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1.
Summary The cross-sectional view of pitting between various cell types inPinus banksiana Lamb. was studied at the ultrastructural level. Cell types inPinus banksiana include longitudinal tracheids, ray tracheids, ray parenchyma cells, buffer cells and epithelial cells. Two common characteristic features of bordered pit-pairs between longitudinal tracheids are an initial pit border and a thickened torus at the center of the pit membrane. The shape and size of the pit border and torus of bordered pit-pairs between two compression wood cells, and between the last-formed latewood longitudinal tracheid and first-formed earlywood longitudinal tracheid were different from those in the earlywood and latewood longitudinal tracheids. The pit border on the ray tracheid side varied in size and shape due to wall dentation. No initial pit border was found on the pit border of the ray tracheid side. The shape of bordered pit-pairs between two ray tracheids varied considerably due to irregularity of the dentate cell wall. The size of bordered pit-pairs in longitudinal tracheids was between 16 m to 20 m, which was twice the diameter of bordered pit-pairs in ray tracheids. Bordered pitpairs at the end wall of two ray tracheids appeared to be the smallest at 5 m, Pit aspiration occurred in the bordered pit-pairs with or without a torus. In the heartwood zone, some half-borders pit-pairs between tracheary and ray parenchyma cells showed an additional secondary wall on the ray parenchyma cell side. Plasmodesmata were found in the half-bordered pit-pairs as well in the simple pit-pairs. Blind pits were observed between a ray tracheid and a longitudinal tracheid. Bordered pit-pairs between two buffer cells were also observed. The possible functions of buffer cells were discussed.Use of transmission electron microscope provided by the Science Instrumentation Lab, Lakehead University and the technical assistance provided by Mr. A. MacKenzie, Director of Science Instrumentation Lab are gratefully appreciated 相似文献
2.
T. E. Timell 《Wood Science and Technology》1973,7(2):79-91
Summary A study has been made of the histology and ultrastructure of opposite wood in Larix laricina, Picea rubens, and Pinus resinosa. The width of the growth rings varied considerably, in one case from 0.1–1.0 mm, with the wide rings containing a much higher proportion of latewood than the narrow ones. The earlywood tracheids were square in outline and more regularly arranged than in normal wood. In the latewood they were sometimes irregular and distorted. The S3 layer in the tracheids was 0.2 m thick in the earlywood and 0.4–0.8 m in the latewood, as compared to a thickness in normal wood of 0.1–0.2 m in both zones. The S3 was often buckled in the latewood and was terminated towards the lumen by a spiral thickening. The cell wall structure of the tracheid pit border was described. Normal coniferous wood might be regarded as an intermediate between opposite wood and compression wood.This paper is dedicated to Dean Edwin C. Jahn in honor of his 70th birthday. 相似文献
3.
Marjan Sedighi-Gilani Homeira Sunderland Parviz Navi 《Wood Science and Technology》2005,39(6):419-430
The pattern and extent of variation of microfibril angle (MFA) in normal and compression tracheids of softwood were investigated
by using confocal laser scanning microscopy technique. All measurements support the idea that the orientation of microfibrils
in single wood tracheids is not uniform. MFA of the radial wall of earlywood tracheids was highly non-uniform and had an approximately
circular form of arrangement around the bordered pits (inside the border). Between the bordered pits the measured MFAs were
less than the other parts of the tracheid. In the latewood tracheids MFA was less variable. The average orientation of simple
pits in the crossfield region was consistent with the mean MFA of the tracheids; however some of the measurements showed a
highly variable arrangement in the areas between the simple pits. In many cases the local measured MFAs of compression wood
tracheids agreed with the orientation of natural helical cavities of compression wood. Comparing the measured results in different
growth rings showed that MFAs in juvenile wood are generally larger than in perfect wood. 相似文献
4.
