Dissertations / Theses on the topic 'Subtropical production'

Subtropical gyres represent the single largest oceanic biome and may be very important for carbon cycling on account of their areal extent, yet our understanding of how these regions operate biologically is lacking. To address this issue measurements of NO3-, NH4+ and urea uptake were made using the 15N technique on 2 Atlantic Meridional Transect (AMT) cruises between 50oS and 50oN in May-June 2003 (AMT12) and April-June 2004 (AMT14). Distinct vertical profiles in the uptake of each nutrient were evident with urea uptake primarily confined to tropical and subtropical surface waters, NH4+ uptake to surface and intermediate waters and NO3- uptake peaking at depth leading to the observation of deep maxima in NO3- uptake within the subtropical gyres often coincident with the nutricline and with the deep chlorophyll maximum. Comparisons between the two cruises reveal interannual changes including an increase in the uptake rates of all three nutrients during AMT14, particularly NO3- which is driven by an increase in ambient NO3- concentrations. Several other parameters (e.g. chlorophyll, 14C carbon fixation, other nutrients) were also higher during AMT14 compared to AMT12 suggesting gyre scale variation. Estimates of NO3- based new production, obtained via a stoichiometric (Redfield) ratio, for the two cruises reveal relatively consistent rates within the tropics and subtropics within each cruise but higher rates of new production during AMT14. A greater proportion of new production was observed to occur in the lower 15% of the euphotic zone than in the surface layer reflecting the position and influence of the nutricline. A northward increase in new production in the lower regions of the euphotic zone was also observed which is hypothesized to represent a seasonal signal implying a degree of seasonality in the behaviour of the deep chlorophyll maximum and of deep NO3- uptake. The historical AMT database (AMT cruises 1-14) has been used to further examine the deep chlorophyll maximum. The observations of high NO3- uptake at depth, in excess of 14C based productivity nitrogen requirements and new production estimates exceeding total production rates suggests that nitrogen and carbon uptake may be decoupled at depth or that the measured NO3- uptake may not in fact represent new production. Integrated rates of new production were also occasionally found to locally exceed integrated community gross production and community respiration. Comparisons between new production and 234Th export production during AMT14 reveal that the two measurements are not equal, most likely on account of the different time scales of the two techniques, but comparisons with other parameters (carbon fixation, gross and net production and respiration) reveal that none of the parameters produce exact answers although similar patterns and magnitudes of carbon flux can be obtained. This would suggest that local decoupling of all rate processes is likely.

Globally agriculture and livestock producers have come under increasing pressure over the environmental impact of production systems. The objectives of this study were to re-calculate the direct methane (CH4) and nitrous oxide (N2O) emissions of livestock production systems in South Africa, taking into consideration the uniqueness of the South African scenario and to identify and evaluate possible greenhouse gas mitigation strategies for extensive production systems. It is important to generate accurate greenhouse gas (GHG) baseline figures to develop South Africa’s capacity to understand and reduce GHG emissions emitted from the livestock sector. Livestock produce GHG’s in the form of methane from enteric fermentation and nitrous oxide and methane from manure management and manure deposited on pastures and rangeland by grazing animals. Agriculture, forestry and land use (corrected for carbon sink values) emitted an estimated 4.9% of South African GHG gases in 2004, which makes it the third largest GHG contributor in South Africa after the energy industry and industrial processes. Livestock produced approximately 27% of the national methane emissions and 98% of the agricultural sector’s methane emissions in 2004. Methane is a potent GHG that remains in the atmosphere for approximately 9 to 15 years and is 28 times more effective in trapping heat in the atmosphere than carbon dioxide (CO2) over a 100-year period. Nitrous oxide has an atmospheric lifetime of 150 years and a global warming potential of 265 times that of CO2 over a 100-year period. South African livestock production is based on a unique combination of commercial (intensive and extensive) and emerging and communal (subsistence) production systems. The levels of productivity and efficiency in these production systems vary greatly in certain areas and it is important to distinguish between them when calculating GHG emissions. Previous inventories were conducted on a national scale utilizing IPCC default values (Tier 1 approach) for some or all of the emission calculations. These emission factors do not distinguish effectively between classes of animals, production efficiencies, and production systems. They are often based on assumptions of animals utilizing diets which are not representative of South African production systems. The IPCC Tier 2 methodology seeks to define animals, animal productivity, diet quality and management circumstances to support a more accurate estimate of feed intake for use in estimating methane production from enteric fermentation. It was also considered important to do separate calculations for each province as provinces differ in vegetation or biomes and production systems which may require different approaches to mitigation recommendations. Due to the heterogeneity of available feed types within South Africa it was considered important to use methodologies that could reflect such differences and was developed under similar conditions. The methodology utilized is based on the Australian national greenhouse account’s National Inventory Report, which contains Australian country-specific and IPCC default methodologies and emission factors. Emission factors specific to South African conditions and management systems were calculated where possible. A Tier 2 approach was adopted for all major livestock categories including privately owned game in accordance with the IPCC Good Practice requirements. Recently game farming has become a recognized commercial enterprise in the agricultural sector which needs to be included as an anthropogenic emissions source. Methane emissions from South African livestock were estimated at 1328 Giga gram (Gg) during 2010. Dairy and beef cattle contributed an estimated 964 Gg or 72.6% of the total livestock methane emissions in South Africa during 2010. Beef cattle in extensive systems were the largest contributor (83.3%), followed by dairy cattle (13.5%), and feedlot cattle (3.2%). The estimated direct enteric methane emission factors for dairy and beef cattle were higher than the IPCC default factors for Africa. The Eastern Cape recorded the highest dairy and beef cattle methane emissions, whereas Gauteng showed the highest feedlot methane emissions primarily due to cattle numbers. Small stock was responsible for 15.6% of the total livestock emissions contributing an estimated 207.7 Gg, with sheep producing 167 Gg and goats producing 40.7 Gg. Calculated enteric methane emission factors for both commercial and communal sheep were higher than the IPCC default values for developing countries. A similar tendency was found with goat emission factors. The highest sheep and goat methane emissions were reported for the Eastern Cape province. The pig and ostrich industry both contributed approximately 8 Gg CH4 during 2010. The North- West province produced the highest commercial pig GHG emissions with the highest communal pig emissions originating from the Eastern Cape. The poultry industry was the largest direct N2O producer of the non-ruminant livestock industries, contributing 2.3 Gg or 92.8% of the total nonruminant N2O emissions. The privately owned game industry contributed an estimated 131.9 Gg of methane emissions with the provinces of Limpopo, Eastern Cape and Northern Cape being the three largest contributors with 43.4, 37.3 and 21 Gg methane, respectively. The total privately owned game population was estimated at 2 991 370 animals, utilizing 20.5 million hectares. Beef cattle are the major contributors to livestock GHG emissions in South Africa followed by sheep, privately owned game, dairy cattle, goats, pigs, ostriches, equine, and poultry. The IPCC default values for Africa underestimate emission factors across all livestock categories. The methane emission factors calculated for commercial livestock production systems are more comparable to emission factors from developed countries and the emerging/communal production systems to those of developing countries. This emphasizes the need to develop country-specific emission factors through quantitative research for livestock in all provinces and on all types of production systems to produce accurate baseline figures, which is critical to future mitigation protocols. As part of this study fourteen tropical grass species typical of transitional rangeland regions of South Africa were characterised in terms of chemical composition, in vitro total gas and in vitro methane production. The results of the study demonstrated that in vitro methane production varied between tropical grass species typical of transitional rangeland in South Africa. The variation between species allows for the potential to identify and select species with a lower enteric methane production potential. Panicum maximum, Eragrostis curvula and Elionurus miticus were the three species which produced the lowest in vitro methane production but which also had a crude protein (CP) concentration of more than 3.5% of dry matter (DM) and with an in vitro organic matter digestibility (IVOMD) above the group average for the study. Furthermore, the results of the study revealed that in vitro methane production was higher in Decreaser species compared to Increaser species. Improving the quality of available forages through the use of cultivated pastures and fertilization is known to improve ruminant production efficiency. The effect of level of nitrogen (N) fertilization on certain qualitative parameters and in vitro total gas and methane production of improved grass species commonly utilised in South Africa was evaluated. Treatments included seven grass species divided into two photosynthetic pathways (C3 and C4) with three levels of N fertilization (0, 50 and 100 kg N/ha). No effect was found for N fertilization on in vitro total gas or methane production. The CP concentration increased (P < 0.05) and the NDF concentration tended to decrease (P < 0.1) as the level of N fertilization increased for both C3 and C4 species. Increasing the level of N fertiliser increased (P < 0.05) the methanogenic potential of Dactylis glomorata, Festuca arundinacea and Cenchrus ciliaris after the 24 hour incubation period but no effects (P>0.05) were found after the 48 hour incubation period. Results suggests that the stage of physiological development of forages might have a greater influence on the methanogenic potential of forages compared to the effect of N fertiliser application.
Thesis (PhD)--University of Pretoria, 2017.
Animal and Wildlife Sciences
PhD
Unrestricted

This is the first study to investigate alternative fertilisation strategies to increase cereal production while reducing greenhouse gas emissions from the most common soil type in subtropical regions. The results of this research will contribute to define future farming practices to achieve global food security and mitigate climate change. The study established that introducing legumes in cropping systems is the most agronomically viable and environmentally sustainable fertilisation strategy. Importantly, this strategy can be widely adopted in subtropical regions since it is economically accessible, requires little know-how transfer and technology investment, and can be profitable in both low- and high-input cropping systems.

