Studies On Genetic Variation And Early Selection Of Japanese Larch Clones

Japanese Larch clones (Larix kaempferi) is one of the most important coniferous species for pulpwood in China. Direct application of clonal propagation and hybrid utilization of controlled pollination based on selected superior clones is essential for improved breeding and intensive silviculture of the pulpwood-oriented Larix kaempferi. This study was carried out in a 10-year-old clones test of Dagujia Forest Farm in Qingyuan Country ,Liaoning Province .With pulpwood as a cultivated target, the genetic variation of its growth traits ,stem-form and wood qualities of clones was comprehensively and systematically studied ,and the growth variations and prediction of genetic gains of these clones were explored as the first time from both quantitative genetics and biological mathematics. Early selection were studied by Lambeth model of Japanese larch clones. Futhermore, according to its growth trait, stem-form and wood qualities, a number of superior clones and plus trees were selected in the Liaoning Province .Main conclusion from the study were as follows:1. Genetic variations among growth ,stem-form and wood traits. Variance analysis revealed that DBH and height were significantly difference among clones, and so were among individuals within a clones. Among clones ,there were very significant differences at 0.01 level in the crown width ,main-branch diameter ,main-branch angle and main-branch length ; there was significant difference in the taper and no significant difference in the bark thickness. The wood traits index except early-wood ratio wall-lumina and early wall thickness were significantly difference among clones, which mean it possible to carry out improving and selecting of Japanese larch at clone level. The growth, wood qualities and most stem-form of Japanese larch clones ,whose repeatabilities were over 0.5,were moderately of strongly controlled by genetics, while those for taper and bark thickness were low ,only with 0.3.2. Correlation analysis among traits. The correlation analysis among traits of Japanese larch clones indicated that the relationships among traits were complicated, i.e., positive and negative correlations coexisted. It was important to take a comprehensive selection so as to optimize all the traits according to the breeding target. In coincide with the osculation relationships between growth traits and crown width, main-branch diameter, main-branch length and bark thickness. The phenotypic and genetic correlation become the most significant positive among the microfibril angle of early-wood and latewood, wood basic density and early-wood ratio wall-lumina ;which was not significant among the microfibril angle, wood basic density and tracheid length. There was osculation positive relationships among the tracheid length of early-wood and latewood and latewood ratio wall-lumina.3. The radial variation of wood tissue proportion. The prophase variation curve of proportion of...