The lower oxygen limit (LOL) in plants marks the oxygen (O2) level where the metabolism shifts from being predominantly aerobic to anaerobic; recent work has shown that respiratory-based indicators of this metabolic shift are well-correlated with changes in chlorophyll a fluorescence signals. The physiological and biochemical changes at the root of this relationship have not been well-described in the literature. The processes involved are spatially separated: chlorophyll fluorescence is associated with the lightdependent reactions and emanates from the chloroplasts whereas aerobic respiration and fermentation occurs in the mitochondria and cytosol, respectively. Evidences outlined in this thesis are used to suggest the mechanistic link between these three regions of the cell is a fluid exchange of cellular reductant. When mitochondrial respiration is inhibited as a result of inadequate O2, used as a terminal electron acceptor, glycolytic reductant in the form of NADH accumulates in the cytosol. Reductant imbalances between the cytosol and organelles can be adjusted indirectly using translocators. Excess chloroplastic reductant is used to reduce the plastoquinone (PQ) pool via NADPH-dehydrogenase, a component of the chlororespiratory pathway, effectively decreasing the photochemical quenching (qP) capacity thereby inducing a switch from minimum fluorescence (Fo) to a higher relative fluorescence (F) value where qP < 1. Subjecting dark-adapted photosystems to low-intensity light increased Fo to a slightly higher F value due to a lightinduced reduction of the oxidized PQ pool when the O2 was above the LOL, but decreased F as a result of a PSI-driven oxidation of the already over-reduced PQ pool when the O2 was below the LOL. Low O2 was also shown to increase violaxanthin deepoxidation and non-photochemical quenching (qN), likely a reflection of the overreduced state of the photosystems and associated pH decrease. Dynamic controlled atmosphere (DCA) is a fluorescence-based controlled atmosphere (CA) system that sets the optimum atmosphere for fruits and vegetables based on a product’s fluorescence response. Experiments in this thesis on the relationship between O2, temperature, light, metabolism, pigmentation and chlorophyll fluorescence were used to interpret the physiology behind fluorescence changes, suggest improved DCA techniques and outline potentially profitable avenues for future research.

The chlorophyll a/b binding (CAB) genes play a very central role in all photosynthetic systems and are for Avena sativa (oat) totally unexplored. This dissertation investigates a large number of EST sequences and this investigation characterises the CAB genes in oat, with help from the evolutionary background of oat and the comparison to a reference organism and similar species.

Remote sensing has been used as an effective chlorophyll-a detection method in inland lakes and reservoirs. Concentration estimates of chlorophyll-a approximate the amounts of algae and phytoplankton in a body of water, can indicate the existence of large blooms and high nutrient loading, and can be used as an indicator of water quality. These biomasses pose potential threats to the quality of the water and the local environment by depleting oxygen, influencing the taste of the drinking water and detrimentally affecting aesthetics and recreation. Deer Creek Reservoir exhibited eutrophic tendencies in the early 1990's, caused by phosphorus pollution. This was made evident by accelerated algae growth. Following remediation efforts, Deer Creek Reservoir, as well as nearby Jordanelle Reservoir have been closely monitored with regular field sampling. These field data have been used to develop remote sensing methods using Landsat images to provide supplementary information for reservoir management. These remote sensing methods allow for mapping of the distribution of chlorophyll-a, which provides spatial distribution average, and maximum estimates of chlorophyll-a concentrations, data and information that are not feasible with in-field sampling. In this thesis, traditional methods for remote sensing models are discussed, and a novel sub-seasonal approach based on seasonal algal succession is proposed and demonstrated. Each seasonal model is created using a standard stepwise regression using historic field data and the associated Landsat images and is statistically tested for leverage to ensure unbiased model development. These sub-seasonal detection models are applied to 5 reservoirs in the central-Utah region to provide a more comprehensive description of reservoir behavior and water quality trends over the past 30 years. Historic trends of the average and maximum chlorophyll-a estimates are provided for each of the reservoirs. Example color maps are presented to demonstrate the ability of remote sensing to represent the spatial distribution of algae (using chlorophyll as an indicator). Limitations for this approach are discussed, as well as applications for remotely sensed water quality data on a regional scale.