Atmospheric nitrogen deposition to the ocean has more than doubled in the past 150 years due to anthropogenic activity, reaching levels comparable with nitrogen fixation in the subtropical North Atlantic. Previous studies have suggested that atmospherically deposited N may increase export production, decrease surface water phosphate levels, and substantially impact geochemical estimates of nitrogen fixation. This dissertation reports on the magnitude and biogeochemical fate of soluble N and P deposition in the subtropical North Atlantic. Aerosol and wet deposition time-series samples were used to determine the fluxes, sources, and N:P ratios of atmospheric nutrient deposition. Based on the magnitudes of total soluble N and P deposition, atmospheric nutrients are estimated to supply ~10-50% of allochthonous N to the North Atlantic subtropical gyre. Samples gathered in Barbados, the Canary Islands, and Miami indicate that atmospheric N sources are primarily anthropogenic (and thus, increasing) and that P sources are primarily natural (and thus relatively steady). Because inorganic nutrient concentrations in surface waters are in the low nM range, increasing P stress in surface waters may occur as a result of increasing N deposition. This assessment is supported by modeling studies, which also indicate that deposition would enhance surface P depletion. Inorganic N contributes nearly all (85-87%) of atmospherically deposited soluble N; the majority (~60%) of the remaining soluble organic N is comprised of an incompletely characterized pool of volatile basic organic N. Water soluble organic P contributes ~20-50% of soluble P. Because organic P contributes a relatively higher portion of soluble P as compared to organic N, the inclusion of organic matter in deposition estimates could both enhance the expected level of export production and reduce the predicted levels of P stress induced by atmospheric deposition. Further modeling studies indicate that the fate of atmospheric nutrients in the subtropical North Atlantic is controlled by non-Redfieldian processes, and that atmospheric nutrients eventually accumulate in the main thermocline. The research presented here suggests that future increases in atmospheric N emissions could have long-term impacts on surface ocean biology and nutrient cycles in the subtropical North Atlantic.

Thesis (Ph. D.)--University of Maryland, College Park, 2006.
Thesis research directed by: Atmospheric and Oceanic Sciences. Title from t.p. of PDF. On t.p. "x̲" is subscript. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

Bioreactors are a low-cost water treatment technology to mitigate nutrient runoff from agricultural areas. Bioreactors are woodchip-filled trenches installed in the soil, which convert nitrate to dinitrogen, a harmless gas in the atmosphere. Nitrate removal and greenhouse gas production of five on-farm bioreactors were monitored for the first time in Queensland, to reduce the nutrient runoff to the Great Barrier Reef. The bioreactors effectively removed nitrate, with negligible emissions of greenhouse gases. This research expanded the knowledge on bioreactors installed in Subtropical and Tropical climates and contributed to the development of guidelines for the application of bioreactors on Queensland farms.

Made available in DSpace on 2014-06-11T19:26:40Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-02-09Bitstream added on 2014-06-13T18:30:16Z : No. of bitstreams: 1 souza_me_me_botfca.pdf: 1672773 bytes, checksum: 8fa50f74c16dfdc2c8405eeaf258cc48 (MD5)
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Sabendo da importância da bananicultura para o Brasil, sobretudo para o Estado de São Paulo e a expansão de novos cultivos, o presente trabalho teve como objetivo avaliar o desempenho agronômico, caracterizar atributos de qualidade, bem como aspectos sensoriais dos frutos de acessos de bananeira em Botucatu/SP. Foram avaliadas características de crescimento, tais como altura de planta, circunferência do pseudocaule, número de folhas e número de dias entre o florescimento e a colheita. Estas medidas foram feitas na emissão da inflorescência. Foram mensuradas também as características de produção, como peso do cacho, número de frutos, peso médio dos frutos, produtividade, número de pencas; peso, número, comprimento e diâmetro dos frutos da 2ª penca. Em relação à qualidade dos frutos foram, analisados os atributos físicos e químicos: textura; pH; acidez titulável; sólidos solúveis, açúcares redutores totais; amido e potássio, bem como a aceitação desses acessos através da análise sensorial. O delineamento adotado foi o inteiramente casualisado, com 12 tratamentos (acessos), 5 repetições e duas plantas úteis por parcela experimental. Foi utilizado o teste de Tukey (P< 0,05) para a comparação entre as médias de genótipos, dentro de cada grupo genômico. No grupo AAA, „Grand Naine‟ apresentou boas características de crescimento, produção e boa aceitação sensorial, porém teve ciclo longo. „Nanicão‟ apresentou boas características de crescimento, produção, qualidade e boa aceitação sensorial. „Caipira‟ destacou-se apenas nos teores de potássio. „Nam‟ apresentou porte baixo, ciclo curto e maior teores de açúcares, entretanto mostrou-se pouco produtiva. No grupo AAB, „Thap Maeo‟ apresentou menor ciclo, maior número de frutos por cacho, porém apresentou porte alto. „Prata Anã ‟apresentou porte mais baixo e frutos com boa...
Knowing the importance of the culture of banana in Brazil, especially for the São Paulo State, Brazil and the expansion of new crops, the objective of this research was to evaluate the agronomic performance, to characterize the quality attributes and sensory aspects of fruits of different accesses of banana tree in Botucatu/SP. Were evaluated growth characteristics such as plant height, pseudostem circumference, number of leaves, number of days between flowering and harvest, measured at the flowering time. Were also measured production characteristics, such as bunch weight, number fruits, average weight of the fruits, productivity, number of hands and weight, number, length and diameter of the 2nd bunch. For quality fruit were analyzed physical and chemical characteristics: firmness, pH, titratable acidity, soluble solids, total sugars, starch and potassium, and the acceptance of these genotypes by sensory analysis. The experimental design was completely randomized with 12 treatments (accesses), 5 replications and 2 plants per plot. Was used the Tukey test (P < 0.05) for the comparison between the means of accesses within each genomic group. According to the results of the Group AAA, „Grand Naine‟ showed good growth characteristics, production and good sensory acceptance, but had long cycle. „Nanicão‟ showed good growth characteristics, production, quality and good sensory acceptance. Caipira was the cultivar that showed more negative characteristics, highlighting only the levels of potassium. „Nam‟ showed low height, short cycle and higher sugar content, however it was not very productive. In the group AAB, „Thap Maeo‟ showed short cycle and higher number of fruits per bunch, but had high height. „Prata Anã‟ showed low height and fruit firmness. The cultivar Prata Zulu showed fruit with higher concentrations of sugars and starch, low acidity, good firmness... (Complete abstract click electronic access below)

Made available in DSpace on 2017-05-12T14:47:31Z (GMT). No. of bitstreams: 1 Juliana _Matter.pdf: 980208 bytes, checksum: 39b0f232a5a4474d2605637e0dc10ea5 (MD5) Previous issue date: 2015-04-28
Chemical fertilizers management in agriculture is the main source of nutrients for crops development aiming at increasing yield. Thus, phosphorus, among other nutrients, is required by plants since it is the most limiting mineral on yield crops of commercial interest, because of its low availability and immobility in soil, as it also gets unavailable to absorption by the plants. Studies have shown that phosphate solubilization up from bacteria inoculation can improve agricultural production. Many bacteria can take part on the dissolution process through different mechanisms and promote plant growth either by dissolving phosphates or determining nitrogen (N) and indole acetic acid production (IAA). Due to the isolation of these microorganisms, they can be inoculated and make the fixed phosphorus available, reducing the use of fertilizers or readjusting excessive percentages of this element in their formulas to improve a development of sustainable agricultural yield. According to this theme, it was possible to apply a methodology for the isolation of subtropical soil bacteria with maize cropping from different soil fertilization managements. After isolating the micro-organisms, they were submitted to endurance tests after pricking, phosphatase production ability, IAA production with and without L-tryptophan and identification method by rDNA extraction technique. A greater diversity of mineralizing bacteria was found in treatment 1 soil (no fertilization). The results related to the largest percentage increase in Calcium phytate can be justified by the fact that bacterial communities can produce enzymes. The stability of the solubilizing function was greater in calcium phytate when compared to the other culture media that have been used. The study has indicated that soil microbiota keeps a similarity in which Ochrobactrum gender has prevailed and under different management situations, its diversity slightly varies, but it is able to produce metabolites promoters of plant growth; while the isolates of Treatment 2 (mineral fertilization) have kept the best acid phosphatase production. The IAA production, without L-tryptophan addition in T1, suggests that the microbiota uses metabolic pathways for different purposes, since the studied soil is poor in minerals, thus it affects the production of plant growth promoters. It differs from Treatment 3 that received fertilization with swine wastewater, and diversified IAA production for its isolates with stronger values. With this study it was possible to identify genera of bacteria with high phytate mineralization capacity. At last, according to the study results, it was possible to identify the bacteria genera with high capacity to mineralize phytate and produce IAA, indicating the promotion of vegetal growth capacity.
A utilização de fertilizantes químicos na agricultura constitui-se como a principal fonte de nutrientes para o desenvolvimento das culturas visando ao aumento da produtividade. O fósforo, dentre outros nutrientes, é o mais requerido pelas plantas e o que mais limita a produtividade nas culturas de interesse comercial em virtude da sua baixa disponibilidade e imobilização no solo, haja vista ficar indisponível para absorção pelo vegetal. Estudos comprovam que a solubilização de fosfatos a partir da inoculação de bactérias pode ajudar na melhoria da produção agrícola. Muitas bactérias realizam processos de dissolução a partir de diferentes mecanismos e promovem crescimento vegetal tanto pela dissolução de fosfatos como na fixação de nitrogênio (N) e produção de ácido indol acético (AIA). Com o isolamento desses microrganismos, é possível inoculá-los e disponibilizar o fósforo fixado, reduzir o uso de fertilizantes ou readequar as porcentagens excessivas desse elemento em suas fórmulas, visando ao desenvolvimento da produção agrícola sustentável. A partir desta temática, foi utilizada metodologia para isolamento de bactérias de solo subtropical sob cultivo de milho com diferentes históricos de adubação. Além do isolamento, os microrganismos foram submetidos a testes de resistência após repicagem, produção de fosfatases, produção de AIA com e sem L- triptofano e identificação por técnica de extração de rDNA. Uma maior diversidade de bactérias mineralizadores foi encontrada no solo Tratamento 1 (sem adubação). Os resultados relacionados à maior porcentagem de crescimento em fitato de cálcio podem ser justificados pelo fato de as comunidades bacterianas serem capazes de produzir enzimas. A estabilidade da função solubilizadora foi maior em fitato de cálcio do que nos outros meios usados. O estudo indicou que a microbiota do solo mantém similaridade onde prevalece o gênero Ochrobactrum e que, em diferentes situações de manejo, pouco varia sua diversidade, mas apresenta capacidade para produzir metabólitos promotores de crescimento de plantas. Os isolados do Tratamento 2 (adubação mineral) mantiveram a produção de fosfatase ácida mais acentuada. A produção de AIA sem a adição de L-triptofano no tratamento T1 sugere que a microbiota utiliza vias metabólicas distintas para tal, visto que o solo estudado é pobre em minerais. Isso afeta a produção de promotores de crescimento de plantas, contrapondo-se ao Tratamento 3, o qual recebeu adubação com água residuária de suinocultura e diversificou a produção de AIA por seus isolados com valores mais robustos. Finalmente, de acordo com os resultados do presente estudo, foi possível a identificação de gêneros de bactéria com elevada capacidade de solubilização de fitatos e produção de AIA, indicando capacidade de promoção de crescimento vegetal.

