This study was undertaken to determine the effect of vegetation structure (the ratio of re-seeding to re-sprouting plants) on post-fire catchment water yield. Plant communities are the only components of mountain catchments which can be manipulated to augment water supplies on any practical scale. Burning, which is one of the options available to catchment managers, reduces plant biomass and increases water yield by reducing transpiration and interception losses. Communities dominated by re-seeding species tend to recover more slowly after fires than when sprouters predominate. The rate of vegetation recovery will determine the rate at which streamflow returns to pre-fire levels. Sprouters may use more water than seeders in the early post-fire period by virtue of their greater leaf area, which both increases interception and transpiration losses. Leaf area development could be used as a simple determinant of post-fire water yield if transpiration losses per unit leaf area are similar in seedlings and sprouters. In this study, a comparison was made of the transpiration rates of seedlings and sprouters of Protea nitida after a fire in Swartboskloof (Cape Province) in 1987. Plant water potentials were determined (index of the degree of stress) and leaf stomatal conductances were measured. Results indicate that transpiration rates are similar throughout the year except during the short summer drought period when the seedlings have comparatively low transpiration rates (< 1 mmo1 m-2 s-1 compared to 2-3 mmo1 m-2 s-1 of the sprouter), and i immediately after the first winter rains where the seedlings have comparatively high rates (approxi.mately 4 mmol m-2 s-1 compared to 2 mmol m-2s-1.) The 1ow summer rates are thought to be the result of drought stress induced by limited water supply and the shallow root systems of the seedlings. The higher winter rates suggest that the shallow surface roots of the seedlings respond quickly to increased surface moisture. Differences in root structure (Le. shallow seedling roots and well-developed deep sprouter roots) rather than regeneration mode appear to be responsible for the marginal differences observed in transpiration rates. These differences are expected to disappear as seedling roots develop and occupy the profile. Leaf area could therefore, be used as a determinant of catchment water yield. / Thesis (M.Sc.)-University of Natal, 1990

Bibliography: leaves 187-216 / xxi, 216 leaves : ill ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Plant Physiology, 1987

Incldes bibliographical references / 1 v. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Agronomy, Waite Agricultural Research Institute, 1989

[Truncated abstract] Mitochondria play an essential role in diverse metabolic pathways in plants. Their primary roles are the oxidation of organic acids via the tricarboxylic acid cycle and the synthesis of ATP coupled to the transfer of electrons from reduced NAD+ to oxygen via the electron transport chain. Plant mitochondria also contain nonphosphorylating bypasses of the respiratory chain, catalysed by the alternative oxidase (AOX), type II NAD(P)H dehydrogenases (NDHs) and uncoupling proteins (UCPs). Each of these components bypasses energy conservation by either circumventing the formation or utilization of the electrochemical proton gradient, and each is encoded by a small gene family in Arabidopsis. It is proposed that the alterative pathways are likely to be involved in balancing cellular redox and energy status and in minimizing the production of ROS generated by over-reduction of basal respiratory chain components. Furthermore the alternative respiratory pathways are thought to play a role in plant responses to stress. In this study a transcriptomic approach was taken to investigate the role of the alternative respiratory pathways in Arabidopsis, with a focus on elucidating the role and regulation of the AOX gene family. Analysis of the expression of the five AOX genes in Arabidopsis over development and in a range of tissues revealed a unique spatiotemporal expression pattern for each gene. Expression profiling using quantitative RT-PCR, MPSS and microarrays detected an abundance of the AOX1a transcript throughout the plant and over development. The expression patterns of other AOX genes provide insight into their putative roles, AOX1b was expressed predominantly in the flower, AOX1d was particularly abundant in senescing leaves and AOX2 expression was only observed in the seed.

