柚木幼林期生长与分枝性状的无性系变异与选择

Clonal variation and selection for growth and branch traits in young Tectona grandis plantations

[目的]研究柚木Tectona grandis无性系生长与分枝性状遗传变异及相关性,综合评价并筛选速生、优良枝型的柚木无性系。[方法]调查位于广西凭祥市的19个5年生柚木无性系的生长和分枝性状,进行重复力估算和相关性分析,并通过主成分分析计算每个无性系的综合得分。[结果]柚木无性系间树高、胸径和单株材积差异极显著(P<0.001),变异系数28.2%~38.8%,重复力0.821~0.863;不同无性系间平均分枝角度、分枝基径和分枝长度呈极显著差异(P<0.001),变异系数16.3%~57.9%,重复力0.497~0.817;生长和分枝性状之间存在极显著(P <0.01)或显著(P <0.05)相关;利用主成分得分值大小和15%的入选率,兼顾生长和分枝性状,选出了3个优良的柚木无性系(7765、6601、7703),其综合得分大于对照,它们的树高、胸径、单株材积的平均值分别为5.68 m、6.20 cm和11.52 dm3,分别比相应均值提高了10.65%、15.39%和31.51%,选择后现实增益分别达到了9.07%、10.69%和30.20%。[结论]5年生柚木无性系间生长与枝条性状存在丰富的遗传变异,有较高的改良潜力。生长和分枝性状受中等至较强的遗传控制。通过对5年生柚木无性系综合评价,选出了3个速生且分枝特性优良的柚木无性系,可作为优质柚木无性系材料在桂西南地区推广种植。

[Objective]This study aims to investigate the genetic variation and correlation of the growth and branch traits of teak clones,and to comprehensively evaluate and select teak clones with rapid growth and excellent branch types.[Method]We investigated the growth and branch traits of 19 teak clones at 5-year old located in the Pingxiang City of Guangxi,and conducted repeatability estimation and phenotype correlation analysis.The comprehensive score of each clone was calculated through principal component analysis.[Result]There were significant differences(P<0.001)in tree height(H),diameter at breast height(DBH),and individual volume(V)among the teak clones,with coefficients of variation ranging from 28.2%to 38.8%,and repeatability ranging from 0.821 to 0.863.There were significant differences(P<0.001)in average branch angle(Ang),branch base diameter(BD),and branch length(BL)among different clones,with coefficients of variation ranging from 16.3%to 57.9%,and repeatablity ranging from 0.497 to 0.817.There were significant correlations(P<0.01 or P<0.05)between growth and branch traits.Using the principal component scores and a selection rate of 15%,three excellent teak clones(7765,6601,7703)were selected,with their comprehensive scores exceeding the control.Their average values for H,DBH and V were 5.68 m,6.20 cm and 11.52 dm3 respectively,representing increases of 10.65%,15.39%and 31.51%compared to the corresponding averages.After selection,the real gains in H,DBH and V were 9.07%,10.69%and 30.20%respectively.[Conclusion]The growth and branch traits of 5-year-old teak clones exhibit rich genetic variation and high potential for improvement.The growth and branch traits are moderately to strongly controlled by genetic factors.Through comprehensive evaluation of the 5-year-old teak clones,three teak clones with rapid growth and excellent branch characteristics were selected.These clones can serve as high-quality genetic materials for teak clones and can be promoted in the southwest region of Guangxi.