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    四倍体白桦木材纤维性状比较及优良母树选择

    Comparison of tetraploid Betula platyphylla wood fiber traits and selection of superior seed trees

    • 摘要: 为选出不仅生长速度快而且木材纤维性状表现优良适于制浆造纸的四倍体白桦母树。以制种园中31株四倍体白桦为研究对象,测量其胸径生长指标,测定木材密度、纤维长度、纤维宽度以及木质素、纤维素、综纤维素含量等木材品质指标,并对其进行了方差分析和多重比较。结果显示:各性状在母树间的差异均达到极显著水平(P<0.01),在31株四倍体母树中24株的纤维长显著高于二倍体对照。有13株母树综纤维素含量大于70%,12株母树纤维素含量高于50%,说明白桦染色体加倍后对木材纤维性状影响显著,在四倍体母树中可选出用于纸浆材的优良母树。参试母树胸径生长量为2.00或2.00 cm以上的有8株母树,并且均为四倍体白桦;根据胸径生长量及材性指标,采用隶属函数法对参试母树进行综合评价,表现最优的7株母树均为四倍体母树,说明染色体加倍可提高白桦的生长量及木材品质。虽然四倍体在树干通直度方面表现较差,仅有42%母树通直度为Ⅱ级或Ⅰ级,但作为纸浆材对该性状的要求可适当放宽,最后初步选出19株母树生长和材性均表现优良,其中5株兼具生长、材性、干型最优。在种子园中,生长及材性性状表现均较差的5株四倍体母树将被淘汰。

       

      Abstract: In this paper, we compared 31 tetraploid seed trees and three diploid Betula platyphylla seed trees in terms of their wood property traits and growth characteristics. The measured traits include DBH growth increment, stem straightness, wood density, fiber length, ratio of fiber length to width, content of lignin, cellulose, and holocellulose. The measured data were then analyzed in terms of variance with multiple comparisons. The results showed as the following: the differences in traits among the seed trees reached a significant level (P < 0.01). Of the 31 tetraploid seed trees, the fiber length of 24 was significantly higher than that of the diploid birch. In addition, the cellulose content of 13 seed trees was greater than 70%, and that of 12 was higher than 50%, which indicated that birch had significant effects on the traits of wood fiber after chromosome doubling, thus we can choose the good seed trees used for pulp material in tetraploid trees. Among the experimental seed trees, there were eight seed trees with a DBH amount of 2.00 cm or above, and all of them were tetraploid birch. According to the DBH growth and wood traits, using the subordinate function to comprehensively evaluate the experimental seed trees, the results showed that: the seven best performing birch seed trees were all tetraploid seed trees, which indicated that chromosome doubling can improve the growth of birch trees and the material properties of pulp and paper. Although the performance in terms of stem straightness was poor, with only 42% of the seed trees having straightnesses of grade Ⅱ orⅠ, but as pulpwood, the requirements of traits may be less strict. Finally, 19 seed trees were preliminary selected, of which the DBH growth and wood traits were all excellent, and five of them had optimal performance in terms of growth, wood properties and trunk shape. In the seed orchard, five tetraploid seed trees which have poor growth and wood properties will be eliminated.

       

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