RESUMO: Objetivou-se mensurar o efeito da associação entre caracteres agronômicos relacionados à produtividade de grãos de canola cultivada em diferentes épocas de semeadura, através da análise de trilha. Assim como também objetivou-se obter um método para predizer o teor de óleo nos grãos, ajustando um modelo multivariado através da análise por espectroscopia na região do infravermelho próximo. O experimento foi conduzido em campo, utilizando-se o delineamento de blocos ao acaso, em parcelas subdivididas no tempo, sendo quatro parcelas (épocas de semeadura) e seis subparcelas (híbridos de canola), com quatro repetições. Em cada híbrido foram realizadas observações fenológicas e determinada a produtividade de grãos. Os dados foram submetidos à análise de variância em ambiente R pelo teste F, a cinco de probabilidade. O teor de óleo nos grãos foi determinado pelo método químico tradicional, e com base na assinatura espectral no infravermelho próximo de amostras dos grãos foi estabelecida regressão dos mínimos quadrados parciais (PLS-R) para estimar o teor de óleo nos grãos de canola. As épocas de semeadura influenciaram os componentes de produção e o teor de óleo dos grãos de todos híbridos. Os caracteres número de grãos em cinco plantas (0,6857) e altura (0,4943) apresentaram maiores estimativas de correlação positiva com a produtividade de grãos, assim como os maiores valores de efeito direto positivo sobre a produtividade, 0,2494 e 0,1595 respectivamente. Entretanto, o ciclo total (-0,7848), juntamente com dias em florescimento (-0,4520) apresentou correlação significativa negativa com a produtividade. A técnica NIR associada à PLS-R foi capaz de predizer o teor de óleo nos grãos, resultando em bons modelos preditivos (R2 de 0,86 e RMSE de 1,56 na validação externa) que podem ser usados com sucesso na análise da qualidade das amostras após colheita e nos programas de melhoramento genético.

ABSTRACT: This study measured the effect of the association between agronomic traits related to the yield of canola grains grown at different sowing dates through path analysis. Another objective was to obtain a method to predict the oil content in the grains, fitting a multivariate model through near-infrared (NIR) spectroscopy analysis. The experiment was conducted in the field using a randomized block design in plots subdivided by time, with four plots (sowing dates), six subplots (canola hybrids), and four replicates. In each hybrid, phenological observations were performed, and the grain yield was determined. The data were subjected to analysis of variance in the R environment using the F test at 5% probability. The oil content in the grains was determined by the traditional chemical method, and based on the NIR spectral signature of the grain samples, partial least squares regression (PLS-R) was established to estimate the oil content in the canola grains. The sowing dates influenced the production components and oil content of the grains of all hybrids. The trait number of grains in five plants (0.6857) and their height (0.4943) had greater estimates of positive correlations with grain yield, as well as higher values of positive direct effects on yield (0.2494 and 0.1595, respectively). The NIR technique combined with PLS-R was able to predict the oil content in the grains, resulting in good predictive models (R2 of 0.86 and root mean square error (RMSE) of 1.56 in external validation).

ABSTRACT Background: Determining the basic density of the wood is usually defined as a simple process, but it requires caution and the operator’s skill to avoid errors in the analysis. In addition, it involves sample preparation and time to saturate the wood until obtaining the dry sample mass. The development of alternative measurement techniques could reduce the time to obtain the results and provide reliable values. Therefore, this study aimed to develop multivariate models to estimate the basic density of native woods using near-infrared spectra (NIR). Basic densities were determined by the water immersion method, and the values were associated with NIR signatures. Spectra were directly collected on the wood transversal and radial faces with an integrating sphere. Partial least squares regression (PLS-R) was calibrated and validated to estimate basic density based on spectral signatures. Results: In the cross-validation and prediction of the models, the results were promising. The coefficients of determination varied from 0.87 to 0.93 with a standard error of 0.01 %. The partial least squares discriminant analysis (PLS-DA) efficiently classified the wood species. The ratio of performance to deviation obtained satisfactory values, a minimum of 2.81 and a maximum of 4.20. Conclusion: The statistical parameters of the models based on NIR spectra showed potential for density measurements in floors, furniture, and solid wood products.

