Correlations among wood density, wood physical mechanics index and growth trait, and selection of elite families for production of building products in Larix olgensis

The growth traits and wood density of 14 families of 24-year-old Larix olgensis progeny testing forests composed of 13 openpollinated families and one control were selected as the research object of this tractate, which went through genetic variation analysis and deviation analysis. The results showed that there were larger variations in both the growth traits among families and wood basic density, the differences of growth traits among families were extremely significant, the differences of wood basic density values were significant, and that the heritability values of height, diameter at breast height, timber volume and wood basic density were 0.73, 0.72, 0.80 and 0.60 respectively, which indicated that there was rather large potential for improving the family levels. The results of the correlation analysis of growth traits, wood basic density and physical mechanics indices showed positive but insignificant correlation between the growth traits and wood basic density, analytic timber basic density and drying density respectively and insignificant correlation between the growth traits and most physical mechanics indices; the wood basic density positively and extremely significantly correlated with analytic timber basic density, drying density, diametric cleavage strength, modulus of elasticity, bending strength, crushing strength parallel to grain and the hardness of the diametric plane, and the regression analysis model was ideal to predict the physical mechanics index values and indirectly select and assess the superior families of L. olgensis construction timber by use of diameter at breast height. Afterwards, the 166 and 169 were selected as the superior families after the synthesized analysis of the growth traits and wood basic density, which was the same as the superior families selected according to the physical mechanics traits of analytic timber; the heritability gains of height, diameter at breast height, timber volume and wood basic density were 14.27%, 19.96%, 48.12% and 14.06% respectively; the values of height, diameter at breast height, timber volume and wood basic density of superior families were higher than those of control by 7.20%, 13.31%, 38.46% and 4.76% respectively.