Distribution of IAA and ABA Levels and Reaction Wood Formation in Inclined Stems of Angiosperm Trees

倾斜双子叶树表现出与针叶树相同的偏心生长和反应木特征。而被子植物的反应木形成于学习茎的上部，在解剖结构上与裸子植物不同。此外，倾斜的树木并不总是表现出明显的张力木变化，因为一些物种没有表现出明显的张力木偏心和解剖特征。在针叶树中，吲哚-3-乙酸（IAA）的作用已经被假设和理解为控制压缩木材形成的因果因素。但是，将这一概念应用于被子植物中形成的张力木一定是困难的，因为IAA浓度在自然中是否在倾斜茎的上侧比下侧高是值得怀疑的。本研究观察了sioji （Fraxinus s . More paethiana）、mizunara （Quercus crispula）和oobaasagara （Pterostyrax hispida）三种双子叶乔木在人工倾斜的情况下，整个茎部都出现了偏心生长和张力木的解剖特征。此外，还定量检测了IAA和脱落酸（ABA）在倾斜茎两个位置上的分布与张力木材形成的关系。(1)虽然sioji和mizunara两个物种在倾斜后表现出偏心生长，但在oobaasagara中未被发现。结果表明，有些物种的倾角与偏心现象无关。(2)在斜茎上发现了sioji和mizunara具有张力木的解剖特征，而oobaasagara没有。在sioji倾斜茎的上部，通过观察红花绿染色的切片证实了木质化的减少，尽管在次生壁内部没有发现凝胶纤维，这是张力木材的解剖典型特征。水原木质部倾斜后形成的月牙形浅色印记，可以用肉眼观察到，这是张力木的一个特征，证实了张力木的形成。(3)水原典型拉伸木材倾斜后的IAA水平在上、侧、下侧均无明显差异。可以认为IAA对针叶树张力木的形成作用很小或很小，而对压缩木的形成作用很大。在双子叶树木中，ABA可能是更重要的张力材形成物质，定量分析结果有待期待。少

Inclined dicotyledonous trees show characteristics of eccentric growth and reaction wood in common with coniferous trees. But in case of angiosperm trees, the reaction wood is formed on upper side of learning stem, and it exhibits anatomically different features from gymnosperms. Additionally, leaning trees do not always exhibit pronounced changes of tension wood, because some species show no marked eccentric and anatomical features as tension wood. In conifers the role of indole-3-acetic acid (IAA) has been postulated and understood as causal factors in controlling the formation of compression wood. But application of the concept to tension wood formed in angiosperms must be difficult, because it is questionable whether IAA concentration becomes higher in nature on upper side of inclined stem than lower side. In this study, appearances of eccentric growth and anatomical features as tension wood were, observed throughout stems in three species of dicotyledonous trees, sioji (Fraxinus s … More paethiana), mizunara (Quercus crispula) and oobaasagara (Pterostyrax hispida), inclined artificially. Furthermore, distribution of IAA and abscisic acid (ABA) levels were quantitatively examined on two positions of leaning stems, in relation to formation of tension wood.(1) Although two species, sioji and mizunara, exhibited eccentric growth after inclination, in oobaasagara it was not recognized. It was substantiated that there are some species which the inclination was not associated with appearance of eccentricity. (2) Anatomical features as tension wood were recognized in leaning stems of sioji and mizunara, but not oobaasagara. On upper side in inclined stems of sioji, reduction of lignification was confirmed by observing sections stained with safranine-fastgreen, though the gelatinous fibers were not found the inside of secondary walls which was anatomically typical features of tension wood. In mizunara the formation of tension wood was confirmed by appearance of crescent-shaped and light colored marks in xylem formed after inclination which was able to observe with the naked eye, as a feature of tension wood. (3) IAA levels examined in mizunara forming typical tension wood after inclination exhibited no apparent differences among upper, lateral and lower sides. It may be considered that IAA has little or a little role in tension-wood formation, whereas it effects strongly on compression-wood formation in conifers. In case of dicotyledonous trees, ABA may be more important substance for formation of tension wood, and the result of the quantitative analysis will be expected. Less