ABSTRACT Background: The fibres dimensions vary along a tree trunk, and these variations are related to the apical meristem and vascular cambium activities; understanding these variations would guide the best use of wood. There have been studies on the pattern of fibres dimensions variation along the tree trunk in the radial and longitudinal directions; however, the vast majority do not take into account the structure of the annual growth rings. Hence, this study aimed to obtain the pattern of fibres dimensions variation and their quality indexes along the tree trunk take into account the structure of the annual growth rings. Two Eucalyptus urophylla x Eucalyptus grandis hybrid clones were used in the study. Ten-year-old trees were selected and discs were removed from 13 longitudinal positions. The disks were prepared and the growth rings were subsequently identified and the samples used for maceration were collected. Twenty fibres were measured in the annual growth rings present in each longitudinal position. Results: In the longitudinal direction, within the annual growth rings, the fibre dimensions and their quality indices did not show a well-defined pattern of variation. In the radial direction, the length, cell wall thickness, wall fraction, and Runkel ratio of the fibres tended to increase following the pith-bark direction, while the lumen diameter and flexibility coefficient decreased. Conclusion: Nevertheless, the fibre width and fibre slenderness index did not present a well-defined pattern of variation in the radial direction.

Abstract: The aim of this study was to know the variation profile of the specific energy consumption required to cut woods with varying densities and moisture contents. Therefore, peripheral cuts were performed in the longitudinal direction of the grain with numerical control controlled by Computational Numerical Command in woods of different densities, established at different drying stages. An energy analyzer, capable of calculate the specific energy consumed during the wood processing, was used to measure the energy information. The results indicated that the higher the wood density, the greater the positive influence of the moisture content on the specific cutting energy. In the anhydrous condition, the higher the wood density, the higher the cutting energy. With increased moisture content, less cutting power was required during the wood processing. Therefore, it was possible to conclude that during the milling type mechanical processing of wood, moisture content has a great influence on the specific cutting energy consumption.

ABSTRACT The objective of this study was to establish multivariate models for the prediction of wood basic density with reference to the values of average density of trees and near infrared (NIR) spectra measured in the breast height. The wood basic density of 39 Eucalyptus clones was determined in the laboratory by means of the mean longitudinal positions of 0%, 2%, 10%, 30%, 50% and 75% of the commercial height of the tree by the gravimetric method. NIR spectra were recorded using a spectrometer using optical fiber probe and integrating sphere directly on the transverse plane of the solid wood in disks collected from diameter at breast height and later in the sawdust. The performance of the NIR based models was evaluated according to the spectral acquisition method and sample preparation. The results showed that the best model for basic density estimation using indirect measurements was developed from the average spectra per clone measured in solid wood disks (R2cv of 0.77 and RMSEcv of 15 kg.m-³).

ABSTRACT The non-structural carbon reserves in the various organs of trees are associated with their growth and the mechanism of resilience when exposed to environmental stresses, especially the water deficit. The goal of this study was to develop multivariate models to estimate the amount of non-structural carbohydrates (starch, sucrose, reducing sugars, total sugars and total non-structural carbohydrates) based on near infrared (NIR) spectra measured in solid wood and material reduced to powder. Partial least squares regression was used to associate the amount of non-structural carbohydrates (NSC) obtained by conventional laboratory analysis with NIR spectral signatures. The best predictive models were obtained from the wood reduced to powder. Validity for the NSC prediction in an external set of data presented the following statistics: reducing sugars with R²=0.90 and root mean square error (RMSE) of 2.54% dry matter, total sugars (R²=0.88, RMSE=2.76%), total NSC (R²=0.90, RMSE=2.58%), sucrose (R²=0.82, RMSE=0.06%) and starch (R²=0.80, RMSE=1.03%). The ability of models to estimate the NSC concentration in the growth rings and under divergent environmental conditions demonstrates the potential of the NIR tool to study the physiological responses of plants to different environmental stresses.

