Phytoplankton chlorophyll-a fluorescence, measured in situ, can be applied as a tool to estimate primary production in the ocean over a large range of temporal and spatial scales. This non-invasive technique allows for fast assessments of photo-physiological parameters in contrast to the traditional methodologies (14C uptake and O2 evolution). The main photo-physiological parameters derived by the available instruments are yields, and as such, require careful interpretation. The comprehension of the main sources of variability of the photochemical and the light absorption efficiencies in marine phytoplankton has increased in the past years, largely by studies using monospecific cultures. In natural communities, however, the development of primary production models based on chlorophyll-a fluorescence remain limited as they are simultaneously subjected to a wide range of environmental and biological factors. This study will test the hypothesis that photo-physiological models for primary production estimates can be improved when key phytoplankton features, such as the pigments composition and dominant cell size, are taking into account. The approach was to contrast the photo-physiological parameters derived from measurements in distinct oceanographic regions, as well as those derived in a specific environment with presented different nutrient concentration according to the time of sampling. In addition, we showed for monospecific cultures, how the photo-physiological parameters are quantitatively related to the production of carbon under the interactive effects of taxonomic composition and cell size. The proportions of photosynthetic and photoprotective pigments present in the community were related to the bulk photochemical efficiency and the cross-section of light absorption, but varied among oceanographic regions and the depth of the water column. A parameterization of fluorescence-derived primary production rates, using four dominant size classes, was derived for natural phytoplankton communities under different nutrients conditions in a coastal environment, showing that the parameters differed among size classes above a threshold of nutrient concentration. The direct conversion rates between fluorescence-derived primary production and carbon assimilation rates, computed for two distinct phytoplankton cell sizes grown in controlled laboratorial conditions, showed that cell size strongly influences the efficiency of light absorption and photochemistry, however species-specific responses in photosynthetic energy allocation dominated the differences observed in how absorbed light is utilized to carbon assimilation, i.e., in the electron requirements for carbon assimilation. The results highlighted the importance of the tight coupling of nutrients availability and phytoplankton communities, as well as for measurements of chlorophyll-a fluorescence in the ocean and primary production models. This work presents a novel contribution to the increasing efforts to apply fluorescence-based techniques to understand and parameterize primary production estimates in marine systems, especially at highly dynamic environments. / A fluorescência da clorofila-a do fitoplâncton, medida in situ, pode ser uma ferramenta para estimar produção primária no oceano em grande escala temporal e espacial. Esta técnica não-invasiva permite análises rápidas de parâmetros foto-fisiológicos ao contrário de metodologias tradicionais (assimilação de 14C e produção de O2). Os principais parâmetros foto-fisiológicos de instrumentos disponíveis hoje tratam-se de eficiências, e como tal, requerem cuidados em serem interpretados. A compreensão das principais fontes de variabilidade da eficiência fotoquímica e de absorção de luz no fitoplâncton marinho tem aumentado nos últimos anos, em sua maioria em cultivos monoespecíficos. Em comunidades naturais, entretanto, o desenvolvimento de modelos de produção primária baseados na fluorescência da clorofila-a ainda é limitado uma vez que estão sujeitos à uma ampla gama de fatores ambientais e biológicos. Esse estudo testa a hipótese de que modelos foto-fisiológicos para estimar produção primária podem ser aprimorados considerando-se características fundamentais do fitoplâncton, como a composição de pigmentos e tamanho celular dominante. A estratégia foi contrastar parâmetros foto-fisiológicos derivados de medidas em regiões oceanográficas distintas, assim como medidas em um ambiente específico com diferentes concentrações de nutrientes ao longo do período amostrado. Adicionalmente, apresentamos através de cultivos monoespecíficos, como parâmetros foto-fisiológicos são quantitativamente relacionados à produção de carbono e os efeitos interativos da composição taxonômica e tamanho celular nessa relação. A