The hypothesis is examined that, among individual tracheids of coniferous woods, the weights of holocellulose and alpha-cellulose skeletons are a direct quantitative function of their length, independent of species. A total of 28 annual increments, representing wood from nine coniferous genera and seven families, separated into earlywood and latewood fractions, was delignified with peracetic acid and subsequent reduction with NaBH₄. Further reduction to alpha-cellulose followed for a portion of the holocullulose skeletons. About 750 individual holo- and alpha-cellulose tracheid skeletons were measured for length and weight. A specially developed quartz ultra micro-balance, having a weighing range of 0.06 to 14 μg and a precision ± 0.03 μg, was constructed and used to weigh; individual tracheids. Statistical analyses indicated a significant positive curvilinear relationship between length of tracheid and weight of its carbohydrate fraction. Estimated variations accounted for in holocellulose and alpha-cellulose skeleton weights, by the length factor alone were, respectively, 91.9 and 95.7 per cent for pooled data of all the species. No significant differences in holocellulose skeleton weights were evident within species for the same tracheid length, whereas weights of alpha-cellulose skeletons within species, and both the holo- and alpha-cellulose between species, differed significantly. Radial variation for single tracheid weights followed trends similar to those established by others for specific gravity, and percentage of cellulose based on gross wood analyses. Individual tracheids of juvenile wood had significantly lower (1% level) alpha-cellulose skeleton weights than those from mature and overmature wood, while differences were nonsignificant for holocellulose. Overmature wood tracheids were significantly lighter (carbohydrate skeleton weight) than those from mature wood, for the same tracheid length. Differences between earlywood and latewood were explored. For the same tracheid length, both earlywood and latewood tracheids contained similar amounts of alpha-cellulose, whereas the amount of holocellulose per tracheid was higher in latewood. Examination of compression wood also provided positive evidence for the length-weight relationship in tracheids. When weights of compression wood tracheids were compared with those of regular (normal) wood, no significant differences were apparent for holocellulose tracheid skeletons, whereas significant differences were found for alpha-cellulose. It was concluded that, for the same tracheid length, compression wood tracheids may have a lower amount of alpha-cellulose than those from mature (normal) wood, but a higher amount than those from juvenile wood. Changes in Douglas-fir tracheid weights were studied in wood formed before and following tree fertilization. Variations, for the most part, were found to be associated with changes in tracheid length. Qualitative differences attributable to treatment composition (Urea vs. NPK vs. (NH₄)₂SO₄) were also noted, in that some treatments resulted in less weight of alpha-cellulose per unit length of tracheid, when compared with normal wood tracheids. This reduction in cellulose fraction was suggested as a possible factor for differences observed in gross wood specific gravity in wood of some fertilized trees. Results were compatible with the proposed hypothesis. / Forestry, Faculty of / Graduate

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A method was developed for the isolation of tissue fractions from the middle lamella and secondary wall of black spruce (Picea mariana) tracheids. The concentrations of cellulose and glucomannan were found to be lower in the middle lamella tissue than in the secondary wall tissue, while the reverse was found for galactan and arabian. The content of glucuronoarabinoxylan was essentially the same in both morphological areas. The concentration of phenolic hydroxyl groups in the lignin in the two tissue fractions was determined by turbidimetric spectrophotometry and by pyrolytic gas chromatography. Secondary wall lignin was found to contain more than twice as many phenolic hydroxyl groups per phenylpropane unit as middle lamella lignin. The concentration of methoxyl groups in secondary wall lignin was 1.6 times the concentration in middle lamella lignin, indicating that about 40% of the lignin polymer in the middle lamella consisted of para-hydroxyphenyl residues. Most of the carbonyl groups in the lignin in wood were found in the middle lamella lignin. The carboxyl content of the middle lamella was about three times that of the carboxyl content of the secondary wall. Secondary wall lignin was more reactive towards chlorine, chlorine dioxide and sodium bisulphite. Secondary wall lignin was also more quickly dissolved than middle lamella lignin in kraft, acid-sulphite, and acid-chlorite pulping. The activation energies, towards kraft pulping, of middle lamella and secondary wall "bulk" lignin were found to be essentially the same. However, it was discovered that while most of the secondary wall lignin followed first order reaction kinetics, 70% of middle lamella lignin did not. It was also discovered that the majority of milled wood lignin originated in the secondary wall of the tracheid.

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Thesis (doctoral)--Swedish University of Agricultural Sciences, 2002. / Thesis documentation sheet inserted. Appendix reprints four papers and manuscripts, three co-authored with others. Includes bibliographical references. Issued also electronically via World Wide Web in PDF format; online version lacks appendix.