Daudet François-Alain, Améglio Thierry, Cochard Hervé, Archilla Olivier, Lacointe André
UMR PIAF (INRA-Université Blaise Pascal), Site INRA de Crouelle, 234 av. du Brezet, F-63039 Clermont-Ferrand Cedex 2, France.
J Exp Bot. 2005 Jan;56(409):135-44. doi: 10.1093/jxb/eri026. Epub 2004 Nov 29.
The variations of stem diameter as they can be accurately measured by Linear Variable Differential Transformer (LVDT) reflect the addition of four components: irreversible radial growth, reversible living-cell dehydration/rehydration, thermal expansion and contraction, and expansion of dead conducting elements due to the increase and relaxation of internal tensions. The correct interpretation of LVDT signals, with respect to the practical applications, should make an exact distinction between these four components. This paper describes a set of two experiments with potted hybrid walnut trees. Double girdling, water stress, and duration of the day versus night periods were used in the phytotron as experimental factors to induce variations of the carbon and water status of plant tissues. The latter were assessed, respectively, by water potential and transpiration, and by local stem respiration and carbohydrate content. The results are interpreted in terms of carbon or water limitation effects on stem diameter variations where radial growth and tissue elasticity could be distinguished. Moreover, they suggest no or very low involvement of CO2 originating from a distance, i.e. carried by the transpirational flux of xylem sap, in the total stem CO2 efflux rate.
通过线性可变差动变压器（LVDT）能够精确测量的茎直径变化反映了四个组成部分：不可逆的径向生长、活细胞的可逆脱水/再水化、热膨胀和收缩，以及由于内部张力的增加和松弛导致的死导水组织的膨胀。就实际应用而言，对LVDT信号的正确解释应准确区分这四个组成部分。本文描述了一组针对盆栽杂交核桃树的两个实验。在人工气候室中，采用双环割、水分胁迫以及昼夜时长作为实验因素，以诱导植物组织碳和水状态的变化。分别通过水势和蒸腾作用，以及局部茎呼吸作用和碳水化合物含量来评估后者。在能够区分径向生长和组织弹性的情况下，根据碳或水限制对茎直径变化的影响来解释结果。此外，结果表明，远距离运输的二氧化碳（即通过木质部汁液的蒸腾流携带）对茎总二氧化碳排放速率的贡献不大或非常低。
