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杉木８２个无性系间１～４年生树高差异极显著，生长量最大相差达１．６～２．７倍．遗传变异系数１２．５～２２．８％，广义遗传力估值０．６３３～０．９４１，遗传变异幅度和遗传控制程度都有随树龄增大而变小的趋向．按１０％的入选率，中选无性系的树高平均遗传增益可达２５％左右，但无性系相对于种子园子代的树高生长优势可能因树龄小而尚未表达出来．２年生与３～４年生树高生长量相关紧密．对杉木树高遗传力变化、年度相关趋势及优良无性系选择年限进行了分析和讨论，认为以提高木材产量为目标选择优良无性系的工作宜在林龄６～７年生时进行．
There were significant differences in tree height of 1 ~ 4 years between 82 clones of Chinese fir and the maximum difference of growth was 1.6 ~ 2.7 times. The coefficient of genetic variation was 12.5 ~ 22.8%. The generalized heritability was estimated at 0.633 ~ 0.941. The genetic variation and genetic control tended to decrease with age. According to the selection rate of 10%, the average genetic gain of tree height of the selected clones is up to 25%, but the height growth advantage of the clones relative to the seed orchard generation may not be expressed due to their small age. 2-year-old and 3 to 4 years old tree height growth are closely related. This paper analyzed and discussed the heritability changes, annual related trends and years of selection of excellent clones in fir plantations. It is concluded that the selection of excellent clones with the goal of increasing timber production should be carried out at the age of 6-7 years.