Determinação da composição química e potencial de polpação da madeiraPterogyne nitens Tul.Determination of the chemical composition and the wood pulping potential of Pterogyne nitens Tul. ResumoA grande dependência por madeiras das espécies dos gêneros Eucalyptus e Pinus associada à busca por produtos de diferentes qualidades impulsionam estudos acerca de madeiras alternativas para fins industriais, principalmente de espécies do bioma Caatinga, pouco estudado para fins florestais. O objetivo deste estudo foi caracterizar quimicamente a madeira da espécie Pterogyne nitens assim como analisar seu potencial para produção de polpa celulósica. Foram colhidas três árvores representativas de 9 anos, em um plantio experimental localizado na Universidade Estadual do Sudoeste da Bahia -Campus Vitória da Conquista, e amostradas cinco seções do fuste entre as posições 0, 25, 50, 75 e 100% da altura comercial.Os toretes foram transformados em cavacos e homogeneizados formando uma amostra composta representativa para a análise de densidade básica e composição química completa, bem como para a realização da polpação Kraft (cinco cozimentos utilizando diferentes cargas de álcali efetivo objetivando um Número Kappa 18). A densidade básica da madeira Pterogyne nitens foi de 641 kg/m³, sua composição química apresentou 41,9% de celulose, 24,7% de hemiceluloses, 26,5% de lignina, 7,3% de extrativos e 0,5% de cinzas. O rendimento do cozimento para Número Kappa 18 foi 46,4% e viscosidade 1075 dm 3 /kg. A espécie não se apresentou como uma alternativa interessante para a produção de polpa celulósica (baixo teor de celulose e rendimento depurado), mas bastante promissora para aplicação na área de energia da madeira. AbstractThe strong dependence on wood from species like Eucalyptus and Pinus genus, associated to the search for products of different qualities, led to studies about alternative wood for industrial use, mainly about species from the Caatinga biome and which is understudied for forest purposes. The aim of this study was to characterize chemically the wood from the species Pterogyne nitens and analyze its potential for pulp production. Three representative trees of 9 years old were harvested in an experimental plantation located in the southwest of Bahia state, the University of Vitória da Conquista Campus, and sampled five short logs at 0, 25, 50, 75 and 100% of the commercial height. Logs were transformed in chips and homogenized to obtain a representative composed sample for the total chemical analysis (cellulose, hemicelluloses, lignin, extractives and ashes content) and Kraft pulping (five cooking using different effective alkali loads to establish Kappa number 18). Pterogyne nitens wood basic density was 641 kg/m³, its chemical composition showed contents of cellulose (41.9%), hemicelluloses (24.7%), lignin (26.5%), extractives (7.3%) and ashes (0.5%). Pulping yield at Kappa number 18 was 46.4% and viscosity 1075 dm 3 /kg. The species did not suggest as an interesting alternative for pulp production (low cellulose conte...
Pterogyne nitens is commonly known in northeastern Brazil as a lesser-known fast-growing species in the Caatinga biome, which is a difficult place for tree development due to the low natural fertility soils and low availability of water. Due to the importance of expanding information about the anatomical wood properties of Caatinga native species, the aim of this work was to characterize the anatomical elements, to macroscopically describe the wood and make inferences about its possible end-uses. Maceration was performed which enabled measuring fiber dimensions, pore frequency and the following technological indexes: cell wall fraction, slenderness ratio, Runkel index and flexibility coefficient. Histological sections enabled describing the arrangements of the cellular elements in different observation sections and to determine the pore diameter. P. nitens wood has anatomical arrangements characterized by confluent axial parenchyma, being diffuse-porous with the presence of tylosis and heterogeneous/stratified rays (biseriate). The fibers were classified as very short (length 0.81 mm), not flexible and Runkel index 0.82. The pores were few in number with a frequency of 32.9 pores/mm2, distributed in a diffuse format and many were obstructed by tylosis. Based on the anatomical results and considering other technological studies, P. nitens wood is most suitable for charcoal production.
Biostimulants consist of a mixture of growth regulators that, when they are sprayed on plants, act on hormonal balance, enhancing its development. Stimulate® is a biostimulant composed by indole butyric acid (0.005%), kinetin (0.009%) and gibberellic acid (0.005%) which promotes root growth, improves water and nutrients uptake, and helps restore plant hormonal balance. This research was based on the hypothesis that Stimulate® spraying can be an alternate way to mitigate negative effects of soil water-limiting on plant growth. The experimental work was performed in greenhouse and aimed to evaluate physiological responses of young plants of Eucalyptus urophylla sprayed with different Stimulate® concentrations and submitted to the following irrigation regimes: full, partial and no irrigation. Leaf water potential, relative water content, net photosynthesis, plant height and main root length were measured. Under water-limited conditions, plants sprayed with Stimulate® showed higher net photosynthesis and relative water content had a less decrease, due to osmotic adjustment. Spraying with Stimulate® also provided greater plant height and longer main root length in plants under water deficit. We conclude that the use of Stimulate® can be a viable option to mitigate negative water stress physiological effects in young plants of Eucalyptus urophylla, helping to partially maintain the plant growth under water-limited conditions.
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