves show horizontal or vertical orientation, but they may also have intermediate angles. We investigated whether the leaf angles of S. camporum have any influence on photosynthetic performance. Photosynthetic response curves in response to increasing light were measured on both surfaces (adaxial and abaxial) of horizontal and vertical leaves. In addition, a water deficiency experiment was performed. In this experiment, gas exchange rates, chlorophyll a fluorescence and plant water relations values were also monitored on both surfaces of both leaf types. Results showed that, in S. camporum, vertical leaf orientation is not related to structural photoprotection and that, in this species, such leaf orientation could be related to the optimization of CO2 assimilation since both leaf surfaces are potentially exposed to direct sunlight / Mestre

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(農学) / 甲第18312号 / 農博第2037号 / 新制||農||1020(附属図書館) / 学位論文||H26||N4819(農学部図書室) / 31170 / 京都大学大学院農学研究科地域環境科学専攻 / (主査)教授 天野 洋, 教授 田中 千尋, 教授 松浦 健二 / 学位規則第4条第1項該当

Made available in DSpace on 2014-06-11T19:23:02Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-03-31Bitstream added on 2014-06-13T20:49:43Z : No. of bitstreams: 1 feistler_am_me_rcla.pdf: 2057196 bytes, checksum: 1dd5c4217d5f2fc7654f38047f5240ef (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / As folhas são órgãos adaptados para a captação de energia luminosa e sua transformação em energia bioquímica. Entretanto, a irradiância interceptada pelas folhas é maior do que a irradiância que é de fato absorvida e aproveitada de forma eficiente, o que torna os mecanismos de fotoproteção essenciais. Esses mecanismos podem minimizar a absorção da irradiância ou ativar respostas metabólicas responsáveis pela proteção do sistema fotoquímico. Styrax camporum é uma espécie com ampla distribuição no cerrado sensu lato. Suas folhas possuem orientação horizontal ou vertical, mas também podem apresentar ângulos intermediários. Com a finalidade de observar a influência que a orientação foliar exerce sobre o desempenho fotossintético, foram avaliadas as curvas das taxas fotossintéticas em resposta ao aumento da disponibilidade de luz para ambas as faces (adaxial e abaxial) de folhas horizontais e verticais. Além disso, foi realizado um experimento de deficiência hídrica no qual as trocas gasosas, a fluorescência da clorofila a e as relações hídricas foram acompanhadas em ambas as faces dos dois tipos foliares. Os resultados mostraram que, em S. camporum, a orientação vertical de parte das folhas não está relacionada à fotoproteção estrutural e que, nessa espécie, o posicionamento vertical das folhas poderia estar relacionado à otimização da assimilação de CO2 em decorrência da potencial exposição de ambas as faces foliares à radiação direta / Leaves are organs adapted to sunlight interception and conversion of light energy into biochemical energy. However, the irradiance that is intercepted by leaves is greater than the absorbed irradiance that is effectively used in photosynthesis, making photoprotective mechanisms essential. Such mechanisms may reduce the amount of absorbed irradiance or may activate metabolic activities that are responsible for protecting the photochemical system. Styrax camporum is a woody species that is widely distributed in the cerrado sensu lato areas. S. camporum leaves show horizontal or vertical orientation, but they may also have intermediate angles. We investigated whether the leaf angles of S. camporum have any influence on photosynthetic performance. Photosynthetic response curves in response to increasing light were measured on both surfaces (adaxial and abaxial) of horizontal and vertical leaves. In addition, a water deficiency experiment was performed. In this experiment, gas exchange rates, chlorophyll a fluorescence and plant water relations values were also monitored on both surfaces of both leaf types. Results showed that, in S. camporum, vertical leaf orientation is not related to structural photoprotection and that, in this species, such leaf orientation could be related to the optimization of CO2 assimilation since both leaf surfaces are potentially exposed to direct sunlight

