Abstract:
Objective By studying the genetic variation of the growth, heartwood and wood character of 15 year old T. ciliata var. pubescens families for selecting the fast growing and high quality families of T. ciliata var. pubescens.
MethodsBased on A 15-year old family test forest of T. ciliata var. pubescens in Kaihua forest farm, Zhejiang Province, the tree height, DBH, volume, heartwood percentage, heartwood volume and wood basic density were measured, and the variance, correlation and principal component analysis were performed.
ResultsThere were significant differences in tree height, DBH, wood volume, heartwood percentage, heartwood volume and wood basic density among families, and heartwood and wood properties had high genetic stability, but there were no significant differences in crown width and height at crown base among families. Phenotypic and genetic correlation analysis showed that there was a significant positive correlation between DBH and heartwood volume and volume, and DBH could indirectly realize the selection of volume and volume of heartwood. The results of principal component analysis showed that volume (V), heartwood volume (Vh), diameter at breast height (D), tree height (H) and heartwood ratio (Rh) represented the quality and economic traits of T. ciliata var. pubescens, and contributed significantly to the first two principal components, PC1 and PC2. By constructing a comprehensive index selection equation for four characters: volume, heartwood percentage, heartwood volume, and wood basic density, two excellent families meeting the improvement conditions were selected. The average genetic gains of volume, heartwood percentage, heartwood volume and wood basic density were: 52.84%, 0.49%, 66.23% and 2.13%.
Conclusion The breeding objectives of T. ciliata var. pubescens should focus on growth and heartwood traits, but heritability of crown width and height at crown base are small and the differences between families are not significant, which indicates that crown width and height at crown base are not suitable targets for genetic improvement.