Anatomical characteristics in 20-year-old Zelkova serrata trees from eight half-sib families

Zelkova serrata (Thunb.) Makino (‘‘keyaki’’ in Japanese) is an important broad-leaved species for the wood industry in Japan. To analyze the among-family variation of anatomical characteristics in Z. serrata, wood f iber length (WFL), vessel element length in earlywood (VEL), fiber wall thickness (FWT), and vessel diameter in earlywood (VD) were investigated for 20-year-old trees from eight half-sib families. Mean values of WFL, VEL, FWT, and VD ranged from 1.31 to 1.51 mm, 0.19 to 0.22 mm, 1.2 to 2.1 lm, and 131 to 188 lm, respectively. Relatively higher F values were obtained by analysis of variance for WFL and VEL, suggesting that these charac teristics might be improved though the selection of mother trees under tree breeding programs. In addition, growth characteristics were not significantly correlated with anatomical characteristics, except for FWT.