Research On Genetic Variation In Wood Properties Of Provenances Of Eucalyptus Cloeziana

In this thesis,the basic density,shrinkage,compressive strength parallel to grain,modulus of elasticity(MOE),bending strength(MOR) and toughness of the 17-year-old plantation of Eucalyptus cloeziana wood from 11^thprovenances in Dongmen Forest Farm were studied.Then the variation of these properties among provenances and different heights were analysised.The correlation between wood properties and its of growth traits and wood properties were also analysised.The heritability of growth traits and wood properties of E.cloeziana and the correlation of between these traits and geographical factors of origin were studied. By means of principal component analysis and clustering analysis,the 11^thprovenances were evaluated comprehensively and superior provenances were selected from them.The results are as follows:1.Among the provenances of E.cloeziana,there were significant differences in tree height and diameter at breast height(DBH),and significant or very significant differences in wood basic density, tangential shrinkage of oven dried wood,radial shrinkage of oven dried wood,volumetric shrinkage of oven dried wood,variance shrinkage, compressive strength parallel to grain,MOE,MOR and toughness.A good effect could be obtained by selection among the provenances.2.Among different tree heights,there existed no significant differences in volumetric shrinkage of oven dried wood and toughness,significant differences in other wood properties.The properties have no unified variation pattern with height in the tree.3.The linear regression were analyzed by taking basic density as independent variable,volumetric shrinkage of oven dried wood, compressive strength parallel to grain,MOR and toughness as dependent variable respectively.The results show the regression were significant. Correlation coefficients between volumetric shrinkage of oven dried wood and basic density range basically from 0.336 to 0.620,between MOR and basic density range basically from 0.465 to 0.800,between compressive strength parallel to grain and basic density range basically from 0.462 to 0.893,between toughness and basic density range basically from 0.352 to 0.810.The linear regression were also analyzed by taking MOR as independent variable and MOE as dependent variable,the result shows the correlation coefficients between MOE and MOR was above 0.691,and the regression was significant.It is feasible to estimate other wood properties by basic density.4.Correlation analysis of traits of E.cloeziana showed that the height have significant positive correlation with MOE and toughness,no significant correlation with other traits.The DBH have on significant correlation with tree height and all other wood properties.It can be selected separately.All traits have no Significant correlation with longitude and altitude of origin.The basic density,volumetric shrinkage of oven dried wood and compressive strength parallel to grain have significant negative correlation with latitude of origin.5.The results of genetic parameter estimation of wood properties show that:the heritability of wood density,shrinkage and compressive strength parallel to grain are between 0.553-0.719,these properties were under medium or above medium genetic control.However the heritability of MOR,MOE and toughness were less,these properties were under lower genetic control.This just have proved that wood properties of E.cloeziana have potential to be improved,the selection of provenances can obtain good effects.6.By using principal component analysis and hierarchical clustering analysis,five superior provenances were screened out,that is the provenances of 12196,D47,17008,B47 and 14127.