oalib
Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Efficiency of phosphorus use in young plants of Eucalyptus urophylla S. T. Blake  [PDF]
Thais Galhardo Godoy,Sebasti?o Carlos da Silva Rosado
CERNE , 2011,
Abstract: The objective of this study is to select superior genotypes for efficiency of phosphorus use in seedlings of Eucalyptus urophylla, correlating them with initial height growth in the field, at age eight months. A completely randomized block design was used in the nursery, consisting of eight clones, three replicates and four plants per plot. The same design was used in the field, consisting of eight clones, four replicate blocks and nine plants per plot. Data being collected in the nursery at age 120 days included: phosphorus concentration in shoot (CPPA); phosphorus concentration in root (CPR); phosphorus content in shoot (CtPPA); phosphorus content in root (CtPR); total phosphorus content in seedling (CtPT); phosphorus use efficiency in shoot (EUP-PA); phosphorus use efficiency in root (EUP-R) and total phosphorus use efficiency (EUP-T). Analyses of variance showed significant genetic differences among clones for all traits and, given the high heritability values found, estimated genetic gains were generically very high. As regards predicted indirect genetic gain, it was noted that selection on nursery seedlings for all EUPs provided the highest values of indirect gain in height of field seedlings.
Longitudinal and radial variation of extractives and total lignin contents in a clone of Eucalyptus grandis W.Hill ex Maiden x Eucalyptus urophylla S. T. Blake  [PDF]
Marina Donária Chaves Arantes,Paulo Fernando Trugilho,José Tarcísio Lima,Angélica de Cássia Oliveira Carneiro
CERNE , 2011,
Abstract: The objective of this work was to determine concentrations of extractives and total lignin along with their radial and longitudinal variations in wood from a clone of Eucalyptus grandis W.Hill ex Maiden x Eucalyptus urophylla S. T. Blake at age six years. Longitudinal samples were taken at 2%, 10%, 30% and 70% of the commercial height of trees, and radial samples were taken from each longitudinal position, the number of samples depending on the diameter of each disk. Results led to the conclusion that, overall, concentrations of extractives and total lignin in the wood tended to decrease with increasing distance from the pith and tended to increase in portions closer to the tree base.
Estimativa da biomassa e do comprimento de raízes finas em Eucalyptus urophylla S.T. Blake no município de Santa Maria-RS
Witschoreck, Rudi;Schumacher, Mauro Valdir;Caldeira, Marcos Vinicius Winckler;
Revista árvore , 2003, DOI: 10.1590/S0100-67622003000200008
Abstract: this study aimed to estimate the amount of biomass and the length of fine roots (< 2mm of diameter) in different soil depths for the 10 -year-old species eucalyptus urophylla s.t. blake. the experiment was conducted santa maria, rs on the campus of the federal university of santa maria. the plots were 27 m long and 14 m wide and 3 m x 2 spaced. four monoliths of 25 cm x 25 cm x 60 cm were sampled and divided into six geometric sections at depths of 0-10, 10-20, 20-30, 30-40, 40-50, 50-60 cm. roots were separated from the soil by using a set of two sieves (2 mm and 1 mm) and water jets. the intersection method was used to determine root length producing photos with the use of a scanner. the results showed a high concentration of fine roots in the first 20 cm of the soil. fine root total biomass found for eucalyptus urophylla was 1.451,6 kg/ha, 57.9% were concentrated in the first 20 cm of soil. the total length of fine roots was 27.968,9 km/ha, with 64.3% being in the first 20 cm of depth.
Morphological characterization of calli of Eucalyptus urophylla S. T. Blake subjected to concentrations of boron and calcium  [PDF]
Raquel Trevizam,Gilvano Ebling Brondani,Felipe Uassurê Nery,Antonio Natal Gon?alves
CERNE , 2011,
Abstract: This study aimed to evaluate the effect of B and Ca concentrations on morphological responses and size of calli in Eucalyptus urophylla. Calli were obtained from the mid portion of hypocotyls removed from in vitro germinated seedlings. The callus structures were cultivated for 21 and 31 days, being kept in a modified N7 medium with concentrations of B (0; 25; 50; 100 and 200 μM H3BO3) and Ca (0; 3.75; 7.5; 11.25 and 15 mM CaCl2.2H2O). Size of calli, presence of roots, friability, viscosity, presence of globular structures on the surface and presence of pigments were analyzed. Overall, the shorter culture period (21 days) allowed better development of callus structures. The combination of 50 μM H3BO3 with 7.5 mM CaCl2.2H2O at 21 days, and 100 μM H3BO3 with 1.13 mM CaCl2.2H2O at 31 days, provided best results. Rhizogenesis responded differently according to B and Ca concentrations. Simultaneous omission of B and Ca inhibited the rhizogenesis, causing disruption of the callus, favored formation of globular and friable structures, with presence of anthocyanin. High concentrations of calcium promoted root induction in calli.
