Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-07-15T18:16:10Z No. of bitstreams: 1 marcelaaparecidacamposnevesmiranda.pdf: 2269537 bytes, checksum: 9bf86ff2517e2014e98028114505af4e (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-07-22T14:58:32Z (GMT) No. of bitstreams: 1 marcelaaparecidacamposnevesmiranda.pdf: 2269537 bytes, checksum: 9bf86ff2517e2014e98028114505af4e (MD5) / Made available in DSpace on 2016-07-22T14:58:32Z (GMT). No. of bitstreams: 1 marcelaaparecidacamposnevesmiranda.pdf: 2269537 bytes, checksum: 9bf86ff2517e2014e98028114505af4e (MD5) Previous issue date: 2011-04-12 / Alterações no padrão de distribuição de luz em ambientes aquáticos podem afetar as características fisiológicas das cianobactérias, e com isso, influenciar na ocorrência de suas florações. Microcystis e Cylindrospermopsis estão entre os gêneros mais comuns formadores de florações em sistemas brasileiros. Conhecer e entender os requerimentos por luz e seu efeito no crescimento dessas duas cianobactérias é de fundamental importância para a compreensão e manejo de florações em ambientes aquáticos continentais. Este trabalho buscou avaliar o efeito de diferentes intensidades luminosas (25, 50, 300, 600 μmol de fótons m-2 s-1) na ecofisiologia de M.aeruginosa (cepa MIRF-01) e de C. raciborskii (cepa CYRF-01) e a interação entre uma cepa de M. aeruginosa (MIRF-01) com duas cepas de C. raciborskii (CYRF-01 e T3) em duas intensidades luminosas (50 e 500 μmol de fótons m-2 s-1). Para avaliar a ecofisiologia as células das duas espécies foram previamente aclimatadas por três gerações as intensidades luminosas utilizadas e os parâmetros avaliados foram turbidez, densidade do fluxo de fótons, densidade celular, pigmentos totais, atividade fotossintética e a morfologia das duas espécies. A interação entre as espécies foi verificada através da taxa de crescimento. O aumento na densidade celular ao longo do tempo promoveu aumento da turbidez e reduziu a disponibilidade da intensidade luminosa por volta de 50% em todos os tratamentos, devido ao auto-sombreamento. MIRF apresentou taxa de crescimento maior do que CYRF (0,38 ± 0,015 e 0,29 ± 0,019 respectivamente) em todos os tratamentos. Em ambas as cepas houve um aumento na concentração de pigmentos ao longo do tempo e uma diminuição com o aumento da intensidade luminosa. O aumento na relação carotenóide/clorofila, nas culturas de CYRF cultivadas em alta intensidade luminosa (CYRF-300 e CYRF-600), justifica a mudança na coloração de “verde” viii para “verde-amarelada” das culturas de C. raciborskii. As duas espécies apresentaram taxa de transferência de elétrons semelhantes entre os tratamentos, não sendo verificados mecanismos de dissipação de energia. Em relação a morfologia MIRF apresentou agregação celular em baixas intensidade luminosas (25 e 50 μmol de fótons m-2 s-1) e CYRF apresentaram alterações nos tricomas cultivados as altas intensidade luminosas (300 e 600 μmol de fótons m-2 s-1), levemente curvados com diferenciação nas extremidades e filamentos bifurcados. A interação entre M.aeruginosa e C. raciborskii foi evidente para as cepas coexistentes MIRF e CYRF. Em baixa intensidade luminosa (50 μmol de fótons m-2 s-1), CYRF apresentou menor taxa de crescimento quando na presença de MIRF; em alta intensidade luminosa (500 μmol de fótons m-2 s-1) MIRF apresentou maiores taxas de crescimento quando na presença de CYRF do que quando em monocultura. M.aeruginosa e C. raciborskii quando aclimatadas não apresentaram diferenças em relação à ecofisiologia nas diferentes intensidades luminosas utilizadas. E a interação entre cepas coexistentes pode refletir no crescimento das espécies com a alteração da intensidade luminosa. / Changes in the distribution pattern of light in aquatic environments can affect the physiological characteristics of cyanobacteria and, thus, influence on the occurrence of blooms. Cylindrospermopsis and Microcystis are among the most common bloomforming genera in Brazilian systems. Knowing and understanding the requirements for light and its effect on the growth of these two cyanobacteria are important for the understanding and management of algal blooms in freshwater ecosystems. This study evaluated (1) the effect of different light intensities (25, 50, 300, 600, μmol photons m-2 s-1) on growth, physiology and morphology of the species M. aeruginosa (strain MIRF) and C. raciborskii (strain CYRF) and; (2) the interaction between one strain of M.aeruginosa (MIRF-01) with two strains of C. raciborskii (CYRF-01 and T3) at two light intensities (50 and 500 μmol photons m-2 s-1). Both strains were previously acclimated. Cell density, total pigments, turbidity, density of photon flux, photosynthetic activity and morphology of the two species were analized. The interaction between two species was verified by changes in growth rates. The increase in cell density over time promoted increase in turbidity and reduced the availability of light intensity by about 50% in all treatments, due to self-shading. MIRF showed higher growth rate than CYRF (0.38 ± 0.29 ± 0.015 and 0.019 respectively) in all treatments. There was no difference in the growth rates between treatments for MIRF and CYRF in different light intensities. In both strains, there was an increase in pigment concentration over time and decrease with increasing irradiance. The increase in the ratio carotenoid/chlorophyll-a in cultures grown in high irradiance CYRF (CYRF-300 and CYRF-600) explains the change in color from green to green-yellow of cultures of C. raciborskii. The rapid light curves were similar among treatments, and was not verified x down regulation mechanisms. It was also noted that while MIRF showed cell aggregation at low light intensities (25 and 50 mmol photons.m-2.s-1), CYRF showed morphological changes in the trichomes at high light intensities (300 and 600 μmol photons.m-2.s-1), slightly curved filaments and bifurcate at the ends. The interaction between M.aeruginoa and C.raciborskii was evident for coexisting MIRF and CYRF strains. In low light intensity (50 μmol photons.m-2.s-1), CYRF showed a lower growth rate in the presence of MIRF. In high light-intensity (500 μmol photons.m-2.s-1) MIRF growth rates were higher in the presence of CYRF than in monoculture. When M.aeruginosa and C.raciborskii are acclimated there is no ecophysiology difference in different light intensities. The interaction between coexisting strains may reflect the growth of species in different light intensity.