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长期以来对于杉木优良无性系都是根据其生长性状按方差分析的方法进行选择的。本研究根据湖南省永州市金洞林场66个杉木无性系在6a、10a、16a、26a每木调查(树高和胸径)的数据进行聚类,用聚类分析的方法来揭示不同林龄时期选择优良无性系的差异。结果表明:在不同林龄时期即使是最优类群也都存在着显著的差异性。如果以26a聚类分析的最优类群确立为最终选定的优良无性系,结果 6a时最优类群中的7个无性系到26a时只有1个还继续保留,因此,6a时选择其准确率仅是14.29%;同样10a最优类群中的5个杉木无性系到26a时只有2个还继续保留,其准确率是40.00%;16a时最优类群中的5个杉木无性系到26a时有4个还保留着,其准确率是80.00%。由此可知,随着选择年龄的增长,最优类群的准确率会越来越高。虽然在成熟龄期选择其准确率会达100%,但从单位时间获得的遗传增益和生产增益的效果来看:在16a进行选择至少能提前10年获得优良品种的利用,虽有风险但还是值得的。
For a long time, the excellent clones of Chinese fir were selected according to the analysis of variance according to their growth traits. Based on the data of 66 fir fir clones at Jindong Forest Farm, Yongzhou, Hunan Province in each surveyed (tree height and DBH) at 6a, 10a, 16a and 26a, the data of cluster analysis were used to reveal the relationship between different forest age Select the difference between excellent clones. The results show that there are significant differences even among the best taxa in different age groups. If the best cluster analyzed by cluster analysis was 26a, the results showed that 7 clones in the optimal cluster at 6a were only retained until 26a, so the accuracy was selected at 6a Only 14.29%. In the same ten-year-old population, only five of the fir clumps in the same 10a group remained at 26a with an accuracy rate of 40.00% 4 still retained, the accuracy rate is 80.00%. It can be seen that with the increase of age, the accuracy of the best taxa will be higher and higher. Although the accuracy of selection at mature ages will reach 100%, the effect of gaining genetic gain and production gain per unit time is as follows: Choosing at least 16 years prior to access to elite varieties 10 years ahead of schedule is risky worth it.