Economic breeding objectives were developed for production of radiata pine (Pinus radiata D. Don) structural timber in Australia. Production systems of eight companies, including plantation growers, sawmills, and integrated-system companies, were examined. A bioeconomic model linking the breeding-objective traits mean annual increment (MAI), stem sweep, average branch size, and modulus of elasticity (MoE) with production-system components was constructed using data obtained from industry and published sources. For a plantation grower the most important trait for improvement was MAI (31% improvement of net present value after a 10% trait improvement). For a sawmill the most important trait was MoE (29% improvement of profit after a 10% trait improvement). For an integrated-system company the two most important traits were MoE and MAI (24% and 21% improvement of net present value after a 10% trait improvement, respectively). There was a high correlation between breeding objectives of plantation growers within a region (rG > 0.99), but a negative correlation between breeding objectives of plantation growers and sawmills (rGS = –0.32) and only an intermediate correlation (rGI < 0.65) between those of growers and integrated-system companies.

-A total of 360 bark-to-bark-through-pith wood strips were sampled at breast height from 180 trees in 30 open-pollinated families from two rotation-aged genetic trials to study inheritance, age-age genetic correlation, and early selection efficiency for wood quality traits in radiata pine. Wood strips were evaluated by SilviScan and annual pattern and genetic parameters for growth, wood density, microfibril angle (MFA), and stiffness (modulus of elasticity: MOE) for early to rotation ages were estimated. Annual ring growth was the largest between ages 2-5 years from pith, and decreased linearly to ages 9-10. Annual growth was similar and consistent at later ages. Wood density was the lowest near the pith, increased steadily to age 11-15 years, then was relatively stable after these ages. MFA was highest (35• ) near the pith and reduced to about 10• at age 10-15 years. MFA was almost unchanged at later ages. MOE increased from about 2.5 GPa near the pith to about 20 GPa at ages 11-15 years. MOE was relatively unchanged at later ages. Wood density and MOE were inversely related to MFA. Heritability increased from zero near the pith and stabilised at ages 4 or 5 for all four growth and wood quality traits (DBH, density, MFA and MOE). Across age classes, heritability was the highest for area-weighted density and MFA, lowest for DBH, and intermediate for MOE. Age-age genetic correlations were high for the four traits studied. The genetic correlation reached 0.8 after age 7 for most traits. Early selection for density, MFA and MOE were very effective. Selection at age 7-8 has similar effectiveness as selection conducted at rotation age for MFA and MOE and at least 80% effective for wood density.early selection / microfibril angle / modulus of elasticity / wood density / radiata pine Résumé -Efficacité d'une sélection précoce pour les propriétés du bois adulte chez le pin radiata. Cette étude a pour objectif d'estimer les paramètres génétiques (héritabilités et corrélations juvéniles-adultes) pour différentes propriétés du bois chez le pin radiata et d'évaluer l'efficacité d'une sélection précoce. Trois cent soixante échantillons diamétraux de bois ont été prélevés dans deux dispositifs génétiques adultes sur trente familles de pin radiata issues de pollinisation libre, puis analysés avec le SilviScan . Les caractéristiques annuelles de la croissance, de la densité du bois, de l'angle des microfibrilles (MFA) et de la rigidité (module d'élasticité : MOE) ont été analysées et les paramètres génétiques de ces caractères ont été estimés du stade juvénile à l'âge de la révolution. La croissance radiale est la plus forte entre 2 et 5 ans (depuis la moelle) puis décroît linéairement jusqu'à neuf-dix ans et se stabilise ensuite. La densité du bois est la plus faible près de la moelle ; elle augmente fortement jusqu'à 11-15 ans puis se stabilise. MFA est le plus élevé (35 • ) près de la moelle ; il diminue ensuite pour atteindre environ 10• vers 10-15 ans. MFA ne varie pratiquement plus au-delà de cet âge. MOE passe d...

Genetic variation for wood quality traits and diameter growth for radiata pine (Pinus radiata D. Don) at age 20/21 years was estimated from eight trials in Australia. The traits studied were wood density, acoustic time-offlight (an indirect measure of stiffness) and diameter at breast height (DBH). Wood density and DBH exhibited significant additive genetic variation whereas non-additive effects were not significantly different from zero. Time of flight was also not significantly different from zero for both additive and non-additive effects, respectively. Average single-site heritability estimates (±SE) for wood density and DBH were 0.38±0.10 and 0.16±0.08, respectively. Pooledsite heritability estimates for wood density and DBH were 0.38±0.10 and 0.08±0.10, respectively. For density, there was little evidence of genotype-by-environment interaction (GEI) across the eight trials at the additive level (type B additive genetic correlation; r BADD =0.73±0.08) and type B genetic correlation for full-sib families (r BFS =0.64±0.08). In contrast, the type B additive genetic correlation for DBH was lower, (r BADD =0.51±0.14), suggesting evidence of GEI. However, type B genetic correlation for full-sib families was moderate (0.63±0.11) for DBH, suggesting that there may be some stable full-sib families. On the basis of the results of this study, GEI should be considered in order to optimise deployment of improved germplasm in Australia.

No abstract