Made available in DSpace on 2014-06-11T19:26:47Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-02-24Bitstream added on 2014-06-13T20:34:45Z : No. of bitstreams: 1 000755829.pdf: 2108564 bytes, checksum: 4f4daa3d9e0c5226baf19fdd8a878477 (MD5) / Dentre aspectos mais importantes para o sucesso da agricultura irrigada destaca-se o manejo da água aplicada. No mercado existe uma diversidade de metodologias e instrumentos para tal fim, entretanto, o monitoramento do nível de água no solo utilizando o tensiômetro tem se mostrado eficaz. Nesse trabalho foram avaliados dois métodos de manejo da irrigação conhecidamente de baixo custo, um baseado na tensão da água no solo e o outro com base da depleção da água disponível, com o objetivo de verificar qual deles promove maior produtividade de grãos para a cultura do feijoeiro (Phaseolus vulgaris L.) em três diferentes texturas de solo. O experimento foi dividido em três ensaios, cada um correspondendo a uma textura de solo (arenosa, média e argilosa). Os tratamentos foram compostos por cinco níveis de tensão (– 30, – 40, – 50, – 60 e – 70 kPa) e cinco níveis de depleção (30, 40, 50, 60 e 70% da AD), com quatro repetições delineados em blocos casualizados. O experimento foi desenvolvido em ambiente protegido no Departamento de Solos e Recursos Ambientais (UNESP/FCA), Botucatu - SP. Avaliou-se os parâmetros: Número de vagens por planta (NVP); Produção de vagens por planta (PVP, g); Comprimento da vagem (COMPV, cm); Número de grãos por vagem (NGV); Peso de grãos por vagem (PGV, g); Peso de 100 grãos (P100G, g) e Produção de grãos (PG, g planta-1). Para o solo de textura arenosa não foram encontradas diferenças significativas entre os métodos de irrigação, entretanto, as maiores produtividades de grãos de feijão deram-se para a tensão de – 30 kPa, resultando em 12,10 g planta-1 e 11,04 g planta-1 para 40% da AD. No solo argiloso os melhores resultados foram obtidos com a utilização do método da depleção, pois a produtividade de grãos atingiu 15,36 g planta-1 em 30% da AD, diferindo do solo de textura média onde o oposto foi verificado utilizando... / One of the most important contributors to the success of irrigated agriculture is an efficient management of the water applied by irrigation. Despite indirectly evaluating the water deficit of a produce, soil water tension control has proven to be effective. This study tested which of the irrigation management criteria, tension or depletion-based, yields a greater productivity from crops of the common bean Phaseolus vulgaris. The experiment was conducted in three different soil textures and for that, three tests were needed, one for each texture (sandy, medium and clay). Treatments comprised of five tensions (– 30, – 40, – 50, – 60 and – 70 kPa) and five levels of depletion (30, 40, 50, 60 and 70% of AD), with four replications designed in randomized blocks. The experiment took place in a protected environment in the Natural Resources / Soil Sciences Department (22º30’ S; 48°15’ W and 830 meters) within the Lageado Experimental Farm, property of Faculdade de Ciências Agronômicas of UNESP – Campus of Botucatu, São Paulo State. The following variables were analyzed: number of pods per plant (NVP); Pod production per plant (PVP, g); Pod length (COMPV, cm); Number of grains per pod (NGV); Grain weight per pod (PGV, g); weight of 100 grains (P100G, g) and grain production (PG, g plant-1). The irrigation management using the tension criterion showed the highest production rate in the sandy soil with a tension of – 30 kPa, resulting in 12.10 g plant-1; the clay soil reached a productivity rate of 13.8 g plant-1 corresponding to a – 30 kPa tension. The medium-textured soil resulted in 12.11 g plant-1 for a tension of – 30 kPa. In regard to water depletion in the soil, the highest bean productivity rate for clay soil was 15.36 g plant-1 to 30% of AD. The highest rate in sandy soil was 11.04 g plant-1 to 40% AD and finally, the medium-textured soil had a 30% depletion that produced ...

