Abstract

We surveyed 55 genetic studies published from 1960 to 2007 involving 11 growth-, form-, and wood-quality traits in Pinus radiata D. Don, including seedling and clonal trials. Estimated genetic parameters evidently varied according to populations, environments, and ages. Overall, estimated heritability for wood-quality traits (except shrinkage) was always higher than for growth and form traits. Wood density had the highest grand-mean of estimated heritability (0.63) among the six wood-quality traits, followed by microfibril angle (0.61), spiral grain (0.55), fibre (tracheid) length (0.54), stiffness (0.50), and shrinkage (0.20). Selective breeding for these woodquality traits (except shrinkage) would be very effective. Among the five growth and form traits, branch cluster frequency had the highest heritability (0.35), followed by branch size (0.27), branch angle (0.25), diameter at breast height (0.23), and stem straightness (0.23). Broad-sense heritability estimates were higher than narrow-sense heritability, particularly for diameter at breast height (average 0.39 versus 0.21). This indicates there is considerable nonadditive genetic variance that should be exploited in breeding and deployment programmes for P. radiata. There was a higher and more complex genotype by environment interaction (G × E) for diameter at breast height in Australian sites than in New Zealand sites. Growth rate (dbh) was adversely correlated with all wood-quality traits (for both density and mean stiffness rg = –0.48). Breeding for overcoming or at least coping with adverse genetic correlations and effective utilisation of non-additive genetic variation are two of the most challenging issues in the advanced generations of P. radiata tree improvement and deployment programmes.

Keywords

genetics; tree breeding; genetic parameters; heritability; geneticcorrelation; Pinus radiata

Published in

New Zealand Journal of Forestry Science
2008, Volume: 38, number: 1, pages: 56-87

UKÄ Subject classification

Forest Science


Permanent link to this page (URI)

https://res.slu.se/id/publ/106527