| In this paper,10 Eucalyptus dunni Maiden provenances at age nine were researched to study the genetic variation of retention rate,growth traits,and wood quality.The correlations among traits and selection of superior provenances were also studied.The main results were as follows:1.The average retention rate of all the 9-year-old provenances was 42.58%,and there was a significant difference in the retention rate among provenances.Among the 10 provenances,the highest conservation rate of provenance was D9503 at 65.28%.The minimum conservation rate of the provenance D9505 and D9506 was 19.70%and 29.85%,respectively.Provenance D9503 showed better adaptability.2.The growth traits such as tree height,DBH,individual volume,height-diameter ratio,and the wood trait including basic density,fiber width,fiber double wall thickness showed significant or extremely significant differences among provenances.There was no significant difference in green density and fiber length among the provenances.3.The basic density,green density,fiber length,fiber width,fiber aspect ratio,fiber double wall thickness,and fiber wall cavity ratio of wood from various provenances were in accordance with the variation rule of sapwood>middle wood>heartwood.The absolute moisture content of wood and the ratio of fiber cavity diameter showed the trend of sapwood<middle wood<heartwood.4.The provenance heritability ranges of the growth traits and wood traits of Eucalyptus dunni were 0.2217 to 0.8520 and 0.2327 to 0.7881,respectively.The growth traits showed different degrees of genetic variation from different growth stages.When the trees reached the age of 9 years,the heritability of tree height,DBH,individual volume,height-diameter ratio,basic density,absolute moisture content,fiber width,fiber double wall thickness,fiber cavity diameter ratio and fiber wall cavity ratio was higher,and they were controlled by medium or middle genetics with greater potential for provenance selection5.The juvenile-mature genetic correlation coefficient for tree height was 0.295 to 0.921,DBH was 0.096 to 0.997 and individual volume was 0.172 to 0.996.The genetic correlation coefficient between tree height and 9-year individual volume was less than the DBH at the same time.The age-age correlation between earlier ages and the age of nine for all traits showed an increasing trend with the increase of stand age.6.Traits of Eucalyptus dunni indicated that the relationships among traits were complicated in that positive and negative correlation coexisted.Based on genetic and phenotypic correlation of growth traits,there were significant or extremely significant positive correlation between individual volume and DBH,tree height,stem form,crown width,but a significant negative correlation was found in height to diameter ratio.There were negative genetic correlation between DBH and height to diameter ratio,under branch height and relative value of branch height,but a significant positive correlation was found in crown width.There were positive genetic correlation among basic density and green density,fiber length-width ratio,fiber double wall thickness to cavity ratio,but negative correlation were found in fiber width,fiber cavity to width ratio.In addition,there were negative correlation among basic density and DBH,individual volume.Fiber length,fiber width,fiber length to width ratio,fiber cavity to width ratio and fiber double wall thickness to cavity ratio were not significantly correlated with DBH,tree height and individual volume,and the correlation coefficient was small,which indicated that there was a certain independence between growth traits and fiber traits.7.3 excellent provenances were selected to realize growth traits,wood traits and stem form improvement at the same time.The selected provenances were D9506,D9507 and D9508.The average genetic gains of DBH,tree height,basic density,fiber length-width ratio,and fiber-chamber-cavity ratio were 0.49%,2.82%,7.23%,0.70%and 4.65%,respectively.The average stem form reached 3.38. |
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