proporção de pigmentos fotossintéticos e fotoprotetores da comunidade foram relacionados à eficiência fotoquímica e seção transversal de absorção de luz, porém variaram de acordo com a região oceanográfica e profundidade na coluna d\'água. Uma parameterização de taxas de produção primária derivadas da fluorescência, usando quatro classes de tamanho dominantes, foi proposta para comunidades naturais de fitoplâncton sob condições de nutrientes diferentes em um ambiente costeiro, mostrando que os parâmetros diferiram entre as classes de tamanho acima de um limiar de concentração de nutrientes. As taxas de conversão diretas entre produção primária derivada da fluorescência e taxas de assimilação de carbono, computadas para dois tamanhos de fitoplâncton crescidos em condições controladas em laboratório, mostraram que tamanho celular influencia as eficiências de absorção de luz e fotoquímica, porém respostas espécie-específicas na alocação de energia fotossintética dominaram as diferenças observadas em como a luz absorvida é utilizada para assimilação de carbono, ou seja, na razão de elétrons exigidos para assimilação de carbono. Os resultados destacam a importância do acoplamento da disponibilidade de nutrientes com a comunidade fitoplanctônica, assim como das medidas de fluorescência da clorofila-a no oceano e nos modelos de produção primária. Este trabalho apresenta uma contribuição inédita nos esforços crescentes em aplicar técnicas baseadas na fluorescência para entender e parameterizar estimativas de produção primária nos sistemas marinhos, especialmente em ambientes altamente dinâmicos.

Air pollutant exposure poses a health risk to humans and impacts negatively on agriculture. High levels of air pollution resulted in extensive crop damage and yield reduction in Europe and USA. The Highveld region in South Africa, a very important area for maize and soya production, has already been declared an air pollution hot spot, with SO2 being the most concerning air pollutant. Most of the SO2 over the Highveld originates from the burning of coal for power generation. Developing countries, such as South Africa, are highly dependent on agriculture for food security and high levels of air pollution pose serious risks to the agricultural industry. Currently very little information is available on the effects of air pollution on crop production in South Africa. This study aimed to establish exposure-response relationship for SO2 on soybean and the quantification thereof on the morphological, physiological and biochemical characteristics. Two soybean cultivars were used, namely: LS 6164 and PAN 1666. The plants were fumigated for 7 hours, 7 days a week with 0 (carbon filtered control; CF), 25, 75 and 150 ppb SO2. The effect of SO2 was investigated on the growth, photosynthetic capabilities, photosynthetic gas exchange, peroxidase activity and lipoxygenase activity of the cultivars. Foliar injuries and interveinal chlorosis were visible with increasing levels of SO2 as well as a decrease in biomass accumulation, especially in root biomass; a more prominent feature of LS 6164. The number of nodules of both cultivars decreased insignificantly as the levels of SO2 increased. The number of pods per plant and the average weight of 30 seeds indicated a downward trend with an increase in SO2 concentration. The chlorophyll content of PAN 1666 was lower compared to LS 6164. PAN 1666 had the largest reduction in stomatal conductance at 150 ppb SO2 fumigation. The photosynthetic vitality index indicated that LS 6164 was more sensitive to SO2 inhibition from 25 ppb SO2 and higher, whereas PAN 1666 mostly became sensitive to SO2 from 75 ppb SO2. A decrease in the ability to absorb light energy, the trapping of excitation energy to transfer electrons beyond QA-, and the reduction of end electron acceptors all contributed to the decline in the vitality index. Sulphur content increased significantly in the 75 ppb and 150 ppb treatments of both cultivars. Induced peroxidase and lipoxygenase activity was seen in both cultivars, especially at higher concentrations of SO2 treatments. PAN 1666 had a higher rate of peroxidase and lipoxygenase activity compared to LS 6164. The implication for SO2 on crop production in the highly industrial Highveld area was demonstrated to be potentially of great concern. The dose-response relationships plotted for OJIP parameters emphasized that SO2 is an inhibitor of photosynthesis and phytotoxic of nature. Both cultivars experienced limitations from 75 ppb, especially at the 150 ppb SO2 concentration. From these results it appears that PAN 1666 is more adapted to SO2 compared to LS 6164 and levels of 75 ppb SO2 and higher become toxic to these plants. / Thesis (Master of Environmental Sciences)--North-West University, Potchefstroom Campus, 2013