Orientador: Sarita Leonel
Banca: Giuseppina Pace Pereira Lima
Banca: Renata Aparecida de Andrade
Resumo: Sabendo da importância da bananicultura para o Brasil, sobretudo para o Estado de São Paulo e a expansão de novos cultivos, o presente trabalho teve como objetivo avaliar o desempenho agronômico, caracterizar atributos de qualidade, bem como aspectos sensoriais dos frutos de acessos de bananeira em Botucatu/SP. Foram avaliadas características de crescimento, tais como altura de planta, circunferência do pseudocaule, número de folhas e número de dias entre o florescimento e a colheita. Estas medidas foram feitas na emissão da inflorescência. Foram mensuradas também as características de produção, como peso do cacho, número de frutos, peso médio dos frutos, produtividade, número de pencas; peso, número, comprimento e diâmetro dos frutos da 2ª penca. Em relação à qualidade dos frutos foram, analisados os atributos físicos e químicos: textura; pH; acidez titulável; sólidos solúveis, açúcares redutores totais; amido e potássio, bem como a aceitação desses acessos através da análise sensorial. O delineamento adotado foi o inteiramente casualisado, com 12 tratamentos (acessos), 5 repetições e duas plantas úteis por parcela experimental. Foi utilizado o teste de Tukey (P< 0,05) para a comparação entre as médias de genótipos, dentro de cada grupo genômico. No grupo AAA, „Grand Naine‟ apresentou boas características de crescimento, produção e boa aceitação sensorial, porém teve ciclo longo. „Nanicão‟ apresentou boas características de crescimento, produção, qualidade e boa aceitação sensorial. „Caipira‟ destacou-se apenas nos teores de potássio. „Nam‟ apresentou porte baixo, ciclo curto e maior teores de açúcares, entretanto mostrou-se pouco produtiva. No grupo AAB, „Thap Maeo‟ apresentou menor ciclo, maior número de frutos por cacho, porém apresentou porte alto. „Prata Anã ‟apresentou porte mais baixo e frutos com boa... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Knowing the importance of the culture of banana in Brazil, especially for the São Paulo State, Brazil and the expansion of new crops, the objective of this research was to evaluate the agronomic performance, to characterize the quality attributes and sensory aspects of fruits of different accesses of banana tree in Botucatu/SP. Were evaluated growth characteristics such as plant height, pseudostem circumference, number of leaves, number of days between flowering and harvest, measured at the flowering time. Were also measured production characteristics, such as bunch weight, number fruits, average weight of the fruits, productivity, number of hands and weight, number, length and diameter of the 2nd bunch. For quality fruit were analyzed physical and chemical characteristics: firmness, pH, titratable acidity, soluble solids, total sugars, starch and potassium, and the acceptance of these genotypes by sensory analysis. The experimental design was completely randomized with 12 treatments (accesses), 5 replications and 2 plants per plot. Was used the Tukey test (P < 0.05) for the comparison between the means of accesses within each genomic group. According to the results of the Group AAA, „Grand Naine‟ showed good growth characteristics, production and good sensory acceptance, but had long cycle. „Nanicão‟ showed good growth characteristics, production, quality and good sensory acceptance. Caipira was the cultivar that showed more negative characteristics, highlighting only the levels of potassium. „Nam‟ showed low height, short cycle and higher sugar content, however it was not very productive. In the group AAB, „Thap Maeo‟ showed short cycle and higher number of fruits per bunch, but had high height. „Prata Anã‟ showed low height and fruit firmness. The cultivar Prata Zulu showed fruit with higher concentrations of sugars and starch, low acidity, good firmness... (Complete abstract click electronic access below)
Mestre

A grande procura por mirtilos, principalmente por países do Hemisfério Norte, está associada aos benefícios nutracêuticos do seu consumo em relação a prevenção de doenças. Em resposta à esta alta demanda, produtores de regiões e países que antes não cultivavam a fruta, iniciaram seus plantios nos últimos anos, sendo o clima, fator limitante à expansão de novas áreas uma vez que o mirtileiro, originário de regiões temperadas, necessita acumular alto número de horas de frio hibernal para completar seu desenvolvimento. No Brasil, predomina-se o plantio de mirtileiros nos estados da região sul, além de pequenas regiões de altitude no estado de São Paulo e Minas Gerais, utilizando cultivares tradicionais. A introdução de novos materiais genéticos, de baixa exigência em frio, desenvolvidos pela Universidade da Flórida possibilitou avaliar o desempenho das plantas e a qualidade dos frutos das cultivares Emerald e Jewel plantadas em Piracicaba - SP, sem ocorrência de frio hibernal. No período de maio de 2014 a maio de 2015 foi realizada a caracterização das fases de crescimento vegetativo, brotação, florescimento, frutificação e produção de frutos dessas cultivares. O crescimento dos ramos ocorre até o início da produção, interrompendo-se em seguida. A cultivar Emerald apresenta dois picos de florescimento e frutificação, com a colheita principal ocorrendo de agosto a outubro, enquanto a cultivar Jewel apresenta dois picos de emissão de botão floral, mas apenas um pico de florescimento e uma colheita que ocorre entre os meses de outubro e janeiro. A produção ocorre durante o período de entressafra do mercado interno e externo, que possibilita melhores preços da fruta. É possível obter-se produção das cultivares de mirtileiros Jewel e Emerald em região subtropical, mas a exigência de um número de horas de frio para estimular a emissão de botão floral e o florescimento parece ser mais baixa que a recomendada na literatura. Em agosto e outubro de 2015 também foram determinados para essas cultivares, parâmetros da qualidade físico-química dos frutos como massa fresca de frutos, diâmetro, comprimento, formato, volume, firmeza, coloração de casca, teor de sólidos solúveis totais, pH, acidez titulável, ratio, compostos fenólicos totais, teor de antocianinas, quercetina e atividade antioxidante pelo sequestro dos radicais DPPH e ABTS, que foram armazenados à temperatura ambiente (22 °C) avaliados no dia de colheita, e a cada três dias, até o décimo segundo dia. Frutos de mirtilos colhidos em agosto são maiores e mais arredondados, porém apresentam menor teor de sólidos solúveis totais e maior acidez. Por outro lado, os frutos colhidos em outubro apresentam maior ratio, e coloração mais intensa. \'Emerald\' possui frutos com maior atividade antioxidante que \'Jewel\'. Os teores de antocianinas, quercetinas, compostos fenólicos totais e atividade antioxidante diferem entre as cultivares de acordo com as épocas e aumentam ao longo dos dias após a colheita, enquanto pH, acidez e firmeza decrescem.
The high demand for blueberries, mainly by the Northern Hemisphere markets, is associated with their nutraceutical attributes and the health benefits of its consumption. In response to this high demand, countries that had never cultivated the fruit, started growing blueberries in recent years. The climate is a limiting factor to the expansion of new areas as these species are originated from temperate regions, an so, has a high chill requirement for a full development. In Brazil, blueberry cultivation of traditional areas are restricted to the southern states, and to small areas of altitude in São Paulo and Minas Gerais state, using traditional cultivars. The introduction of new genetic material, with low chill requirement, released by the University of Florida made possible to evaluate the performance of plants and fruit quality of Emerald and Jewel cultivars planted in Piracicaba - SP, without the occurrence of temperatures below 7.2 °C. From May 2014 to May 2015 vegetative growth, bud break, flowering, fruiting and fruit production of these cultivars were assessed. Branches grew until flowering period. Emerald cultivar has two peaks of flowering and fruiting, with the main harvest occurring from August to October, while \'Jewel\' has two bud break peaks, but only a peak of flowering and the harvest takes place between October and January. The production occurs during the off-season of the domestic and northern hemisphere markets, resulting in higher fruit prices. The results indicate that it is possible to cultivate blueberry cultivars Jewel and Emerald in subtropical regions because the chill requirement to induce bud and flowering break is much lower than it is cited in the literature. In August and October 2015 \'Jewel\' and \'Emerald\' were assessed for parameters of physical and chemical quality of the fruit. It were evaluated fresh fruit mass, diameter, length, shape, volume, firmness, peel color, soluble solids content (SST), pH, titratable acidity (AT), SST/AT ratio, total phenolic compounds, total anthocyanins content, total quercetins content and antioxidant activity using DPPH and ABTS methods on the harvest day, and every three days, until the twelfth day of the fruits harvested and stored at room temperature (22 °C). Fruits from August harvest have higher diameter and are more roundish, but have lower soluble solids content and higher titratable acidity. On the other hand, the fruits harvested in October have higher SST/TA ratio and higher chroma value. \'Emerald\' has higher antioxidant activity than \'Jewel\'. The content of anthocyanins, quercetins, total phenolic compounds and antioxidant activity differ with cultivars and harvest periods and increases during storage, while pH, acidity and firmness decrease.