Efeito da incorpora??o de casca de café nas propriedades físico-mecanicas de painéis aglomerados de Eucalyptus urophylla S.T. Blake
Mendes, Rafael Farinassi;Mendes, Lourival Marin;Guimar?es Júnior, José Benedito;Mori, Fábio Akira;César, Antonia Amanda da Silva;
Ciência e Agrotecnologia , 2010, DOI: 10.1590/S1413-70542010000300012
Abstract: the objective of this study was to evaluate the influence of the incorporation of coffee husks in the production of particleboard with eucalyptus urophylla s.t. blake. the panels were produced incorporating 25%, 50%, and 75% of coffee husks at three levels of resin phenol-formaldehyde (6, 9 and 12%) and 1% of paraffin. the nominal density of the panels was 0.7 g/cm3 and the cycle of pressing consisted in a pressure of 3.92 mpa under a temperature of 180°c for 8 minutes. by the results it was possible to observe that the physical properties of the particleboard have a linear relationship decreasing with the increase in the level of resin, and increasing with the increase in the percentage of coffee husks, showing higher values of water absorption and thickness swelling. the mechanical properties show a linear relationship growing with the increase of resin level, and decreasing with a reduction the percentage of coffee husk association. the way that the search was conducted, the incorporation of the coffee husks harms the quality of the panels produced.
Estimativa da biomassa e do comprimento de raízes finas em Eucalyptus urophylla S.T. Blake no município de Santa Maria-RS
Witschoreck Rudi,Schumacher Mauro Valdir,Caldeira Marcos Vinicius Winckler
Revista árvore , 2003,
Abstract: O objetivo do presente trabalho foi estimar a biomassa e o comprimento de raízes finas (< 2 mm de diametro), em diferentes profundidades do solo, para a espécieEucalyptus urophylla S.T. Blake, com 10 anos de idade. O estudo foi realizado no município de Santa Maria-RS, no campus da Universidade Federal de Santa Maria. O talh o plantado com eucalipto tem 27 m de comprimento por 14 m de largura, em espa amento 3 x 2 m. Foram amostrados quatro monolitos de 25 x 25 x 60 cm. Os monolitos foram divididos em seis perfis geométricos, nas profundidades de 0-10, 10-20, 20-30, 30-40, 40-50, 50-60 cm. A separa o das raízes do solo foi por meio de um conjunto de duas peneiras (2 e 1 mm de malha) e jatos d'água. Na determina o do comprimento de raízes foi utilizado o método de intersec o, produzindo fotos com o uso de scanner. Os resultados revelaram alta concentra o das raízes finas nos primeiros 20 cm de solo. A biomassa total de raízes finas encontradas para o Eucalyptus urophylla foi de 1.451,6 kg/ha, devendo ser ressaltado que 57,9% estavam concentradas nos primeiros 20 cm de solo. Constatou-se que o comprimento total de raízes finas foi de 27.968,9 km/ha e que 64,3% destes estavam nos primeiros 20 cm de profundidade.
RADIAL VARIATION OF MICROFIBRIL ANGLE AND WOOD DENSITY AND THEIR RELATIONSHIPS IN 14-YEAR-OLD Eucalyptus urophylla S.T. BLAKE WOOD  [PDF]
Paulo Ricardo Gherardi Hein,Lo?c Brancheriau Mail
BioResources , 2011,
Abstract: The orientation of cellulose microfibrils in the cell wall along the stem axis has major effects on stiffness and longitudinal shrinkage and is of key importance in wood quality. The aim of this study was to investigate the radial variability of MFA and wood density (ρ) and their relationships in Eucalyptus urophylla wood. Three MFA values were estimated by X-ray diffraction at three points of each one of the 175 tangential sections, and the basic density was measured. A decrease of microfibril angles from pith to bark can be observed in most samples; however, some radial strips presented different patterns of variation. For basic density, a linear significant increase from pith to bark was confirmed. There was no significant correlation between microfibril angle and density. The relationships among the three MFA estimated on tangential sections of wood were strong. The “curvature effect” due to the growth rings had a negligible effect on the three measurements of tangential sections cut near to the pith. This study showed that a single T value measurement by X-ray diffraction, preferably at the centre of the tangential section, is precisely sufficient to estimate the mean MFA of Eucalyptus urophylla wood.
Propriedades de chapas fabricadas com partículas de madeira de Eucalyptus urophylla S. T. Blake e de Schizolobium amazonicum Herb.
Naumann, Rafael Baptista;Vital, Benedito Rocha;Carneiro, Angêlica de Cássia Oliveira;Lucia, Ricardo Marius Della;Silva, José de Castro;Carvalho, Ana Márcia Macêdo Ladeira;Colli, Andréia;
Revista árvore , 2008, DOI: 10.1590/S0100-67622008000600020
Abstract: this work aimed to evaluate the properties of particleboards produced with eucalyptus urophylla (density 0.55 g/cm3) and schizolobium amazonicum (density 0.30 g/cm3).five wood proportions and two types of particle (shavings and chips) were used to manufacture the boards. board dimension was 60 cm x 60 cm x 1 cm and average density 0.60g/cm3. eight percent of urea-formaldehyde adhesive was used. boards were pressed at 170 oc and 32 kgf/cm2 of pressure in 8 minute cycles. board properties were determined according to nbr 14810-3 standard. there was no influence of the variables on board density and linear expansion. generally,increasing the percentage of paricá increased the values of some properties such as moe, mor, screw holding, water absorption after 24 hours and internal bond, probably due to increased compaction rate. the type of particle used affected only the internal bond and thickness swelling of the boards. the boards produced with wood chip-originated particles (smaller slenderness ratio) presented higher internal bond. however, thickness swelling was higher.
