Mesoporosity as a new parameter for understanding tension stress generation in trees
Mesoporosity as a new parameter for understanding tension stress generation in trees
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DOI：
10.1093/jxb/erp133
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发表时间：
2009-07-01
影响因子：
6.9
通讯作者：
Gril, Joseph
中科院分区：
文献类型：
--
作者：
Chang, Shan-Shan;Clair, Bruno;Gril, Joseph
被子植物树木定向的机制是基于在倾斜轴上侧产生高张应力。在许多物种中，应力水平与纤维细胞壁中称为G层的特殊层的存在密切相关。G-层的结构最近被描述为水凝胶，这归因于超临界干燥样品的N-2吸附-解吸等温线显示出高的中孔隙率（孔径为2-50 nm）。这使我们重新审视了G层的概念，到目前为止，G层的概念仅从解剖学观察中得到描述。本文测定了六种热带树种正常材和抗拉材的吸附等温线。测量结果表明，具有典型厚G层的受拉木材的中孔率较高，而具有较薄G层的受拉木材的中孔率较低，有时不超过正常木材。没有G层的受拉木材的中孔率与正常木材一样低。不取决于孔的量，孔径分布总是集中在6-12 nm左右。这些结果表明，在产生具有G层的纤维的物种之间，物种之间存在G层的大的结构差异。
The mechanism for tree orientation in angiosperms is based on the production of high tensile stress on the upper side of the inclined axis. In many species, the stress level is strongly related to the presence of a peculiar layer, called the G-layer, in the fibre cell wall. The structure of the G-layer has recently been described as a hydrogel thanks to N-2 adsorption-desorption isotherms of supercritically dried samples showing a high mesoporosity (pores size from 2-50 nm). This led us to revisit the concept of the G-layer that had been, until now, only described from anatomical observation. Adsorption isotherms of both normal wood and tension wood have been measured on six tropical species. Measurements show that mesoporosity is high in tension wood with a typical thick G-layer while it is much less with a thinner G-layer, sometimes no more than normal wood. The mesoporosity of tension wood species without a G-layer is as low as in normal wood. Not depending on the amount of pores, the pore size distribution is always centred around 6-12 nm. These results suggest that, among species producing fibres with a G-layer, large structural differences of the G-layer exist between species.