The increasing world population and with it the increased pressure on food production are likely to challenge the availability of quality fresh water resources in the near future. To compound the looming water crisis, caused by an increased demand for water available for agricultural production, the quality of our fresh water resources is also likely to suffer from the consequences of increased population pressure, i.e. urbanization of land and growth of industries, and food production, i.e. agricultural use of land. Moreton Bay, South East Queensland, Australia, is listed under the United Nations Convention on Wetlands and is also a declared Marine Park. The Moreton Bay area, however, is already one of the five fastest growing urban areas in the developed world. Prognoses about future population growth and urban and industrial development in the area, have hence given rise to growing concerns about the future water quality in this international environmentally important area. Therefore the aim of the current study was to investigate the fate of nutrients in freshwater streams in the Moreton Bay area in order to gain a better understanding of nutrient pathways in aquatic systems and assist in refining the National Water Quality Management Strategy to provide better management of our waterways. To achieve this, the effects of land use on water quality were determined at 22 study sites in the Brisbane River Catchment. Within the catchment five main types of land use were identified, including urban, rural residential, cropping, grazing and mixed types of land use. Water quality was sampled during three seasons: the pre-wet (October - November), wet (December - March) and dry (April - August) season. Nitrogen and phosphorus concentrations in ambient stream water varied significantly spatially, i.e. types of land use, and temporally, i.e. seasons. At some sites, during certain times of the year, nutrient concentrations were found to exceed the range recommended by the Australian Water Quality guidelines. Nutrient concentrations were particular high in urban areas, especially during the dry season. It was also found that the 15N signatures in aquatic plants, i.e epipelic algae, correlated strongly with in-stream nitrogen concentrations. The large variability of in-stream nutrient concentrations, and the related changes in nitrogen isotopic signatures in aquatic plants, made it obvious to suggest that changes in land use may significantly impact on water quality in the catchment. Other changes in land use, for example riparian vegetation clearing, are also commonly observed in areas under urban, industry and/or agricultural growth pressure. This is of particular concern, given riparian vegetation is important not only in controlling nutrient and other organic matter input into streams, but also in regulating light levels for in-stream primary production. Previously riparian zones have been shown to be a prime source of carbon and energy for aquatic food webs in some studies, whereas other studies suggested the main driver of food webs is in-stream primary production. The current study used stable isotope analysis track carbon and nitrogen pathways through aquatic systems and determine the primary source of carbon and energy in aquatic food webs. Despite large spatial and temporal variability of 13C, aquatic consumers were closely tracking the carbon isotope signatures of plants and it was suggested that epilithic and epipelic algae are the main contributors to the carbon and energy budget of aquatic consumers.In realizing this importance of algae in aquatic systems, the next step in this study was to examine the relative importance of light and nutrient availability to periphyton and the effects of changes of these variables on plant biomass and primary production. In an in-situ experiment the levels of light and nutrients available to periphyton, were altered. Although nutrients and light may have colimited standing crop of periphyton, other variables were clearly limited by light. Parallel to this experiment on periphyton, the nutrient availability to Vallisneria spp. was experimentally altered to investigate the effects of changes in nutrient availability and nutrient limitation on other aquatic plants. The biomass of this submerged macrophyte increased three-fold in nitrogen and phosphorus sufficient areas over nutrient limited treatments. The physiological response, i.e. changes in concentrations of amino acids, of periphyton to changes in environmental conditions was also investigated on a large scale, i.e. spatial and temporal variability of amino acids, and a local scale, i.e. amino acid changes in artificially altered light and nutrient availability. This response was of particular interest in this study, as it was previously shown that physiological changes in plants impact on the quality of plants as food for consumers. The physiological changes in aquatic plants could thus provide an important link between nutrient input into streams (e.g. from terrestrial sources), impacts on aquatic plants (e.g.. nutrient uptake and physiological responses in plants) and effects on aquatic consumers (e.g. changes in food quality of plants and therefore impacts on biomass, growth and overall health of aquatic consumers).

A Lagoa Mangueira é uma extensa lagoa rasa subtropical localizada no sul do estado do Rio Grande do Sul, Brasil. É um ambiente que varia de oligo à mesotrófico, com extensa área litoral colonizada por macrófitas aquáticas, fornecendo grande área de substrato para o desenvolvimento da comunidade aderida. A parte sul da lagoa é caracterizada pela alta transparência e alto pH, e a parte norte é mais rasa com alta concentração de ácidos húmicos devido a interação com banhado. Devido sua forma e posição geográfica a lagoa sofre constante ação dos ventos de direção NE, com mudanças para o quadrante SE-SO durante as frentes frias. O vento neste ambiente é um fator regulador da hidrodinâmica, afetando espacial e temporalmente as comunidades aquáticas (fitoplâncton, zooplâncton, e peixes), podendo ser considerado um distúrbio constante no ambiente. Entretanto, ainda há uma lacuna quanto à contribuição das algas epifíticas para a teia trófica, bem como a resposta dessa comunidade à hidrodinâmica. O Capítulo 1 apresenta um estudo que testou se as diatomáceas epifíticas respondem a heterogeneidade espacial da lagoa durante dois verões em três pontos distantes (Norte, Centro e Sul). Verificou-se que as diatomáceas exibem um gradiente longitudinal NS e a área central assume características semelhantes aos pontos Norte e Sul dependendo da dinâmica do vento. No Capítulo 2, foi avaliada a sucessão das algas epifíticas no Sul da lagoa, durante 60 dias no verão de 2012, para investigar os fatores reguladores do desenvolvimento da comunidade in situ, considerando o zooplâncton como potencial predador. O estudo evidenciou que a fase avançada da sucessão foi dominada por diatomáceas fortemente aderidas e adaptadas às altas médias da velocidade do vento (±15 m s-1). O epifíton mostrou-se uma grande fonte de produtividade primária para a teia trófica e fortes correlações provaram que a comunidade sustentou o controle bottom-up da comunidade zooplanctônica. O Capítulo 3 descreve o estudo que testou a resposta do epifíton à dinâmica do vento (velocidade e direção) durante frentes frias (inverno de 2013) em três situações diferentes: comunidade natural, sucessão em um banco de macrófitas e um mesocosmo (protegido da ação do vento). O epifíton revelou-se resiliente, uma vez que o vento favoreceu a colonização e estabilização, recuperando-se rapidamente após o distúrbio. O mesocosmo diminuiu a ação do vento atrasando a deposição das células metafíticas para início da colonização e a sucessão só começou após um grande distúrbio (vento 10 m s-1) que nivelou a água do mesocosmo e a água circundante. Dominância de diatomáceas foi registrada em todos os experimentos. As diversidades das comunidades de todos os experimentos responderam à dinâmica do vento, sendo mais baixas quando a velocidade do vento excedeu a média encontrada para o período (5 m s -1).
Mangueira Lake is a large shallow subtropical lake located in the Southern Rio Grande do Sul State, Brazil. The lake ranges from oligo to -mesotrophic conditions and presents a large littoral zone covered by macrophytes, providing large area for attached community development. The southern area of the lake is characterized by high transparency and high pH and the northern area is shallower with high concentration of humic acids because of its interaction with the wetland. Due to its shape and geographic position, the lake undergoes constant wind action from NE direction and from SE‒SW during cold-fronts. The wind regulates the hydrodynamics in this environment affecting spatial and temporally the aquatic communities (phytoplankton, zooplankton and fishes), and can be considered a constant disturbance. However, epiphytic algae contribution for food-web, as well as their responses to hydrodynamics, are still a lack. Chapter 1 presents a study in which we tested if epiphytic diatoms respond to the lake spatial heterogeneity during two summers in three distant sites (North, Center and South). As a result we noted that diatoms exhibited a longitudinal gradient from NS whereas the center area assumes characteristics similar to both North and South areas depending on wind dynamics. In Chapter 2, we investigated epiphyton succession during 60 days in southern part of the lake in the summer of 2012, aiming to describe the driving factors of the community development in situ, considering zooplankton as a potential grazer. The study highlighted that the advanced phase of succession was dominated by tightly attached diatoms adapted to high wind mean velocity (±15 m s-1). We also showed that epiphyton was great source of primary production for the food-web and strong correlations proved that the community is handling zooplankton bottom-up control. Chapter 3 describes a study that tested the response of the epiphyton to the wind dynamics (velocity and direction) during cold-fronts (2013 Winter) in three different situations: natural community, succession in a macrophyte bank and in an enclosure (protected from the wind). As a result, epiphyton revealed to be resilient once wind favored colonization and stabilization, rapidly recovering after disturbance. The enclosure acted buffering wind forces delaying succession derived by settlement of metaphytic cells and the succession only started after a huge disturbance (wind 10 m s-1) which leveled the enclosure water and the lake water. Dominance of diatoms was registered in all experiments. The communities‟ diversities responded to wind dynamics, whereas all experiments showed lower diversities when wind velocity exceeded the system‟s means (5 m s-1).

