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.

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.

-Rigidimeter is a device developed in order to determine the modulus of elasticity (MOE) of standing trees. It was used on a hybrid Larch clonal test located at INRA, Orléans, France. Some of the examined trees were felled and remeasured. The goal of this study was to contribute to the validation of the Rigidimeter, as a fast non-destructive and reliable tool for rapid evaluation of MOE, an important mechanical property of wood. Two measurements in orthogonal directions improve the accuracy especially in the presence of reaction wood. We have showed that two measurements of diameter including bark with a precision of ± 1 mm are sufficient to obtain a reliable second moment of area, which is an important parameter for the estimation of trunk MOE. Bark MOE is small compared to wood MOE, but bark thickness influences the measurement of tree diameter. A correction may be necessary to account for the presence of bark. We propose a method for estimating MOE of different trunk layers, such as bark and mature wood layer.genetic improvement / modulus of elasticity / standing tree evaluation / larch Résumé -Mesure rapide du module d'élasticité des arbres sur pied à l'aide du Rigidimètre. L'appareil que nous avons développé pour mesurer le module d'élasticité (MOE) des arbres sur pied, le Rigidimètre, est utilisé dans un test de mélèze hybride à l'INRA d'Orléans en France. L'objectif de l'étude est de contribuer à la validation de sa fiabilité pour la détermination rapide de cette propriété mécanique importante. Nous évaluons ici (1) la méthode de mesure du diamètre du tronc, (2) l'influence de l'écorce, (3) quelques détails de la procédure de mesure sur la pré-cision de l'estimation du MOE du tronc. La méthode de mesure du diamètre proposé permet d'estimer correctement le moment quadratique de la section du tronc, un paramètre important de l'estimation du MOE. L'écorce influence l'estimation du MOE, non pas au travers de son MOE propre qui semble très faible, mais par l'intermédiaire de son épaisseur qui fait varier le diamètre sur écorce. Nous proposons une méthodologie de l'utilisation de l'appareil qui permet d'estimer le MOE des derniers cernes fabriqués, c'est-à-dire du bois adulte dans l'arbre sur pied.génétique / module d'élasticité / arbre sur pied / mélèze

-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

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