Abstract:

This paper dealts with the appropriate trials and optimum age for early selection of clone in Chinese fir(Cunninghamia lanceolata Hook) .The estimated parameters of early selection were based on tree heightand diameters at brast height (D.B.H) of four clonal trials, which included 107 clones.The height of trees was measured at 2～6、8～9、13～15 a; D.B.H was measured at 4～6、8～9、13～15 a after planting. The last investigation was carried out in 1999, for trial 8401 and 8402 was 15 year old, but 8501 and 8502 was 14-year-old. The correlation matrix of age-age genetic and phenotype for height and D.B.H of clones was analyzed. It was calculated that genetic variance accounted for percent of total variance.The average heritabilities and coefficient of genetic variance for every clone were also calculated. The results showed that clonal selection or elimination of clone in Chinese fir might be carried out at early age.Comparing the results of selection at 2～3 a,5～6 a、8～9 a,13～14 a for four trial forests,it was euggested that the clonal selection should not be carried out at 2～3 a,the first selection should be at 4～6 a、the second selection at 8～9 a.If the selection age was earlier,the wrong and lack was more.For the selected clone at 8～9 a,the actual gain of hieght,D.B.H and volume was 17.87%,23.48% and 64.50%,respectively;the genetic gain of height,D.B.H and volume was 15.19%,20.41% and 55.47%,respectively.

Key words: Cunninghamia lanceolata Hook, Clone, Early selection, Optimum age, Gain