Air pollutant exposure poses a health risk to humans and impacts negatively on agriculture. High levels of air pollution resulted in extensive crop damage and yield reduction in Europe and USA. The Highveld region in South Africa, a very important area for maize and soya production, has already been declared an air pollution hot spot, with SO2 being the most concerning air pollutant. Most of the SO2 over the Highveld originates from the burning of coal for power generation. Developing countries, such as South Africa, are highly dependent on agriculture for food security and high levels of air pollution pose serious risks to the agricultural industry. Currently very little information is available on the effects of air pollution on crop production in South Africa. This study aimed to establish exposure-response relationship for SO2 on soybean and the quantification thereof on the morphological, physiological and biochemical characteristics. Two soybean cultivars were used, namely: LS 6164 and PAN 1666. The plants were fumigated for 7 hours, 7 days a week with 0 (carbon filtered control; CF), 25, 75 and 150 ppb SO2. The effect of SO2 was investigated on the growth, photosynthetic capabilities, photosynthetic gas exchange, peroxidase activity and lipoxygenase activity of the cultivars. Foliar injuries and interveinal chlorosis were visible with increasing levels of SO2 as well as a decrease in biomass accumulation, especially in root biomass; a more prominent feature of LS 6164. The number of nodules of both cultivars decreased insignificantly as the levels of SO2 increased. The number of pods per plant and the average weight of 30 seeds indicated a downward trend with an increase in SO2 concentration. The chlorophyll content of PAN 1666 was lower compared to LS 6164. PAN 1666 had the largest reduction in stomatal conductance at 150 ppb SO2 fumigation. The photosynthetic vitality index indicated that LS 6164 was more sensitive to SO2 inhibition from 25 ppb SO2 and higher, whereas PAN 1666 mostly became sensitive to SO2 from 75 ppb SO2. A decrease in the ability to absorb light energy, the trapping of excitation energy to transfer electrons beyond QA-, and the reduction of end electron acceptors all contributed to the decline in the vitality index. Sulphur content increased significantly in the 75 ppb and 150 ppb treatments of both cultivars. Induced peroxidase and lipoxygenase activity was seen in both cultivars, especially at higher concentrations of SO2 treatments. PAN 1666 had a higher rate of peroxidase and lipoxygenase activity compared to LS 6164. The implication for SO2 on crop production in the highly industrial Highveld area was demonstrated to be potentially of great concern. The dose-response relationships plotted for OJIP parameters emphasized that SO2 is an inhibitor of photosynthesis and phytotoxic of nature. Both cultivars experienced limitations from 75 ppb, especially at the 150 ppb SO2 concentration. From these results it appears that PAN 1666 is more adapted to SO2 compared to LS 6164 and levels of 75 ppb SO2 and higher become toxic to these plants. / Thesis (Master of Environmental Sciences)--North-West University, Potchefstroom Campus, 2013

Made available in DSpace on 2016-12-23T13:48:27Z (GMT). No. of bitstreams: 1 Maisa Melo Duarte.pdf: 764941 bytes, checksum: aa0a48046e085c3043f3e0c44eb327b9 (MD5) Previous issue date: 2011-12-22 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Papaya (Carica papaya L.) plant is susceptible to environmental changes that demand answers, physiological characteristics and reproductive during its development. Because it is of great economic importance to the state of Espirito Santo, studies on the effects of environmental stress in this species are essential to ensure better production and fruit quality. In order to know the effect of environmental stresses on the photochemical performance of papaya were analyzed with the chlorophyll a fluorescence transient in leaves and epicarp of the fruit during its development. The growth and photosynthetic activity were also monitored in leaves during the vegetative stage. The growth of papaya showed remarkable differences in canopy architecture and leaf number between the vegetative and reproductive stages. A higher stomatal conductance (gs) and carbon assimilation rate (A) increased to 30 days after planting (DAP), during which there was an increase in precipitation. Also, 150 DAP, fruiting period and increased demand for assimilates, we observed a higher rate of A. A smaller leaf photochemical performance was evidenced by the kinetics of chlorophyll fluorescence, at planting and at 30 and 90 DAP, but this same period, A and gs were high. At the beginning of fruit