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-04-25T12:11:22Z No. of bitstreams: 1 camiladocarmoalmeida.pdf: 15878287 bytes, checksum: 7ce86267329e6481b097f64af841fe34 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-04-25T15:26:02Z (GMT) No. of bitstreams: 1 camiladocarmoalmeida.pdf: 15878287 bytes, checksum: 7ce86267329e6481b097f64af841fe34 (MD5) / Made available in DSpace on 2017-04-25T15:26:02Z (GMT). No. of bitstreams: 1 camiladocarmoalmeida.pdf: 15878287 bytes, checksum: 7ce86267329e6481b097f64af841fe34 (MD5) Previous issue date: 2014-08-29 / Este trabalho teve por objetivos projetar um sistema eletrônico de controle destinado a fornecer uma alternativa simplificada e eficiente para estudos de fisiologia vegetal envolvendo luz artificial, bem como para sua utilização em determinados processos de cultivo de plantas em estufas. O trabalho apresenta uma revisão sobre a interação entre a iluminação artificial e o cultivo de plantas, tanto para o propósito de uma cultura comercial quanto para possibilitar a interpretação do comportamento de plantas em estudos botânicos. Este sistema eletrônico possibilita a determinação das quantidades radiométricas de interesse quando a iluminação artificial é usada como suplemento ou como única fonte de iluminação em cultivos. Com base em estudos anteriores, é proposto a produção de um sistema autônomo constituído por um aparelho de iluminação composto por LEDs brancos e/ou coloridos. Além disso, foram realizados alguns experimentos radiométricos preliminares utilizando luminárias comerciais de LEDs, visando sua utilização em associação com o sistema de controle proposto. Os parâmetros medidos mais relevantes foram o fluxo de fótons fotossinteticamente ativos, fluxo luminoso e a temperatura de cor correlata. Espera-se que o protótipo desenvolvido apresente características que agreguem flexibilidade e comportamento radiométrico relevante para cultivos controlados. / This work aims to develop an electronic control system with the purpose to drive a simplified and efficient alternative for vegetal physiology studies involving artificial light as well as for its utilization in certain plants crop at greenhouses. Additionally, this work presents a brief review regarding the interaction between artificial lighting and plants, with purposes of commercial crops and the possibility of interpretation of plants behavior in botanic studies. This electronic system enables the determination of the radiometric quantities of interest when the lighting is used as a supplement or as the only lighting source in crops. Using the latest studies, it is proposed an autonomous system consisting basically of white and/or colored LEDs. Besides, it were performed radiometric experiences using commercial luminaires with LEDs aiming the use of them in the proposed control system. The more relevant measured parameters were the photosynthetic photon flux, luminous flux and correlated colour temperature. The proposed system shows flexibility and relevant radiometric behavior, which are particularly useful in Plant Physiology.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-05-16T12:20:41Z No. of bitstreams: 1 cristianoferraraderesende.pdf: 1487750 bytes, checksum: df886d8f9947076302c4078f4a93546e (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-05-17T16:14:20Z (GMT) No. of bitstreams: 1 cristianoferraraderesende.pdf: 1487750 bytes, checksum: df886d8f9947076302c4078f4a93546e (MD5) / Made available in DSpace on 2017-05-17T16:14:20Z (GMT). No. of bitstreams: 1 cristianoferraraderesende.pdf: 1487750 bytes, checksum: df886d8f9947076302c4078f4a93546e (MD5) Previous issue date: 2016-08-22 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / FAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas Gerais / Syzygium jambos (L.) Alston é uma espécie da família Myrtaceae, conhecida popularmente como “jambo-rosa” e originária da Ásia Tropical. Apresenta grande plasticidade fenotípica a condições ambientais contrastantes e uma elevada capacidade invasora, sendo capaz de adaptar-se tanto a áreas abertas quanto de dossel fechado. Seus indivíduos formam uma copa densa, impedindo a colonização de plantas nativas e o estabelecimento de espécies mais dependentes de luz. É, por isso, de grande importância ecológica. Apesar de ser uma espécie invasora de diversas ilhas oceânicas e áreas continentais tropicais, trabalhos que visem entender os mecanismos ecofisiológicos subjacentes a essa capacidade são inexistentes. Dessa forma, objetivou-se descrever as alterações morfológicas, bioquímicas e metabólicas de plantas de S. jambos cultivadas em diferentes condições de luminosidade e fertilização, além de verificar a viabilidade da utilização do clorofilômetro portátil SPAD-502 na determinação indireta dos teores de pigmentos fotossintéticos foliares. Para tal, sementes foram coletadas de um indivíduo estabelecido no Instituto de Ciências Biológicas da UFJF e germinadas, período durante o qual a mobilização de carboidratos cotiledonares foi avaliada. As sementes foram plantadas em copos descartáveis, e após o crescimento até cerca de 11 cm foram transplantadas para vasos de 25 L, preenchidos com substrato formado por terra e areia (controle), substrato adicionado de esterco bovino e um terceiro com adição de adubo químico. As plantas foram transferidas para diferentes ambientes luminosos, denominados de baixa radiação (BR), radiação intermediária (RI) e alta radiação (AR), permanecendo por cerca de 11 meses. Os resultados do presente trabalho demonstraram importantes respostas adaptativas das plantas de S. jambos aos diferentes ambientes luminosos, como, por exemplo, menor desenvolvimento da parte aérea, maior alocação de biomassa nas raízes, menor comprimento de internódios e a presença de folhas em posição mais vertical em plantas a pleno sol. Por sua vez, as plantas sob baixas radiações apresentaram folhas com áreas maiores, além de teores de pigmentos fotossintéticos significativamente maiores, que as plantas sob maiores