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Fibre/wood Ratio (wood + ratio)
Selected AbstractsGrowth and Wood/Bark Properties of Abies faxoniana Seedlings as Affected by Elevated CO2JOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 3 2008Yun-Zhou Qiao Abstract Growth and wood and bark properties of Abies faxoniana seedlings after one year's exposure to elevated CO2 concentration (ambient + 350 (± 25) ,mol/mol) under two planting densities (28 or 84 plants/m2) were investigated in closed-top chambers. Tree height, stem diameter and cross-sectional area, and total biomass were enhanced under elevated CO2 concentration, and reduced under high planting density. Most traits of stem bark were improved under elevated CO2 concentration and reduced under high planting density. Stem wood production was significantly increased in volume under elevated CO2 concentration under both densities, and the stem wood density decreased under elevated CO2 concentration and increased under high planting density. These results suggest that the response of stem wood and bark to elevated CO2 concentration is density dependent. This may be of great importance in a future CO2 enriched world in natural forests where plant density varies considerably. The results also show that the bark/wood ratio in diameter, stem cross-sectional area and dry weight are not proportionally affected by elevated CO2 concentration under the two contrasting planting densities. This indicates that the response magnitude of stem bark and stem wood to elevated CO2 concentration are different but their response directions are the same. [source] Postponed sowing does not alter the fibre/wood ratio or fibre extractability of fibre hemp (Cannabis sativa)ANNALS OF APPLIED BIOLOGY, Issue 3 2009W. Westerhuis Abstract Because hemp is a short-day plant, postponing the sowing date might be a suitable strategy to obtain shorter and smaller plants around flowering, when primary fibres are ,ripe' enough to be harvested. Smaller plants can be processed on existing flax scutching and hackling lines and might have fibre characteristics that are desirable for producing high-quality ,long fibres' for yarn spinning. It was investigated whether sowing beyond the normal sowing period in the Netherlands affects the ratio in which fibres and wood are produced, and what proportion of these fibres are long fibres, suitable for long fibre spinning. About 400 stem samples were fractioned into retting losses, wood, tow, and long fibre, and the ratios between fractions were analysed using multiple linear regression analyses. A normal sowing date at the end of April was compared with a postponed sowing date at the end of May. The total fibre/wood ratio was not affected. More than 95% of the variance in total fibre was accounted for by the wood weight per stem (55.5%), the variety (+33.3%) and the stem part (+6.5%). The amount of long fibre per stem mainly depended on the amount of the total fibre per stem (95.4% variance was accounted for) and the stem part (+2.0%). For economic reasons, it could be interesting to grow two successive high-quality hemp crops in one growing season. Therefore, in an additional experiment with one variety, the effect of sowing fibre hemp up to 12 weeks later than normal on the quantity and quality of the fibres was studied. Postponing the sowing date up to 12 weeks had no important effects on retting losses, the total fibre/wood ratio, and the long fibre/total fibre ratio. It is therefore technically possible to grow two successive hemp crops. Whether this fits well in farming systems and a hemp production chain remains to be studied. [source] Sowing density and harvest time affect fibre content in hemp (Cannabis sativa) through their effects on stem weightANNALS OF APPLIED BIOLOGY, Issue 2 2009W. Westerhuis Abstract Sowing density and harvest time are considered important crop management factors influencing fibre quantity and quality in hemp (Cannabis sativa). We investigated whether the effects of these factors are essentially different or that both factors affect stem weight and thereby total and long-fibre content. The effects of all combinations of three sowing densities and three harvest times were studied for six different stem parts. Almost 500 samples consisting of stem parts from 50 plants and with a length of 50 cm were tested. Fibres were extracted by a controlled warm-water retting procedure, followed by breaking and scutching. The initial sample weight was fractionated into retting losses, wood, tow and long fibre. In both Italy and the Netherlands, crops were successfully established with different stem densities (99,283 m,2), plant heights (146,211 cm) and stem diameters (4.5,8.4 mm) at harvest. Stem dry matter yields (6.8,11.7 Mg ha,1) increased with a delay in harvest time but were not affected by sowing density. Retting loss percentages were lower in lower stem parts and decreased with later harvest because maturation was associated with increasing amounts of fibre and wood. Within a certain stem part, however, the absolute retting losses were constant with harvest time. Multiple linear regression analyses showed that the amount of fibre in a hemp stem is almost completely determined by the weight and the position of that stem part. When the plant grows, the increase in dry matter is split up into fibres and wood in a fixed way. This total fibre/wood ratio was highest in the middle part of the stem and lower towards both bottom and top. Sowing density and harvest time effects were indirect through stem weight. The long-fibre weight per stem increased with the total fibre weight and hence with stem weight. Stem weight increased with harvest time; as harvest time did not affect plant density, the highest long-fibre yields were obtained at the last harvest time. The long fibre/total fibre ratio was lowest in the bottom 5 cm of the stems but similar for all other parts. Sowing density and harvest time effects again were indirect. Fibre percentages in retted hemp decreased with increasing stem weights towards a level that is presumably a variety characteristic. The dry matter increase between harvests, however, is much more important with respect to total and long-fibre yield. [source] Characterization of liquefied wood residues from different liquefaction conditionsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2007Hui Pan Abstract The amount of wood residue is used as a measurement of the extent of wood liquefaction. Characterization of the residue from wood liquefaction provides a new approach to understand some fundamental aspects of the liquefaction reaction. Residues were characterized by wet chemical analyses, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM). The Klason lignin content of the residues decreased, while the holocellulose and ,-cellulose contents increased as the phenol to wood ratio (P/W) increased. A peak at 1735 cm,1, which was attributed to the ester carbonyl group in xylan, disappeared in the FTIR spectra of the residues from liquefied wood under a sealed reaction system, indicating significantly different effects of atmospheric versus sealed liquefaction. The crystallinity index of the residues was higher than that of the untreated wood particles and slightly increased with an increase in the P/W ratio. The SEM images of the residues showed that the fiber bundles were reduced to small-sized bundles or even single fibers as the P/W ratio increased from 1/1 to 3/1, which indicated that the lignin in the middle lamella had been dissolved prior to the cellulose during liquefaction. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007 [source] Waterlogged archaeological wood,chemical changes by conservation and degradationJOURNAL OF RAMAN SPECTROSCOPY, Issue 10 2006M. Christensen Abstract Conservation of waterlogged archaeological wooden artefacts from the Nydam Bog in the southern part of Denmark was investigated by Raman spectroscopy. Two different conservation methods were used: the cellosolve/petroleum method and the polyethylene glycol (PEG)/freeze-drying method. Conservation with cellosolve/petroleum at both room and elevated temperatures was used to preserve archaeological arrows made from pinewood and ash wood. The double bonds in lignin were affected by the warm treatment. Holocellulose in the archaeological wooden arrows had decomposed completely. A band around 180 cm,1 in the R(v)-representation of the low-wavenumber Raman spectrum was used to monitor the presence of water in PEG2000 with a structure like the one in ,free' bulk water. The lignin/PEG2000 relative band intensities were used to make a quantitative estimate of the wood/PEG2000 ratio in a PEG2000 impregnated piece of hardwood. A decreasing degradation of holocellulose was observed from the surface to the centre of an oak piece from the Kolding Cog, built around 1200 A.D. A broad background was observed in the spectra recorded close to the surface of the plank. A similar, very intense, broad background was seen in untreated collapsed ash wood from the Nydam Bog. This broad background, most probably arising from fluorescence, was too intense to allow a Raman spectrum to be seen. In these cases, ATR-FTIR spectroscopy is a valuable complementary tool in studies of waterlogged archaeological wood, confirming that holocellulose degrades more rapidly than lignin. Copyright © 2006 John Wiley & Sons, Ltd. [source] | ||||||||||