Florações de microalgas potencialmente nocivas têm aumentado em termos globais e causado impactos na aquicultura, no turismo, na saúde humana e em vários aspectos do funcionamento dos ecossistemas. No Brasil, uma atenção cada vez maior tem sido dada ao tema, em virtude do elevado potencial de nossas águas para o cultivo de bivalves marinhos, um dos grupos de invertebrados mais afetados. Deste modo, a preocupação com a contaminação de consumidores humanos tem gerado projetos voltados para a detecção de espécies potencialmente nocivas e de suas toxinas, mas ainda há poucos estudos sobre interações alimentares entre as espécies de fitoplâncton e zooplâncton. No presente trabalho interações entre dinoflagelados potencialmente nocivos e organismos pertencentes ao zooplâncton marinho foram investigadas em dois capítulos. Capítulo 1: O presente estudo tem como objetivo avaliar a influência do dinoflagelado potencialmente nocivo Alexandrium tamiyavanichii na alimentação e reprodução do copépode planctônico marinho Temora turbinata. Taxas de produção de ovos e sucesso de eclosão naupliar foram estimadas para fêmeas alimentadas em misturas de A. tamiyavanichii e do dinoflagelado Prorocentrum minimum, tratado aqui como alimento controle. Capítulo 2: O principal objetivo deste estudo foi analisar os efeitos de exsudatos de dinoflagelados e células intactas na sobrevivência e mobilidade de táxons zooplanctônicos de uma região subtropical (Ubatuba, Brasil). Efeitos letais foram observados em cinco dos seis táxons testados, três dos quais (náuplios de copépodes, tintinídeos e larvas de gastrópodes) quando expostos a exsudatos e dois (rotíferos e larvas de braquiúros) quando expostos a células intactas. Em adição, larvas de gastrópodes demonstraram comprometimento da mobilidade após exposição à exsudatos. Apenas larvas de poliquetas não foram aparentemente afetadas no curso dos experimentos.
Harmful algae blooms have increased globally and caused impacts in aquaculture, tourism, and human health and in various aspects of ecosystem functioning. In Brazil, increasing attention has been given to this issue, because of the high potential of our waters for marine bivalve farming. Therefore, there are risks of contamination of the crops, and consequent poisoning of the consumers. This concern has led research projects to mostly focus on the detection of potentially harmful species and their toxins, with few initiatives to understand feeding interactions among species of phytoplankton and zooplankton. In this research interactions between potentially harmful dinoflagellates and marine zooplankton were investigated in two chapters. Chapter 1 - This study aims to evaluate the influence of the potentially harmful dinoflagellate Alexandrium tamiyavanichii on Temora turbinata feeding and reproduction. Egg production rates and hatching success were estimated for females fed on mixtures of A. tamiyavanichii and P. minimum. Chapter 2: The aim of this study was to analyze the effects of dinoflagellate exudates and intact cells on the survivorship and mobility of zooplankton taxa from a subtropical location (Ubatuba, Brazil). Lethal effects were observed in five out of six taxa investigated, three of which (copepod nauplii, tintinnids and gastropod larvae) when exposed to dinoflagellate exudates and two (rotifers and brachyuran zoeae) when exposed to intact cells. In addition, gastropod larvae displayed mobility impairment during exposure to dinoflagellate exudates. Only polychaete larvae were not apparently affected during the course of the experiments.

O presente estudo avalia como a estrutura e a produção da comunidade de copépodes pelágicos da plataforma interna ao largo de Ubatuba (SP, Brasil) responderam às variações ambientais durante o período de julho de 2005 a junho de 2008. Durante estes três anos, a produção secundária dos copépodes foi estudada por meio da aplicação de modelos empíricos de crescimento e de estimativas de crescimento peso-específico obtidas através de experimentos de produção de ovos. Aspectos reprodutivos de 16 espécies de copépodes (9 calanóides, 3 ciclopóides e 4 harpacticóides) foram analisados neste período, através de experimentos de incubação e de métodos indiretos de obtenção de taxas de produção e viabilidade dos ovos. A comunidade de copépodes esteve representada por 70 espécies e foi caracterizada por altos valores de riqueza, diversidade e eqüitabilidade. Os copépodes apresentaram grande variabilidade nos valores médios de densidade (4726 ± 3711 ind. m-3) e de biomassa (7,42 ± 5,64 mg C m-3) e foram dominados por espécies de pequeno porte (< 1000 µm), destacando-se as fêmeas adultas de Oncaea waldemari e os copepoditos imaturos de paracalanídeos e clausocalanídeos. Quando comparada com outros ambientes tropicais e subtropicais, a região estudada apresentou valores elevados de densidade e biomassa. Da mesma maneira, a produção secundária média apresentou variabilidade temporal elevada (1,13 ± 1,11 mg C m-3 dia-1), com uma importante contribuição dos copepoditos imaturos de espécies dispersoras de ovos. No geral, os valores médios registrados foram considerados altos quando comparado com outros ambientes tropicais e subtropicais, embora a razão Produção/Biomassa média tenha sido similar às registradas nestes locais. A intrusão periódica da ACAS parece ter sido a principal responsável pelas alterações observadas na estrutura e produção da comunidade. A maioria dos meses não influenciados pela ACAS apresentou valores de densidade, biomassa e produção inferiores às respectivas médias. Entretanto, os resultados observados sugerem que as flutuações da comunidade de copépodes podem responder não apenas à intrusão da ACAS, mas também a uma complexa conjunção de fatores, incluindo as próprias relações inter e intra-específicas. Com relação à reprodução, as espécies dispersoras de ovos apresentaram taxas médias de produção de ovos similares às obtidas em outras regiões tropicais e subtropicais, enquanto que as retentoras apresentaram valores levemente inferiores. Entretanto, foram registrados picos ocasionais de produção destas últimas espécies, sugerindo que estes copépodes possuem estratégias que compensam os meses de baixa produtividade. A reprodução de algumas espécies analisadas parece ser associada a fatores intra-específicos, tais como o tamanho dos ovos e a razão entre machos e fêmeas. Além disso, as espécies dispersoras analisadas são provavelmente influenciadas pela temperatura e pelo alimento. A relação entre os tamanhos e pesos de fêmeas e ovos de 32 espécies de copépodes pelágicos mostrou que a variabilidade interespecífica observada nessas proporções é similar à tendência observada para espécies de altas latitudes. Comparando as taxas de produção estimadas a partir das equações empíricas com as obtidas experimentalmente, observa-se diferenças expressivas nas estimativas de produção secundária, o que sugere a influência de outras variáveis além daquelas consideradas pelos modelos.
The present study evaluates how the pelagic copepod community structure and production from the inner shelf off Ubatuba (SP, Brazil) responded to environmental variability from July 2005 to June 2008. During these three years copepod secondary production was studied by the application of growth empirical models and weight-specific growth estimates obtained through egg production experiments. Reproductive aspects of 17 copepod species (10 calanoid, 3 cyclopoid and 4 harpacticoid) were analyzed through incubation experiments and indirect methods to obtain production and egg hatching success rates. Copepod community was represented by 70 species and was characterized by high values of richness, diversity and evenness. Copepods had great variability in mean abundance values (4,726 ± 3,711 ind. m-3) and biomass (7.42 ± 5.64 mg C m-3) and were dominated by small size species (< 1,000 µm), especially Oncaea waldemari adult females and immature copepodites of paracalanids and clausocalanids. When compared to other tropical and subtropical environments, the copepod community in the study area had high average abundance and biomass. Mean secondary production rates had high temporal variability (1.13 ± 1.11 mg C m-3 day-1), with an important contribution from immature copepodites of broadcast spawner species. Production values were also high but mean Production/Biomass ratios were similar when compared to other tropical and subtropical environments. The periodic SACW (South Atlantic Central Water) intrusions seem to be the main responsible for the variability in community structure and production. Most months non-influenced by SACW had abundance, biomass and production values lower than the annual average. However, copepod community fluctuations may not have responded only to SACW intrusions, but also to inter- and intra-specific relations. Broadcast spawner species had mean egg production rates similar to the ones obtained in other tropical and subtropical regions, while sac spawners showed slightly lower values. Nevertheless, occasional production peaks were recorded for the latter, suggesting that these copepods have reproductive strategies to compensate for low productivity periods. Some species reproduction traits seem to be related to intra-specific factors, such as egg size and the male/female ratio. Besides, broadcast spawners were probably influenced by temperature and food. The relationship between female and egg size and weight from 32 pelagic copepod species showed that inter-specific variability observed in these proportions was similar to those observed for high-latitude species. When reproduction rates estimated from empirical equations with those obtained experimentally are compared, expressive differences in secondary production estimates emerge, which suggests the influence of other variables in addition to those accounted for by empirical models.