A new range of multi-plankton biogeochemical models have recently been developed, designed to advance our understanding of the ocean carbon cycle to improve predictions of its future influence on climate. Synoptic measurements of the different phytoplankton communities are required to validate and ultimately improve such models. Measuring ocean colour from satellite is the only method currently available for synoptically monitoring wide-area properties of ocean ecosystems, such as phytoplankton chlorophyll biomass. Recently, a variety of bio-optical methods have been established that use satellite data to identify and differentiate between either phytoplankton functional types (PFTs) or phytoplankton size classes (PSCs). In this thesis, several of these techniques were evaluated against in situ observations (6504 samples) to determine their ability to detect dominant phytoplankton size classes (micro-, nano- and picoplankton). Results show that spectral-response, ecological and abundance-based approaches can all perform with similar accuracy. However, abundance-based approaches provide better spatial retrieval of PSCs. Based on insights into the abundance-based models, and by utilising a large pigment database, a new three-component model was developed which calculates the fractional contributions of three phytoplankton size classes (micro-, nano- and picoplankton) to the overall chlorophyll-a concentration. Using a globally representative, independent, coupled pigment and satellite dataset the model estimates fractional contributions with a mean accuracy of 9.2 % for microplankton, 17.1 % for nanoplankton and 16.1 % for picoplankton. The effect of optical depth on the model parameters was also investigated and explicitly incorporated into the model. Using the three-component model, the two-component absorption model of Sathyendranath et al. (2001) and Devred et al. (2006) was extended to three-component populations of phytoplankton, namely, pico-, nano- and microplankton. The new model infers total and size-dependent phytoplankton absorption as a function of the total chlorophyll-a concentration. A main characteristic of the model is that all the parameters that describe it have biological or optical interpretation. The three-component model performs better than the two-component model, at retrieving total phytoplankton absorption. Accounting for the contribution of pico- and nanoplankton, rather than the combination of both used in the two-component model, improved significantly the retrieval of phytoplankton absorption at low chlorophyll-a concentrations. The three-component model was applied to a decade of ocean colour observations. In the equatorial region of the Pacific and Indian Oceans, phytoplankton size class anomalies (% total chlorophyll-a) were highly correlated with indices of both the El Niño (La Niña) Southern Oscillation and the Indian Ocean Dipole. Furthermore, in these regions, micro- and nanoplankton size class anomalies were negatively correlated with anomalies of the sea surface temperature, sea surface height and stratification. Whereas, the picoplankton size class anomalies were positively correlated with these physical variables. Results from this thesis indicate that phytoplankton size class can be retrieved from Earth Observation with reasonable accuracy. It is recommended that such information can now be assimilated into multi-plankton biogeochemical models, or alternatively, verify them.

>Magister Scientiae - MSc / Maize is one of the most abundantly produced cereals and contributes to about 40% of the global cereal production. This figure will have to increase in order to feed the ever-growing human population. One of the major environmental constraints that impact maize production is drought. Plants use antioxidant defences to cope with drought stress. Understanding and improving these defence mechanisms will be important to improve overall drought tolerance. A previous study done by Gokul and authors in 2016 showed that 3,3’-diindolylmethane (DIM) improves both seed germination and seedling shoot growth in Brassica napus. Plants belonging to the Brassicaceae family have the metabolic machinery to synthesize glucosinolates such as DIM, which play vital roles in physiological and stress responses. These responses have not been investigated in plants such as maize, which lack the machinery to produce DIM. Therefore, this study investigated the effects of exogenously applied DIM on the physiological and biochemical responses of maize under drought stress. Physiological parameters such as relative water content, chlorophyll content and lipid peroxidation, were determined in order to understand how drought and DIM , as separate or combined treatments, affected the plants. Additionally, proline accumulation was also assessed because free proline plays a role as an osmoprotectant during stress. The accumulation of ROS, namely hydrogen peroxide, was measured using spectrophotometric assays to determine how the above treatments affect ROS accumulation in maize. As a result of changes in the ROS content in due to the treatments, it would only be natural to investigate the changes in antioxidants as well. Given that hydrogen peroxide was the ROS to be measured, we therefore investigated the antioxidant enzymatic activities responsible for hydrogen peroxide scavenging. Therefore, changes in Ascorbate peroxidase (APX) and catalase (CAT) were assessed. An improved drought response was observed in maize plants treated with DIM as these plants had better ability to maintain their water status than when no DIM was applied. This is indicated by water-deprived plants treated with DIM having a higher RWC than water-deprived plant without DIM.

