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首页> 外文期刊>Journal of Experimental Botany >Root hydraulic conductivity measured by pressure clamp is substantially affected by internal unstirred layers
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Root hydraulic conductivity measured by pressure clamp is substantially affected by internal unstirred layers

机译：压力钳测量的根部水力传导率基本上受内部未搅拌层的影响

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摘要

Using the root pressure probe in the pressure clamping (PC) mode, the impact of internal unstirred layers (USLs) was quantified for young corn roots, both in experiments and in computer simulations applying the convection/diffusion model of Knipfer et al. In the experiments, water flows (JVrs) during PC were analysed in great detail, showing that JVrs (and the apparent root hydraulic conductivity) were high during early stages of PC and declined rapidly during the first 80 s of clamping to a steady-state value of 40–30% of the original. The comparison of experimental results with simulations showed that, during PC, internal USLs at the inner surface of the endodermis substantially modify the overall force driving the water. As a consequence, JVr and Lpr were inhibited. Effects of internal USLs were minimized when using the pressure relaxation mode, when internal USLs had not yet developed. Additional stop-clamp experiments and experiments where the endodermis was punctured to reduce the effect of internal USLs verified the existence of internal USLs during PC. Data indicated that the role of pressure propagation along the root xylem for both PC and pressure relaxation modes should be small, as should the effects of filling of the capacities during root pressure probe experiments, which are discussed as an alternative model. The results supported the idea that concentration polarization effects at the endodermis (internal USLs) cause a serious problem whenever relatively large amounts of water (xylem sap) are radially moved across the root, such as during PC or when using the high-pressure flow meter technique.
机译：在Knipfer等人的对流/扩散模型的实验和计算机模拟中，使用处于压力夹紧（PC）模式的根部压力探针，对内部未搅拌层（USL）的影响对年轻的玉米根部进行了量化。在实验中，对PC期间的水流（J Vr s）进行了详细分析，显示J Vr s（和表观根部水力传导率）在早期非常高。 PC阶段，并在钳夹的前80 s迅速下降至原始值的40–30％的稳态值。实验结果与模拟结果的比较表明，在PC期间，内胚层内表面的内部USL会显着改变驱动水的总力。结果，J Vr 和Lp r 被抑制。当内部USL尚未开发时，使用压力松弛模式将内部USL的影响降至最低。其他的钳夹实验和穿刺内胚层以减少内部USL效应的实验证实了PC期间内部USL的存在。数据表明，对于PC模式和压力松弛模式，沿根木质部传播的压力的作用应该很小，在根压探针实验期间填充容量的影响也应小，这将作为替代模型进行讨论。结果支持这样的想法，即当相对大量的水（木质部树液）在根部径向移动时（例如在PC期间或使用高压流量计时），内胚层（内部USL）的浓度极化效应会引起严重的问题。技术。

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