人工兴安落叶松次生木质部的解剖学研究 总被引：1，自引：0，他引：1
运用木材解剖图像分析系统和显微照相的方法对人工兴安落叶松次生木质部的解剖结构进行研究,结果表明:落叶松具正常树脂道和受伤树脂道两种类型,前者常见于晚材。落叶松生长轮内的早晚材在干和枝内急变,在根内缓变。早材管胞呈六边形至多边形,胞壁常见单列具缘纹孔,偶见对列具缘纹孔;晚材管胞多呈矩形,胞壁鲜见具缘纹孔,通常为单列具缘纹孔。落叶松木射线同时具有单列木射线和纺锤形木射线两种类型,纺锤形木射线中仅含一枚纵行树脂道。纵行管胞与木射线交叉形成的纹孔场为云杉型。从根到干再到枝,管胞逐渐细化,管胞长度逐渐减小,木射线分布由密到疏。 相似文献
5.
Summary The effects of air-drying and solvent-drying on the sapwood of Abies grandis have been investigated by a new method for the determination of the size and number of conducting tracheid lumina and pit membrane pores which involves the measurement of gaseous permeability at various mean pressures. Both earlywood and latewood tracheids (83% of the total) were found to be conducting in solvent-dried wood, but in air-dried wood only latewood tracheids (32% of the total) were conducting. In solvent-dried wood there were on average 27,000 pit membrane pores per conducting tracheid compared with only 600 in air-dried wood. In both, the average pit membrane pore radius was about 0.1 m.Liquid permeabilities have been predicted from the calculated radii and numbers. The liquid permeability of solvent-dried wood was 31 times greater than that of air-dried wood in which the lumina were responsible for 13% of the total resistance to flow. The lumina were responsible for 39% of the resistance in solvent-dried wood and it is suggested that in first-formed earlywood the lumina may cause more than half the total resistance.A new method is described for the cleaning of direct carbon replicas of wood. In this the cellulose is removed by cellulase instead of sulphuric acid, and no wax backing is required. This provides much cleaner replicas. Electron micrographs have been obtained of both earlywood and latewood dried by the two methods.The authors wish to thank Mr. A. R. Sayers for preparing the computer programme used in this work, Dr. R. Ph. C. Johnson for his help and advice regarding the electron microscopy and Professors Matthews and Weatherley for their advice and encouragement. 相似文献
6.
Variation of measured cross-sectional cell dimensions and calculated water vapor permeability across a single growth ring of spruce wood 总被引：1，自引：1，他引：0
A statistical study of the cell dimensions in a growth ring of spruce along the radial and tangential directions is performed. The data are used to study the variation of the cell vapor permeability in the growth ring. Studying cell rows within one growth ring, the frequency distributions of the cell wall thickness in the radial direction and of the lumen dimension in the tangential direction are found to be both unimodal. In contrast, the frequency distributions of these dimensions in the other directions are bimodal, where the different modes can be attributed to earlywood and latewood. Analysis of the bimodal distributions results in the determination of threshold values of cell wall thickness and the lumen dimension for earlywood and latewood tracheids. The cell dimensions are used to predict cell porosity and water vapor permeability distribution within a growth ring. The bimodal frequency distributions of the tangential cell wall thickness and the radial lumen dimension provide an explanation for the observed bimodal frequency distribution of the cell water vapor permeability both in radial and in tangential directions. Contrary to measured macroscopic vapor permeability results, the tracheid geometry results in lower cell vapor permeability in radial than in tangential direction. This confirms that rays play an important role in the vapor permeability of wood, as they can be considered as pathways for vapor transport in radial direction. The dataset analyzed in this paper leads to a set of parameters characterizing the earlywood and latewood cell dimensions. Such characterization can be used, for example, for producing synthetic data for computational modeling studies. 相似文献
7.
Cornelia Krause Sergio Rossi Maxime Thibeault-Martel Pierre -Y. Plourde 《Annals of Forest Science》2010,67(4):402-402
8.