intensidades luminosas. Houve correlação positiva significativa entre os teores de pigmentos fotossintéticos aferidos espectrofotometricamente e os índices SPAD obtidos com auxílio do clorofilômetro portátil, validando sua utilização na quantificação indireta desses teores em plantas de S. jambos. Com relação ao metabolismo antioxidativo, foram evidenciadas diferentes estratégias de combate à geração de espécies reativas de oxigênio. De forma geral, ressalta-se a maior atividade de enzimas antioxidativas nos ambientes mais sombreados, bem como a maior produção de carotenoides nas folhas desenvolvidas a pleno sol. Os parâmetros fotossintéticos e de fluorescência evidenciaram importantes respostas à variação na luminosidade. Independentemente do ambiente luminoso, as plantas de S. jambos apresentaram crescimento e desenvolvimento, permanecendo viáveis. Os dados do presente trabalho nos permitem concluir que os atributos morfológicos, fisiológicos e bioquímicos apresentados pela espécie invasora Syzygium jambos em condições contrastantes de luminosidade são de grande importância na sua aclimatação e permanência em ambientes naturais diversos, contribuindo para a sua capacidade invasora. / Syzygium jambos (L.) Alston is a species of the Myrtaceae family, popularly known as “rose-apple” and originated in tropical Asia. It has great phenotypic plasticity to contrasting environmental conditions and high invasiveness, being able to adapt to both open areas as closed canopy. Its individuals form a dense crown, preventing colonization of native plants and the establishment of more light dependent species. It is therefore of great ecological importance. Despite being an invasive species in many tropical oceanic islands and continental areas, works aimed at understanding the ecophysiological mechanisms underlying this capacity are scarce. Thus, this study aimed to describe the morphological, biochemical and metabolic alterations in S. jambos plants grown under different light conditions and fertilization systems, and verify the feasibility of using the SPAD-502 chlorophyll meter in indirect determination of the levels of leaf photosynthetic pigments. For that, seeds were collected from one individual established in the Institute of Biological Sciences of UFJF and placed to germinate, during which the mobilization of cotyledon carbohydrates was assessed. The seeds were planted in plastic cups, and after raising to about 11 cm they were transplanted into pots of 25 L, filled with substrate formed by land and sand (control), substrate added with bovine manure and a third with the addition of chemical fertilizer. The plants were transferred to different light environments, called low radiation (BR), intermediate radiation (RI) and high radiation (AR), where they stood for about 10 months. The results of this study showed significant adaptive responses of S. jambos plants to different light environments, such as lower development of the aerial part, higher allocation of biomass in the roots, shorter internodes and the presence of leaves in a more vertical position in plants at full sun. In turn, plants under low radiation showed leaves with larger areas than plants under higher light intensities, in addition to significantly higher levels of photosynthetic pigments. There was a significant positive correlation between the levels of photosynthetic pigments measured spectrophotometrically and the SPAD indices, obtained with the help of chlorophyll meter, validating its use in indirect quantification of these levels in S. jambos plants. Regarding the antioxidative metabolism, there were different strategies to combat the formation of reactive oxygen species. Overall, the study highlights the increased activity of antioxidant enzymes in shadier environments, as well as increased production of carotenoids in the leaves developed in full sun. The photosynthetic and fluorescence parameters showed significant responses to changes in light condition. Regardless of the ambient light, plants of S. jambos showed growth and development while remaining viable. The present data allow us to conclude that the morphological, physiological and biochemical attributes presented by the invasive species Syzygium jambos in contrasting light conditions are of great importance for their acclimation and permanence in different natural environments, contributing to its invasiveness.

Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / Mancozeb has been the protective fungicide with a multi-site mechanism widely used associated with fungicide programs in soybean cultivation. This compound has provided significant increases in the systemic fungicides performance in the soybean rust control. Besides the obvious fungicide effect, mancozeb has provided also effects on physiological parameters in plants promoting benefits such as fungicide phytotoxicity reduction and increases in plant vigor. The studies aimed to understand the interaction of mancozeb associated to systemic fungicides against the soybean rust control, in addition to determine the physiological plants responses from the product versus plant relation. The experiments were conducted in greenhouse and field, divided in four chapters in manuscript format. The first study investigates the effect of the mancozeb interaction with commercial mixtures of QoI + DMI based on two methodologies. From this, it was possible to verify that mancozeb increases significantly the control efficiency when associated with less efficient mixtures. In such interactions was obtained a control synergistic response. However it is expected at least an additive response, when associated to mixtures with high efficiency, the increase in control is lower. The second study consisted of the enzymes activity linked to the antioxidant response, the photosynthetic pigments concentration and lipid peroxidation investigation in plants exposed to the fungicide trifloxystrobin + prothioconazole, with potential to cause phytotoxicity, associated or not with mancozeb. Antioxidant enzymes activity increase, reduction in pigment concentration and cell damage due to increased lipid peroxidation were observed in plants exposed to systemic fungicide. These damages were attenuated when the systemic