Improving the timber quality of Sitka spruce through selection and breeding

Authors
Citation
Sj. Lee, Improving the timber quality of Sitka spruce through selection and breeding, FORESTRY, 72(2), 1999, pp. 123-133
Citations number
32
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Plant Sciences
Journal title
FORESTRY
ISSN journal
0015-752X → ACNP
Volume
72
Issue
2
Year of publication
1999
Pages
123 - 133
Database
ISI
SICI code
0015-752X(1999)72:2<123:ITTQOS>2.0.ZU;2-9
Abstract
The genetic improvement of Sitka spruce (Picea sitchensis (Bong.) Cart) com menced in 1963 with the objective of developing breeding populations well a dapted to a range of site types, with improved stem form and growth potenti al and wood qualities satisfactory for the sawn timber market. Assessments of wood density, diameter and stem form in progeny tests have determined a strong negative genetic correlation between diameter and wood density while stem form has no significant correlation with either diameter or wood dens ity. If home grown Sitka spruce is to replace slower grown imported materia l in the construction markets, it is important that tree breeders retain a balance between improvements for diameter and wood density; diameter should not be increased at the expense of wood density, and ultimately timber str ength. Multi-trait selection index techniques were used to combine estimated breed ing values for diameter, stem form and wood density based on the mean perfo rmance of their progeny relative to the unimproved control of Queen Charlot te Island origin after 15 to 22 growing seasons in replicated tests. Final index rankings vary according to the economic weight applied to each select ion trait. By applying a range of economic weights, breeders are now able t o offer forest managers a choice in the genetic quality of planting stock a ccording to their perceived relative values. The objective of the General P roduction Populations is to maximize genetic gains for diameter and stem fo rm while preventing a fall in wood density. Alternative production populati ons offer further gains in wood density and stem form respectively, althoug h managers must accept more modest diameter gains as a consequence.