GENETIC PARAMETERS IN FIBRE TRAITS FROM A FULL DIALLEL OF EUCALYPTUS UROPHYLLA IN SOUTHERN CHINA

Fibre traits were assessed for 6 × 6 full-diallel families of Eucalyptus urophylla measured at 10 years old. Analysis of variance showed that there were significant combination effects and no block differences on any fibre traits except fibre width. The mean fibre length, fibre width, fine percent, mean curl, fibre kink index and kink angle of controlled crossed families were 0.57 mm, 19.74 μm, 27.38%, 0.039°, 0.64 and 8.24° respectively. The heritability of fibre traits was at low to middle level, and the coefficients of variation ranged from 8.58 (width) to 39.30% (kink angel). Inbreeding depressions of fibre length and width were observed in most families, and the largest inbreeding depressions were estimated at -61.76 and -15.45%. Heterosis ranged from -42.42 to 103.84%. Kink angle had higher general combining ability and fine percent had higher estimation of specific combining ability. Genotypic correlation between fibre length and fibre width were positive, implying these two traits could be selected simultaneously. As an important indicator of pulp yield, fibre traits should be used for breeding E. urophylla.