fungicide was associated with mancozeb. Moreover, photosynthesis and chlorophyll a fluorescence parameters were analyzed in plants exposed to mancozeb and trifloxystrobin + prothioconazole, constituting the third study. Decreased in the photosynthetic efficiency was verified in plants treated with systemic fungicide characterizing a significant phytotoxic effect. The parameters evaluated elucidate a beneficial effect of mancozeb reducing the damages caused by the systemic fungicide. The fourth study aimed to evaluate changes in the leaves soybean nutritional status exposed to mancozeb. Macro and micronutrients concentration were determined on 4th and 8th days exposure. Significant changes in concentration of S, Mn and Zn were observed. Such changes were related to “green effect” on plants after mancozeb exposure. All data provide new information regarding the recent use of the mancozeb molecule in soybean. The contribution is original and presents data that can contribute to the definition of strategies in anti-resistance management and increase site-specific systemic fungicides effective life commonly used in soybean. In addition, the results present important physiological responses on plants induced Figure 1by mancozeb that can aggregate on development, vigor and productivity. / Mancozebe tem sido o fungicida protetor com mecanismo multi-sítio amplamente utilizado associado aos programas fungicidas na cultura da soja. Este composto tem proporcionado incrementos significativos no desempenho de fungicidas sistêmicos no controle da ferrugem da soja. Além do efeito evidente como fungicida, tem sido relatado efeitos sobre parâmetros fisiológicos nas plantas conferindo benefícios como redução de fitotoxicidade de outros fungicidas e incrementos no vigor de plantas. Nossos estudos objetivaram compreender a interação de mancozebe associado a fungicidas sistêmicos frente ao controle da ferrugem da soja, além de determinar respostas fisiológicas das plantas oriundas da relação produto versus planta. Foram conduzidos ensaios em casa de vegetação e a campo, aqui divididos em quatro capítulos no formato de manuscritos. Em um primeiro estudo o efeito da interação de mancozebe com misturas comerciais de IQo + IDM foi investigado com base em duas metodologias. A partir disso foi possível verificar que mancozebe agrega mais significativamente a eficácia de controle quando associado a misturas menos eficientes. Em tais interações obteve-se uma resposta sinérgica de controle. Quando associado a misturas com alta eficácia o incremento no controle foi menor, entretanto no mínimo uma resposta aditiva é esperada. Em um segundo estudo a atividade de enzimas ligadas à resposta antioxidante, a concentração de pigmentos fotossintetizantes e a peroxidação lipídica foi investigada em plantas expostas ao fungicida trifloxistrobina + protioconazol, com potencial de causar fitotoxidade, estando este associado ou não ao mancozebe. Aumento na atividade de enzimas antioxidantes, redução no conteúdo de pigmentos e danos celulares evidenciadas pela maior peroxidação de lipídios foram verificadas em plantas expostas ao fungicida sistêmico. Tais danos foram atenuados quando o fungicida sistêmico foi associado ao mancozebe. Nesse mesmo sentido, parâmetros de fotossíntese e fluorescência da clorofila a foram analisados em plantas expostas a mancozebe e trifloxistrobina + protioconazol, sendo este o terceiro estudo aqui apresentado. Decréscimo na eficiência fotossintética foi verificado em plantas tratadas com o fungicida sistêmico caracterizando um efeito fitotóxico significativo. Os parâmetros avaliados elucidam um efeito benéfico de mancozebe reduzindo os danos causados pelo fungicida sistêmico. Um quarto e último estudo visou avaliar alterações no estado nutricional de folhas de soja expostas a mancozebe. Concentração de macro e micronutrientes foram determinadas aos 4 e 8 dias após exposição. Alterações significativas na concentração de S, Mn e Zn foram observadas. Tais alterações foram relacionadas a incrementos na coloração verde da cultura após exposição à mancozebe. Os dados trazem informações novas em relação ao recente uso da molécula mancozebe em soja. A contribuição é original e apresenta dados que podem contribuir na definição de estratégias no manejo anti-resistência e aumento da vida efetiva dos fungicidas sistêmicos sítio-específico comumente utilizados em soja. Além disso, os resultados apresentam uma série de respostas fisiológicas importantes de mancozebe sobre as plantas que podem agregar em termos de desenvolvimento, vigor e produtividade.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Due to the historical application of cupric fungicides in vineyards, the amounts of copper (Cu) in these soils can reach levels that cause toxicity to plants. Recently researchers have tried alternative products to the cupric ones, in order to reduce the amount of Cu applied to the vineyards, which usually shows zinc (Zn) in its composition. This study aimed to evaluate the biochemical and physiological changes in corn plants, grown in soil with a high content of Cu and different levels added of Zn. In November 2011 the soil was collected from the 0-15 cm layer of a vineyard with high Cu content and in an area of native grass adjacent to the vineyard, with low concentrations of Cu and Zn, which served as treatment control, and both soils were classified as Typic Hapludalf. The experiment was performed in a greenhouse and was divided into two corn crops, the first between March and April, and the second between October and November, both in 2012. The treatments were the doses of 0, 30, 60, 90, 180 and 270 mg kg-1 of Zn added to the soil of the vineyard, plus the control treatment. Treatments had pH values in water and levels of available phosphorus and exchangeable potassium similar. At 35 days after emergence the plants were harvested and the accumulation of dry matter from roots and shoots and the concentration of Cu and Zn in leaves were determined. It was also evaluated the operation of the photosynthetic apparatus from the fluorescence of chlorophyll a and the photosynthetic pigments, biochemical parameters related to oxidative stress in leaves of plants, such as activity of superoxide dismutase (SOD) and of non-specific peroxidase (POD) were evaluated. The high concentrations of Cu and Zn in soil caused toxicity to corn plants and provided foliar concentrations above the levels considered normal in the leaves, from both cultivations. The Zn toxicity was evidenced by the decrease in the growth of both roots and shoots, as well as the induction of symptoms of toxicity and deficiency in photosynthetic parameters, reflecting photoinhibition. Moreover, it was observed oxidative stress and the antioxidant system of maize plants was not effective enough to reverse the condition of stress, especially in cultivated soils received higher doses of Zn. / Devido ao histórico de aplicação de fungicidas cúpricos em vinhedos, os teores de cobre (Cu) nestes solos podem atingir níveis que causam toxicidade às plantas. Recentemente tem-se buscado produtos alternativos aos cúpricos, com o intuito de reduzir a quantidade de Cu aportado aos vinhedos, os quais geralmente apresentam zinco (Zn) em sua composição. O objetivo foi avaliar se o aumento na concentração de Zn no solo poderia significar toxidez adicional às plantas de milho cultivadas, em um ambiente já contaminado com alto teor de Cu no solo. Em novembro de 2011 o solo foi coletado na camada de 0-15 cm de um vinhedo com alto teor de Cu e em uma área de campo nativo adjacente ao vinhedo, com baixos teores de Cu e Zn, o qual serviu como tratamento controle, sendo que ambos os solos foram classificados como Argissolo Vermelho. O experimento foi conduzido em casa de vegetação e foi dividido em dois cultivos de milho. O primeiro entre março e abril, e o segundo entre outubro e novembro, ambos no ano de 2012. Os tratamentos foram as doses de 0, 30, 60, 90, 180 e 270 mg kg-1 de Zn adicionadas ao solo de vinhedo, mais o tratamento controle, todos com valores de pH em água e teores de fósforo disponível e potássio trocável semelhantes. Aos 35 dias após a emergência as plantas foram coletadas e o acúmulo de matéria seca de raízes, de parte aérea e a concentração de Cu e Zn nas folhas foram determinados. Foi avaliado também o funcionamento do aparato fotossintético a partir da fluorescência da clorofila a e os pigmentos fotossintéticos, parâmetros bioquímicos ligados ao estresse oxidativo nas folhas das plantas, tais como atividade das enzimas superóxido dismutase (SOD) e das peroxidases não específicas (POD). Os teores elevados de Cu e Zn no solo causaram toxicidade às plantas de milho e proporcionaram teores foliares acima dos níveis considerados normais nas folhas das plantas, nos dois cultivos. A toxicidade de Zn se evidenciou através da diminuição no crescimento, tanto das raízes, como da parte aérea, bem como pela indução de sintomas de toxicidade e deficiência nos parâmetros fotossintéticos, refletindo na fotoinibição. Além disso, foi observado estresse oxidativo e o sistema antioxidante das plantas de milho não foi suficientemente eficaz para reverter a condição de estresse, especialmente nas plantas cultivadas nos solos que receberam as maiores doses de Zn.

Tabernaemontana catharinensis, popularly known as cobrina, is a native tree, which belongs to the family Apocynaceae. This species is suitable for reforestation, it is rich in phytochemicals compounds and it is used in folk medicine in the form of tea or infusion of its leaves and barks. Impacts of the indiscriminate extraction of seeds and vegetative parts of native species have increased in recent years, being the cultivation of plants on a large scale in a sustainable manner one of the challenges for production - without compromising natural resources. However many species still lack ecological, physiological and agronomic information. Then, the aims of this study were to evaluate the physiological quality of seeds and morphophysiological parameters of T. catharinensis propagated in vitro and ex vitro. In this regard, ripe fruits were collected in mid lateral third of five arrays with approximately four meters high and located in the remaining vegetation in the city of Ijuí, Northwest region of Rio Grande do Sul (28° 26' 07 "S and 53° 57' 50"W). The experiments were performed in laboratory and in greenhouse. In the laboratory, seeds were germinated in the presence of light (photoperiod of 16 hours) and in the absence of light (continuous dark), by testing five temperatures: 15, 20, 25, 30 °C and alternating 20 to 30 °C (night-day). Three conditions and storage temperatures: 25 ± 1 °C (growth room), 10 ± 1 °C (refrigerator) and 4 ± 1 °C (cold room), were part of the experiment. They were used to check the germination behavior and the water content during six periods seed storage (30, 60, 90, 120, 150 and 180 days). We observed that, regardless of photoperiod (photoperiod of 16 hours and continuous darkness), 25 and 30 °C temperatures promoted the highest percentage of germination of T. catharinensis seeds. T. catharinensis seeds behave as neutral photoblastic. The storage of seeds of T. catharinensis for 180 days reduces the water content of the seeds, not occurring the reduction in germination potential, which demonstrates an orthodox behavior. For the experiments in vitro conditions, in order to obtain seedlings and the establishment of T. catharinensis, seeds were pre-soaked in gibberellic acid (GA3) at concentrations of 0.0; 300 and 600 mg L-1 in two regimes of time 24 and 48 hours. Afterwards, the cotyledon segments of 1 cm seedlings obtained in vitro germination. With 70 days old, they were inoculated in culture medium with 100% of minerals MS (MURASHIGE; SKOOG, 1962), plus combinations of 6-benzylaminopurine (BAP) 0.0; 1.0; 2.0; 4.0; 6.0 mg L-1 and naphthaleneacetic acid (NAA) 0.0; 0.1; 0.2; 0.4; 0.6 mg L-1. For in vitro rooting experiment, microcuttings of 90 days, with three pairs of leaves, were inoculated in MS medium (MURASHIGE; SKOOG, 1962), supplemented with IBA concentrations 0.0; 1.0; 2.0; 4.0; 6.0 mg L1. The percentage of germination was not significantly different in pre-soaked seeds in GA3, however we observed a reduction in the speed of germination at concentrations of 300 and 600 mg L-1 of GA3 for 48h of immersion. In vitro establishment, we verified the direct organogenesis of adventitious shoots from cotyledons of cobrina without the need for growth