Genetic variation of wood density in Luanta fir tested in central Taiwan

Forty-nine wind-pollinated families representing 8 provenances of Luanta fi r (Cunninghamia konishii) were sampled from the species' range in Taiwan. T he study plantation was established in central Taiwan with 49 ten-tree line ar plots in each of 5 blocks in the randomized complete black design. In Ju ly 1998 at plantation age 25, a 0.45-cm caliber increment core sample was e xtracted at breast height in the east cardinal direction from the best tree per plot; altogether 245 cores (1 core/family/plot x 49 families x 5 block s) were sampled. From each core, only the 6 outermost growth rings (near th e bark) were used to determine extracted specific gravity according to the maximum moisture content method. Genetic variations among provenances and a mong families within provenances were tested following a general linear mod el. There was no apparent geographic variation pattern, and the main source of specific gravity variation was attributable to differences among famili es within provenance. Overall specific,gravity was 0.36 and the narrow-sens e family heritability was 0.46. Wood specific gravity is strongly controlle d by additive genetic variance, suggesting that this trait would respond to selection breeding. The importance of family selection was emphasized in t he improvement of this wood property in Taiwan.