| Options for incorporating wood quality in the British Columbia's interior spruce improvement program were investigated. Special attention was given to quantitative variation in tracheid characteristics and its effects on pulp and paper properties. Growth and wood density were examined for 160 half-sib families from Prince George and East Kootenay regions. Tracheid characteristics were examined for 90 of those families, by using an efficient technique for quantitative assessment. Univariate and multivariate REML estimates of genetic parameters were obtained. Estimates of genetic variances and heritabilities differed greatly across sites for a number of traits, especially after transplantation between the regions. No significant decrease in heritability was found for ring width and latewood percentage in successive rings. Genetic age-age correlations were generally high for those two traits, with a decreasing trend with increasing difference in age. Within different ring portions, tracheid characteristics had significant family variation. There were limited benefits from considering component traits for avoiding negative genetic correlation between wood density and growth rate. Selection for volume as a single objective could bring significant improvements, positively influencing dry weight, and some pulp and paper properties. Simultaneous improvement of volume growth and other objectives would always require trade-offs, and multiobjective optimization would be beneficial. Expected genetic response in volume was by far the most superior, and any additional objective would need to have a high relative value to justify risk reduction strategies, including diversification through a multiple-population breeding strategy. |