Les gyres subtropicaux du Pacifique, occupant 45% de la surface des océans, sont les plus grands écosystèmes marins. La biomasse et la production phytoplanctonique sont faibles tout au long de l’année au centre de ces régions. Néanmoins, de part leur taille immense, leur contribution à la production primaire océanique globale est significative (i. E. 45%). Cependant, la variabilité temporelle de la biomasse phytoplanctonique et des flux de carbone associés reste largement méconnue. Ce constat provient de l’éloignement de ces zones où l’échantillonnage répétitif par des campagnes océanographiques est impossible. Récemment, des capteurs bio-optiques miniaturisés ont été intégrés sur des flotteurs profileurs, permettant désormais l’acquisition de variables biogéochimiques à une échelle saisonnière. Dans cette thèse, nous avons étudié la dynamique saisonnière de la biomasse phytoplanctonique et des flux de carbone associés dans les gyres subtropicaux du Pacifique en utilisant ces nouvelles plateformes. La première partie a consisté au développement de méthodes pour calibrer les propriétés optiques mesurées par les flotteurs profileurs en variables biogéochimiques. Ensuite, grâce aux observations simultanées des propriétés physiques et biogéochimiques, nous avons proposé une interprétation mécanistique de la variation saisonnière de la biomasse phytoplanctonique en fonction de changements d’éclairements et de sels nutritifs. Enfin, l’estimation des taux de production et de pertes du carbone organique particulaire à partir du cycle journalier du coefficient d’atténuation particulaire, a permis d’examiner le statut métabolique des gyres subtropicaux du Pacifique
Pacific subtropical gyres are the largest ecosystems in the ocean occupying 45 % of the surface of the ocean. Although phytoplankton biomass and primary production are low throughout the year in the center of these regions, their immense size makes their contribution to global ocean primary production significant (i. E. 45 %). However, there are a great amount of unknowns and uncertainties regarding the dynamics of phytoplankton biomass and associated carbon fluxes as well as the driving forces of these dynamics. This is due, in part, to their remoteness, implying that to date, repetitive ship-based investigations are impossible. Recently, miniaturized bio-optical sensors have been implemented on profiling floats, thus offering new observational capabilities of key biogeochemical variables at seasonal scales. During this doctoral research, we investigated the seasonal dynamics of phytoplankton biomass and associated carbon fluxes in the Pacific subtropical gyres using data from these bio-optical profiling floats. The first part of the thesis was dedicated to develop methods to retrieve biogeochemical variables from the optical parameters acquired by the profiling floats (e. G. Chlorophyll-a content). Secondly, thanks to the synchronous in-situ observations of physical and biogeochemical parameters, we proposed a mechanistic interpretation of the seasonal variation of phytoplankton biomass according to changes in irradiance and nutrients. Finally, the estimation of production and loss rate of particulate organic carbon from the daily cycle of the attenuation coefficient (a proxy of the particle load), allowed to examine the metabolic balance of Pacific subtropical gyres

Made available in DSpace on 2017-07-10T17:37:31Z (GMT). No. of bitstreams: 1 Tania Pires da Silva.pdf: 493041 bytes, checksum: 3d9daa71e02d7c679bf5b90cf21bb3c5 (MD5) Previous issue date: 2008-12-09
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
The aim of the work was to evaluate the phytotechnical performance of different rootstocks in the formation level on field conditions and the initial development of the graft, as well as the application of auxiliaries technicians to the root potential increment of the rootstocks cuttings of VR 043-43 in nursery conditions. Ligneous cuttings from grapevine VR 043-43 , measuring 20 cm, were stratified for 48h (under the temperature of 4 oC), part of the cuttings were kept under environment temperature (25 } 5 oC). All the cuttings were treated with indolbutyric acid (IBA) in different concentrations of 0, 1.000, 2.000 and 3.000 mgL-1, associated and not associated to boric acid at concentration of 150 μg L-1 for 10sec. The cuttings were planted into polyethylene plastic bags (capacity of 2,5L), filled with clay soil. They were kept in nursery made of shading screen providing 50% of luminosity. The evaluations occurred 120 days after the experiment deployment. In November, the seedlings originated from the rooted cuttings of 17 grapevine rootstocks ( SO4 , Teleki 8B , Harmony , Golia , Riparia de Traviu , Paulsen , 420 A , 99R , 5C , RR101-14 , Kober 5BB , Rupestris Du Lot , IAC 313 Tropical , IAC 766 Campinas , IAC 572 Jales , VR 043-43 and IAC 571-6 Jundiai ) were taken to the field under subtropical conditions (24o33 40 S and 54o04 12 W, 420 m height and Cfa Koppen climate, with annual maximum average temperature of 28,5 oC and minimum of 17,5 oC). After four months, it was evaluated the anthracnose and rust severity on the grapevine leaf sprouting from the rootstocks and more five months of vigor (total branch number, average diameter, biggest branch length and total leaf area fresh mass). In the sequence, it was performed winter graft using BRS Violeta . The evaluated characteristics for this part of the experiment were percentage of tissue union, diameter and graft average length, which happened after 60 days of grafting. It was concluded that the stratification of the cutting is not fundamental to increase the efficiency of the rooting process of the rootstock VR 043-43 . The cuttings should only be treated with IBA at 3.000 mg L-1 in association to boric acid. The rootstocks IAC 572 Jales and IAC 313 Tropical were resistant to the anthracnose and rust. The rootstock IAC 572 Jales was the one that showed greater performance on field, before grafting. The rootstocks SO4 , Harmony , Paulsen and IAC 766 Campinas showed greater vigor to the development of the graft BRS Violeta
O trabalho teve como objetivo avaliar o desempenho vegetativo de diferentes porta-enxertos na fase de formacao a campo e o desenvolvimento inicial do enxerto, bem como o emprego de tecnicas auxiliares para o incremento do potencial rizogenico de estacas do porta-enxerto VR 043-43 em condicoes de viveiro. Estacas caulinares lenhosas de 20 cm comprimento do porta-enxerto de videira VR 043-43 , estratificadas por 48 h (sob temperatura de 4 oC) ou não (ambiente de 25o } 5 oC), foram tratadas em solucao de acido indolbutirico (AIB) nas concentracoes de 0, 1.000, 2.000 e 3.000 mg L-1, associado ou nao com acido borico a 150 μg L-1, por 10 seg. As estacas foram plantadas em saco plastico de polietileno (capacidade de 2,5 L), contendo solo com textura argilosa como substrato e mantidas sob viveiro constituido de tela de sombreamento de 50% de luminosidade, sendo avaliadas apos 120 dias. Em novembro, mudas oriundas de estacas enraizadas de 17 porta-enxertos de videira ( SO4 , Teleki 8B , Harmony , Golia , Riparia de Traviu , Paulsen , 420 A , 99R , 5C , RR101-14 , Kober 5BB , Rupestris Du Lot , IAC 313 Tropical , IAC 766 Campinas , IAC 572 Jales , VR 043-43 e IAC 571-6 Jundiai ) foram levadas a campo, em condicoes subtropicais (24o33 40 S e 54o04 12 W, altitude de 420 m e clima Cfa Koppen, com temperatura media maxima anual de 28,5 oC e minima de 17,5 oC). Passados quatro meses, avaliou-se a severidade da antracnose e ferrugem da videira nas folhas das brotacoes dos porta-enxertos e mais cinco meses o vigor dos mesmos (numero total de ramos, diametro medio, comprimento do maior ramo e massa fresca total media dos ramos). Em seguida, realizou-se a enxertia invernal com garfos da videira BRS Violeta e avaliou-se apos 60 dias a porcentagem de pegamento, o diametro e o comprimento medio do enxerto. Concluiu-se que a estratificacao das estacas nao e fundamental para que haja maior eficiencia do processo de enraizamento do porta-enxerto VR 043-43 , devendo as estacas apenas serem tratadas com 3.000 mg L-1 de AIB, associada ao acido borico. Os porta-enxertos IAC 572 Jales e IAC 313 Tropical foram resistentes a antracnose e a ferrugem. O porta-enxerto IAC 572 Jales foi o que promoveu maior desempenho a campo, previamente a operacao de enxertia. Os porta-enxertos SO4 , Harmony , Paulsen e IAC 766 Campinas promoveram maior vigor ao desenvolvimento do enxerto de BRS Violeta

