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The Genetic Variation and Multi-Trait Associated Selection of the Growth Traits and Material Quality Traits of the Excellent Progenies of Larix Olgensis

Author: LiYanXia
Tutor: ZhangHanGuo
School: Northeast Forestry University
Course: Tree Genetics and Breeding
Keywords: Larix olgensis open-pollinated pulpwood construction timber geneticvariations Combination selection
CLC: S791.22
Type: PhD thesis
Year: 2012
Downloads: 39
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Abstract


In this study, the testing forest of the24-year-old Larix olgensis excellent progenies in the Jiangshanjiao experimented forest station of Heilongjiang Academy of Forestry was treated as the research object, which went through the DBH wood core and felled wood sampling methods. Then the growth traits and wood core material traits (4traits totally involved), analytic wood material traits (21traits involved), pulp and paper making properties (16traits) and the mechanics traits (20ones) of the14families went through genetic variation analysis, square variance, correlation analysis and comprehensive index analysis.After these analyses, I obtained the genetic variation regulations of growth traits and wood material quality traits among families, researched the relations among these traits, established the regression models of wood basic density, tracheid traits and the correspondent traits of analytic wood, and finally selected out two superior families that can be utilized in both paper pulp manufacturing and construction. In addition, these results provided theories for thinning and reconstructing of vegetative seed garden of the rudimentary degree, and laid better foundations for the parent selection of hybrid breeding and the selecting of the excellent tree species of the far latter generations in the seed garden.1. The genetic variation of traits. There are larger variations in growth traits, wood basic density, wood tracheid traits, the material traits of analytic wood, pulp and paper making traits and the mechanics intensity of the timber, and there are abundant variations among the individuals within the same family. The differences among the growth traits of each family are very significant, and the heritability values of height, breast diameter and timber volume are0.73,0.72and0.80respectively; the differences in the wood basic density and wood tracheid traits among families are significant, and the heritability values are between0.56and0.80; the differences in the micro fiber angle of earlywood of analytic wood, tracheid length, the ratio of well lo cavity of earlywood. ligin. arabinose content, tensile strength, tearing strength, etc. are very significant, and the heritability values are between0.63and0.86; the basic density of analytic wood,the differences in latewood rate, the ratio of tracheid length to width, holocellulose content, etc. are significant, and the heritability values are between0.51and0.61; the differences in cleavage strength of the tangential facet, the end-face hardness and the hardness of the tangential facet are very significant, and the heritability values are0.77,0.62and0.72respectively; the differences in drying density, latewood rate, volume shrinkage rate, the cleavage strength of the diametric facet, the MOE and the shearing strength of the diametric facet along the grain are significant, the heritability values are between0.52and0.60, and because these traits are controlled by heritability of medium and higher intensity, there is larger potential for improving them.2. The correlation analysis among traits. The growth traits and the tracheid length are positively and very significantly correlated whose correlation relations are mainly controlled by genetic mechanisms, the two are also insignificantly correlated with wood density, the ratio of tracheid length to width and most of the mechanics intensity indices of the timber, and therefore, the two can be selected independently; wood density is significantly or very significantly and positively correlated with latewood rate, the diametric shrinkage rate, the tangential cleavage strength. MOE. bending strength, the shearing strength of the diametric facet along the grain, the crushing strength along the grain, the hardness of the end-face and the diametric facet, but insignificantly correlated with the other traits of pulpwood, which proves that the improvement of wood density is beneficial to the synthesized improvement of the mechanics traits of the timber, and both the wood density and the traits of pulpwood can be selected independently; the ratio of the trachied length to width is significantly or very significantly and positively correlated with the tangential diameter of earlywood, the tensile strength of paper, tensile index, tearing degree and tearing index, and negatively and very significantly correlated with tracheid ratio. Holocellulose is very significantly and positively correlated with the yield rate of gross pulp and fine pulp, and significantly or very significantly and negatively correlated with the content of the extracted substance from Phenylpropanol, the substance from cold water, arabinose content and the hardness of pulp. The micro fiber angle of earlywood is positively and very significantly correlated with the dual wall-thickness and negatively and significantly correlated with tracheid length, the ratio of tracheid length to width, tearing strength degree and index and MOE; latewood rate is positively and very significantly correlated with cleavage strength, MOE, bending strength, crushing strength parallel to the grain, positively and significantly correlated with the ratio of wall to cavity of earlywood, the ratio of length to width of pulp fiber and the hardness of the end-face, significantly or very significantly and negatively correlated with the diametric diameter of earlywood, the resin canal ratio, the pulp fiber width, the ratio of wall to cavity of pulpwood, tensile strength, tensile index, bursting strength and index.3. Wood basic density, tracheid length, tracheid width and the ratio of tracheid length to width are very significantly and positively correlated with the correspondent traits of analytic wood and the regression model is rather ideal and I can take advantage of the traits of wood at the breast height to predict the values of a single plant and indirectly select and assess the superior families specialized in pulpwood.The wood basic density is positively and significantly correlated with the basic density of analytic wood, drying density, the diametric cleave strength, MOE, bending strength, the crushing strength parallel to the grain and the hardness of the diametric facet, the regression model is rather ideal and I can take advantage of the value of the wood density at the breast height to predict the index values of mechanics and indirectly select and assess the superior families specialized in construction timber.4. Through the synthesized analysis of growth traits, wood basic density and the ratio of wood tracheid length to width. No.166and169families were selected as the superior families, The heritability gains of the timber volume, wood basic density and the ratio of the wood tracheid length to width are48.34%,14.01%and19.89%respectively and larger than the contrast ones by38.46%,3.68%and6.41%respectively.5. The pulpwood was treated as the breeding target, through synthesized assessment of the growth traits, material traits and pulp and paper making traits, which was in line with the results obtained according to the growth traits, material quality traits and the physical traits of paper pulp of analytic wood. The sleeted families of the holocellulose content, tensile index, tearing degree larger than the contrast ones by3.05%,3.74%and1.10%, the the ratio of well to cavity of earlywood less than the contrast ones by21.44%.6.The construction timber was treated as the breeding target, through synthesized assessment of growth traits and mechanics traits, which was in line with the results obtained according to the material quality traits and the physical traits of paper pulp of analytic wood, the superior families of the diametric cleave strength, MOE, hardness of the tangential facet larger than the contrast ones by2.50%.6.90%and45.24%respectively, microfiber angle of early and latewood, latewood rate and volume shrinkage rate less than2.51%,15.08%and13.30%.

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CLC: > Agricultural Sciences > Forestry > Forest tree species > Coniferous > Larch
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