A videira \'Niágara Rosada\' é a principal cultivar de mesa produzida no estado de São Paulo. A videira por ser uma planta sarmentosa e de hábito trepador, necessita de um sistema de suporte para conduzir o crescimento dos ramos, permitir uma boa penetração de luz no dossel e atingir o equilíbrio entre a área foliar e fruto. No estado de São Paulo, os sistemas de condução mais utilizados são a latada, a espaldeira e o \'Y\'. O uso de diferentes sistemas de condução sugere uma resposta diferenciada das plantas em função da disposição das folhas e o microclima que se forma em torno do dossel, o qual muda a capacidade fotossintética e consequentemente o seu crescimento, produção e qualidade dos cachos. O objetivo do trabalho foi caracterizar as variáveis fisiológicas e produtivas da videira \'Niágara Rosada\' com diferentes idades e em três sistemas de condução: espaldeira, latada e \'Y\'. Desta forma, foram realizados dois experimentos nos ciclos produtivos de 2014 e 2015, no município de Piracicaba - SP. No primeiro experimento foram avaliadas videiras conduzidas nos sistemas em espaldeira e em \'Y\', no primeiro e segundo ano de produção. No segundo experimento foram avaliadas videiras conduzidas nos sistemas em latada e em espaldeira, no sétimo e oitavo ano de produção. Nos dois experimentos, a duração do ciclo em dias e graus-dia não foi afetada pelos sistemas de condução. Entre os sistemas de condução em espaldeira e em \'Y\' não há diferenças nas relações entre a área de superfície foliar e a produção, porém, a produtividade é superior no sistema em espaldeira em função do maior número de plantas por hectare. No experimento com os sistemas de condução em latada e em espaldeira, a latada apresenta melhores relações entre a área de superfície foliar e a produção. No sistema em espaldeira, as videiras produzem frutos de melhor qualidade, com maior concentração de sólidos solúveis totais, antocianinas e flavonóis. / The \'Niagara Rosada\' vine is the main cultivar of table grapes produced in São Paulo state. As a climbing plant, the vine needs a support system for growth that best allow light interception through the canopy in order to reach a balance between leaf area and fruit production. In Sao Paulo state, the most commonly training systems used are pergola, vertically shoot-positioned (VSP) and \'Y\' shaped training system. The use of different training systems suggests a different response of the plant due to the arrangement of leafs and the microclimate around the canopy, which changes the photosynthetic capacity and consequently their growth, yield and quality of grapes. The aim of this study was to characterize the physiological and productive variables of \'Niagara Rosada\' vine with different ages and three training systems: pergola, VSP and \'Y\' shaped training system. Thus, two experiments were performed during 2014 and 2015 seasons, in Piracicaba - SP. In the first experiment vines on VSP and \'Y\' shaped training system were evaluated in their first and second year of production. The second experiment evaluated vines conducted in pergola systems and VSP, in the seventh and eighth year of production. In both experiments, total of days and degree-days to complete the production cycle was not affected by training systems. Among VSP and \'Y\' shaped systems, there is no difference in leaf surface area and production ratio, however, yield is higher in VSP due to the higher number of plants per hectare. The seven-year-old plants in pergola system have a more efficient ratio between leaf surface area and production. In the VSP, vines produce fruit with better quality as it have the highest soluble solids, anthocyanins and flavonols contents.