O equilíbrio ecológico dos ecossistemas aquáticos é fundamental para a conservação da biodiversidade e para que tais ambientes possam desempenhar seus serviços ambientais. O metabolismo dos riachos pode ser utilizado como um indicador funcional do nível de perturbação do ambiente, devido à influência das condições da bacia hidrográfica sobre as características e estrutura dos ecossistemas aquáticos. A presente pesquisa avaliou a variação espaço-temporal das taxas de produção primária bruta (PPB) e respiração (R) em riachos localizados no Cerrado, como subsídio para o entendimento da influência de algumas características da água, do substrato e da vegetação ripária sobre o seu metabolismo. Para isso, foram estudados seis riachos em ambientes subtropicais (São Carlos e Brotas, SP, Brasil) com diferentes condições ambientais. O metabolismo foi modelado pelas mudanças de curto prazo nas concentrações de oxigênio dissolvido (OD) e da radiação solar fotossinteticamente ativa, a cada 10 min em períodos de 24h. Além disso, a modelagem considerou o coeficiente de reaeração em cada riacho, que foi estimado por meio de traçador gasoso (SF6). Foram determinadas variáveis de qualidade da água, hidrológicas, do substrato e porcentagem de cobertura vegetal. Modelos de regressão foram utilizados, entre outras análises estatísticas, para avaliar as principais variáveis preditoras das taxas metabólicas. Os riachos apresentaram vazões sempre inferiores a 100 L.s-1, e a porcentagem de cobertura vegetal variou entre 39 e 86%. As concentrações médias de nitrogênio e fósforo totais variaram entre 0,8-1,3 mg.L-1 e 9,4-42,4 μg.L-1, respectivamente, sendo os riachos classificados entre oligo e mesotróficos. A amplitude média das variações diárias de OD foi de 0,2 a 1,2 mg.L-1. As taxas de PPB apresentaram variação de 0,01 a 0,68 gO2 m-2.dia-1. Já as taxas de R variaram entre 0,61-42,08 gO2 m-2.dia-1. A partir do balanço entre a PPB e a R, os seis riachos apresentaram condições heterotróficas (respiração excedeu a produção primária bruta, com a produção primária líquida negativa), o que torna esses ambientes mais vulneráveis ao eventual aporte de cargas orgânicas que gerem demanda por oxigênio. Embora as concentrações de fósforo tenham sido correlacionadas com as taxas metabólicas, as principais variáveis preditoras, pelos modelos de regressão, foram vazão e a porcentagem de cobertura vegetal. A cobertura vegetal provavelmente foi responsável pela redução da incidência de radiação solar e, consequentemente, o principal limitante da disponibilidade de luz subaquática para algas bentônicas. A vazão apresentou possível efeito na redução da biomassa de algas pela abrasão decorrente da velocidade da água. Espera-se que, além de gerarem um conjunto de dados sobre ambientes aquáticos de um bioma ainda relativamente pouco estudado, o Cerrado, as informações apresentadas sobre os principais fatores intervenientes nos processos metabólicos dos riachos possam oferecer direcionamentos a projetos para sua conservação e para a manutenção de seus serviços ambientais.
The ecological balance of aquatic ecosystems is fundamental for biodiversity conservation and for to perform the environmental services. Stream metabolism can be used as a functional indicator of the level of disturbance of the environment due to the influence of watershed conditions on the characteristics and structure of aquatic ecosystems. The present study evaluated the spatial-temporal variation of gross primary production (GPP) and ecosystem respiration (R) rates, in streams located in the Cerrado, as to understanding the influence of water and the substrate characteristics and vegetation in metabolism. For this, six subtropical streams (São Carlos and Brotas, SP, Brazil) were studied with different environmental conditions. The metabolism was modeled by the short-term changes in the concentrations of dissolved oxygen (DO) and the photosynthetically active solar radiation, every 10 min in periods of 24h. In addition, the modeling considers the reaeration rates in each stream, which was estimated by gas tracer (SF6). Variables of water quality, substrate, hydrological characteristics, and percentage of canopy cover were determined. Regression models were used, among other statistical analyzes, to evaluate the main predictors of metabolic rates. The streams had discharge rates lower than 100 L.s-1, and the percentage of canopy cover varied between 39 and 86%. The mean concentrations of nitrogen and phosphorus varied between 0.8-1.3 mg.L-1 and 9.4-42.4 μg.L-1, respectively, and the streams were classified as oligo and mesotrophic. The mean amplitude of daily DO variations was 0.2 to 1.2 mg.L-1. Rates of GPP ranged from 0.01 to 0.68 gO2 m-2.day-1. R rates varied from 0.61 to 42.08 gO2 m-2.day-1. From the balance between PPB and R, the six streams presented heterotrophic conditions (respiration exceeded gross primary production, with negative net primary production), which makes these streams more vulnerable to the eventual contribution of organic loads that generate demand for oxygen. Although phosphorus concentrations were correlated with metabolic rates, the main predictors of metabolic rates, by regression models, were discharge and canopy cover percentage. The canopy cover was probably responsible for reducing the incidence of solar radiation and, consequently, the main limitation of the availability of underwater light for benthic algae. The discharge indicated a possible effect on the algae biomass reduction due to the abrasion caused by the water velocity. It is expected that, in addition to the generation of data set on aquatic environments of the relatively little studied biome, the Cerrado, the information presented about the main drivers in the metabolic processes of the streams can offer directions to projects for its conservation and for the support of their environmental services.

Table grape (cv. Menindee Seedless) production from a vineyard in Emerald, Central Queensland, demonstrated a strong alternate bearing pattern in seven consecutive seasons (P < 0.02) and irregular bearing in another seven seasons. Variation in vine yield was 78–90% attributable to the variation in bunch number. A sampling methodology for estimation of vine yield was recommended, and a machine vision-based system for rapid estimation of berry number and size was introduced. Low yields were attributed to low bud fertility, with only one inflorescence primordium (IP) in fruitful buds, and to poor development of IP during hot summers. IP developmental stages stretched across two seasons, with IP initiation and development in season 1 and floral primordia formation on IP in season 2. The hypothesis that IP initiation and survival is related to carbohydrate availability was not supported by the results of a two season sucrose supplementation trial. Total non-structural carbohydrate (TNC) reserves did not recover between flowering and harvest in untreated (control) plants, and decreased in root and trunk tissues from 13.5% and 7.5% w/dw at leaf fall to 7.2% and 3.7% w/dw at flowering, respectively. A continuous low pressure (69 kPa) stem injection system delivered an average of 150 g of sucrose per season into vines estimated to contain 500 g of carbohydrate at flowering but this did not alter the root or trunk TNC reserve content. Tissue δ13C (‰) values were consistent with partitioning of injected sucrose to young shoots. The comparatively low sucrose loading and variability between vines in the field by stem injection was ascribed to necrotic xylem and a decline in hydraulic conductance. Sucrose equivalent to 37% of the total plant dry weight was introduced into shoot cuttings through transpiration flow over four days, however photosynthetic rate is decreased, limiting impact of sucrose injection on TNC status. Hydraulic conductance of shoot cuttings was enhanced about 20% by perfusion with 10 mM KCl compared to water, a result attributed to an effect on pectin hydrogels in pit membranes, but conductance nevertheless had declined by approximately 90% in 72 hours. Gibberellic acid (GA3) applied at earlier stages of flowering (10% and 30% caps-off) increased inflorescence count per vine in the following season by 93% to 122% per vine relative to a control with no GA3 application, justifying a proposed split application strategy. Future research should test the proposal that inter-seasonal yield variation in Menindee Seedless is linked to low bud fruitfulness, triggered by extreme temperatures during IP formation.

碩士
國立虎尾科技大學
生物科技系碩士班
107
Along with the advancement of science and technology, facility cultivation is becoming more and more popular, and there are lots of different kind of plants suitable for greenhouse cultivation, including. Fruits &vegetables and flowers. Baby Cherry Tomato is among of the popular products because of its low hazard ratio and level of popularity in the market. It is obvious that the competitions need to face cut-throat competition . In addition to high-quality crops, the transformation of the Sixth-Industrialization is becoming increasingly important, and the development of business models has become a major reform task. This study takes Guolai farm as the research object, applies Osterwalder & Pigneur (2012) business model as analysis theory uses in-depth interviews to explore the current state of its business model, and then explores the insights of target audience through focus group interviews, and finally through advantages-disadvantages- Opportunity-threat (SWOT) analysis, an overall business model assessment, and then provide practical advice. Focusing on the conclusion of the future business direction of the target farm, the key objectives are: 1. E-commerce platform development / IoT integration, 2. Customized service, 3. Government cooperation marketing, 4. Leisure agriculture transformation, 5. Companion development 6. Enhance visibility.

碩士
國立臺灣大學
園藝暨景觀學系
106
The red raspberry (Rubus idaeus L.) is a perennial berry crop originated in the temperate area. In recent years, the demand for fresh raspberry has been increasing in Taiwan and mostly supplied by import products from the USA. Traditional florican-fruiting raspberry cultivars are difficult to grow in the subtropical climate due to heat stress in summer and lack of chilling in winter. However, the new primocane-fruiting cultivars has brought up the possibility to produce raspberries in the warm climate. In this thesis, scheduling techniques to increase the number of flowering laterals on primocanes were tested. In addition, photosynthetic heat tolerance mechanisms of raspberries were investigated by comparing a primocane-fruting cultivar with three relative subtropical species native to low land Taiwan. In chapter two, a scheduling production trial was conducted from October 2016 to February 2017. Shoot bending and night breaking treatments to induce lateral shoots on primocanes and winter harvest were tested in raspberry ‘Summer Festival’ grown in a greenhouse in Taipei. The results showed that neither treatments promoted flowering or lateral development. Most laterals were emerged from 20th -40th node on the primocanes and had the highest flower number per lateral. During the experiment period, the high relative humidity in the greenhouse resulted in poor pollination and servere fungus disease. In chapter three, photosynthesis of the raspberry and three native subtropical species in the same subgenus Idaeobatus were evaluated in July 2017. Gas exchange and chlorophyll fluorescence were simultaneously measured at 25, 30, or 35℃. Light response curves and CO2 response (A/Ci) curves were obtained and key photosynthetic variables were fitted with a modified FvCB model. Differences in net assimilation rate among different species and environmental factors were partitioned into the correspondence of each variable by a numerical integration method. At 35℃under PPFD=1200 μmol·m-2·s-1, the raspberry had the lowest net assimilation rate. The results from partitioning indicated that diffusional factors in the FvCB model were the main contributor to the differences, and stomatal conductance and mesophyll conductance each contributed about 50% of the total difference. Biochemical factors such as the maximum value of carboxylation and electron transportation rate increased in all species as the temperature increased and their contributions to net assimilation differences were little. Temperature differences between leaf surface and the air showed that the native species had a more efficient transpiration cooling mechanism at 35℃ than the raspberry.