regulator, but the use of BAP associated with NAA maximized the number of shoots, leaves and fresh mass of shoots. For the in vitro experiment rooting supplementation of 1.0 and 6.0 mg L-1 of IBA to the culture medium resulted in the highest rooting rate (96.5 and 89%, respectively) and root length (15.96 and 15.60 cm, respectively). The absence of growth regulators (IBA) decreased the number of tips and root volume and the contents of chlorophyll b. For the experiment in the greenhouse, the treatments were Mecplant® substrate compositions (commercial substrate), fine texture vermiculite (V) and carbonized rice husk (CRH), by evaluating their influence on the emergence, vigor and morphophysiological parameters of T. catharinensis. We found out that the isolated use of commercial substrate 100% Mecplant® occurred less emergency and IVG seedlings, which negatively affected the growth characteristics. The commercial substrate associated with inert material vermiculite in formulations 50% Mecplant® + 50% V and 25% Mecplant® + 75% V showed higher expression of seed vigor and greater seedling growth, proving to be more appropriate, from the study to the formation of cobrina seedlings. Levels of chlorophyll b, as well as the total carotenoid are not influenced by the substrates. The ratio of chlorophyll a/b is higher in the treatments T2 (75% Mecplant® + 25% V), T4 (25% Mecplant® + 75% V) and T5 (75% Mecplant® + 25% CRH). / Tabernaemontana catharinensis, conhecida popularmente como cobrina, é uma árvore nativa, pertencente à família Apocynaceae. Essa espécie é indicada para reflorestamento e rica em compostos fitoquímicos além de ser utilizada na medicina popular na forma de chá ou infusão de suas folhas e cascas. Impactos decorrentes da extração indiscriminada de sementes e partes vegetativas de espécies nativas vêm crescendo nos últimos anos, sendo um dos desafios para a produção o cultivo das plantas em larga escala de modo sustentável, sem o comprometimento dos recursos naturais. Contudo muitas espécies ainda carecem de informações ecológicas, fisiológicas e agronômicas. Assim, os objetivos deste trabalho foram avaliar a qualidade fisiológica das sementes e os parâmetros morfofisiológicos de T. catharinensis propagadas in vitro e ex vitro. Para isso, frutos maduros foram coletados no terço médio lateral de cinco matrizes com cerca de quatro metros de altura e localizadas em remanescente vegetal, no município de Ijuí, região Noroeste do Rio Grande do Sul (28° 26' 07"S e 53° 57' 50"O). Os experimentos foram desenvolvidos em condições de laboratório e em casa de vegetação. Em laboratório, sementes foram colocadas para germinar na presença de luz (fotoperíodo de 16 horas) e ausência de luz (escuro contínuo), testando-se cinco temperaturas: 15, 20, 25, 30 ºC e alternada 20-30 ºC (noite-dia). Três condições e temperaturas de armazenamento: 25 ±1 ºC (sala de crescimento), 10 ±1 ºC (refrigerador) e 4 ±1 ºC (câmara fria), constituíram o experimento para verificar o comportamento germinativo e o teor de água durante seis períodos de armazenamento das sementes (30, 60, 90, 120, 150 e 180 dias). Observou-se que, independente do regime de luz (fotoperíodo de 16 horas e escuro contínuo), temperaturas de 25 e 30 ºC, promoveram maior percentagem de germinação das sementes de T. catharinensis. Sementes de T. catharinensis comportam-se como fotoblásticas neutras. O armazenamento das sementes de T. catharinensis por 180 dias reduz o teor de água das sementes, não ocorrendo redução no potencial germinativo, demonstrando um comportamento ortodoxo. Nos experimentos em condições in vitro, para obtenção de plântulas e estabelecimento de T. catharinensis, sementes foram pré-imersas em ácido giberélico (GA3) nas concentrações de 0,0; 300 e 600 mg L-1 em dois regimes de tempo 24 e 48h. Posteriormente, segmentos cotiledonares de 1 cm de plântulas obtidas da germinação in vitro, com 70 dias de idade, foram inoculados em meio de cultura com 100% dos sais minerais de MS (MURASHIGE; SKOOG, 1962), acrescidos das combinações de 6-benzilaminopurina (BAP) 0,0; 1,0; 2,0; 4,0; 6,0 mg L-1 e ácido naftalenoacético (ANA) 0,0; 0,1; 0,2; 0,4; 0,6 mg L-1; para o experimento de enraizamento in vitro, microestacas de 90 dias, com três pares de folhas, foram inoculadas em MS (MURASHIGE; SKOOG, 1962), acrescido com concentrações de ácido indolbutírico (AIB) 0,0; 1,0; 2,0; 4,0; 6,0 mg L1. A percentagem de germinação não diferiu significativamente em sementes préimersas em GA3, contudo ocorreu redução na velocidade de germinação nas concentrações de 300 e 600 mg L-1 de GA3 por 48h de imersão. No estabelecimento in vitro, ocorreu a organogênese direta de brotações adventícias de explantes cotiledonares de cobrina sem a necessidade de fitorreguladores de crescimento, porém o uso de BAP associado ao ANA maximizou o número de brotos, folhas e a massa fresca de brotações. Para o experimento de enraizamento in vitro a suplementação de 1,0 e 6,0 mg L-1 de AIB ao meio de cultura proporcionou maiores taxas de enraizamento (96,5 e 89%, respectivamente) e comprimento de raiz (15,96 e 15,60 cm, respectivamente). A ausência de fitorreguladores de crescimento (AIB) reduziu o número de pontas e volume de raízes e os teores de clorofila b. Para o experimento em casa de vegetação, os tratamentos constaram de composições do substrato Mecplant® (substrato comercial), vermiculita de textura fina (V) e casca de arroz carbonizada (CAC), avaliando-se a influência destes na emergência, vigor e nos parâmetros morfofisiológicos de T. catharinensis. Verificou-se que no uso isolado de substrato comercial 100% Mecplant® ocorreu menor emergência e IVG de plântulas, afetando negativamente as características de crescimento. O substrato comercial associado ao material inerte vermiculita nas formulações 50% Mecplant® + 50% V e 25% Mecplant® + 75% V propiciaram maior expressão do vigor de sementes e maior crescimento de mudas, evidenciando ser mais adequado, dentre os estudados, para a formação de mudas de cobrina. Teores de clorofila a, b, total e carotenoides não são influenciados pelos substratos formulados. A relação da clorofila a/b é mais elevada nos tratamentos T2 (75% Mecplant® + 25% V), T4 (25% Mecplant® + 75% V) e T5 (75% Mecplant® + 25% CAC).

