A critical re-examination of pressure-volume analysis of conifer shoots: comparison of three procedures for generating PV curves on shoots of Pinus resinosa Ait. seedlings
A critical re-examination of pressure-volume analysis of conifer shoots: comparison of three procedures for generating PV curves on shoots of Pinus resinosa Ait. seedlings
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针叶树芽压力-体积分析的关键重新检查：在松树芽上生成 PV 曲线的三种程序的比较。
DOI：
10.1093/jxb/46.11.1701
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发表时间：
1995
影响因子：
6.9
通讯作者：
A. Colombo
中科院分区：
文献类型：
--
作者：
W. Parker;A. Colombo
根据压力-体积 (PV) 曲线对红松 (Pinus resinosa Ait.) 的水关系属性进行的预测会根据使用的三种方法中的哪一种而有所不同。汁液压榨方法需要将枝条封闭在压力室中，并通过施加恒定的选定压力来压榨木质部汁液，直至液流停止，此时测量木质部水势和枝条重量。树液表达 PV 曲线是通过聚合水势-重量测量值对形成的，每对由 25 个芽中的一个提供。重复加压方法涉及在实验室工作台上重复测量木质部水势和单个芽干燥的芽重量。重复加压 PV 曲线是根据单次射击提供的数据构建的。该复合方法利用对 25-30 个不同枝条的木质部水势和枝条重量进行单次测量，通过台式干燥获得相对含水量范围为约 1.0 至 0.5。复合 PV 曲线是根据芽群提供的汇总数据构建的。使用重复加压和液流表达方法生成的所有 PV 属性都非常一致。相比之下，采用复合PV方法，PV曲线线性区域的斜率存在根本差异，导致完全膨压和膨压损失时的渗透势更负，并且膨压损失时的相对含水量更低，共质体分数更高。在相同含水量范围内比较复合和重复加压PV曲线并没有消除导出的水关系属性的差异。与所使用的 PV 程序相关的水势等温线的差异表明，长期或重复暴露于高压气体可能会在水关系属性的估计中引入错误。
Prediction of water relations attributes for red pine (Pinus resinosa Ait.) derived from pressure-volume (PV) curves varied depending on which of three methods was used. The sap expression method entailed the enclosure of a shoot in a pressure chamber and expression of xylem sap by applying a constant selected pressure until sap flow ceased, at which point xylem water potential and shoot weight were measured. A sap expression PV curve was formed by aggregating pairs of water potential-weight measurements, each pair supplied by one of 25 shoots. The repeat pressurization method involved repeatedly measuring xylem water potential and shoot weight on a single shoot drying on a laboratory bench. Repeat pressurization PV curves were constructed from data provided by a single shoot. The composite method utilized single measurements of xylem water potential and shoot weight on 25-30 different shoots ranging in relative water content from about 1.0 to 0.5 achieved by bench drying. Composite PV curves were constructed from aggregate data supplied by a population of shoots. There was close agreement in all PV attributes generated using repeat pressurization and sap expression methods. In contrast, with the composite PV method, there was a fundamental difference in the slope of the linear region of the PV curves, causing osmotic potentials at full turgor and turgor loss to be more negative, and relative water content at turgor loss to be lower and symplast fraction to be higher. Comparison of composite and repeat pressurization PV curves over the same ranges in water content did not eliminate differences in derived water relations attributes. Differences in water potential isotherms related to the PV procedures used suggest that prolonged or repeated exposure to gas at high pressure may introduce errors in the estimation of water relations attributes.