A videira \'Niágara Rosada\' é a principal cultivar de mesa produzida no estado de São Paulo. A videira por ser uma planta sarmentosa e de hábito trepador, necessita de um sistema de suporte para conduzir o crescimento dos ramos, permitir uma boa penetração de luz no dossel e atingir o equilíbrio entre a área foliar e fruto. No estado de São Paulo, os sistemas de condução mais utilizados são a latada, a espaldeira e o \'Y\'. O uso de diferentes sistemas de condução sugere uma resposta diferenciada das plantas em função da disposição das folhas e o microclima que se forma em torno do dossel, o qual muda a capacidade fotossintética e consequentemente o seu crescimento, produção e qualidade dos cachos. O objetivo do trabalho foi caracterizar as variáveis fisiológicas e produtivas da videira \'Niágara Rosada\' com diferentes idades e em três sistemas de condução: espaldeira, latada e \'Y\'. Desta forma, foram realizados dois experimentos nos ciclos produtivos de 2014 e 2015, no município de Piracicaba - SP. No primeiro experimento foram avaliadas videiras conduzidas nos sistemas em espaldeira e em \'Y\', no primeiro e segundo ano de produção. No segundo experimento foram avaliadas videiras conduzidas nos sistemas em latada e em espaldeira, no sétimo e oitavo ano de produção. Nos dois experimentos, a duração do ciclo em dias e graus-dia não foi afetada pelos sistemas de condução. Entre os sistemas de condução em espaldeira e em \'Y\' não há diferenças nas relações entre a área de superfície foliar e a produção, porém, a produtividade é superior no sistema em espaldeira em função do maior número de plantas por hectare. No experimento com os sistemas de condução em latada e em espaldeira, a latada apresenta melhores relações entre a área de superfície foliar e a produção. No sistema em espaldeira, as videiras produzem frutos de melhor qualidade, com maior concentração de sólidos solúveis totais, antocianinas e flavonóis. / The \'Niagara Rosada\' vine is the main cultivar of table grapes produced in São Paulo state. As a climbing plant, the vine needs a support system for growth that best allow light interception through the canopy in order to reach a balance between leaf area and fruit production. In Sao Paulo state, the most commonly training systems used are pergola, vertically shoot-positioned (VSP) and \'Y\' shaped training system. The use of different training systems suggests a different response of the plant due to the arrangement of leafs and the microclimate around the canopy, which changes the photosynthetic capacity and consequently their growth, yield and quality of grapes. The aim of this study was to characterize the physiological and productive variables of \'Niagara Rosada\' vine with different ages and three training systems: pergola, VSP and \'Y\' shaped training system. Thus, two experiments were performed during 2014 and 2015 seasons, in Piracicaba - SP. In the first experiment vines on VSP and \'Y\' shaped training system were evaluated in their first and second year of production. The second experiment evaluated vines conducted in pergola systems and VSP, in the seventh and eighth year of production. In both experiments, total of days and degree-days to complete the production cycle was not affected by training systems. Among VSP and \'Y\' shaped systems, there is no difference in leaf surface area and production ratio, however, yield is higher in VSP due to the higher number of plants per hectare. The seven-year-old plants in pergola system have a more efficient ratio between leaf surface area and production. In the VSP, vines produce fruit with better quality as it have the highest soluble solids, anthocyanins and flavonols contents.