Made available in DSpace on 2017-07-10T17:36:53Z (GMT). No. of bitstreams: 1 2014_Diss_Anderson_Santin.pdf: 2075563 bytes, checksum: c35b4b0d2b620adb609fb0e13986da25 (MD5) Previous issue date: 2014-02-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The use of cover crops and planting density is directly related to productivity of strawberry plants grown in the field. Given to above, the aim of the present work was to evaluate the productive characteristics and levels of photosynthetic pigments of two cultivars of strawberry on types of mulchings, and numbers of rows per bed planting in the open system The experiments were carried out between May and December/2012 at the Experimental Farm "Prof. Dr. Antônio Carlos dos Santos Pessoa belonging to Unioeste, Campus of Marechal Cândido Rondon, PR. The first experiment was conducted in a randomized block design, factorial 2x4 (Two cultivars, being 'Camarosa' and 'Camino Real' x 4 types of mulchings, being black low-density polyethylene, silver low-density polyethylene, non woven tissue and no mulching) containing three replications. The second experiment was conducted in randomized complete blocks, 2x4 factorial (two cultivars being Camarosa and 'Camino Real' x 4 arrangements of plants per plot, with 1, 2, 3, 4 rows per plot), containing four replication. It was evaluated as pigment, the chlorophylls a and b, chlorophyll a+b and a/b ratio, average number of fruits plant-1, productivity (ton ha-1) or average mass plant-1, average fruit weight-1, soluble solids (Brix), total acidity, pH and soluble solids/total acidity. The mulchings of silver low-density polyethylene and non woven tissue presented lower productivity, not being recommended for the cultivation of strawberry cultivars Camarosa and Camino Real. From among the mulchings used in the present work, black low-density polyethylene was what gave better results, being recommended its use for cvs. Camarosa and 'Camino Real'. The spatial arrangement of plants with two and three rows were presented better results in productivity in the cultivation of the strawberry field / A utilização de cobertura de solo e densidade de plantio estão diretamente relacionadas a produtividade de morangueiros em cultivo a campo. Diante do exposto, objetivou-se com o presente trabalho avaliar as características produtivas e teores de pigmentos fotossintéticos de duas cultivares de morangueiro, sobre tipos de mulchings, e números de linhas por canteiro em sistema de plantio a céu aberto. Os experimentos foram realizados entre maio e dezembro/2012, na Fazenda Experimental Prof. Dr. Antônio Carlos dos Santos Pessoa , pertencente a Unioeste, Campus Marechal Cândido Rondon, PR. O primeiro experimento foi realizado no delineamento de blocos ao acaso, esquema fatorial 2x4 (duas cultivares, sendo Camarosa e Camino Real x 4 tipos de mulchings, sendo polietileno de baixa densidade preto, polietileno de baixa densidade prata, tecido não tecido e ausência de mulching), contendo três repetições. O segundo experimento foi realizado em delineamento de blocos ao acaso, esquema fatorial 2x4 (duas cultivares, sendo Camarosa e Camino Real x 4 arranjos de plantas no canteiro, sendo 1, 2, 3, 4 linhas por canteiro), contendo quatro repetições. Avaliaram-se como teores de pigmentos, as clorofilas a e b, clorofila a+b e relação a/b, número médio de frutos planta-1, produtividade (ton ha-1), massa média fruto-1, sólidos solúveis (°Brix), acidez total, pH e relação sólidos solúveis/acidez total. A Camarosa apresentou maior produtividade que a Camino Real . O TNT não é recomendado como mulching, pois não resistiu ao período de cultivo, e não se mostrou eficaz no controle de plantas daninhas. No PEBD preto obtiveram-se melhores resultados no cultivo de Camarosa e Camino Real . A Camarosa apresentou maior produtividade média e maior número de frutos por planta que a Camino Real . A Camino Real apresentou frutos maiores e de melhor qualidade. O cultivo com duas e três linhas por canteiro apresentaram melhores resultados para MMP e NMFP, podendo empregar três linhas a fim de otimizar a área de plantio, ou duas linhas quando se busca facilitar colheita e tratos culturais

