Variation Analysis on Growth and Wood Quality Traits of Cunninghamia lanceolata Clones in Lechang Germplasm Bank

Some growth and wood quality traits of 103 clones of Cunninghamia lanceolata in ‘Longshan’ Germplasm Bank were tested to analyze the differences among the clones in these criteria including tree height (TH), diameter at breast height (DBH), standing volume (VOL) and wood basic density (DEN), tracheid length (TL) and width (TW), as well as lengthwidth ratio of tracheid (LRT). The variance analysis results indicated that all the traits varied either significantly or extremely significantly among the clones. There was the largest difference in the VOL trait among the all criteria measured, whose variation coefficient was 3623%. The repeatability of the traits of TH, DBH, VOL, and DEN, and TW was relatively high (>50%). The genetic correlation analysis indicated that the trait of DEN was negatively correlated with TH, DBH, VOL, TW criteria, and there was negative correlationship between TW and LRT criteria. There were positive correlations among the different growth traits, between TL and TW, TL and LRT, DEN and LRT, TL and LRT, DBH and VOL. A considerable number of C. lanceolata clones were separately selected as superior ones by the indexfree or indexrestricted methods. Compared to the indexfree method, the restricted approach was more efficient in selection that could effectively exclude the clones in low DEN level. Profoundly, when genetic gain in VOL was 2877% (20% was the threshold) obtained by the indexrestricted method, the DEN trait represented a peak in genetic gain. While the maximum genetic gain of VOL was achieved, a moderate genetic gain for TL（062%）was observed (under the threshold of 10% by indexrestricted method). Thus, it was hypothesized that the comprehensive selection by multiple criteria and improvement of C. lanceheolata clones simultaneously with optimal growth and wood quality traits was possible.