Selection On Supierior Clones Of Chinese Fir For Pulpwood

Variation of growth traits, wood properties, genetic control and genetic correlation between traits were studied systematically on 55 Chinese fir (Cunninghamia lanceolata) clones, which planted in a clonal test on Yangkou forest farm, Fujian province in 1990. Twelve clones among the 55 were selected for the study on the pulping and papermaking characteristics and their relationship both on growth traits and wood properties. One growth trait and five wood properties which were closely related to pulping and papermaking characteristics including pulp yield, wood consumption and strength of pulp and handsheet were selected by stepwise regression. Six superior clones on wood properties for pulp & paper wood were selected by index selection. The main results were asibllows:1. Clonal variation among Chinese fir clones. There were significant or highly significant differences among clones in growth traits such as height, DBH (diameter at breast height) , bole volume and also wood properties such as wood basic density, microfibril angle, tracheid length, tracheid width, the ratio of length to width, lumen diameter, double wall thickness, the ratio of wall thickness to lumen diameter, lumen perimeter and lumen area, but no significant difference were found in circularity index of lumen among clones.2. Genetic control of traits for Chinese fir clones. Broad-sense heritability in height, DBH and volume varied from 0.389 to 0.771, 0.169 to 0.703 and 0.377 to 0.674 respectively. Broad-sense heritability varied from 0.335 to 0.607 in wood basic density and from 0.734 to 0.867 in microfibril angle. Broad-sense heritability varied from 0.470 to 0.822, 0.391 to 0.820 and 0.313 toO.701 in tracheid length, tracheid width, the ratio of length to width for tracheid respectively, and varied from 0.522 to 0.618, 0.468 to 0.639 and 0.509 to 0.699 in lumen diameter, double wall thickness and the ratio of wall thickness to lumen diameter respectively, and varied from 0.473 to 0.830 and 0.488 to 0.602 in lumen perimeter and lumen area respectively. The results showed that growth traits and wood properties of Chinese fir clones were under middle to strong genetic control in most conditions.3. Genetic gains by single trait selecting at 10% of selection ratio. According to selection intensity, the estimation of genetic gains of height, DBH and volume were 4.27%, 6.36% and 15.56% respectively; basic density was 3.64%; fibril angle was 19.51%; tracheid length, tracheid width, the ratio of length to width for tracheid were 5.91%, 6.76% and 6.81% respectively; lumen diameter, double wall thickness and the ratio of wall thickness to lumen diameter were 7.27%, 12.89% and 18.84% respectively. Compared with averages of two CK , the estimation of genetic gains of volume was 23.17%; basic density was 1.64%; fibril angle was 10.79%; tracheid length , tracheid width, the ratio of length to width for tracheid were 5.14%, 7.50% and 9.00% respectively; lumen diameter, double wall thickness and the ratio of wall thickness to lumen diameter were 5.55% 9.81% and 15.13% respectively.4. Correlation of between traits. Correlation between growth and wood properties was showed as follows: The negative genetic relationship of height, DBH and volume with wood basic density, tracheid length, tracheid width, the ratio of length to width and lumen diameterranged from non-significance to significance. Positive genetic relationship of height, DBH and volume with double wall thickness and the ratio of wall thickness to lumen diameter were significant. The negative genetic relationship of DBH and volume with microfibril angle were not significant. Positive genetic relationship between height and microfibril angle were not significant. Correlation of inter-wood properties was showed as follows: The negative genetic relationship of wood basic density with tracheid length was significant, and with tracheid width and the ratio of length to width were not significant. Positive genetic relationship of wood basic density with double wall thickness and the ratio of wall thickne...