ABSTRACT Many wood species have been employed as floorings, however their performance can vary greatly according to the wood properties and the type of application. Mechanical tests can be performed for simulating the wood floorings in service, but there are no standards for sorting the materials according to their quality as flooring. In this study, the tests carried out in commercial wood species to simulate the performance as flooring and propose a standard of classes resistance. Thus, the performance as wood flooring of Bowdichia nitida Benth (Spr.), Dipteryx odorata (aubl.) Willd, Mimosa scabrella Benth and Tabebuia impetiginosa in service were investigated. These commercial woods flooring were submitted to the falling ball, rolling load, floor surface indentation from small area loads and static and dynamic friction tests. The indentations caused were measured by micrometer coupled to a computer. According to the wood flooring performance in the simulation tests three resistance classes were established: high for indentations lower than 0.005 mm in floor surface indentation from small area loads, intermediate for depressions from 0.121 to 0.300 mm in rolling load test, and low for depressions higher than 0.301 in falling ball test. These classes can be used for predicting the performance, as wood flooring, of lesser known species.

ABSTRACT The objective of this study was to evaluate the influence of particle size of charcoal samples on the predictive model statistics of charcoal chemical composition based on the NIR spectroscopy. Spectra of Acacia and of Eucalyptus charcoal were collected in the 100, 60 and 40 mesh granulometry, besides the powder remaining at the bottom of the sieves sets. They were subjected to principal component analysis and partial least square regression in order to estimate of volatile material (VMC), ash (AC) and fixed carbon content (FCC) values. The estimation of the FCC, VMC and AC of Eucalyptus based on NIR was more accurate using spectra of lower-particle-size powder. The models for Acacia charcoal were better using spectra measured at 40 mesh to predict FCC, 100 mesh for AC, and smaller size for VMC. NIR spectroscopy was efficient in estimating the immediate chemical composition of charcoal, except for AC.

ABSTRACT Currently, there is a little and sparse information about how the growing conditions influence the spatial variation of wood along the stem. Thus, the aim of this study was to compile the knowledge from literature in a manuscript for better understanding to what extent the growing conditions influence the spatial variation of wood properties in Eucalyptus plantations. The wood characteristics may present variations in their properties and can be caused by both genetic and environmental factors. However, how genetic and environmental factor acts on wood variation along the trunk is still unclear. Another point is that even with new genetic breeding programs, the mechanical properties of wood have not been considered in these programs, since the selection of new material is always based on the growing rate, cellulose and lignin content and wood density.

Abstract: Comparison between flexural wood strength values obtained from three-point and four-point bending tests in wood were only reported in few previous works, but remains unclear. Thus, the aim of this study was to determine the relationship between wood strength (MOR) obtained by 4-point and 3-point bending tests in Eucalyptus. Two or three specimens were cut from the same scantling (thus considered as twin) and submitted to flexural vibration tests. Then 190 wood specimens were tested by 4-point bending tests and 138 twin specimens were submitted to 3-point bending tests. Wood strength determined from 3-point bending test presented significantly higher mean value (76,8 MPa) than that from 4-point bending test (73 MPa). A linear regression for converting MOR from 3-point to 4-point bending test was proposed for these Eucalyptus specimens: MOR4p = 0,889 × MOR3p + 5,14 in MPa (R²=0,74). The correlation of MOR in 3-point bending with density was higher (R²=0,57) than in 4-point bending (R²=0,45). The correlations between dynamic elastic moduli and moduli of rupture were similar (circa R²=0,57 for MOR3p and R²=0,65 for MOR4p).

RESUMO O objetivo deste estudo foi avaliar a variação do teor e espessura da casca e da densidade básica da madeira de Eucalyptus e Acacia plantados em monocultivo e consórcio. Cinco árvores de Eucalyptus urophylla × E. grandis e cinco de Acacia mangium foram investigadas em plantios monoespecíficos e mistos, totalizando 20 árvores. O teor e espessura da casca produzida pela Acacia em monocultivo (47,5% e 1,32 cm) foram aproximadamente três vezes superiores, quando comparadas àquelas do plantio consorciado (15,2% e 0,51 cm). A partir desses resultados, conclui-se que não há diferença significativa entre as médias da densidade básica das madeiras de Eucalyptus e Acacia provenientes dos plantios monoespecíficos e mistos. Contudo, há variação longitudinal significativa em termos de densidade básica da madeira das árvores de Acacia e de Eucalyptus provenientes tanto do plantio monocultivado como do consorciado, indicando que há diferença na qualidade da madeira manejada para uso múltiplo.

