Microfibril angle (MFA) is a key biological trait contributing to wood stiffness, which is a common breeding objective for solid wood products in many tree species. To explore its genetic architecture, area-weighted MFA was measured in two Eucalyptus nitens progeny trials in Tasmania, Australia, with common open-pollinated families. Radial strips were extracted from 823 trees in 131 families and MFA assessed using SilviScan-2^®. Heritability, genotype-by-environment interaction and inter-trait genetic correlations were evaluated to examine the genetic variability and stability of MFA and its relationships with other solid wood and pulpwood selection traits. Significant family variation was found for MFA in both trials. There was no significant genotype-by-environment interaction and the across-site narrow-sense heritability was 0.27. MFA was genetically independent of basic density, growth, and tree form. However, MFA was strongly and favourable genetically correlated to acoustic wave velocity in standing trees, modulus of elasticity and kraft pulp yield (KPY). The present study has shown that genetic improvement of E. nitens for pulpwood selection traits is unlikely to have adversely affected MFA, and thus timber stiffness. Rather these results suggest the possibility that selection for increased KPY may have indirectly improved MFA favourably for solid wood products.

中文翻译：

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塔斯马尼亚岛两个桉树后代试验中微纤丝角的遗传变异及其与实木和纸浆性状的关系

微纤丝角（MFA）是导致木材刚度增加的关键生物学特性，这是许多树木物种中实木产品的常见育种目标。为了探究其遗传结构，在澳大利亚塔斯马尼亚岛的两个桉树后代试验中，对面积偏多的MFA进行了测量，该试验具有常见的开放授粉家庭。径向条从823种树木131个家庭提取和使用SilviScan-2 MFA评估^®。遗传力，基因型与环境之间的相互作用和性状间的遗传相关性进行了评估，以检查MFA的遗传变异性和稳定性以及其与其他实木和纸浆木选择性状的关系。在两项试验中，MFA均发现明显的家族变异。没有显着的基因型与环境之间的相互作用，跨站点的狭义遗传力为0.27。MFA在遗传上与基本密度，生长和树形无关。但是，MFA与立木中的声波速度，弹性模量和牛皮纸浆得率（KPY）密切相关且具有良好的遗传关系。本研究表明，尼氏大肠杆菌的遗传改良纸浆木的选择性状不太可能对MFA产生不利影响，因此对木材的刚度没有影响。相反，这些结果表明，选择增加KPY可能间接有利于实木产品改善MFA。