development (0-35 days), the specific flow of dissipated energy (DI0/RC) was high, suggesting an adaptive strategy while the fruits are perpendicular to the vertical axis of the plant. The photochemical performance total (PITOTAL) was higher in leaves than in fruits, due to the higher density of active reaction centers (RC / ABS) and the best performance of the redox reactions of photosystem I [δR0 / (1-δR0) ]. The results suggest that the epicarp of the fruits, unlike leaves, the photosynthetic apparatus has an important protective function, since the beginning of its development dissipate excess incident energy, thus maintaining the quality of the fruit / O mamoeiro (Carica papaya L.) é uma planta sensível às alterações ambientais o que demanda respostas, nas características fisiológicas e reprodutivas, durante o seu desenvolvimento. Por ser de grande importância econômica para o Estado do Espírito Santo, estudos sobre os efeitos dos estresses ambientais nesta espécie são fundamentais para garantir melhor produção e qualidade dos frutos. Com o objetivo ampliar o conhecimento da ação dos estresses ambientais sobre o desempenho fotossintético do mamoeiro foram realizadas análises da fluorescência transiente da clorofila a nas folhas e no epicarpo dos frutos durante o seu desenvolvimento. O crescimento e a atividade fotossintética foram também monitorados nas folhas durante o estádio vegetativo. Ocorreramdiferenças marcantes na arquitetura da copa e no número de folhas entre o estádio vegetativo e reprodutivo. Aos 30 dias após o plantio (DAP), período em que houve um aumento na precipitação, verificou-se a maior condutância estomática (gs) e a maior taxa assimilatória de carbono (A). Também, aos 150 DAP, época de frutificação e de maior demanda por fotoassimilados, observou-se maior A. Um menor desempenho fotoquímico das folhas, revelado pela cinética da fluorescência da clorofila a, ocorreu durante os primeiros 90 DAP, porém, neste mesmo período, A e gs foram altas. No início do desenvolvimento dos frutos (de 0 a 35 dias) o fluxo específico de energia dissipada (DI0/RC) foi elevado sugerindo uma estratégia adaptativa dos frutos enquanto se encontram perpendiculares ao eixo vertical da planta. O desempenho fotoquímico total (PITOTAL) foi maior nas folhas do que nos frutos, devido a maior densidade de centros de reação ativos (RC/ABS) e o melhor desempenho das reações de oxi-redução do fotossistema I [δR0/(1-δR0)]. Os resultados obtidos sugerem que no epicarpo dos frutos, diferentemente das folhas, o aparelho fotossintético tem a importante função de proteção, uma vez que no início de seu desenvolvimento dissipa o excesso de energia incidente, mantendo, assim, a qualidade do fruto

Nos últimos 100 anos, a temperatura média global aumentou aproximadamente 0,6ºC e deverá continuar a subir a uma taxa rápida podendo atingir 2ºC. No entanto, não se sabe como as plantas responderão a essa mudança climática, pois existem poucas informações sobre as respostas fisiológicas das plantas a incrementos de temperatura. Este trabalho tem por objetivo avaliar os efeitos de duas condições luminosas e duas condições de temperatura (com interação entre eles), em perspectiva futura, sobre o comportamento morfológico, fisiológico e bioquímico de quatro espécies da Floresta Mesófila Semidecídua: Aspidosperma cylindrocarpon e Aspidosperma polyneuron (Apocynaceae); Cariniana estrellensis e Cariniana legalis (Lecythidaceae). As plantas foram submetidas aos seguintes tratamentos: 100% de radiação e temperatura ambiente (100%RTA), 100% de radiação e temperatura elevada em +2ºC (100%RTE), 20% de radiação (por sombreamento) e temperatura ambiente (20%RTA), e 20% de radiação e temperatura elevada em +2ºC (20%RTE). Aspidosperma polyneuron apresentou-se como a espécie mais sensível a radiação intensa, seguida de C. legalis ambas já ameaçadas de extinção. Os parâmetros morfológicos confirmam a teoria de que plantas cronicamente fotoinibidas continuam crescendo, porém, em menores taxas. Os dados bioquímicos reforçam os fisiológicos mostrando fragilidade das espécies secundárias à radiação intensa e os efeitos principalmente negativos do aquecimento aplicado. / In the last 100 years the average global temperature increased by 0.6ºC and it might increase in a fast rate reaching up to 2ºC. However, little is known about how plants might respond to the climate change because there is not enough information about the physiological alterations plants might suffer due to increased temperature. We evaluated morphological, physiological and biochemical alterations under the effects of two light/temperature conditions and its interactions in four different plant species of the Semideciduous Mesophitic Forest: Aspidosperma cylindrocarpon and