《Scandinavian Journal of Forest Research》2012,27(5):462-469
Abstract Wood properties, including tracheid cross-sectional dimensions, show a large degree of variation. To improve the properties of products made from wood, different methods to control variation have been developed. This study aims to determine the theoretical efficiency of three control strategies: the fractionation of pulped tracheids into earlywood and latewood, the separation of juvenile and mature wood, and sorting of logs according to tree size. The efficiency of each method was studied by first constructing virtual trees from measured tracheid cross-sectional dimensions, then simulating the efficiency of above-mentioned methods. The tracheid dimension data include Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.). The simulations show that separation into earlywood and latewood classes has the highest theoretical efficiency and yields the lowest variances in raw material. Classification into juvenile and mature wood groups is the second most efficient method, and the sorting of logs according to the size class of the tree is the least efficient method. It was also concluded that the variation in cell-wall thickness and radial diameter mainly originates from differences between earlywood and latewood, whereas the variation in tangential diameter mainly originates from differences between mature and juvenile wood. 相似文献
9.
中国裸子植物木材管胞瘤状层的电镜观察 总被引：4，自引：2，他引：4
本文对中国裸子植物11科、41属、99种木材管胞瘤状层进行了系统观察。瘤状层的有无及形态特征是区分裸子植物材的重要标志。此外并对5种针叶树材在一个年轮内,瘤状层从早材到晚材大小、分布密度的变化做了观察;12种针叶树材的切片,用0.5％次氯酸钠溶液处理后,瘤状物减小、以至消失;在另6个树种的管胞内,观察到瘤状层被白腐菌或软腐菌溶解。 相似文献
10.
Hydraulic and mechanical properties of young Norway spruce clones related to growth and wood structure 总被引：3，自引：0，他引：3
Stem segments of eight five-year-old Norway spruce (Picea abies (L.) Karst.) clones differing in growth characteristics were tested for maximum specific hydraulic conductivity (k(s100)), vulnerability to cavitation and behavior under mechanical stress. The vulnerability of the clones to cavitation was assessed by measuring the applied air pressure required to cause 12 and 50% loss of conductivity (Psi(12), Psi(50)) and the percent loss of conductivity at 4 MPa applied air pressure (PLC(4MPa)). The bending strength and stiffness and the axial compression strength and stiffness of the same stem segments were measured to characterize wood mechanical properties. Growth ring width, wood density, latewood percentage, lumen diameter, cell wall thickness, tracheid length and pit dimensions of earlywood cells, spiral grain and microfibril angles were examined to identify structure-function relationships. High k(s100) was strongly and positively related to spiral grain angle, which corresponded positively to tracheid length and pit dimensions. Spiral grain may reduce flow resistance of the bordered pits of the first earlywood tracheids, which are characterized by rounded tips and an equal distribution of pits along the entire length. Wood density was unrelated to hydraulic vulnerability parameters. Traits associated with higher hydraulic vulnerability were long tracheids, high latewood percentage and thick earlywood cell walls. The positive relationship between earlywood cell wall thickness and vulnerability to cavitation suggest that air seeding through the margo of bordered pits may occur in earlywood. There was a positive phenotypic and genotypic relationship between k(s100) and PLC(4MPa), and both parameters were positively related to tree growth rate. Variability in mechanical properties depended mostly on wood density, but also on the amount of compression wood. Accordingly, hydraulic conductivity and mechanical strength or stiffness showed no tradeoff. 相似文献
11.
对10个10年生日本落叶松无性系的木材基本密度、管胞参数进行了测定.结果表明:木材基本密度,早、晚材管胞宽度和早材长宽比无性系间差异显著;木材基本密度,早、晚材管胞长度,早晚材管胞宽度和早晚材长宽比径向变异模式相似,即从髓心向外以曲线形式不断增加,有时亦有起伏;早材从髓心向外以近似直线的形式缓慢增加,晚材从髓心向外以曲线形式增加,初期增加幅度较大,到一定年龄后趋于水平变化并略有波动;材质性状与树木年轮间的关系以对数方程、幂函数方程、指数方程拟合效果较好;除了晚材壁腔比和早材壁厚外,其它木材性质的重复力均在0.5以上,受中度或中度以上的遗传制约,按照20%的选择率,长宽比和晚材管胞长能获得较高的遗传增益. 相似文献
12.
