963 resultados para Eucalyptus grandis - Crescimento


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Pós-graduação em Agronomia (Energia na Agricultura) - FCA

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Pós-graduação em Agronomia (Energia na Agricultura) - FCA

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Pós-graduação em Agronomia (Irrigação e Drenagem) - FCA

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Pós-graduação em Agronomia (Proteção de Plantas) - FCA

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Pós-graduação em Ciências Biológicas (Botânica) - IBB

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This study aimed to evaluate the effect of thermal treatment on the physical properties of juvenile and mature woods of Eucalyptus grandis. Boards were taken from 30-year-old E. grandis trees. The boards were thermally modified at 180 °C in the Laboratory of Wood Drying and Preservation at UNESP, Botucatu, Sao Paulo state, Brazil. The results showed that thermal modification caused: (1) decrease of 6.8% in the density at 0% equilibrium moisture content of mature wood; (2) significant decreases of 14.7% and 35.6% in the maximum volumetric swellings of juvenile and mature woods, respectively; (3) significant decreases of 13.7% and 21.3% in the equilibrium moisture content of juvenile and mature woods, respectively. The influence of thermal modification in juvenile wood was lower than in mature wood and caused greater uniformity in the physical variations between these types of wood in E. grandis.

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In this study, we aimed evaluate the behavior of the brown-rot fungus Gloeophylum trabeum and white-rot fungus Pycnoporus sanguineus on thermally-modified Eucalyptus grandis wood. To this end, boards from five-year-eleven-month-old E. grandis trees, taken from the Duratex-SA company stock, were thermally-modified between 180 ºC and 220 ºC in the Laboratory of Wood Drying and Preservation at Universidade Estadual Paulista - UNESP, Botucatu, Sao Paulo state Brazil. Samples of each treatment were tested according to the ASTM D-2017 (2008) technical norm. The accelerated decay caused by the brown-rot fungus G. trabeum was compared with the decay caused by the white-rot fungus P. sanguineus, studied by Calonego et al. (2010). The results showed that (1) brown-rot fungus caused greater decay than white-rot fungus; and (2) the increase in temperature from 180 to 220 ºC caused reductions between 28.2% and 70.0% in the weight loss of E. grandis samples incubated with G. trabeum.

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Although highly weathered soils cover considerable areas in tropical regions, little is known about exploration by roots in deep soil layers. Intensively managed Eucalyptus plantations are simple forest ecosystems that can provide an insight into the belowground growth strategy of fast-growing tropical trees. Fast exploration of deep soil layers by eucalypt fine roots may contribute to achieving a gross primary production that is among the highest in the world for forests. Soil exploration by fine roots down to a depth of 10 m was studied throughout the complete cycle in Eucalyptus grandis plantations managed in short rotation. Intersects of fine roots, less than 1 mm in diameter, and medium-sized roots, 1-3 mm in diameter, were counted on trench walls in a chronosequence of 1-, 2-, 3.5-, and 6-year-old plantations on a sandy soil, as well as in an adjacent 6-year-old stand growing in a clayey soil. Two soil profiles were studied down to a depth of 10 m in each stand (down to 6 m at ages 1 and 2 years) and 4 soil profiles down to 1.5-3.0 m deep. The root intersects were counted on 224 m(2) of trench walls in 15 pits. Monitoring the soil water content showed that, after clear cutting, almost all the available water stored down to a depth of 7 m was taken up by tree roots within 1.1 year of planting. The soil space was explored intensively by fine roots down to a depth of 3 m from 1 year after planting, with an increase in anisotropy in the upper layers throughout the rotation. About 60% of fine root intersects were found at a depth of more than 1 m, irrespective of stand age. The root distribution was isotropic in deep soil layers and kriged maps showed fine root clumping. A considerable volume of soil was explored by fine roots in eucalypt plantations on deep tropical soils, which might prevent water and nutrient losses by deep drainage after canopy closure and contribute to maximizing resource uses.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Wood basic density (BD) is related to other wood characteristics and its determination is important in forest inventory, though BD must be differentiated from the apparent density (AD), which relates to the moisture content (MC) of wood. The aim of this study is to demonstrate a reliable conversion from BD to AD for any MC of Eucalyptus grandis wood based on two exponential and linear models that relate volumetric shrinkage to MC. To this end, wood specimens were submitted to drying and the volumetric shrinkage was determined as a function of MC. The two models proved to be efficient in the conversion of BD to AD and vice versa.

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The process of milling wood is widely used in operations such as planing and manufacturing frames . Machines like planers , desengrossadeiras , routers , moldureiras and machining centers employ the milling process for cutting wood . In this work the process of milling CNC machining center of Eucalyptus grandis was studied because this is very much used in furniture , but without consistent studies on this process . This work a CNC machining center brand TECH Z1 for analysis of surface quality ( Ra ) in relation to the variation of cutting speed and feed in concordant and discordant tangential milling and face milling was used . We used Eucalyptus grandis . Four forward speeds ( 3, 5 , 7, and 9 m / min ) for four shear rates ( 5,9; 8,4; 10,9 and 13,4 m/s ) were used. Was used for testing a cutter finishing top speed steel with helical teeth 16mm in diameter . 6 repetitions for each test condition were performed . From the results it was observed that the best results for roughness Vc = 10,9 m / s were obtained for the milling concordant with the forward speed Vf = 7 m / min. As for Vf = 5 m / min the best finish was achieved with Vc = 8,4 m /s in discordant for milling . The feedrate and cutting influenced the roughness . The senses of concordant and discordant and cut the top and the top had a significant difference in roughness

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A biotecnologia define-se pelo uso de conhecimentos sobre os processos biológicos e sobre as propriedades dos seres vivos, com o fim de resolver problemas e criar produtos de utilidade. É importante frisar que uma das principais vantagens da biotecnologia moderna voltada para a área vegetal é a de poder gerar estratégias de melhoramento aplicáveis a diferentes culturas. Uma das principais estratégias de ação nessa área trata da produção de plantas geneticamente modificadas com transgenes de interesse. Nesse contexto, a identificação e caracterização de promotores com padrão de expressão tecido-específico é essencial para que a expressão de tais transgenes em plantas de interesse agronômico e florestal, como em eucalipto, fique limitada a determinados órgãos/tecidos. Assim, o presente trabalho teve por objetivo clonar e sequenciar a região promotora de um gene com expressão específica em raiz de eucalipto cujo produto gênico tem similaridade a uma aquaporina. Uma vez clonado, o promotor foi introduzido em vetor binário e inserido em plantas de tabaco visando a sua caracterização funcional. Além disso, a expressão do gene em estudo foi investigada em eucalipto, e uma analise filogenética comparativa com outras angiospermas foi empreendida