Aspidosperma polyneuron (Apocynaceae); Cariniana estrellensis and Cariniana legalis (Lecythidaceae). All plants suffered the following treatments: 100% radiation and environment temperature (100%RTA), 100% radiation and environment temperature +2ºC (100%RTE), 20% radiation (shade) and environment temperature (20%RTA), and 20% radiation (shade) and environment temperature +2ºC (20%RTE). Aspidosperma polyneuron was shown to be the most sensible specie to high radiation, followed by C. legalis, both threatened with extinction. Morphological parameters confirmed the theory that chronically photo-inhibited plants keep growing, but at lower rates. Biochemical findings also confirmed our physiological data showing increased fragility of the secondary species to high radiation and heating.

The main aim of this study was to investigate the effects of water availability and SO2 pollution, imposed separately or simultaneously, on the photosynthetic metabolism of Augea capensis Thunb., a succulent of the Namib Desert in the region of Skorpion Zinc mine, Namibia. The main driver for this investigation was the need to distinguish between the effects of water availability on plants native to a desert environment, where water availability dominates plant response, but where the possibility of anthropogenic SO2 pollution poses a new threat to the unique succulent vegetation. Fifteen measuring sites were selected in the vicinity of the mine to determine how rainfall influenced the physiological status of the vegetation. Chlorophyll a fluorescence measurements, and analysis of recorded OJlP fluorescence transients with the JIP-test, were used for this purpose. A series of laboratory experiments were also conducted on A. capensis to determine the precise physiological response that water deprivation and SO2 pollution had under controlled growth conditions. Potted plants were exposed to water deprivation or SO2 fumigation in the light or dark. Besides chlorophyll a fluorescence, photosynthetic gas exchange and Rubisco activity were also measured. Changes in fast fluorescence rise kinetics observed under field conditions suggest considerable modulation of photosystem II function by rainfall with concomitant involvement of a heat stress component as well. In both the field and laboratory experiments, one of the JIP-test parameters, the so-called performance index (PIABS), was identified as a very sensitive indicator of the physiological status of the test plants. Moreover, under laboratory conditions, a good correlation existed between the water deprivation-induced decline in CO2 assimilation rates and the decline in PIABS values. The JIP-test in general, and the PIABS in particular, shows considerable potential for application in the investigation of water availability influences on desert ecosystems. In the laboratory experiments, water deprivation caused stomatal closure but also a slight elevation in intercellular C02 concentration and inhibition of Rubisco activity, suggesting that mesophyll limitation was the dominant factor contributing to the decrease in C02 assimilation rates. Following re-watering, A. capensis showed remarkable recovery capacity. Fumigation of A. capensis with 1.2 ppm SO2 in the dark or light revealed relatively small effects on C02 assimilation. The inhibitory effects on photosynthesis were also fully reversible, indicating no permanent metabolic/structural damage. The effects on photosynthesis were more pronounced when fumigation occurred in the dark. This phenomenon might be related to diurnal differences in cellular capacity for SO2 detoxification. When long-term moderate water deprivation was combined with simultaneous SO2 fumigation, there was no additional inhibitory effect on photosynthesis. These findings suggest that water deprivation do not increase sensitivity towards SO2 pollution in A. capensis. Fumigation with SO2, singly or in combination with water deprivation also had no major effect on chloroplast ultrastructure. It appears that A. capensis is remarkably resistant to SO2 pollution even in the presence of low water availability, which is a common phenomenon in desert ecosystems. Since A, capensis seems to be highly tolerant to S02, its suitability as an indicator species for the detection of SO2 pollution effects at Skorpion Zinc mine is questionable. Because water availability dominates the physiological/biochemical response in this species, subtle SO2 pollution effects might be difficult to detect against this dominant background. The high water content of A. capensis and similar succulents might act as a substantial sink for SO2 and could convey considerable tolerance against this form of air pollution. / Thesis (M.Sc. (Botany))--North-West University, Potchefstroom Campus, 2006.