To improve wood quality for pulpwood industries, it is important to examine not only wood density but also its components, especially tracheid characteristics. We studied genetic variations in the following tracheid traits by earlywood (EW) and latewood (LW): tracheid length (TL), double wall thickness (WT), radial lumen diameter (R_D1), tangential lumen diameter (T_D1), radial central diameter (R_D2), and tangential central diameter (T_D2). We also studied the relationship with the following growth traits: diameter at breast height (DBH), height (H), crown breadth south-north axis (NSC), crown breadth east–west axis (EWC), ring width (RW), latewood percentage (LWP), and wood density (WD). All sample materials were collected from a 33-year old clonal seed orchard of Pinus tabuliformis Carr. Genetic variation among clones was moderate for all tracheid traits, 9.49–26.03%. Clones significantly affected WT, R_D1, R_D2, T_D1, T_D2, and the two ratios WT/R_D1 and TL/T_D2 in EW but had no effects in LW. Clones significantly affected TL in LW but had no effects in EW. \( H\frac{2}{C} \) was higher in LW (0.50) than in EW (0.20) for TL, while \( H\frac{2}{C} \) was higher in EW (0.27–0.46) for other tracheid traits and the two ratios (TL/T_D2 and WT/R_D1) than in EW (0.06–0.22). WD and TL were significantly positively correlated, but WT and TL were negatively correlated both at individual and clone levels; all tracheid diameters and the four ratio values (EW_WT/R_D1, LW_WT/R_D1, EW_TL/T_D2 and LW_TL/T_D2), were strongly positively correlated with DBH, H, NSC, WEC and RW, and strongly negatively correlated with WD both at individual and clone levels. The most important variables for predicting WD were LW_TL, EW_WT and R_D1 in both EW and LW (r2 = 0.22). Selecting the top 10% of the clones by DBH would improve DBH growth by 12.19% (wood density was reduced by 0.14%) and produced similar responses between EW and LW for all tracheid traits: a reduction of 0.94 and 3.69% in tracheid length and increases in tracheid diameters (from 0.36 to 5.24%) and double wall thickness (0.07 and 0.87%). The two ratios WT/R_D1 and TL/T_D2 across tissues (EW and LW) declined 0.59 and 4.56%, respectively. The decreased tracheid length and the ratio between tracheid length and diameter is disadvantageous for pulp production. The unfavorable relationship of tracheid traits with wood density indicate that multiple trait selection using optimal economic weights and optimal breeding strategies are recommended for the current long-term breeding program for P. tabuliformis. 相似文献
13.
14.
Nakai Takashi 《中国林业科技(英文版)》2003,(2)
A comprehensive analysis on the variation pattern of early- and latewood tracheid morphological parameters along tree (Cunninghamia lanceolata Hook.) height, including length and width, wall thickness, tissue proportion, cell wall percentage, width of growth rings, and on the relationship among them are conducted. The results indicate an initially rapid and then gentle increase of tracheid length and width, thickness of the radial wall and tangential wall of tracheid, area percentage of tracheid from pith to outward, while S2 microfibril angle (Mfa) of tracheid, and rays percentage gradually decrease and then tend to be stable. The variation of all anatomical parameters but earlywood cell wall thickness shows no significance along tree height. The radial variation pattern of width of growth rings is characterized with initially slight decrease followed immediately by a rapid and then much more gentle increase from pith to outward. The delimitation age between juvenile and mature wood is 14-16 years. Com 相似文献
15.
