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首页> 外文期刊>Journal of Experimental Botany >Relationship between ultrasonic properties and structural changes in the mesophyll during leaf dehydration
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Relationship between ultrasonic properties and structural changes in the mesophyll during leaf dehydration

机译：叶片脱水过程中超声波特性与叶肉结构变化的关系

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The broad-band ultrasonic spectroscopy technique allows the determination of changes in the relative water content (RWC) of leaves with contrasting structural features. Specifically, the standardized frequency associated with the maximum transmittance (f/fo) is strongly related to the RWC. This relationship is characterized by the existence of two phases separated by an inflexion point (associated with the turgor loss point). To obtain a better understanding of the strong relationship found between RWC and f/fo, this work has studied the structural changes experienced by Quercus muehlenbergii leaves during dehydration in terms of ultrasounds measurements, cell wall elasticity, leaf thickness, leaf density, and leaf structure. The results suggest that the decrease found in f/fo before the turgor loss point can be attributed to the occurrence of changes in the estimation of the macroscopic effective elastic constant of the leaf (c33), mainly associated with changes in the bulk modulus of elasticity of the cell wall (ε). These changes are overriding or compensating for the thickness decreases recorded during this phase. On the other hand, the high degree of cell shrinkage and stretching found in the mesophyll cells during the second phase seem to explain the changes in the acoustic properties of the leaf beyond the turgor loss point. The formation of large intercellular spaces, which increased the irregularity in the acoustic pathway, may explain the increase of the attenuation coefficient of ultrasounds once the turgor loss point threshold is exceeded. The direct measurement of c33 from ultrasonic measurements would allow a better knowledge of the overall biomechanical properties of the leaf further than those derived from the P–V analysis.
机译：宽带超声光谱技术可以确定具有相对结构特征的叶片相对含水量（RWC）的变化。具体而言，与最大透射率（f / f o ）相关的标准化频率与RWC密切相关。这种关系的特征是存在两个由拐点（与膨胀损失点相关）分开的相。为了更好地了解RWC与f / f o 之间的紧密关系，这项工作从超声测量，细胞壁弹性，叶片等方面研究了栎在脱水过程中经历的结构变化。厚度，叶片密度和叶片结构。结果表明，在f / f o 出现膨胀损耗点之前的减少可归因于叶片宏观有效弹性常数估算值的变化（c 33 ），主要与细胞壁体积弹性模量（ε）的变化有关。这些更改将覆盖或补偿在此阶段记录的厚度减少。另一方面，在第二阶段的叶肉细胞中发现的高度的细胞收缩和拉伸似乎可以解释叶片的声学特性在超出膨胀损失点后的变化。大的细胞间空间的形成增加了声波通路的不规则性，这可能解释了一旦超过了充盈损失点阈值，超声衰减系数的增加。通过超声测量直接测量c 33 可以比通过PV分析得出的信息更好地了解叶片的整体生物力学特性。

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