Weslley Wilker Corrêa Morais

Deficiência hídrica no solo e seu efeito sobre transpiração, crescimento e desenvolvimento de mudas de duas espécies de eucalipto

Water is a critical component of plant metabolism, and a reduction in soil water availability may affect crop growth, development and yield. The objective of this study was to quantify the influence of soil water deficit on transpiration and on some growth (plant height and stem diameter) and development (main stem leaf number) parameters of Eucalyptus grandis (Hill ex Maiden) and E. saligna (Smith) seedlings. For this purpose, a greenhouse experiment was conducted at the Federal University of Santa Maria, RS, Brazil). The seedlings were planted on 10/1/2005 (PD1) and 5/12/2006 (PD2). Soil available water, expressed as the fraction of transpirable soil water (FTSW), and other parameters were measured daily during the period of water stress. Transpiration, which is an indicator of stomata closure, started to decrease at a FTSW of 0.9 (PD2) or 0.7 (PD1) in E. grandis, and at 0.7 for planting dates for E. saligna. These results suggest that stomata closure, in response to soil water deficit, occurs earlier in these two perennial species than in annual agricultural crops. Seedling growth and development parameter values began to decrease immediately after the onset of soil water deficit, even before transpiration was affected by the reduced soil water availability.

RESISTÊNCIA BIOLÓGICA DA MADEIRA TRATADA DE Eucalyptus grandis E Eucalyptus cloeziana A FUNGOS APODRECEDORES EM ENSAIOS DE LABORATÓRIO

A presente pesquisa teve por objetivo avaliar a resistencia biologica da madeira tratada de Eucalyptus grandis e Eucalyptus cloeziana sob a acao de organismos biodeterioradores em ensaios de laboratorio. Para tanto, foram utilizadas arvores de Eucalyptus grandis e Eucalyptus cloeziana, ambas com 16 anos de idade, as quais foram desdobradas em tabuas e submetidas ao tratamento preservativo em autoclave com arseniato de cobre cromatado (CCA). Em seguida, confeccionaram-se os corpos de prova para conducao do ensaio de apodrecimento acelerado com os fungos Trametes versicolor e Gloeophyllum trabeum, seguindo as recomendacoes da norma ASTM. A partir dos resultados obtidos, observou-se para o fungo Trametes versicolor que o tratamento preservativo foi eficiente na reducao da degradacao biologica da madeira das duas especies, com reducao da perda de massa em 35,17 e 82,31% para a madeira de Eucalyptus grandis e Eucalyptus cloeziana, respectivamente, ja para o fungo Gloeophyllum trabeum, a perda de massa foi reduzida em 6,79 e 96,65%, em comparacao a testemunha. Com base nas condicoes de realizacao do presente estudo observou-se que o tratamento preservativo com CCA e eficiente no aumento da resistencia biologica da madeira a acao dos fungos apodrecedores Trametes versicolor e Gloeophyllum trabeum.

USO DE Bambusa tuldoides E Eucalyptus grandis PARA CONFECÇÃO DE PAINÉIS AGLOMERADOS

The bamboo panels particleboards can be advantageous when produced with a mixture of some kinds of wood. However, there are few studies using Bambusa tuldoides for the production of homogeneous particleboards or in combination with wood particles. Therefore, the aim of this study was to evaluate the physical-mechanical quality of particleboard made of different percentages of B ambusa tuldoides and E ucalyptus grandis . To do so, 36 panels were produced composed of a mixture of 0, 25, 50, 75 and 100% of dry matter. The tests realized were moisture, mass density, swelling thickness and water absorption. The mechanical tests were bending, internal bond and screw withdrawal (ASTM 1037, 1999). The results submitted to the correlation test and analyzed by regression. The panels did not get the minimum values of the standards (ANSI A 208.1, 1987) for mechanical tests. It is concluded that the homogeneous bamboo panels obtained superior performance in physical tests than the eucalyptus panels, which are usually used in the industrial sector. However, the insertion of bamboo particles impaired the performance of the panels in the mechanical tests.

AVALIAÇÃO DAS PROPRIEDADES FÍSICO-MECÂNICAS DE PAINÉIS DE CASCA DE ARROZ E ADESIVO TANINO-FORMALDEÍDO

Rice husk, waste produced by processing of rice, has become a problem of environmental, economic and public health. As a result, this research aims to explore the potential of these underutilized resources in Brazil in the development of particleboard glued with tannin-formaldehyde. Therefore, panels were manufactured with rice husk compacted at different density (0.65, 0.95 and 1.15 g/ cm³), levels of adhesives (7, 10 and 13%) and particles types (natural and processed), totaling 54 panels. The pressing was carried in hydraulic press at 30 kgf /cm² for 8 minutes at 180°C of temperature. The physical tests performed were moisture content, density, water absorption and thickness swelling while mechanical properties evaluated were static bending, screw withdrawal and internal bond. In general, the use of rice hulls prouced a reduction in strength when compared to those made with wood particles. All particleboard were below the minimum standards in physical and mechanical properties; only the panels with 13% resin provided minimum values required by market standards regarding dimensional stability. The results indicate that the material cannot be used in conditions requiring great structural efforts.

PROPRIEDADES FÍSICO-MECÂNICAS DE PAINÉIS AGLOMERADOS COM Bambusa tuldoides E Pinus taeda

This study investigated the physical and mechanical properties of particleboards formed of bamboo (Bambusa tuldoides) and pine (Pinus taeda) and combinations between them. To this end, panels were made, defined by the use of each type of particle (pure or mixed), being set 0, 25, 50, 75 and 100% of proportion to the dry weight, total of 36 panels. The physical tests performed were the moisture content, mass density observed, absorption of water and swelling in thickness and the mechanics were static bending test, screw withdrawal test and internal bond. The results tested for simple correlation and regression analysis. In general, panels pure pine showed better results than just the panels formed by bamboo. The inclusion of bamboo decreases mainly the mechanical properties of panels. All panels were below the minimum standards for the physical and mechanical tests, only internal bond in panels of pine homogeneous had higher values ​​than commercial standards.

Biological resistance of Eucalyptus grandis and Eucalyptus cloeziana woods treated to the decay fungi under laboratory conditions

The present study aimed to evaluate the biological resistance of treated wood from Eucalyptus grandis and Eucalyptus cloeziana under the action of biodeteriorative organisms in laboratory testing. Thus, we used trees of Eucalyptus grandis and Eucalyptus cloeziana, both 16 years old, which was converted into planks and subjected to preservative treatment in an autoclave with chromate copper arsenate (CCA). Then, it was made the specimens for the conduct of accelerated decay test, as recommended by ASTM. From the results, it was observed for the fungus Trametes versicolor that the preservative treatment was effective in reducing the biological degradation of the wood of the two species, with reduced mass loss in 35.17 and 82.31% for wood Eucalyptus grandis and Eucalyptus cloeziana, respectively, as for the fungus Gloeophyllum trabeum mass loss was reduced by 6.79 and 96.65%, compared to the control. Based on the conditions of realization of the present study, it was observed that preservative treatment with CCA is effective in the increasing the biological resistance of the wood under the action of fungi Trametes versicolor and Gloeophyllum trabeum.