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Title: Genetic selection in Sitka spruce : balancing wood properties and improved growth
Author: Macdonald, Elspeth
ISNI:       0000 0004 7972 5257
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 2019
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Sitka spruce (Picea sitchensis) is the main commercial softwood species grown in Great Britain, providing raw material for a well-developed wood processing industry. An extensive programme of tree improvement has achieved significant gains in Sitka spruce growth rate and stem form, but there are concerns that negative genetic correlations between growth rate and wood properties might affect timber suitability for use in construction. This study investigated the potential for using selection and breeding to improve key wood properties (particularly stiffness), while maintaining or adding to gains in growth rate and stem form. Data were collected from a Sitka spruce full-sibling progeny trial of 61 families planted in 1985 on three sites, and on timber from a sub-sample of 29 of these families from two of the sites. Growth rate, stem form and indirect wood quality traits (Pilodyn pin penetration, acoustic velocity and spiral grain angle beneath the bark) were measured on standing trees. Spiral grain angle, wood density, stiffness and strength were measured on timber cut from felled trees. Heritability estimates for indirectly- and directly-measured wood quality traits were moderate to high, and generally greater than for growth and stem form traits. Heritability of spiral grain angle increased radially from the pith, with genetic control weakest in the juvenile core. Although there were negative genetic correlations between diameter growth and strength-grade determining wood properties (density, stiffness and strength), some families combined above average performance for all of these traits. The strength of cross-site correlations between family means suggested a greater degree of genotype x environment interaction for growth traits than for stem form or wood quality traits. Pilodyn pin penetration, acoustic velocity and underbark measurements of spiral grain angle were effective means of identifying the best families for wood density, stiffness and internal spiral grain angle respectively.
Supervisor: Cameron, Andrew David ; Lee, Steve Sponsor: Forestry Comission ; Inverness College UHI
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Sitka spruce ; Stems (Botany)