ESTADO NUTRICIONAL DE Eucalyptus urophylla S.T. Blake SOB DIFERENTES ESPA AMENTOS NA REGI O DE CERRADOS DE MINAS GERAIS NUTRITIONAL STATE OF Eucalyptus urophylla S.T. Blake PLANTATIONS UNDER DIFFERENT SPACINGS IN THE SAVANNAH OF THE MINAS GERAIS STATE, BRAZIL  [cached]
Renato Lara de Assis,Mozart Martins Ferreira,Alberto Cargnelutti Filho
Pesquisa Agropecuária Tropical , 2007, DOI: 10.5216/pat.v36i3.2036
Abstract: O presente estudo teve por objetivo avaliar o estado nutricional de popula es de eucaliptos (Eucalyptus urophylla), om três anos de idade, plantadas em diferentes densidades, nos eguintes espa amentos: 3,0 m x 2,0 m,0; 3,0 m x 3,0 m; 3,0 m x ,0 m,0; 3,0 m x 5,0 m; 4,0 m x 2,25 m; 6,0 m x 1,5 m; 5,0 m x 1,8 ; e 9,0 m x 1,0 m. O experimento foi conduzido no município de Bocaiúva-MG. Foram avaliados os teores de N, P, K, Ca, Mg, S e B nas folhas, em sete épocas de amostragem. Os teores de nutrientes variaram com a época de amostragem, sendo os menores teores encontrados no período seco, para os nutrientes N, P e K. n o houve intera o entre espa amentos e épocas para os teores de Mg. Os menores teores de Ca ocorreram no mês de dezembro, com exce o da popula o no espa amento 9,0 m x 1,0 m. Os teores de N, P, S e B n o foram influenciados pelos espa amentos, e n o apresentaram níveis considerados como deficientes, independentemente do espa amento e da época. PALAVRAS-CHAVE: Eucalipto; nutri o mineral; densidade. This study aimed to evaluate the mineral nutrition of three years old Eucalyptus urophylla plantations, grown in different population densities in the following spacings: 3.0 m x 2.0 m; 3.0 m x 3.0 m; 3.0 m x 4.0 m; 3.0 m x 5.0 m; 4.0 m x 2.25 m; 6.0 m x 1.5 m; 5.0 m x 1.8 m; and 9.0 m x 1.0 m. The experiment was carried out at Bocaiuva, Minas Gerais State, Brazil. N, P, K, Ca, Mg, S, and B leaf content was evaluated at seven sampling dates. The nutrient content varied with sampling date; N, P, and K lowest levels were found in the dry period. No interaction was observed between spacing and sampling date for Mg. Lowest Ca levels occurred in December, except for 9.0 m x 1.0 m spacing. Spacing did not influence N, P, S, and B content. Independently of spacing and sampling date, N, P, S, and B leaf content did not present levels considered as deficient. KEY-WORDS: Eucalyptus; mineral nutrition; population density; savannah.
PHYSICAL AND MECHANICAL PROPERTIES OF THE WOOD OF Eucalyptus urophylla S.T. Blake IN THE BARK-TO-PITH DIRECTION AND ALONG THE STEM
Wescley Viana Evangelista,José de Castro Silva,Ricardo Marius Della Lucia,Lilian Messias Lobo
Revista Ciência da Madeira , 2010,
Abstract: The objective of this work was to evaluate some wood properties of a clone of Eucalyptus urophylla in the radial direction and in two positions along the trunk. The studied material came from Votorantim Metais Zinco S.A., and the plantations, located in Vazante, State of Minas Gerais, Brazil, were six years old. Six trees were harvested from which were cut two logs with three meter long each. Those logs were sawed into thick diametral slabs. A one-meter sample was obtained from these planks in the radial direction. Following this,samples were taken for the evaluation of specific gravity and apparent density, shrinkage from green or from 12% moisture, fiber and vessel sizes and static bending properties. It was foundthat basic and apparent specific gravities, total longitudinal shrinkage, fiber length, vessel diameter and moduli of rupture and elasticity tended to increase in the bark-to-pith direction,while partial longitudinal shrinkage, the tangential/radial ratios and the vessel frequency were reduced. Radial and tangential shrinkages, width, lumen diameter and fiber wall thickness showed different patterns of variation. Only partial volumetric, radial shrinkages and vessel frequency showed different values between the two logs taken from the same tree. The main correlations observed were between modulus of elasticity and of rupture with either specific gravity or apparent density and between fiber lumen diameter with specific gravity, total longitudinal shrinkage and with modulus of rupture in static bending.
Page 1 /100
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.