Optimization of multiple trait selection in western hemlock (Tsuga heterophylla (Raf.) Sarg.) including pulp and paper properties

Abstract

Options for incorporating wood quality in British Columbia's hemlock breeding program were investigated. Seventy half-sib fami- lies were examined. Attention was given to quantitative variation in tracheid characteristics and its effects on pulp and paper properties. Based on the existing knowledge of relationships between fibre properties and paper quality, the potential gain in yield and wood quality was estimated for different selection strategies. Improvement without much trade-off was possible for volume and tensile strength of pulp and paper. Significant trade-offs would be required to improve the volume, tear strength of paper and strength of mechanical pulp. Therefore, multiobjective optimiza- tion would be beneficial. Conservative selection strategies seem realistic, and compromises with gain in volume growth may be profitable. The potential loss arising from the uncertainty about economic values for objectives can be overcome by using different selection indices in multiple breeding populations.