======Hydraulic resistivity======

**通水抵抗度**

水の流れにくさを示す指標で、[[h:hydraulic_resistance|通水抵抗]]を試料（枝など）の長さで標準化した値。[[h:hydraulic_conductivity|通水度]]（K<sub>h</sub>）の逆数。

$R ＝r / l$

（$s・MPa・m^{-4}$ 、$s・MPa・kg^{-1}$ もしくは $s・MPa・mmol^{-1}$）

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  - Tyree MT,  Ewers F (1991) The hydraulic architenture of trees and other woody plants. New Phytologist, 119: 345-360 
  - Sperry JS (1995) Limitation on stem water transport and their consequences. In: Gartner BL(ed), Plant stems  Physiology and functional morpholog, 105-106. Academic Press, San Diego