In this study we investigated quantitative genetic variation in tracheid characteristics in two genetic tests of British Columbia's interior spruce (the common name for white spruce, Picea glauca (Moench) Voss; Engelmann spruce, Picea engelmanni Parry ex Engelm.; and their hybrids). The study included 88 half-sib families from the East Kootenay and Prince George regions. We have developed a technique for quantitative assessment of tracheid characteristics by measuring cross-sectional dimensions. We obtained cell size, wall thickness and their ratio in early-, transition-, and late-wood classes within a growth ring. Tracheid length and microfibril angle were measured in the transition wood. A number of tracheid characteristics showed significant genetic variation, but heritability, phenotypic, and genetic correlation estimates varied across test sites within and outside regions of origin of parental trees. Ring width was determined, both phenotypically and genetically, by the number of tracheids and to a lesser extent by the by their mean size. On average, rings with larger tracheids did not have significantly thicker walls. Wider rings had lower mean wall to tracheid size ratio. Faster growth did not result in shorter tracheids in the transition wood. Longer tracheids had lower micro fibril angle. There were no particular benefits from considering the anatomical component traits for breaking the negative genetic correlation between growth and wood density.

No abstract

Frequency data from six polymorphic allozyme loci and measurements of six quantitative traits were used to examine geographic differentiation among 65 British Columbia provenances of red alder (Alnus rubra Bong.). Principal components analysis showed that variation in quantitative traits can be reduced to two underlying dimensions, one representing general vigor including the termination of the growing period and the other being the start of the growing period. Canonical correlation analysis among quantitative traits, allozyme frequencies, and geographic variables revealed complex associations of quantitative traits with the latitude, distance to the coast, and elevation of the seed source. There were no significant correlations among allozyme frequencies and quantitative traits, but the frequency of the most common allele at most loci decreased with latitude. Further, cluster analysis based on Nei's genetic distance revealed a strong differentiation among island and mainland provenances at one allozyme locus. This differentiation can be interpreted as a result of migration from two different refugia since the last glaciation. The island populations presumably originate solely from isolated coastal refugia west of the Cordilleran ice sheet, while mainland populations were also recruited from areas south of the ice.

Quantitative genetic variation in growth, latewood percentage, and wood density was investigated for British Columbia's interior spruce (the common name for white spruce, Picea glauca (Moench) Voss; Engelmann spruce, Picea engelmanni Parry ex Engelm.; and their hybrids). The study included 160 half-sib families from the East Kootenay and Prince George regions. At the time of sampling, progeny tests for those two regions were 20 and 22 years old, respectively. Univariate and multivariate restricted maximum likelihood (REML) estimates of genetic parameters were obtained. Estimates of genetic variances and heritabilities differed greatly across planting sites for the examined traits, especially after transplantation between the regions. Significant negative genetic correlation between overall growth and wood density was found for the East Kootenay progenies, while negative but nonsignificant genetic correlation between these traits was found for the Prince George progenies. Generally, there was no significant decrease in heritability for ring width and latewood percentage in successive growth rings. A general age trend for genetic correlation between those traits was not apparent, except that the correlation remained negative during the observed period. Our results show that it is not possible to select certain families as superior based on 1-year results because of the family by growing season interactions. Nevertheless, genetic age–age correlations for cumulative increments were high, having a decreasing trend with increasing difference in age.

-Options for incorporating wood quality in British Columbia's hemlock breeding program were investigated. Seventy half-sib families 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 optimization 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.Tsuga heterophylla / wood quality / index selection / breeding / optimization Résumé -Optimisation de la sélection multi-caractères pour les propriétés de la pâte et du papier chez (Tsuga heterophylla (Raf.) Sarg.). Nous avons étudié plusieurs stratégies d'introduction de la qualité du bois dans le programme d'amélioration génétique de Tsuga heterophylla en Colombie Britannique. Soixante-dix familles de demi-frères ont été examinées. Nous avons observé la variation quantitative des caractéristi-ques des trachéides et analysé ses effets sur les propriétés de la pâte et du papier. En nous basant sur la connaissance des liens entre les propriétés des fibres et la qualité du papier, nous avons estimé le gain potentiel pour le rendement et la qualité du bois pour différentes stratégies de sélec-tion. Il est possible d'améliorer simultanément sans faire beaucoup de compromis le volume et la résistance à la traction de la pâte et du papier. Des compromis importants sont nécessaires pour améliorer simultanément le volume, la résistance à la déchirure du papier, et la résistance à la tension de la pâte TMP. En conséquence, l'optimisation multi-objectifs parait intéressante. Les incertitudes sur les poids économiques des caractères, potentiellement responsables de pertes, peuvent être écartées si on utilise des index de sélection différents sur des populations d'améliora-tion multiples.Tsuga heterophylla / qualité du bois / indice de sélection / amélioration génétique / optimisation