ABSTRACT This study aimed to evaluate the variation of the bark content and thickness, and wood basic density of Eucalyptus and Acacia planted in pure and mixed stands. Five trees of Eucalyptus urophylla × E. grandis and Acacia mangium were investigated in pure and mixed stands, totaling 20 trees. The content and thickness of the bark produced by Acacia in monoculture (47.5% and 1.32 cm) were approximately three times higher than those from mixed stand (15.2% and 0.51 cm). From these results, it can be concluded that there is no significant mean difference between the density for Eucalyptus and Acacia wood from the pure and mixed plantings. However, there is significant longitudinal variation of basic density of Acacia and Eucalyptus wood from pure and mixed stand, indicating differences in the wood quality from logs managed for multiple use.

ABSTRACT The objective of this study was to evaluate the flow of air and water in Eucalyptus grandis and Eucalyptus dunnii wood. Wood was collected from four trees aged 37 years in an experimental plantation of the Federal University of Lavras, Brazil. Planks were cut off the basal logs to produce specimens for air and water permeability testing. Results indicated that the longitudinal permeability to air and water of E. grandis wood were, on average, 5% and 10% higher, respectively, than that of E. dunnii wood. E. grandis and E. dunnii wood showed neither air nor water flow in the test for permeability transversal to the fibers, and longitudinal permeability to air exceeded that to water by approximately 50 fold in both species.

Abstract The effect of planting density on the anatomical characteristics of wood is still matter of debate. The aim of the study was to investigate the influence of planting density on the variation of wood anatomical elements in Eucalyptus and Acacia trees cultivated in areas of high planting density (monospecific) and low planting density (mixed) stands. The fiber length, fiber width, fiber lumen diameter, cell wall thickness, vessel diameter and vessel frequency were evaluated. The measurements were made from wood discs taken from five Eucalyptus urophylla x E. grandis trees and five Acacia mangium trees grown in high planting density (monospecific plantations, 1667 trees/ha) and in low planting density (mixed stands, 500 trees/ha), totalizing 20 trees at 4.5 years old. Eucalyptus and Acacia produced wood with shorter fibers and smaller vessels in high density stands, when compared to its equivalent in low density. Acacia presented more frequent vessels and fibers with walls thicker than its equivalent in low planting density. Eucalyptus presented longer and thinner fibers and vessels more frequent than Acacia, regardless of planting density. On the other hand, in high planting density, Acacia presented fibers with walls thicker than Eucalyptus and in low density of planting their vessels were larger.

Resumen El efecto de la densidad de plantación sobre las características anatómicas de la madera aún es tema de debate. El objetivo de este estudio fue investigar la influencia de la densidad de plantación sobre la variación de elementos anatómicos de la madera de árboles de Eucalyptus y Acacia, creciendo en áreas de alta densidad de plantación (monoespecífica) y en rodales de baja densidad de plantación (mixta). Se evaluaron: longitud, ancho y diámetro de lumen de la fibra, grosor de pared celular, diámetro y frecuencia de vasos. Las mediciones se hicieron en rodajas de madera tomadas de cinco árboles de Eucalyptus urophylla x E. grandis y cinco de Acacia mangium, creciendo en alta densidad de plantación (plantaciones monoespecíficas, 1667 árb/ha) y de otro tanto igual de árboles creciendo en baja densidad de plantación (rodales mixtos, 500 árb/ha), lo que hace un total de 20 árboles de 4.5 años de edad. Eucalyptus y Acacia de rodales de alta densidad produjeron madera con fibras más cortas y vasos más pequeños en comparación con sus equivalentes en baja densidad de plantación. Eucalyptus presentó fibras más largas y delgadas y vasos más frecuentes que Acacia, independientemente de la densidad de plantación. Acacia presentó vasos más frecuentes y fibras con paredes más gruesas que su equivalente en plantación de baja densidad. Por otro lado, en alta densidad de plantación, Acacia presentó fibras con paredes más gruesas que Eucalyptus y en baja densidad de plantación sus vasos fueron mayores.

