Compression wood content in loblolly pine and its impact on tree breeding program for wood properties

All loblolly pine trees, especially the juvenile portion, contain various amount of compression wood. The morphological, chemical and papermaking properties of compression wood are distinctively different from those of normal juvenile wood and mature wood. Compression wood has higher lignin and galactan but lower cellulose and mannan content, shorter average fiber length, lower fiber width but thicker cell wall, higher fiber coarseness and higher microfibril angles as compared with the corresponding normal wood. A micro analytical method has been developed to quantitatively determine the percentage of compression wood in an incremental core so as to eliminate the effects of compression wood on the aforementioned properties. This enables accurate quantitative genetic analyses of these properties in tree breeding program.