碩士
國立臺灣大學
園藝暨景觀學系
107
Biochar is porous co-product from pyrolysis of organic matters. It has been used in soil amendment to improve soil properties and microbial composition, thus increasing crop vigor and productivity. However, the effect of biochar on strawberry growth and production in Taiwan had not been evaluated. This research included two experiments of biochar effects in strawberries. In the first experiment, the effects of biochar amendment on growth, development, and fruit production in greenhouse grown strawberry production was evaluated. Runner plants of ‘Taoyuan No.1’ strawberry were planted in soilless medium without extra amendment or amended with 2.5% or 5.0% (v./v.) biochar made of water caltrop (Trapa natans L.) husk or wood. Biochar improved total leaf area, fresh and dry weight of plants but reduced fruit weight, total yield and the percentage of large fruit. Total soluble solids content of the fruit was not affected. The result indictated that when the substrate was regularly fertigated, biochar amendments improved early vegetative growth in greenhouse strawberry cultivation but had no benefits on fruit production. In the second experiment, effects of incorporating water caltrop husk biochar and molasses in pre-planting soil solarization on growth and fruit production of ‘Aroma’ and ‘Tien-Lai No.1’ strawberry were investigated. Compared to separated treatment of biochar or molasses, the combination of both materials resulted in higher total leaf area, SPAD value, early fruit production, fruit weight, and the percentage of large fruits. Total soluble solids content of the fruit was not affected. Results showed that the combination biochar with molasses in pre-planting soil solarization is a promising approach for organic strawberry production. Overall, biochar amendment combining other materials, such as liquid fertilizers or easily degradable carbon sources, has potentials in improving strawberry growth in Taiwan. However, fertilizer management has to be evaluated based on the cultivation system.

Industrial hemp (Cannabis sativa L.) production is experiencing a significant increase in worldwide production since regaining popularity in many countries since the 1990's. Currently, production in Australia is very limited, and no major grain or fibre processing facilities yet exist, owing to the lack of suitable low THC (A9-tetrahydrocannibinol) varieties. Hemp production in subtropical regions of Australia is particularly limited as short day lengths (photoperiods) result in early plant maturity, and thus, poor yielding crops. The aim of this research is to determine the viability of a new variety of hemp, bred specifically for subtropical production whilst determining the effects of day length and plant density on yield and flowering time. Trials were conducted in Bundaberg, QLD in 2010-2012 in both field and controlled environment (plastic house) settings. Plant densities of 100, 200, 300 and 400 plants m-2 were compared for fibre production and densities of 50, 80, 100 and 150 plants m2 were compared for grain production to assist in the establishment of appropriate commercial sowing rates. Harvested fibre yields were greatest at 300 plants m2 whereas grain yields were greatest at 150 plants m2, with the potential of even higher yields at densities greater than 150 plants m2. Photoperiod experiments were conducted in a controlled plastic house evaluating plant responses to varying photoperiods. Treatments comparing ambient day length, 13 hour 40 minute fixed photoperiod and 14 hour 40 minute fixed photoperiod determined that a 13 hour 40 minute photoperiod did not significantly prolong vegetative growth compared to natural day lengths in the hemp variety BundyGem but at 14 hours 40 minutes maturity times were significantly delayed, thereby contributing to greater plant height and fibre yield. Previous research also suggests that a critical photoperiod of between 14 and 16 hours is required before flowering is delayed in hemp. This theory was supported by a field experiment whereby successive plantings of BundyGem throughout the spring/summer period of 2011/2012, flowered at the same age despite subtle changes in day length for the growing period (never exceeding 13 hours 40 minutes). This research confirms that subtropical fibre hemp is not yet suitable for subtropical production in Australia with existing varieties due to the limitation of photoperiod on yield. Grain production may still be viable despite early plant maturity with yields comparable with those produced in Europe and Canada.

博士
國立中央大學
國際研究生博士學位學程
103
Nitrification is an important intermediate process in nitrogen cycle that oxidizes ammonia to nitrite and/or nitrate and produces N2O as byproduct. Currently, nitrification has been recognized as the major source of N2O, which is regarded as one of the main greenhouse gases. Since 19th century, excessive use of chemical synthesized nitrogenous fertilizer has elevated the total amount of nitrogen in environments. The excess nitrogen remained in soil and leached into aquatic environments may be transformed to N2O through nitrification. In addition, the enhanced soil erosion can elevate the suspended particles in aquatic environments. In this dissertation we determined the rate of nitrification (NR) in turbid environments by the stable isotope tracer method to investigate the role of suspended particles on nitrification and N2O production. In the subtropical mesotrophic Feitsui Reservoir, high NR and N2O were recorded in the aphotic zone where rare ammonium and high particle sinking flux occurred. These fast-sinking particles in the aphotic zone was dominantly brought from the turbid interflows induced by heavy precipitation during cold season and typhoon periods. The light-sensitive nitrifying microorganisms may utilize the remineralized organics on those particles as substrate source for nitrification and also N2O production. In Chang Jiang River plume, simultaneous measurement of NR and community respiration rate (CR) revealed that the oxygen demand of nitrification was greater than that of community respiration. However, the amounts of reactive Fe/Mn oxide of suspended particles seemed enough to support oxidant demand of nitrification. Meanwhile, the reactive Fe/Mn was significantly positive correlated to NR, indicating that the reactive Fe/Mn may serve as an alternative electron acceptor in nitrification. Moreover, the production rate of N2O from ammonium in the turbid river mouth is significantly higher than that in other relatively clear regions. The results suggested that the elevated suspended particles in aquatic environment due to soil erosion may enhance nitrification and also N2O production. Consequently, the increasing N2O may potentially accelerate the global warming.

博士
國立中央大學
國際研究生博士學位學程
106
An 11- year investigation of the free-living and attached bacterial production, abundance and specific growth rates in a mineral-limited, subtropical freshwater system revealed large variability in the dynamics that is influenced by temperature and substrate availability. Temperature has a significant positive effect on bacterial production at several spatial and temporal (hours, seasonal, interannual and decadal) scales; but the effect is modified by the availability of substrate. Free-living and attached bacteria showed dissimilar response to temperature shifts (increasing and decreasing temperature) with a decline in free-living BP during the warmest months. This may be brought about by the limitation and co-limitation with carbon, nitrogen and phosphates that was confirmed during the laboratory manipulation experiments. In addition to thehourly, seasonal, interannual and decadal controls of bacterial production, it was also revealed that episodic events can influence the dynamics of free-living and attached bacteria. Heavy precipitation from strong typhoons caused changes in the dynamics of particulate organic compounds and phosphate which benefitted the attached more than the free-living bacteria. The previously reported dissimilar abilities of the two bacterial lifestyles to process organic matter and the observed dissimilar response to environmental controls showed how the attached bacteria can dominate the total production. This can have important consequences on the assessment of microbial processing of organic matter.

碩士
國立雲林科技大學
工業化學與災害防治研究所碩士班
89
Xylitol is a sugar alcohol which is widely distributed in nature and is also and intermediate of human or mammal metabolic function. Recently, it has drawn greet attention as it can be used as a sweetner in the diet for diabetics, besides, it can prevent dental caries. Some other advantages using xylitol include high solubility and high degree of sweetness. Previously xylitol was produced by chemical process which gave low yield and was difficult to recover it. Since 1980, production of xylitol was shifted to fermentation process since this method showed high yield, less by-product and fast production rate. This study utilizes Candida subtropicalis for xylitol production. Fermentation condition such as substrate concentration, nitrogen source and concentration, temperature, pH, cell concentration, and dissolved oxygen were studied in detail. After the best fermentation conditions were determined, fermentation was performed in a 4L fermentor to determine the optimum mixing rate, kLa, and the effect of dissolved oxygen concentration. The effect of fermentor operating conditions on xylitol yield, xylitol production rate and xylose consumption rate were also investigated. Optimum kLa value was obtained by varying aeration rate and impeller mixing rate in order to understand oxygen mass transfer rate on xylitol production. In batch fermentation conducted in a rotary shaker, production yield of 70% was achieved when temperature was controlled at 30-35℃ and pH was around 4-6. Yeast extract still is the best nitrogen source although 1% soy bean powder hydrolyzed by KOH at 121℃ can perform fairly well giving 62% yield. Initial cell concentration does not affect significantly on production yield. The best shaker speed found to be 150 rpm. As for fermentor operation is concerned, the mixing rate of 300 rpm and the aeration rate of 0.2 vvm can give the highest production rate with good xylitol yield. This culture is a microaerobic and prefers a kLa of 10-15 hr-1 for xylitol production.

碩士
大葉大學
生物產業科技學系
93
Abstract Recently, it was cared by the most population that the functionality in food including the nutrient balance, the promotion in body, and so on. Xylitol, because of its taste of dew likes peppermint, low quantity of heat, the sweetening equals to the sucrose, and anti-cariogenic properties, has been appreciated gradually in the food of new generation. Otherwise, the agricultural residual production abounds with cellulose, hemicellulose, and lignin. When the hemicellulose was hydrolyzed, abundant raw materials like xylose, glucose, and few other sugars (e.g., galactose, mannose, and arabinose) was productive. Hence, the subject of several investigates on the fermentation process for productive of xylitol was discussed the liquid of the lignomicellulose hydrolyzed as the stock. Therefore, it not only reduces cost but also exploits nature resource by the sufficient disposal. In this study, in order to increase the yield and productivity of xylitol in ferment process by yeast, a two-stage fermentation that employ difference concentrations of dissolved oxygen was proposed due to the phenomenon of the diauxic growth when two kinds of main sugar (xylose and glucose) as substrate was used. Results explained that it is increased in xylitol’s yield and productivity when the two composite substrates were applied. According to the object of increasing the biomass yield at first-stage fermentation, the dissolved oxygen was 5~10% for glucose metabolism (μ = 0.356 hr-1). Moreover, at second-stage, metabolism of D-xylose into xylitol, the conditions of the fermentation were 0.25vvm and 130 rpm for the highest yield (0.649 g g-1) and productivity (0.263 g L-1 hr-1) of the xylitol. Based on above of results, an operation procedure that is series connection the fed-batch culture and batch culture was designed. Results of the experiment displayed that xylitol’s yield (0.246 g L-1 hr-1) had been increased effectively. Key world: two-stage fermentation, xylitol, dissolved oxygen, lignocellulose hydrolyzates, and diauxic growth.