The objective of this study was to address the relationship between benthic microalgal communities and the phosphate nutrient dynamics of Florida Bay sediments and how they relate to benthic and water column primary production. In situ phosphate (P) flux between the sediment and the water column was measured in three regions of Florida Bay. Differences in the ratio of inorganic to organic phosphate flux were found between the three regions in relation to the amount of phosphate measured in the water column. Based upon the average sediment flux in my study, more than 1600 metric tons of P would be supplied by the sediment per year in Florida Bay. Based upon my measurements, dissolved nutrient flux from the sediment can be an important contribution to pelagic phytoplankton blooms in Florida Bay, accounting for 6.5 - 41% of demand and TDN accounts for 100% of the N demand. My findings were similar to others for both benthic nutrient flux and benthic microalgal chlorophyll a concentration. Benthic microalgae in Florida Bay contribute 700 kg Chl a per day to the system. Mesocosm experiments demonstrated that benthic microalgae and water column phytoplankton can respond differently to changes in nutrient availability. The dissolved nutrient in least supply in the water column does not necessarily correspond to the limiting nutrient for benthic microalgae. ³³P acted as a tracer between sediment and water column dissolved P pools. The presence of benthic microalgae enhanced the transport of ³³P to the water column as compared to simple Fickian diffusion. This was supported by the positive flux of dissolved P from the sediment to the water column pools in control treatments with a living benthic microalgal layer. Primary production by benthic microalgae were measured using dissolved O2 evolution and PAM fluorometry. Primary production for BMA habitat in Florida Bay was between 400 and 800 tons of C per day, based upon O2 production and PAM fluorometry, respectively.

Orientador: Gilsela Ferreira / Coorientador: Carmen Silvia Fernandes Boaro / Banca: Magali Ferreira da Silva / Banca: João Domingues Rodrigues / Resumo: O presente estudo objetivou avaliar a capacidade de recuperação de Annona emarginata (Schltdl.) H. Rainer após estresse hídrico em função das variações das trocas gasosas, fluorescência da clorofila a e atividade de enzimas antioxidantes. O experimento foi implantado em blocos casualizados com três tratamentos (Irrigação, Suspensão de Irrigação e Reidratação) e quatro repetições de seis plantas por parcela totalizando 24 plantas. Foram avaliadas as seguintes variáveis: conteúdo relativo de água das folhas (CRA), trocas gasosas (assimilação de CO2, A; condutância estomática, GS; transpiração, E; concentração de carbono interno, Ci; eficiência de uso da água, A/E e eficiência de carboxilação, A/Ci), fluorescência da clorofila a (rendimento quântico máximo, FV/FM; fluorescência máxima da folha sob escuro, FM e fluorescência mínima da folha sob escuro, Fo), enzimas antioxidantes (superóxido dismutase, SOD, EC. 1.15.1.1 e peroxidase, POD, EC. 1.11.1.7) e peroxidação de lipídeos. Os dados foram submetidos a analise de variância e as médias comparadas pelo teste Tukey a 5% de probabilidade e/ou desvio padrão. Aos 38 Dias Após o Inicio dos Tratamentos (DAIT) (dia da reidratação), o CRA nas plantas irrigadas apresentou 87% reduzindo para 73% nas plantas sob suspensão de irrigação onde foi verificado assimilação de CO2 nula. Embora o CRA das plantas reidratadas tenha se recuperado ao nível das plantas no inicio dos tratamentos, as trocas gasosas apresentaram recuperação parcial. A atividade das enzimas SOD e POD tanto de folhas como de raízes apresentou recuperação após a reidratação e não foram observadas alterações no nível de peroxidação de lipídeos de folhas e raízes nos três tratamentos. Nas analises de fluorescência da clorofila a não foram detectados danos ao fotossistema II e nem alterações na eficiência do aparato fotoquímico tanto das plantas sob suspensão ... / Abstract: The present study aimed to evaluate the recoverability of Annona emarginata (Schltdl.) H. Rainer after water stress through changes in the gas exchange, chlorophyll a fluorescence and antioxidant enzymes activity. The experiment was implanted in a randomized block design with three treatments (Irrigation, Suspension of Irrigation and Rehydration) and four replicates of six plants per plot totaling 24 plants. The following variables were evaluated: relative water content of leaves (RWC), gas exchange (CO2 assimilation, A; stomatal conductance, GS; transpiration, E; internal carbon concentration, Ci; water use efficiency, A/E and carboxylation efficiency, A/Ci), chlorophyll a fluorescence (maximum quantum yield, FV/FM; maximal leaf fluorescence under dark, FM; minimum leaf fluorescence under dark, Fo), antioxidant enzymes (superoxide dismutase, SOD, EC. 1.15.1.1 and peroxidase, POD, EC. 1.11.1.7) and lipid peroxidation. The data were submitted to analysis of variance and means were compared by Tukey test at 5% probability and/or standard deviation. At 38 Day After Treatments Beginning (DATB) (day of rehydration), the RWC in irrigated plants showed 87% reducing to 73% in plants under suspension of irrigation where has been verified null CO2 assimilation. Although the RWC of rehydrated plants has recovered to the level of the plants in the beginning of treatments, gas exchange showed partial recovery. The activity of SOD and POD of both leaves and roots showed recovery after rehydration and no changes were observed in the level of lipid peroxidation in leaves and roots in the three treatments. In the analysis of chlorophyll a fluorescence were not detected damage in the photosystem II and neither changes in the efficiency of the photochemical apparatus in both plants under suspension of irrigation and rehydrated in relation to irrigated. Therefore, even with the recovery of the activity of SOD and POD ... / Mestre

