Efficiency of early selection for rotation-aged wood quality traits in radiata pine

Abstract

-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...

Considering evolutionary processes in adaptive forestry

“…Studies on growth and wood density in different Pinus species revealed that genetic age-age correlation >0.8 is generally achieved from the age of 10-12 years (Hannrup and Ekberg 1998;Gwaze et al 2000;Wu et al 2007;Bouffier et al 2008). It varies greatly with environmental conditions, and in Pinus radiata, this level of correlation can be reached as soon as 2-5 years in certain sites (Gwaze et al 2000;Wu et al 2007). Matheson et al (2002) showed that genetic age-age correlations in Pinus radiata also vary with the genetic background with higher correlations in presence of inbreeding.…”

Genetic parameters and efficiency of early selection for half rotation-aged growth and form traits in Pinus taeda in China

“…Age-age genetic correlations have been reported in loblolly pine and were generally very high for younger aged trees compared with trees 15 or 20 years old (LAM-BETH et al, 1983;BALOCCHI et al, 1993;GWAZE et al, 1998GWAZE et al, , 2000SVENSSON et al, 1999;LAMBETH and DILL, 2001;. However, Age-age correlation values were usually low to moderate for older aged trees in the Pinaceae at more than half the rotation age (WU et al, 2007).…”

“…Therefore, testing the age-age correlation of economically important traits is critical to determining the optimal age for early forward selection for breeding purpose and backward selection for establishment of seed orchards (LAMBETH et al, 1983;WU et al, 2007;KUMAR and LEE, 2002). Many efforts have also been made to evaluate the efficiency of early selection for growth traits (LAMBETH, 1980;MAGNUSSEN, 1988;BURDON, 1989).…”

Sélection très précoce pour les propriétés du bois massif : détection précoce des individus les plus performants

“…The samples are scanned from pith to bark using X-ray densitometry, X-ray diffractometry and image analysis to measure or predict a range of properties. Different researchers have opted for using an average core value (e.g., Apiolaza et al, 2005), modelling the evolution of the trait (e.g., Apiolaza and Garrick, 2001;Isik et al, 2008;Zamudio et al, 2002) or calculating age-age correlations for area-weighted averages (e.g., Dungey et al, 2006;Kumar et al, 2006;Wu et al, 2007). These studies have assumed that an appropiate goal for a breeding program is to improve an average value for the trait at rotation age.…”