La phototransformation des matières actives à la surface des plantes après pulvérisation a une influence considérable sur l’efficacité des traitements. Dans ce travail, l’ensemble des réactions photochimiques se produisant sur des supports modèles des cires végétales dans des conditions proches des conditions environnementales ont été étudiées dans le cas d’un fongicide (le chlorothalonil) et d’un herbicide (la cycloxydime). Nous avons considéré les réactions photochimiques induites par l’absorption de lumière par les composés eux-mêmes et celles faisant intervenir des sensibilisateurs comme les métabolites secondaires des plantes. Dans chacun des cas, des études mécanistiques détaillées ont été conduites. Nous montrons que le chlorothalonil possède la capacité remarquable de produire de l’oxygène singulet avec un rendement quantique proche de l’unité. En parallèle, la réactivité de la cycloxydime avec l’oxygène singulet a été montrée. De ce fait, la phototransformation de la cycloxydime sur film de cire est accélérée lorsque des sensibilisateurs naturels, tels que les phytoalexines sont ajoutés à la cire, ou lorsque des traces de chlorothalonil sont présents à la surface du modèle foliaire. Ce travail a permis 1) de comprendre le mécanisme de phototransformation par excitation directe et sensibilisées du chlorothalonil et de la cycloxydime, 2) de mesurer de nombreuses données physico-chimiques (constantes de vitesse de réaction, rendements quantiques, durées de vie, caractéristiques spectrales des transitoires) et 3) de mettre au point un protocole expérimental permettant d’étudier la photochimie de molécules à l’état solide incluses dans des films de cire. / The phototransformation of active ingredients on plant surfaces after spraying has a significant impact on the treatment efficiency. In this work, the photochemical reactions taking place on leaf models and environmental conditions close to real ones have been overviewed for two pesticides: chlorothalonil and cycloxydim. We considered the photochemical reactions induced by light absorption by the compounds themselves and the reactions involving natural sensitizers such as plants secondary metabolites. Detailed mechanistic studies were conducted. We show that chlorothalonil has a noteworthy capacity to produce singlet oxygen with a quantum yield close to unity. Besides, the reactivity of cycloxydim towards singlet oxygen was demonstrated. Hence, the phototransformation of cycloxydim deposited on wax films is accelerated when natural sensitizers, such as phytoalexins, are included in the wax, or when chlorothalonil traces are present on the leaf model. This work allowed 1) to understand the mechanism of phototransformation by direct excitation and sensitization of chlorothalonil and cycloxydim, 2) to measure many physicochemical data (reaction rate constants, quantum yields, lifetime, spectral characteristics oft ransients and 3) to put in work an experimental protocol for the photochemical study of organic compounds in solid state and included in wax films.

Aloe L. (Asphodelaceae) is a monocotyledonous group of considerable popularity among succulent plant collectors and with a long history of medicinal use. It comprises ca. 500 species occurring throughout Africa, the Arabian Peninsula and western Indian Ocean islands. The first comprehensive ethnobotanical study of Aloe (excluding the cultivated A. vera) was undertaken using the literature as a surrogate for data gathered by interview methods. Over 1400 use records representing 173 species were collated, the majority (74%) of which described medicinal uses, including species used for natural products. In southern Africa, 53% of approximately 120 Aloe species in the region are used for health and wellbeing. Consensus ratios indicated that the uses of Aloe spp. for medicine and pest control are of the greatest biocultural importance. Utility has contributed to the recognition of diversity, taxonomic complexity, and conservation concerns, in Aloe. A systematic evaluation of the problematic maculate (spotted) species complex, section Pictae, was undertaken. New sequences were acquired of the nuclear ribosomal internal transcribed spacer (ITS), chloroplast trnL intron, trnL–F spacer and matK gene in 29 maculate species of Aloe. A well supported monophyletic (holophyletic) maculate group was recovered in phylogenetic trees of comparable topology generated by parsimony analysis and Bayesian inference. A representative of the related section Paniculatae, A. striata, was recovered in the maculate group, whereas doubtful maculate species with unusual floral morphology (A. leptosiphon and A. suffulta) comprised a sister group. Analogous patterns were identified in chemosystematic and comparative morphological studies of 34 and 36 maculate species, respectively, and insights were gained into interspecific relationships. The flavonoids isoorientin and isovitexin, and a new C-glycosylanthrone, 6′-malonylnataloin, were characterised using hyphenated chromatographic techniques and nuclear magnetic resonance (NMR) spectroscopy. Leaf surface sculpturing, stomata and lobes surrounding the epistomatal pore observed under a scanning electron microscope (SEM) are of potential taxonomic significance. Available evidence indicates that floral characters, namely a basally swollen perianth with constriction above the ovary, are of greater significance than maculate leaves as synapomorphies for section Pictae. An evolutionary hypothesis for section Pictae excludes marginal maculate species with unusual flowers. / Thesis (PhD)--University of Pretoria, 2009. / Plant Science / unrestricted