Genetic Var ia tion ofWood Properties of Japanese Larch Clones

The genetic variations of basic density and tracheid features of 10 Japanese larch clones at 10 yearswereinvestigated. The result revealed that the basic density, tracheid width of earlywood and latewood and tracheidlength2width ratio of earlywood had significant differences among clones. The basic density, tracheid length of earlywood and latewood, tracheid width of earlywood had latewood and tracheid length-width ratio of earlywood and latewood followed the same pattern. The radial variation curveswere increased from p ith to bark , which showed wavessometimes. The tracheid wall thickness of earlywood and latewood and tracheid dull wall thickness-diameter ratiofollowed the same pattern. The latewood was constantly bigger than the earlywood. The radial variation curves of earlywood were slowly increased close to line from p ith to bark. The latewood was increased by curve from p ith to bark.The variation range was large at the initial stages and then became lever variety and slimly waves in a certain age.The variation pattern of wood p ropertity was well fitted by logarithm, power and exponential equations. The repeatabilities of wood p roperty were over 0. 5 excep t tracheid dull wall thickness-diameter ratio of latewood and tracheid wall thickness of earlywood, indicating thatwood p roperty traitswere moderately of strongly genetic control. The genetic gains of tracheid length-width ratio of latewood and tracheid length were higher if 20% of the best cloneswasselected.