Nguyen Duc Kien, Gunnar Jansson, Chris Harwood, Curt Almqvist and Ha Huy Thinh (2008). Genetic variation in wood basic density and pilodyn penetration and their relationships with growth, stem straightness, and branch size for Eucalyptus urophylla in northern Vietnam . New Zealand Journal of Forestry Science 38 (1): pp 160 - 175.

Genetic parameters for wood basic density and pilodyn penetration and their relationships with diameter, height, stem straightness, and branch size were estimated in two thinned open-pollinated progeny trials of Eucalyptus urophylla S. T. Blake in northern Vietnam at the ages of 8 and 9 years. There were 127 families in one trial and 144 in the other trial; all families were from nine natural provenances, and 120 of them were common to both sites. At the time of assessment, each family was represented by four to eight trees in each trial. Wood basic density, estimated from 5-mm increment cores taken at breast height, averaged 0.51 g/cm3 across the two trials. Estimated narrow-sense individual tree heritability (ĥ2) for wood basic density was 0.60, and that for pilodyn penetration it was 0.42. The estimated coefficient of additive genetic variation (CVA) for wood basic density was 6.3%. There were no significant differences between provenances for these two traits. The estimated genetic correlation between pilodyn penetration and wood density was –0.86, indicating that pilodyn could be used reliably as an indirect measurement of wood basic density. The estimated genetic correlations among wood basic density and diameter at breast height, height, stem straightness, and branch size at each site were weak. The strong estimated genetic correlation between inner wood density and total core density indicated that reliable selection for wood density could be carried out at age 3 years. Estimated genetic correlations between sites for both wood basic density and pilodyn penetration were strong, indicating little genotype-by-environment interaction for these traits across these two similar environments.

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