杉木无性系幼树高生长的遗传变异

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衡遗传增益可达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水表达出来，２年生与３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

Genetic Variations in Juvenile Height Growth of Chinese Fir Clones

The height increments of 82 Chinese fir (Cunninghamia lanceolata Hook. ) clones from 1 to 4years of age were different at 1 % level of significance with a dissimilarity of 1. 6 to 2. 7 timesbetween the minimum and the maximum. The estimates of both the genetic coefficient of variation and the heritability that ranged from 12. 5% to 22. 8% and from 0. 633 to 0. 941,respectively,decreased with the incresing clonal ages. The genetic gains of about 25% in height increments were expected when the most superior 10% of the clones tested had been selected. Unfortunately,the heisht srowth of the clones was inferior to that of the seed orchard progeny as being acheck treatment in the testing plantations, which might be due to the juvenility of the clones.There were very significant correlations between 2 and 3 to 4 years old heights. A discussion isheld about the tendency of variations in the heritability estimates of and in the correlation coefficients between the heights at various ages of Chinese fir and about the age at when the superiorclones could be selected, on the basis of which it is suggested that the Chinese fir clones testedshould be selected for their superiorility in growth only when they will have been 6 or 7 yearsold.