中文摘要：

【目的】探索外源激素吲哚乙酸（IAA）和赤霉素（GA_3）对杨树应拉木形成的影响,揭示杨树应拉木的形成机理。【方法】以人工倾斜45°的当年生中林46杨枝条为试材,连续施加不同含量的IAA（0.01,0.10和1.00mg/g）和GA_3（0.10,1.00和10.00mg/g）对枝条生长进行调控,分别观测不同处理下枝条的生长量、角度、偏心率、纤维形态、组织比量和胶质纤维比率,分析这2种外源激素对杨树应拉木形成的影响。【结果】施加1.00 mg/g外源IAA抑制了纤维细胞的生长及胶质纤维和导管的形成,不仅枝条角度变大,而且枝条生长受到限制;施加1.00和10.00mg/g外源GA_3可促进纤维细胞、胶质纤维的形成和枝条的生长,使枝条偏心率显著增大,且高含量GA_3的作用效果更明显;0.01mg/g IAA和0.10mg/g GA_3对枝条的作用效果基本一致,均促进了枝条横向疏导组织的形成,使其偏心率明显减小,但对倾斜枝条应拉木形成的作用并不明显。【结论】IAA和GA_3均能够影响杨树应拉木的形成,高含量的IAA明显抑制应拉木的形成,而高含量的GA_3可明显促进应拉木的形成。

英文摘要：

【Objective】The effect of exogenous indole-3-acid（IAA）and gibberellic acid（GA_3）on tension wood formation of poplar was explored to reveal the tension wood formation mechanism.【Method】The current branches artificially inclined at angle of 45°of poplar Zhonglin-46 were selected and IAA and GA_3 with different contents were continuously applied to regulate the growth of branches.The differences and changes in growth,angle,eccentricity,fiber morphology,tissue proportion,and gelatinous fiber ratio of poplar branch were observed and analyzed for unveiling the effects of these two exogenous hormones on tension wood formation of poplar.【Result】The growth of fiber cells and formation of gelatinous fibers and vessels were inhibited by applying exogenous IAA with content of 1.00mg/g.Branch angles were also increased and the growth of shoots was limited.The formation of fiber cells,gelatinous fibers and growth of branches were promoted by applying GA_3 with the content of 1.00 and 10.00mg/g,and the branch eccentricities also increased significantly.The higher the content of GA_3,the more significant the effect was.The effects of low contents of IAA（0.01mg/g）and GA_3（0.10mg/g）on the branches were similar.They both contributed to the formation of lateral leading organization of the branches so that their eccentricities were significantly reduced.However,the effect on tension wood formation of the sloping branches was not sig-nificant.【Conclusion】The formation of tension wood of poplar was significantly inhibited by IAA with high content,while it was significantly promoted by GA_3 with high content.