Title from second page of PDF document. Includes bibliographical references.

The main aim of this study was to investigate the effects of water availability and SO2 pollution, imposed separately or simultaneously, on the photosynthetic metabolism of Augea capensis Thunb., a succulent of the Namib Desert in the region of Skorpion Zinc mine, Namibia. The main driver for this investigation was the need to distinguish between the effects of water availability on plants native to a desert environment, where water availability dominates plant response, but where the possibility of anthropogenic SO2 pollution poses a new threat to the unique succulent vegetation. Fifteen measuring sites were selected in the vicinity of the mine to determine how rainfall influenced the physiological status of the vegetation. Chlorophyll a fluorescence measurements, and analysis of recorded OJlP fluorescence transients with the JIP-test, were used for this purpose. A series of laboratory experiments were also conducted on A. capensis to determine the precise physiological response that water deprivation and SO2 pollution had under controlled growth conditions. Potted plants were exposed to water deprivation or SO2 fumigation in the light or dark. Besides chlorophyll a fluorescence, photosynthetic gas exchange and Rubisco activity were also measured. Changes in fast fluorescence rise kinetics observed under field conditions suggest considerable modulation of photosystem II function by rainfall with concomitant involvement of a heat stress component as well. In both the field and laboratory experiments, one of the JIP-test parameters, the so-called performance index (PIABS), was identified as a very sensitive indicator of the physiological status of the test plants. Moreover, under laboratory conditions, a good correlation existed between the water deprivation-induced decline in CO2 assimilation rates and the decline in PIABS values. The JIP-test in general, and the PIABS in particular, shows considerable potential for application in the investigation of water availability influences on desert ecosystems. In the laboratory experiments, water deprivation caused stomatal closure but also a slight elevation in intercellular C02 concentration and inhibition of Rubisco activity, suggesting that mesophyll limitation was the dominant factor contributing to the decrease in C02 assimilation rates. Following re-watering, A. capensis showed remarkable recovery capacity. Fumigation of A. capensis with 1.2 ppm SO2 in the dark or light revealed relatively small effects on C02 assimilation. The inhibitory effects on photosynthesis were also fully reversible, indicating no permanent metabolic/structural damage. The effects on photosynthesis were more pronounced when fumigation occurred in the dark. This phenomenon might be related to diurnal differences in cellular capacity for SO2 detoxification. When long-term moderate water deprivation was combined with simultaneous SO2 fumigation, there was no additional inhibitory effect on photosynthesis. These findings suggest that water deprivation do not increase sensitivity towards SO2 pollution in A. capensis. Fumigation with SO2, singly or in combination with water deprivation also had no major effect on chloroplast ultrastructure. It appears that A. capensis is remarkably resistant to SO2 pollution even in the presence of low water availability, which is a common phenomenon in desert ecosystems. Since A, capensis seems to be highly tolerant to S02, its suitability as an indicator species for the detection of SO2 pollution effects at Skorpion Zinc mine is questionable. Because water availability dominates the physiological/biochemical response in this species, subtle SO2 pollution effects might be difficult to detect against this dominant background. The high water content of A. capensis and similar succulents might act as a substantial sink for SO2 and could convey considerable tolerance against this form of air pollution. / Thesis (M.Sc. (Botany))--North-West University, Potchefstroom Campus, 2006.