Due to the invasive nature of quantification techniques, baseline pigment data for coral-dwelling zooxanthellae are not known. In an attempt to develop a model for non-invasive estimation of zooxanthellae pigment concentrations from corals, field samples were taken from Porites rus and P. lutea in Apra Harbor, Guam. In-situ reflectance spectra (R400-R800) from 22 coral colonies were collected. “Coral truthing” was accomplished by extracting corresponding tissue core samples. Subsequent analysis to quantify the concentrations of 6 zooxanthellae pigments (µg cm-2) was performed using HPLC. Trials of multiple linear regressions were attempted (EJ Hochberg) and found inappropriate, despite previous success. The multivariate calibration technique partial least squares regression (PLS-R) is an excellent tool in the case of co-linear variables. Thus, PLS-R was attempted for chlorophyll c2 and peridinin after demonstration of co-linearity. This may be an appropriate approach for development of bio-optical models to estimate zooxanthellae pigment concentrations. Further, the dinoflagellate diagnostic pigment peridinin may be of great value for reef-scale remote sensing of changes in coral status in the future.

Dans les écosystèmes littoraux, les communautés microphytobenthiques sont soumises à des conditions environnementales qui peuvent être extrêmes en particulier en ce qui concerne l'intensité lumineuse. Les mécanismes de protection mis en place dépendent étroitement du type d'habitat où se développent ces communautés et cette thèse a pour objectifs d'analyser les caractéristiques de l'activité photosynthétique et les mécanismes de protection développés par des assemblages microphytobenthiques dans deux écosystèmes littoraux très différents : les vasières intertidales atlantiques de la Baie de L'Aiguillon (France) et la lagune côtière non tidale de Puck Bay dans la Mer Baltique (Władysławowo, Pologne). Pour réaliser ces objectifs, trois études ont été réalisées : (1) la description des communautés microphytobenthiques, (2) la caractérisation de leur activité photosynthétique et (3) l'analyse des mécanismes de photoinhibition et de photoprotection.La structure taxonomique du microphytobenthos a été décrite en se basant sur des observations en microscopie optique et sur la mesure des caractéristiques des pigments photosynthétiques par chromatographie liquide à haute performance (HPLC). L'activité photosynthétique a été étudiée par des méthodes de microrespirométrie volumétrique et de spectrofluorométrie de la chlorophylle a. Les mécanismes de photoinhibition et de photoprotection ont été étudiés par fluorométrie en modulation d'amplitude pulsée (PAM).Les résultats obtenus nous ont permis de montrer que :1) Les communautés atlantiques sont fortement dominées par des diatomées épipéliques, alors que le microphytobenthos de la Mer Baltique est plus diversifié et comporte, outre des diatomées, une large part de cyanobactéries,2) Les microphytobenthos atlantique est bien acclimaté à des valeurs d'intensités lumineuses plutôt faibles, alors que les communautés de la Mer Baltique ont encore une bonne activité photosynthétique à de fortes irradiances,3) Les diatomées atlantiques présentent une plus forte photoinhibition que les microalgues de la Baltique,4) L'activité photosynthétique des communautés microphytobenthiques non perturbées montre un des rythmes circadien et tidal, qui semblent être contrôlés par des facteurs endogènes, qui mettent en jeu des adaptations comportementales comme la migration verticale pour les diatomées atlantiques,5) En ce qui concerne le microphytobenthos de la Mer Baltique, qui n'a pas de capacité migratoire, la photoprotection est assurée en premier lieu par la mise en jeu de processus physiologiques. Nous avons pu montrer la très grande flexibilité du photsystème PSII qui est capable de suivre très rapidement les changements à court terme de lumière ambiante. / The scope of this thesis includes the characteristics and comparison of photosynthetic activity and photoprotection mechanisms of microphytobenthos assemblages inhabiting the Atlantic intertidal mudflats of Aiguillon Bay (Esnandes, France) and the littoral zone of the Baltic Sea in non-tidal Puck Bay (Władysławowo, Poland). In order to accomplish the main aims of the work the following tasks were carried out: (1) characterization of microphytobenthic assemblages; (2) characterization of their photosynthetic activity and (3) description of photoinhibition and photoprotective mechanisms. The structure of microphytobenthos was described based on observation of the material in light microscope (LM) and through the characteristics of photosynthetic pigments using high performance liquid chromatography (HPLC). Photosynthetic activity was described using various methods including classical (volumetric micro-respirometer) and modern (chlorophyll a fluorescence) ones. In addition, the measurements of variable fluorescence were also used to study photoinhibition and photoprotective mechanisms. Based on the obtained results it was stated that:1.) the Atlantic assemblages were strongly dominated by epipelic diatoms, while the Baltic microphytobenthos was more diverse and cyanobacteria, next to diatoms, were also very important component,2.) it was shown that the Atlantic microphytobenthos was well acclimated to rather low light intensities, while the Baltic assemblages showed good utilization of higher irradiance,3.) the Atlantic diatoms were more susceptible to photoinhibition than the Baltic microalgae,4.) the photosynthetic activity described for the undisturbed microphytobenthos communities revealed circadian and circatidal rhythms, which seemed to be controlled by endogenous factors, supporting diatoms’ behavioural adaptations i.e., vertical migration,5.) in case of the Baltic microphytobenthos, the lack of the ability to move caused their physiological processes the first line of defence against excess irradiances. The analysis revealed extreme flexibility of PSII which was able to follow rapidly the short-term changes in ambient light