Summary The distribution of Cu, Cr and As in the walls of tracheids of Scots pine impregnated with Tanalith C at a retention of 2.5 lb/ft3 has been examined at the submicroscopic level in the electron microscope microanalyser, EMMA-4, using the absolute method, as well as in the conventional electron microscope. All three elements are present in all regions examined (probe area 0.2 m diameter). The concentration of Cu ranges from 0.4–0.9% (w/w), that of Cr is about 0.8%, while As ranges from 2%–2.6%. The morphology of this fine deposit is clearly dictated by the run of the cellulose microfibrils. There is in the wall an occasional coarse deposit, almost entirely copper, and the inner face of the tracheid wall is covered by a thin layer 20–30 m thick which contains all these elements at high concentration. 相似文献
16.
The technology of steam explosion was applied to pre-treat sub-alpine fir (Abies lasiocarpa (Hook.) Nutt.) lumber and to improve its drying characteristics. Effects of steam explosion on the appearance and structure of the lumber are discussed in this paper. The structure of the wood was examined using light microscope (LM) and scanning electron microscope (SEM). The following results were obtained. With increasing temperature, pressure, and explosion cycles the color of the lumber darkened gradually. No significant structural difference between treated and untreated samples was observed using LM when the treatments were carried out at temperatures below 130°C with ten explosion cycles (group A or B). Some fractures were observed in bordered pit pairs between tracheids after 20 explosion cycles at 130°C (group C). More fractures occurred in bordered pit pairs between earlywood tracheids at a temperature of 160°C (group D). More or less fractures in pits between ray parenchyma cells and earlywood tracheids were observed using SEM in all four cases of treatments. Although no change in bordered pits in the tracheid walls between group A and the control group was discovered, groups B, C, and D showed different extents of ruptures in bordered pits, which may lead to break aspirated pits and improve permeability. In these groups, wrinkles and separations in the inner tracheid walls and detachments in middle lamella also occurred and became more serious as temperature or cycles of the treatment increased. 相似文献
17.
Alfred J. Stamm 《Wood Science and Technology》1973,7(3):212-217
Summary Measurements of the air pressure required to initially displace a saturating liquid and allow a slow continuous stream of air bubbles to pass through wood cross sections of different thickness, together with the equilibrium surface tension of the saturating liquid, make it possible to calculate the maximum effective opening radii. Previous measurements were made for wood as a whole over complete annual rings. Measurements reported here were made separately for earlywood and latewood. Extrapolating plots of the maximum effective opening radius-cross section thickness, for thicknesses below the maximum fiber length, to zero thickness gave maximum lumen radii of 16 m for the earlywood and 10.3 m for the latewood. The values are only slightly greater than the calculated average values. Extrapolating the plots in the opposite direction to zero opening radius gave approximate maximum lumen or fiber lengths for the earlywood of 6 mm and for the latewood of 5 mm. The maximum effective opening radii for cross sections thicker than the maximum fiber length give maximum effective communicating pore radii. These values continue to decrease, with increasing thickness of the cross sections due to the decreasing probability of the largest openings falling in any one series path through the structures. The maximum effective pit pore radius for passage through fifty pits in series was 0.8 m for the earlywood and 0.28 m for the latewood.Paper No. 3787 of the Journal Series of North Carolina State University Agricultural Experiment Station, Releigh, N. C. 相似文献
18.
