Feasibility study of quality plantation pulpwood breeding on fibre length, vessel element length and their ratio sought by within-tree variations in Eucalyptus trees

The relationship between fibre length and vessel element length was examined by their within-tree variations for breeding quality plantation pulpwood from the view points of pulp properties, that is, shorter vessel element and longer fibre are preferable. Because the genetic difference between trees may express the different ratio of fibre length to vessel element length. Within-tree variations in the trunk of fibre length and vessel element length were studied in Eucalyptus camaldulensis and E. globulus trees grown at the same site. Within-tree variations of both cell length properties in both species were generally high in the upper and outer parts of the trunk in both fibre and vessel. No large difference of tendency was observed between individuals and between species except in the axial variation between individuals of E. globulus for vessel element length by statistical analysis. The relationships between fibre length and vessel element length were significant in all trees although the rate of fibre length to vessel element length was significantly different both between individuals in each species and between species. From these, the breeding program is expected to select a tree possessing genetically longer fibre length (more elongation of cambial initial) indicating higher breaking length with shorter vessel element length (shorter cambial initial) indicating higher printability, regardless the difference in the within-tree variations