Jianmin Xu

Use of the Pilodyn for Assessing Wood Properties in Standing Trees of Eucalyptus Clones

The effectiveness of pilodyn was tested in evaluating wood basic density, outer wood density, heartwood density, and modulus of elasticity (MoE) at 22 four-year-old eucalyptus clones in Guangxi, China. Results indicated that the mean value ranged from 9.44 to 15.41 mm for Pilodyn penetration, 0.3514 to 0.4913 g·cm−3 for wood basic density, and 3.94 to 7.53 Giga Pascal (GPa) for MoE, respectively. There were significant differences (1% level) in pilodyn penetration between different treatments, different directions and among the clones. Generally strongly negative correlations were found between pilodyn penetration and wood properties, and the coefficients ranged from −0.433 to −0.755. Our results, together with other studies, suggest that the use of pilodyn for assessing wood density and MoE was confirmed as a possibility.

Genetic variation and genetic gain in growth traits, stem-branch characteristics and wood properties and their relationships to Eucalyptus urophylla clones

Abstract Growth traits, wood properties, stem-branch characteristics and bark percentage were assessed for 60 Eucalyptus urophylla S.T. Blake clones in southern China measured at age 21, 52, 71 and 96 months. Analysis of variance showed that there were significant differences on growth traits, wood properties and individual tree wood weight among clones. Coefficients of genotypic variation ranged from 12.12% to 53.16% for growth traits, 9.02% to 20.18% for wood properties, 21.75% to 22.71% for stem-branch characteristics, 28.31% for bark percentage and 51.20% for individual tree wood weight. Repeatability ranged from 0.36 to 0.53 for growth traits, 0.35 to 0.51 for wood properties, 0.21 to 0.24 for stembranch characteristics, 0.07 for bark percentage and 0.31 for individual tree wood weight. The strongly negative genotypic correlations suggesting that selection on growth traits at 21 months can not be effective to predict growth traits at 96 months whereas it could be used to predict growth traits at 52 and 71 months. The genotypic correlations between growth traits and basic density were ranged from -0.78 to 0.28 and weakly positive phenotypic correlations were found between growth traits and basic density, ranging from 0.03 to 0.09. The selection gain on diameter at breast height over bark by different selection proportions at 21, 52, 71 and 96 months old expressed that selection gain at 71 months was some what higher than that at other ages during 10% to 30% selection proportion, while selection gain at 52 months was some what higher than that at other ages during 60% to 90% selection proportion. Wood properties and individual tree wood weight which are strongly related to end production and economically important in pulp production should be studied extensively especially for pulp breeding.

Age trends and correlations of growth and wood properties in clone of Eucalyptus urophylla × E. grandis in Guangdong, China

We assessed growth traits and wood properties of DH32-29, a clone of Eucalyptus urophylla × E. grandis, at age of two to six years in Guangdong in China. Analysis of variance of studied traits showed that there were significant differences (1% level) on all studied traits among ages except for wood basic density. Analysis of age trends of growth traits and wood properties revealed that rotation length of DH32-29 should be more than six years or longer. Phenotypic correlations among traits at individual ages indicated that correlations between growth traits were strongly positive. There was significant change in relationship between growth and wood basic density with increasing age, ranging from −0.03 to −0.54 at 2 and 5 year and 0.003 to 0.3 at 3, 4 and 6 year. Correlations between Pilodyn pin penetration and basic density measured on increment cores showed that Pilodyn could rank or group genotypes or sites into density classes, but failure to predict individual tree and individual clone.