Felipe Susin

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.

Uso de estufa solar para secagem de madeira serrada

This study aimed at evaluating the use of a solar kiln for the drying of woods of Eucalyptus tereticornis , Eucalyptus saligna and Corymbia citriodora , as well as comparing such a methodology to the air seasoning practice. In order to do so, it was built a solar kiln composed basically of wood structures, roofing with a double layer of PVC, sunlight internal collector and hot air circulation systems. The efficiency of the solar kiln was compared to the air seasoning in drying time and wood quality. In the same drying schedule, each species was submitted to the two drying approaches using a load of 55 boards in each method. Results indicated that the solar kiln was more efficient in drying time, around 2 to 5 times faster and final moisture content lower than the air drying. Adequate wood quality was observed in both drying methods, and no defects such as cup or collapse were observed. Furthermore, the correct piling up and drying process provided minimization of defects such as bow. The incidence of crook, end and surface checks were not significantly distinct between solar drying and air seasoning for the three woods studied.

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.

Tratamentos térmicos e secagem da madeira serrada de uva-do-Japão

The purpose of this study was ascertaining the influence of heat treatments in the drying rate and wood quality of Japanese raisin tree (Hovenia dulcis Thunb.). In order to do so, four trees with 25 years and average diameter at breast height of 39.5 cm and an average commercial height of 10 m, were harvested and transformed into samples of 40 x 130 x 500 mm (thickness x width x length), and classified as to the radial and tangential orientation of the material. The treatments consisted of heating in water by 12 and 24 h at 85 oC, and freezing by 12 and 24 h at - 18 oC. Then, the lumber was subjected to drying at 75 °C in a forced convection greenhouse until reach 12% of final moisture content. The freezing and heating treatments have proven to be influential on the drying rate, since the first accelerated the drying process, whereas the other one decreased. The freezing treatment by 24 h with samples oriented in the tangential direction showed higher drying rate compared with the others. The treatments presented to be not significant for the reduction of the contractions in the samples related to width, thickness and length. However, the volumetric contraction was significantly higher in samples heated in water. The Hovenia dulcis wood did not show top or surface cracks in any of the treatments used in this study.

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.