Ryuya Takanashi Wataru Ishihara Kei Sawata Yuzou Sano Tomonori Azuma Mitsunori Mori Akio Koizumi Yoshihisa Sasaki Takuro Hirai 《Journal of Wood Science》2014,60(3):186-193
In order to investigate shear failure surface of decayed wood, wood pieces of ezomatsu (Picea jezoensis) were exposed to brown-rot fungus (Fomitopsis palustris), and standard shear test in radial plane was conducted. The failure surfaces were examined by scanning electron microscopy and surface roughness measurements were also conducted. Transwall failure that the crack elongated parallel to the tracheid axis was observed in the earlywood region through all phases of decay. Intrawall failure principally occurred in the latewood region on the early phase of decay. When decay progressed considerably, transwall failure that the crack elongated perpendicularly to the tracheid axis occurred. And transwall failure was also dominant failure morphology in the latewood region. Fragments of tracheids which were partly peeled out from S2 layers were observed in some specimens. Size and appearance frequency of fragments of tracheid were smaller and lower when decay progressed. Arithmetic average roughness, which was the index of fragment size and appearance frequency, had positive correlation to shear strength ratio. Especially, line surface roughness of radial direction, which was measured across the radial files of tracheid, had the highest correlation to the shear strength ratio. The surface roughness would be a good indicator to evaluate the decay degree. 相似文献
19.
Kilpeläinen A Gerendiain AZ Luostarinen K Peltola H Kellomäki S 《Tree physiology》2007,27(9):1329-1338
We studied the effects of elevated temperature and carbon dioxide concentration ([CO(2)]) alone and together on wood anatomy of 20-year-old Scots pine (Pinus sylvestris L.) trees. The study was conducted in 16 closed chambers, providing a factorial combination of two temperature regimes and two CO(2) concentrations (ambient and elevated), with four trees in each treatment. The climate scenario included a doubling of [CO(2)] and a corresponding increase of 2-6 degrees C in temperature at the site depending on the season. Anatomical characteristics analyzed were annual earlywood, latewood and ring widths, intra-ring wood densities (earlywood, latewood and mean wood density), tracheid width, length, wall thickness, lumen diameter, wall thickness:lumen diameter ratio and mass per unit length (coarseness), and numbers of rays, resin canals and tracheids per xylem cross-sectional area. Elevated [CO(2)] increased ring width in four of six treatment years; earlywood width increased in the first two years and latewood width in the third year. Tracheid walls in both the earlywood and latewood tended to become thicker over the 6-year treatment period when temperature or [CO(2)] was elevated alone, whereas in the combined treatment they tended to become thinner relative to the tracheids of trees grown under ambient conditions. Latewood tracheid lumen diameters were larger in all the treatments relative to ambient conditions over the 6-year period, whereas lumen diameters in earlywood increased only in response to elevated [CO(2)] and were 3-6% smaller in the treatments with elevated temperature than in ambient conditions. Tracheid width, length and coarseness were greater in trees grown in elevated than in ambient temperature. The number of resin canals per mm(2) decreased in the elevated [CO(2)] treatment and increased in the elevated temperature treatments relative to ambient conditions. The treatments decreased the number of rays and tracheids per mm(2) of cross-sectional area, the greatest decrease occurring in the elevated [CO(2)] treatment. It seemed that xylem anatomy was affected more by elevated temperature than by elevated [CO(2)] and that the effects of temperature were confined to the earlywood. 相似文献
20.
A. J. Stamm 《Wood Science and Technology》1978,12(3):197-202
Summary There are, on the average, about 300 fibers or tracheids per centimeter in both the tangential and radial directions in cross sections of softwoods when the counts are made over complete annual rings with the extremes varying from about 200 fibers per centimeter for redwood to about 400 fibers per centimeter for Alaska yellow cedar. Fiber widths, including half of surrounding middle lamella, range from about 50 m for redwood to 25m for Alaska yellow cedar, averaging about 33 m. Average lumen widths vary but slightly with changes in the specific gravity of the wood whereas the double cell wall thickness varies directly with the specific gravity. Effects of pulping to different pulp yields on the fiber dimensions are calculated with the use of two newly developed equations. The theoretical thickness of completely collapsed pulp fibers is equal to their double cell wall thickness. Complete collapse rarely if ever occurs as it requires double fractures of the cell wall. In practice, collapse of fibers is incomplete so their thickness is usually two or more times the theoretical minimum.Emeritus Robertson Professor of Wood and Paper Science, North Carolina State University, Raleigh, N.C., U.S.A. 相似文献