Orientador: Hélio Grassi Filho / Banca: Antônio de Padua Sousa / Banca: Rodrigo Domingues Barbosa / Resumo: Dentre aspectos mais importantes para o sucesso da agricultura irrigada destaca-se o manejo da água aplicada. No mercado existe uma diversidade de metodologias e instrumentos para tal fim, entretanto, o monitoramento do nível de água no solo utilizando o tensiômetro tem se mostrado eficaz. Nesse trabalho foram avaliados dois métodos de manejo da irrigação conhecidamente de baixo custo, um baseado na tensão da água no solo e o outro com base da depleção da água disponível, com o objetivo de verificar qual deles promove maior produtividade de grãos para a cultura do feijoeiro (Phaseolus vulgaris L.) em três diferentes texturas de solo. O experimento foi dividido em três ensaios, cada um correspondendo a uma textura de solo (arenosa, média e argilosa). Os tratamentos foram compostos por cinco níveis de tensão (- 30, - 40, - 50, - 60 e - 70 kPa) e cinco níveis de depleção (30, 40, 50, 60 e 70% da AD), com quatro repetições delineados em blocos casualizados. O experimento foi desenvolvido em ambiente protegido no Departamento de Solos e Recursos Ambientais (UNESP/FCA), Botucatu - SP. Avaliou-se os parâmetros: Número de vagens por planta (NVP); Produção de vagens por planta (PVP, g); Comprimento da vagem (COMPV, cm); Número de grãos por vagem (NGV); Peso de grãos por vagem (PGV, g); Peso de 100 grãos (P100G, g) e Produção de grãos (PG, g planta-1). Para o solo de textura arenosa não foram encontradas diferenças significativas entre os métodos de irrigação, entretanto, as maiores produtividades de grãos de feijão deram-se para a tensão de - 30 kPa, resultando em 12,10 g planta-1 e 11,04 g planta-1 para 40% da AD. No solo argiloso os melhores resultados foram obtidos com a utilização do método da depleção, pois a produtividade de grãos atingiu 15,36 g planta-1 em 30% da AD, diferindo do solo de textura média onde o oposto foi verificado utilizando... / Abstract: One of the most important contributors to the success of irrigated agriculture is an efficient management of the water applied by irrigation. Despite indirectly evaluating the water deficit of a produce, soil water tension control has proven to be effective. This study tested which of the irrigation management criteria, tension or depletion-based, yields a greater productivity from crops of the common bean Phaseolus vulgaris. The experiment was conducted in three different soil textures and for that, three tests were needed, one for each texture (sandy, medium and clay). Treatments comprised of five tensions (- 30, - 40, - 50, - 60 and - 70 kPa) and five levels of depletion (30, 40, 50, 60 and 70% of AD), with four replications designed in randomized blocks. The experiment took place in a protected environment in the Natural Resources / Soil Sciences Department (22º30' S; 48°15' W and 830 meters) within the Lageado Experimental Farm, property of Faculdade de Ciências Agronômicas of UNESP - Campus of Botucatu, São Paulo State. The following variables were analyzed: number of pods per plant (NVP); Pod production per plant (PVP, g); Pod length (COMPV, cm); Number of grains per pod (NGV); Grain weight per pod (PGV, g); weight of 100 grains (P100G, g) and grain production (PG, g plant-1). The irrigation management using the tension criterion showed the highest production rate in the sandy soil with a tension of - 30 kPa, resulting in 12.10 g plant-1; the clay soil reached a productivity rate of 13.8 g plant-1 corresponding to a - 30 kPa tension. The medium-textured soil resulted in 12.11 g plant-1 for a tension of - 30 kPa. In regard to water depletion in the soil, the highest bean productivity rate for clay soil was 15.36 g plant-1 to 30% of AD. The highest rate in sandy soil was 11.04 g plant-1 to 40% AD and finally, the medium-textured soil had a 30% depletion that produced ... / Mestre

D.Litt et Phil. (Clinical Psychology) / Please refer to full text to view abstract

Thesis (Ph. D.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2011. / Cataloged from PDF version of thesis. / Includes bibliographical references. / Corals are increasingly threatened by warming sea surface temperatures and other anthropogenic changes. The delicate symbiosis between corals and their algal endosymbionts (zooxanthellae) is easily disrupted by thermal stress, leading to bleaching and eventual mortality. The use of lipid ratios as biomarkers of environmental conditions is well established. Coral biomass contains abundant lipids, and the potential of lipid parameters to diagnose thermal tolerance in zooxanthellae has been previously suggested. In this thesis, I explore the response of specific fatty acids, sterols, and thylakoid membrane lipids to thermal and disease stress in zooxanthellae grown in culture, as well as those isolated from living corals. I present the discovery of a bioactive thylakoid lipid within zooxanthellae cells, and show how this compound is selectively mobilized in thermally stressed cells. I present a plausible mechanism for the breakdown of this compound into products that may cause apoptosis and disrupt the coral-algal symbiosis, eventually causing bleaching. I present two new lipid biomarkers of thermal stress in zooxanthellae, the C18 fatty acid unsaturation ratio, and the fatty acid to sterol ratio. I calibrate the decline of these two parameters to levels of thermal stress comparable to those needed to cause bleaching. I further show that these parameters are sensitive to pathogen stress as well. In several case studies of diseased and thermally stressed corals, I demonstrate that these lipid biomarkers of coral stress may be applied to zooxanthellae isolated from environmental samples. I show that these same compounds are preserved within coral aragonite, which opens up the potential to retrieve lipid-based historical records of coral health from annual layers of coral skeleton. This work demonstrates the value of using lipid biomarkers to assess coral health and better understand the biochemical mechanisms of coral bleaching. / by Jessie Mary Kneeland. / Ph.D.

No description available.

The influence of experience during brain development was investigated on juvenile behavior, adult amphetamine sensitization, and neuronal structural plasticity in rats. Two experiential factors (i.e., tactile stimulation and stress) were studied either before or soon after birth. Early experience feminized social behavior in males; however, only stress enhanced anxiety-like behavior in males. Repeated amphetamine administration resulted in the development and persistence of behavioral sensitization. However, tactile stimulation attenuated the drug-induced behavioral sensitization whereas stress failed to influence the degree of sensitization. Neuroanatomical findings revealed that early experience altered the cortical and subcortical structures. Furthermore, drug exposure reorganized the brain structures involved in addiction but early experience prevented the drug-associated changes. Early adverse experience influences the subsequent exposure to a drug of abuse at anatomical level whereas a favorable experience has an effect both at behavioral and anatomical levels and thus may play a protective role against drug-induced sensitization and addiction. / xii, 263 leaves : ill. ; 29 cm