Magister Scientiae (Biodiversity and Conservation Biology) / Fog and dew interception and utilization by plant canopies remains one of the least considered aspects of vegetation studies at any scale yet the few studies that have been conducted point to their considerable influence on ecological processes and a critical role in modulating climate in southern African arid ecosystems. Their relevance to succulent plant hydrology was investigated in this study.The first study measured stable 18O and 2H isotope ratios in samples of rain, fog and dew water and compared these with those assayed monthly in stem xylem water of six succulent shrub species over a one year period. Negative 18O and 2H ratios were observed in the stem xylem water of all six species signifying a predominance of water derived from fog and dew precipitation which was most conspicuous during the wet winter. This implied that fog and dew are even more important sources of water than rain and corroborated by significant correspondence found between fog and dew frequencies, succulent foliar water contents and quantum yields of photochemistry.The second study monitored variations in stem diameter at 2-hourly intervals in 8 succulent shrub species of diverse growth form over a 9-month period. Two groups of species were distinguished based on whether their daily amplitudes in stem diameter were consistently positively correlated with daily fluxes in vapour pressure deficit, which were indicative of a persistent CAM photosynthetic mode, or intermittently correlated with daily fluxes in vapour pressure deficit, which were indicative of mixed CAM and C3 photosynthetic modes. Among species displaying a persistent CAM photosynthetic mode, high nocturnal fog and dew precipitation amounts corresponded with low daily amplitudes in stem diameter, and vice versa, which pointed to reduced nocturnal stomatal water loss. These patterns, which were indistinct among species displaying mixed CAM and C3 photosynthetic modes, were corroborated by small daily amplitudes in stem diameter also consistently observed in one species displaying a CAM photosynthetic mode in ambient than artificially fog and dew excluded environments.The third study monitored changes in water mass at hourly intervals of quartz gravel substrates with different dwarf succulent species assemblages over an 8-month period.Consistently greater net amounts of water were intercepted daily by quartz gravel substrates containing Agyroderma pearsonii than Cephalophylum spissum plants as well as those without plants. These attributed to a high water repellence of A. pearsonii leaves and less radiation absorbed by the paler silvery to grey-green leaves of A. pearsonii leaves than the dark green leaves of C. spissum resulting in lower leaf temperatures and less water loss by transpiration. Quartz gravel soils devoid of plants intercepted nearly 5-times greater amounts of precipitation contributed by fog and dew than that contributed by rain. These precipitation amounts exceeding the high percentages of total hydrological input contributed by fog and dew reported in other ecosystems.The study concludes that fog and dew are a vital source of water for succulent shrubs in arid South African ecosystems and imply that diminished fog and dew frequencies associated with elevated night time temperatures accompanying global warming could exacerbate plant drought stress.

High temperature limit successful potato cultivation in the lowlands of tropical regions. One effect of high temperature may be an increase in gibberellin activity that is inhibitory to tuberization. Paclobutrazol blocks gibberellin biosynthesis and reduces its level in the plant. The effect of paclobutrazol on potato was examined under non-inductive conditions in a greenhouse and under field conditions in the hot tropical lowlands of eastern Ethiopia. Paclobutrazol was applied as a foliar spray or soil drench at rates equivalent to 0, 2, 3, and 4 kg a. i. per ha. Paclobutrazol increased chlorophyll a and b content, and photosynthetic efficiency, enhanced early tuber initiation, delayed physiological maturity, and increased tuber fresh mass, dry matter content, specific gravity and crude protein content. It reduced the number of tubers per plant and extended the tuber dormancy period. Paclobutrazol reduced shoot growth, and plant height, and increased the partitioning of assimilates to the tubers while reducing assimilate supply to the leaves, stems, roots and stolons. Stomatal conductance and the rate of transpiration were reduced. In addition, paclobutrazol treatment increased tuber N, Ca and Fe content while reducing P, K and Mg content. Growth analyses indicated that paclobutrazol decreased leaf area index, crop growth rate, and total biomass production. It increased specific leaf weight, tuber growth rate, net assimilation rate, and partitioning coefficient (harvest index). Microscopic observations showed that leaves of treated plants developed thicker epicuticular wax layers. The epidermal, palisade and spongy mesophyll cells were larger. It increased the thickness of the cortex and the size of vascular bundles and pith cells of the stem. It also increased the width of the cortex and favoured the formation of more secondary xylem vessels, resulting in thicker roots. Deposition of starch grains in the stem pith cells, and cortical cells of the stem and root, were stimulated in response to paclobutrazol treatment. In most instances the method of application did not affect the efficiency of paclobutrazol. The effect of cultivar and reproductive growth on growth, photosynthetic efficiency, water relations, dry matter production, tuber yield and quality of potato was also the subject of investigation. Non-flowering, flowering and fruiting plants of cultivars Al-624, Al-436, CIP-388453-3(A) and CIP-388453-3(B) were evaluated under field conditions of a sub-humid tropical highland of eastern Ethiopia. Cultivars exhibited differences with respect to leaf stomatal conductance, rate of transpiration, net photosynthesis, biomass production and allocation, tuber yield, tuber size distribution, specific gravity, dry matter content and nutrient composition. Fruiting plants had higher leaf stomatal conductance, and higher rates of transpiration and photosynthesis rates. The leaf area index, tuber growth rate, and partitioning coefficient (harvest index) of the fruiting plants were reduced, but crop growth rates and net assimilation rates were higher. Without affecting total dry matter production, fruit development reduced the amount partitioned to the leaves, stems, roots, and tubers. Fruit development reduced total and marketable tuber mass and tuber numbers. The effect of MCPA and paclobutrazol were studied under greenhouse and field conditions. Single foliar sprays were applied during the early and full bud development stages at rates of 0, 250, 500, and 750 g a.i. ha-1. Both MCPA and paclobutrazol greatly reduced the number of flowers and completely inhibited berry set. MCPA did not affect the number, yield, dry matter content and specific gravity of tubers. Without affecting the number of tubers, paclobutrazol increased tuber yield, dry matter content and specific gravity. / Thesis (DPhil (Horticultural Science))--University of Pretoria, 2007. / Plant Production and Soil Science / unrestricted