Made available in DSpace on 2016-12-23T13:48:27Z (GMT). No. of bitstreams: 1 Dissertacao de Priscilla Nobres dos Santos.pdf: 2094546 bytes, checksum: c80405345425c181dbb6a9991aee2f2a (MD5) Previous issue date: 2011-02-22 / Banana s culture in Brazil and in the state of Espírito Santo presents, in parts, an essential peculiar character, constituting an important source of income for small rural producers. Besides biotical factors, temperature and pluviousity are directly related to the banana tree s growing, because they provoke an effect upon the speed of most metabolic processes, influencing the vegetative cycle, the photosynthetic activity and the breathing activity. Therefore, this assignment has the purpose to evaluate the physiological and biochemical responses of banana trees grown in situ Prata (AAB), Japira (AAAB) and Vitória (AAAB) in two cycles of development stage Mother-plant and Child-plant. The results show that the photochemical behavior of the three cultivars leaves got very compromised in June, a month when temperatures are usually low. A smaller use of energy might have been caused by a bigger destabilization of the membranes, which, as a consequence, might have been determinant for obtaining a smaller rate of total chlorophylls. Among the cultivars analyzed, the physiological behavior of cultivar Prata were the less tolerant to the changes in the non-biotical factors. The cultivars Japira and Vitória presented similar physiological responses, which can be explained for its philogenetic proximity. The nutrients contents did not present significant differences between the months and the cultivars. However, they were pretty significant when ones check the fruit formation. The cultivars Japira and Vitória established, before harvest, a good chemical performance that possibly have favored the fruits formation / A bananicultura no Brasil e no estado do Espírito Santo apresenta, em parte, caráter essencialmente familiar, constituindo-se como uma importante fonte de renda para os pequenos produtores rurais. Além dos fatores bióticos, a temperatura e a pluviosidade são fatores relacionados diretamente com o crescimento da bananeira, pois exercerem efeito sobre a velocidade da maioria dos processos metabólicos, no ciclo vegetativo e na atividade fotossintética e respiratória. Dessa forma, este trabalho tem por objetivo avaliar as respostas fisiológicas e bioquímicas de bananeiras cultivadas in situ Prata (AAB), Japira (AAAB) e Vitória (AAAB) em dois do estádio do desenvolvimento (Planta-Mãe e Planta- Filha). Os resultados mostram que o desempenho fotoquímico das folhas das três cultivares ficou bastante comprometido no mês de junho, período caracterizado por temperaturas mais baixas. Um menor aproveitamento de energia pode ter sido causado por uma maior desestabilização das membranas, que, consequentemente, pode ter sido determinante para a obtenção de um menor índice de clorofilas totais. Das cultivares analisadas, a cv. Prata foi a que apresentou uma resposta fisiológica menos tolerante às alterações nos fatores abióticos. As cultivares Japira e Vitória apresentaram respostas fisiológicas bem semelhantes, o que pode ser explicado pela sua maior proximidade filogenética. Os teores de nutrientes não apresentaram diferenças significativas entre os meses e as cultivares. No entanto, em relação à formação do fruto foram bastante significativas. As cultivares Japira e Vitória estabeleceram, na fase pré-colheita, um bom rendimento químico que, possivelmente, favoreceu a formação dos frutos

Made available in DSpace on 2015-03-26T13:36:38Z (GMT). No. of bitstreams: 1 01 - capa_abstract.pdf: 99910 bytes, checksum: 2d06bc0277aa39546d50a70079c6e1d3 (MD5) Previous issue date: 2009-02-17 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Tomato plants (Solanum lycopersicum Mill) c.v Santa Clara 5600 VF were submitted to increasing concentratíons of NaCl, up to 150 mM. In order were set up two experiments to evaluate the initial effects that affect the primary production and the mechanisms of adaptation to salinity under continuous stress. The plants were cultivated in Hoagland`s hidroponic solution, in the greenhouse. In condition the first experiment, the plants were grown in 0, 50, 100 and 150 mM NaCl solution obtained by gradually