| Eucalyptus is a generic species of Myrtaceae,Corymbia K.D.Hill&L.A.S.Johnson and Eucalyptus L,Herit,which has become the most important industrial timber species in southern China because of its rapid growth,good qualities and properties,high yield,good economic benefits.C lonal afforestation is a most important means to plant eucalyptus plantation,and superior clones have the advantages of strong resistance,orderly forest forms and easy to intensive management.In order to meet the current timber demand,the early selection of clones is needed.In this paper,the growth traits,morphological traits,woody properties and wind resistance of 21 Eucalyptus clones and one control clone Eucalyptus 1 at 33 months were studied and selected comprehensively,and three excellent eucalyptus clones were finally screened out and growth-predicted.Here is the conclusion:1.The difference of growth traits and morphologica l traits among different group of clones showed that tree height,DBH,volume per plant,branch height,crown width,height-diameter ratio,stem form and branched arborization among different group of clones are significantly different,and selecting excellent clones with faster growth and better nature from the tested clones are feasible.The numbers that ranking the top three of average individual volume of experimental Eucalyptus clones are 2#,28#,JJ144,and the value of their average individual volume are 0.0531 m3,0.0529 m3,0.0512 m3,which are respectively 134.43%?133.92%?129.62%times larger than 0.0395 m3of Eucalyptus 1'average individual volume.2.The clonal repeatability of the main growth traits were greater than that in the individual,and the early selection among the clones could obtain better results.The variation range of the lonal repeatability was from 57.22%to 83.92%,which was medium intensity inheritance so that the stability of traits is high.The variation range of phenotypic variation coefficient was from 14.67%to 51.06%and the coefficient of genetic variation was from12.16%to 44.53%.3.The phenotypic correlation coefficient of each trait was nearly consistent with the genetic correlation coefficient.The relevance of tree height,DBH and individual plant volume among tested Eucalyptus clones was significant positively correlated,so the selection of traits could be combined.In addition to crown and height-diameter ratio,the relevance of the growth index and the morphological index was positively correlated.The relevance between the preservation rate and the DBH,the individual volume and the crown was negatively correlated while contrary to other indexes.Besides,Wood density is negatively correlated with other traits,and the correlation coefficient is relatively small so that it can be independently selected.4.The early selection of clones was carried out by using the selection index method in the comprehensive selection.After obtaining the rankings of the clones,the early selection of clones was compared with the selection of individual traits,and three excellent eucalyptus clones were identified at last whose serial numbers are 28#,2#,JJ144.5.The results gained from the five-aged growth prediction o f three selected excellent clones and a control clone Eucalyptus 1 showed that the stand volume of the experimental clones 28#in five-aged rotation is 245.604 m~3/hm~2,the stand volume of the experimental clones 2#is 165.8014 m~3/hm~2,the stand volume of the experimental clones JJ144#is126.7104 m~3/hm~2.All of them are 139.50%,94.18%and 71.97%times the size of that in Eucalyptus 1 respectively,which is 176.055 m~3/hm~2.The individual volume in five-aged of the experimental clones 28#is 0.1164 m~3,of the experimental clones 2#is 0.1153 m~3,of the experimental clones JJ144#is 0.1072 m~3,which are respectively 139.50%,94.18%and71.97%times the size of that in Eucalyptus 1 whose individual volume in five-aged is0.0825 m~3.6.The early selected excellent clones also need to conduct regional trials and pilot test,screen more excellent from the early selected excellent clones,and promote in the local ultimately. |
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