AXIAL AND RADIAL HYDRAULIC RESISTANCE TO ROOTS OF MAIZE (ZEA-MAYS-L)
AXIAL AND RADIAL HYDRAULIC RESISTANCE TO ROOTS OF MAIZE (ZEA-MAYS-L)
复制标题
DOI：
10.1104/pp.91.2.719
复制
发表时间：
1989-10-01
期刊：
影响因子：
7.4
通讯作者：
STEUDLE, E
中科院分区：
文献类型：
--
作者：
FRENSCH, J;STEUDLE, E
采用根压探头对玉米初生根的水力特性进行了测定。完整的根段的水力传导率（LPR）通过施加跨根柱的静水压力和渗透压的梯度来确定。在流体静力学实验中，Lpr沿段沿着是恒定的，除了长度约为20毫米的顶端区，该顶端区由于高轴向阻力而被液压隔离。在渗透实验中，Lpr向根部下降。Lpr（渗透压）显著小于Lpr（流体静力学）。在离根尖不同距离处，通过灌注切除的根段测量单位根长的轴向水力阻力（Rx），或根据Poiquilille定律从横截面估计。计算的Rx比测量的Rx小2至5倍。轴向阻力随距顶端的距离而变化，这是由于早期后生木质部导管的分化所致。除了顶端20毫米，径向水分运动限制水分吸收到根。这对于从根压松弛评价根的Lpr是重要的。利用轴向和径向水力阻力的测量值模拟了根系的静态吸水，以计算出轴向水流和木质部水势的分布。
A root pressure probe was employed to measure hydraulic properties of primary roots of maize (Zea mays L.). The hydraulic conductivity (Lpr) of intact root segments was determined by applying gradients of hydrostatic and osmotic pressure across the root cylinder. In hydrostatic experiments, Lpr was constant along the segment except for an apical zone of approximately 20 millimeters in length which was hydraulically isolated due to a high axial resistance. In osmotic experiments, Lpr decreased toward the base of the roots. Lpr (osmotic) was significantly smaller than Lpr (hydrostatic). At various distances from the root tip, the axial hydraulic resistance per unit root length (Rx) was measured either by perfusing excised root segments or was estimated according to Poiseuille''s law from cross-sections. The calculated Rx was smaller than the measured Rx by a factor of 2 to 5. Axial resistance varied with the distance from the apex due to the differentiation of early metaxylem vessels. Except for the apical 20 millimeters, radial water movement was limiting water uptake into the root. This is important for the evaluation of Lpr of roots from root pressure relaxations. Stationary water uptake into the roots was modeled using measured values of axial and radial hydraulic resistances in order to work out profiles of axial water flow and xylem water potentials.