applied 50 mM of the salt. In the second experiment, the NaCl was add every 12 hours until the final concentration of 150 mM. It were evaluated the osmotic potential (Ψs) of leaves and roots, Na+, Cl-, K+, Ca2+ and Mg2+ íons concentratíons in roots, stem and leaves, proline concentration in leaves, gas exchange, estimative of photorespiration, chlorophyll a fluorescence, chlorophyll a fluorescence image and antioxidative activity in the leaves. The plants submitted to salt stress presented a decreased on ψs of leaves and roots. This decrease might be attributed to accumulation Na+, K+, Cl- and sugars in the cytoplasm, which also contributed to an osmotic adjustment. There was an increase in the proline synthesis, which is attributed the role as osmoprotectant osmolyte protection to salt stress. It was detected decrease in photosynthetic rate in response to stomatal and non-stomatal effects. The contents of chlorophyll a, chlorophyll b, carotenoids and the chlorophyll a/b ratio showed decrease. It was observed decrease in the quantum yield of linear electron flux through PSII. Increments in quantum yield of regulated non- photochemical energy loss in PS II Y(NPQ) and in non- photochemical quenching (NPQ) and high rates of Y(NPQ)/ Y (NO) in plants submitted to salt stress. There was increase of SODs and APXs enzymes activity that participate in water- water cycle. From these results, we can conclude that, tomato plants submitted to salt stress developed osmotic adjustment in order to assure water absorption. The plants also showed efficient mechanisms of photoprotection, through dissipation of excess energy in the electron transport chain. Such mechanisms involve the dissipation of energy as heat, by photorespiration and by water-water cycle. Furthermore, it was possible to monitor the extension of stress through the means of the chlorophyll a fluorescence image. / Plantas de tomateiro (Solanum lycopersicum Mill) cultivar Santa Clara 5600 VF foram submetidas a concentrações crescentes de NaCl até uma concentração de 150 mM. Com o objetivo de avaliar os efeitos iniciais que afeta a produção primária e os mecanismos de adaptação à salinidade sob estresse prolongado, foram implantados dois experimentos. As plantas foram cultivadas em solução nutritiva de Hoagland em casa de vegetação. No primeiro experimento, as plantas foram cultivadas em solução de 0, 50, 100 e 150 mM de NaCl o qual foi aplicado de forma progressiva de 50 mM. No segundo o NaCl foi adicionado a cada 12 horas até atingir 150 mM. Foram avaliados o potencial osmótico (ψs) das folhas e raízes, concentração dos íons Na+, Cl-, K+, Ca2+ e Mg2+ nas raízes, nos caules e nas folhas, concentração de prolina nas folhas, variáveis de trocas gasosas, estimativa da fotorrespiração fluorescência da clorofila a, imagem da fluorescência da clorofila a e atividade antioxidativa nas folhas. As plantas submetidas ao estresse salino apresentaram decréscimo no ψs das folhas e raízes. Tal decréscimo pode ser atribuído ao acúmulo de Na+, K+ e Cl- e açúcares que contribuíram para o ajustamento osmótico. Houve aumento na síntese de prolina, o qual foi relacionado como um osmólito de proteção ao estresse salino. Foi detectada queda na taxa fotossintética em reposta aos efeitos estomáticos e não estomáticos. Os teores de clorofila a, clorofila b, carotenóides e na relação clorofila a/b apresentaram decréscimo. Foi verificado decréscimo na taxa de transporte de elétrons no FSII. Houve aumento no rendimento quântico da dissipação regulada de energia não- fotoquímica no FSII Y(NPQ), na dissipação não-fotoquímica (NPQ) e altas taxas de Y(NPQ)/Y(NO) nas plantas submetidas ao estresse salino. Ocorreu aumento da atividade das enzimas SODs e APXs que participam no ciclo água-água. A partir desses resultados, pode-se concluir que, plantas de tomateiro submetidas ao estresse salino, desenvolveram ajustamento osmótico condicionando a absorção de água. Apresentaram mecanismos de fotoproteção eficientes na dissipação do excesso de energia na cadeia transportadora de elétrons. Tais mecanismos envolvem a dissipação de energia na forma de calor, pela fotorrespiração e pelo ciclo água-água. Além disso, foi possível acompanhar o prolongamento do estresse a partir das alterações na imagem da fluorescência da clorofila a.