Interest in the effect of fish farming practices on the marine environment has arisen because there is concern that the wastes that fish farms produce may be contributing to eutrophication in coastal areas and the problem of harmful algal blooms. The focus of this thesis is an examination of phytoplankton distribution and abundance in relation to tuna fish farms in Boston Bay and near-shore Spencer Gulf. This is the first study in South Australia to define the short-term biomass fluctuations of chlorophyll and in vivo fluorescence, identify phytoplankton species distribution and abundance, including two potentially toxic dinoflagellates, and describe patch distribution relative to tuna fish farms in Boston Bay and the near-shore waters of Spencer Gulf. An ecological interpretation of phytoplankton distribution and abundance is determined and shows that community composition was different in lower Spencer Gulf compared to Boston Bay and upper Spencer Gulf sites. Pico- and nanophytoplankton were often the most abundant organisms. Diatoms and gymnoids were most common. Season and currents predominantly influenced the distribution of phytoplankton in Boston Bay and Spencer Gulf. Individual species may be influenced by inputs from the fish farms. Chlorophyll levels were different between the Spencer Gulf and Boston Bay sites and no differences were recorded, using mean levels of chlorophyll, between tuna cages and controls. Chlorophyll levels were higher east of Boston Island in autumn of 1999. Chlorophyll levels appeared to show a slight increase between years. This may have been an anomalous natural variation and future research may investigate this in the long term. In addition, Principal Components Analysis (PCA) was used to investigate differences between treatments and the functional grouping model supported an ecological interpretation of the factors from the PCA. A total of 131 taxa of phytoplankton were identified in this study. The 14 dominant taxa were used in the PCA and of these, 9 were diatoms. Phytoplankton abundance was not different between tuna cages and controls. However, when examining individual species, Karenia mikimotoi was more prevalent at tuna cages, close to shore, east and west of Boston Island than at other sites. PCA showed how different species bloomed together and were seasonal. Karenia brevis and K. mikimotoi featured predominantly in the PCA with K. brevis the dominant organism during summer and autumn along with Gyrodinium spp. and smaller gymnoids. K. brevis blooms were most likely influenced by water temperatures and fixation of nitrogen from a Trichodesmium erythaeum bloom. K. mikimotoi bloomed bimodally and may be influenced by ammonia excreted from fish from the tuna farms but , on the other hand, may be limited by the high salinities of South Australian waters. Currents in the region distribute both organisms. The final aspect of this study assessed finer temporal and spatial sampling using directional transects around tuna cages and controls using in-vivo fluorescence and size fractionated chlorophyll. The chlorophyll a sampling showed little spatial variability within a site in the 1000 m2 that the sampling area covers but far greater temporal variability (days). In contrast, fluorescence `mapping' expands the window of variability both spatially (within a site) and temporally (along transects and between days). This has given a spatial definition, which is unavailable from a single point sample, and thereby leaves room for much greater interpretation. Small patches are evident from the fluorescence mapping where this is impossible to detect from the single point samples. Therefore, the fluorescence `mapping' and patch definition show that the trend is widespread (spatially) and quite persistent (temporally) around the fish farm area. Size fractionated chlorophyll samples provided further insight into phytoplankton dynamics in this study where diatoms were favored over dinoflagellates and were responsible for the larger fraction of chlorophyll found at the tuna cage one (TC1) site. We suggest that seasonal fluctuations, high nutrient input from the farm activities and turbulence may be responsible for the different chlorophyll/fluorescent structures found at TC1. Future research may look at the long-term regional impact on phytoplankton size structure, biomass and communities from fish farm activities. As a good part of this journey involved counting phytoplankton using the Utërmohl technique, a short paper, published in the Journal of Plankton Research, on reducing the settling time of this method, is presented in Appendix.

Thesis (M.Sc.)--York University, 2004. Graduate Programme in Earth and Space Science. / Typescript. Includes bibliographical references (leaves 126-134). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url%5Fver=Z39.88-2004&res%5Fdat=xri:pqdiss&rft%5Fval%5Ffmt=info:ofi/fmt:kev:mtx:dissertation&rft%5Fdat=xri:pqdiss:MQ99363