Sap flow index as an indicator of plant water status.
Sap flow index as an indicator of plant water status.
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DOI：
10.1093/treephys/19.13.885
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发表时间：
1999-11
期刊：
影响因子：
4
通讯作者：
Nadezhdina
中科院分区：
文献类型：
--
作者：
Nadezhdina
夜间尤其是黎明前树木水分状况是树木干旱胁迫的重要指标。叶片水势（LWP）经常被用作衡量树木水分状况和干旱胁迫的指标；然而，从高大树木中采集树叶并自动确定LWP存在困难。目前的研究是为了确定即使在非常低的流量下也可以自动连续记录的树液流量指数（SFI）是否可以用于估计非限制土壤水分条件下干燥空气对树木造成的干旱胁迫。我们在乌克兰南部半干旱气候下对苹果树（Malus domestica Borkh.）进行了几个生长季节的LWP、热脉冲速度（HPV）和SFI的同时测量。黎明前LWP值与SFI高度相关。在夜间发生的低液流率范围内，其他测量液流的方法不敏感，SFI方法是线性的，非常敏感。通过比较夜间和白天的SFI值，获得了树木水分状况的额外信息。黎明前SFI与正午SFI的比值以及两个SFI最大值之间的时间间隔（无云天气的第一个SFI峰值出现在早晨，第二个SFI峰值出现在晚上）可以用来表征植物内部水分平衡。尽管SFI的日变化过程是可变的，但确定了特定的模式，反映了植物干旱胁迫发展的特定阶段。“空气-干旱-应力曲线”用于描述生长季节空气干旱条件下树木水分胁迫的发展特征。
Night and especially predawn tree water status is an important indicator of drought stress in trees. Leaf water potential (LWP) is frequently used as a measure of tree water status and hence drought stress; however, there are difficulties associated with sampling foliage from tall trees and determining LWP automatically. The current study was undertaken to determine whether sap flow index (SFI), which can be automatically and continuously recorded even during very low flows, can be used to estimate drought stress in trees caused by dry air under non-limiting soil water conditions. We made simultaneous measurements of LWP, heat pulse velocity (HPV) and SFI on apple trees (Malus domestica Borkh.) in the semiarid climate of southern Ukraine over several growing seasons. Predawn values of LWP were highly correlated with SFI. Over the range of low sap flow rates occurring at nighttime, where other methods of measuring sap flow are not sensitive, the SFI method was linear and very sensitive. Additional information about tree water status was obtained by comparing nighttime and daytime values of SFI. The ratio of predawn SFI to midday SFI and the period between the two daily SFI maxima (the first SFI peak occurred in the morning and the second peak occurred in the evening on cloudless days) can be used to characterize internal plant water balance. Although the daily course of SFI was variable, specific patterns were identified that reflected particular stages in the development of plant drought stress. An "air-drought-stress curve" was used to characterize the development of water stress in trees subjected to air drought during the growing season.