ABSTRACT The objective of this study was to establish the correlation between the size of the wood knots and the modulus of elasticity (MOE) and the compressive strength (Fc) in Eucalyptus wood. 156 Eucalyptus urophylla samples with knots were separated into 3 classes (small, medium and large knots), and samples were selected from the same tree and submitted to the parallel fiber compression test for MOE and Fc determination. There was a significant difference between the MOE and Fc of the smaller knot class (Class 1) and the other classes with larger knots (Classes 2 and 3). In general, the larger the knot, the greater the difference between the MOE and Fc. Wood with small knots (8.31 mm2) presents stiffness and strength statistically equal to wood free of defects. Eucalyptus wood stiffness is more sensitive to the presence of knots than the strength when compared to clear wood samples.

RESUMO A caracterização da madeira deve ser feita em grandes populações dos programas de melhoramento de eucaliptos, a fim de selecionar eficientemente árvores potenciais. Neste estudo, a madeira de E. benthamii foi caracterizada de forma não destrutiva e avaliou-se o desempenho da espectroscopia de infravermelho próximo (NIR) na estimativa da densidade básica da madeira, lignina, extrativos, glicose, xilanas e carboidratos totais. Modelos NIR para características da madeira foram realizados a partir de 481 árvores do teste de progênie de E. benthamii (4 anos de idade) destinada a produção de celulose no estado de Santa Catarina, no sul do Brasil. Baguetas foram amostrados para caracterização química e física em laboratório, bem como para análises de espectroscopia NIR. 350 amostras foram selecionadas via PCA para calibrações de modelos, enquanto 131 foram reservadas para o teste de validação independente. A madeira de E. benthamii apresentou os padrões exigidos para processo de polpa Kraft. Os modelos preditivos NIR apresentaram capacidade satisfatória para estimar as propriedades químicas da madeira. Os modelos de predição para teores totais de lignina, extrativos, xilanas e carboidratos totais apresentaram coeficientes de determinação de 0,53, 0,65, 0,36 e 0,53, com valores de RPD variando de 1,3 a 2,3. O modelo preditivo para a densidade básica da madeira e glicose apresentaram baixo coeficiente de determinação (0,13 e 0,10). No entanto, não é possível usar esses últimos modelos para classificação e seleção genética porque não houve correlação. Porém, o modelo para extrativos apresentou boa qualidade e pode ser usado para predição e melhoramento genético. Portanto, a espectroscopia NIR tem potencial para ser aplicada em programas de melhoramento, pois permite uma seleção precoce e não destrutiva de árvores para propriedades químicas do processo de produção de celulose.

ABSTRACT Wood characterization must be done in huge populations of Eucalyptus breeding programs in order to efficiently select potential trees. In this study, Eucalyptus benthamii wood was non-destructively characterized and the performance of near infrared (NIR) spectroscopy in estimating the wood basic density, lignin, extractive, glucose, xylan contents and total carbohydrates was evaluated. NIR models for wood traits were performed from 481 trees from E. benthamii progeny test (4-year-old) managed for pulp cultivated in Santa Catarina state, Southern Brazil. Increment cores were sampled for chemical and physical characterization in laboratory, as well as for NIR spectroscopy analyses. Three 350 samples were selected from PCA for model calibrations whereas 131 were reserved for independent test validation. The E. benthamii wood presented the standards required for Kraft pulp processing. The predictive NIR models showed satisfactory ability for estimating the chemical properties of wood. The prediction models for total lignin, extractive and xylan contents and total carbohydrates showed coefficients of determination of 0.53, 0.65; 0.36 and 0.53, with RPD values for these traits ranging from 1.3 to 2.3. The predictive model for basic density of wood and glucose presented low coefficient of determination (0.13 and 0.10). However, isn’t possible to use these models for ranking in genetic selection because there was no correlation. Therefore, NIR spectroscopy can potentially be applied in breeding programs, as it enables an early, non-destructive selection of trees with adequate physical and chemical properties for pulp production process.