Acoustic emission analysis and experiments with physical model systems reveal a peculiar nature of the xylem tension
Acoustic emission analysis and experiments with physical model systems reveal a peculiar nature of the xylem tension
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DOI：
10.1016/j.jplph.2006.05.004
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发表时间：
2006-10-01
影响因子：
4.3
通讯作者：
Vallen, Hartmut
中科院分区：
文献类型：
--
作者：
Laschimke, Ralf;Burger, Maria;Vallen, Hartmut
先进的声发射分析、特殊的显微镜检查和物理模型系统的实验证明，维管植物的水传导系统中的张力是由无数微小的气泡强烈粘附在木质部管壁的疏水性木质素结构域引起的。我们在几种温带落叶乔木和针叶树中确定了这些气泡。我们的假设是木质部导管的相干泡系统作为一种力传递介质，能够以蠕动波的形式输送水分。利用气泡的高弹性，油气气泡系统能够循环储放能量。我们认为壁挂气泡系统的突然重组是植物声发射的起源。对于秃榆，我们记录了在蒸腾和再水化过程中剧烈的声活动。探测到的声发射频谱和波形与传统假设相矛盾，传统假设认为声发射是由受压水柱的空化破坏引起的。根据内聚理论，我们认为负压是由附壁气泡系统的张力所模拟的。(c) 2006年Etsevier GmbH版权所有。
Advanced acoustic emission analysis, special microscopic examinations and experiments with physical model systems give reasons for the assumption that the tension in the water conducting system of vascular plants is caused by countless minute gas bubbles strongly adhering to the hydrophobic lignin domains of the xylem vessel walls. We ascertained these bubbles for several species of temperate deciduous trees and conifers. It is our hypothesis that the coherent bubble system of the xylem conduits operates as a force-transmitting medium that is capable of transporting water in traveling peristaltic waves. By virtue of the high elasticity of the gas bubbles, the hydro-pneumatic bubble system is capable of cyclic storing and releasing of energy. We consider the abrupt regrouping of the wall adherent bubble system to be the origin of acoustic emissions from plants. For Ulmus glabra, we recorded violent acoustic activity during both transpiration and re-hydration. The frequency spectrum and the waveforms of the detected acoustic emissions contradict traditional assumptions according to which acoustic emissions are caused by cavitation disruption of the stressed water column. We consider negative pressure in terms of the cohesion theory to be mimicked by the tension of the wall adherent bubble system. (c) 2006 Etsevier GmbH. All rights reserved.