@article {Tyree589,
author = {Tyree, Melvin T. and Christy, A. Lawrence and Ferrier, Jack M.},
title = {A Simpler Iterative Steady State Solution of M{\"u}nch Pressure-Flow Systems Applied to Long and Short Translocation Paths},
volume = {54},
number = {4},
pages = {589--600},
year = {1974},
doi = {10.1104/pp.54.4.589},
publisher = {American Society of Plant Biologists},
abstract = {A simple steady state iterative solution of M{\"u}nch pressure-flow in unbranched sieve tubes containing only water and sucrose is derived. The iterative equations can be solved on a programmable desk calculator. Solutions are presented for steady state transport with specific mass transfer rates up to 1.5 {\texttimes} 10-5 mole second-1 centimeters-2 (= 18.5 grams hour-1 centimeters-2) over distances in excess of 50 meters. The calculations clearly indicate that a M{\"u}nch pressure-flow system can operate over long distances provided (a) the sieve tube is surrounded by a semipermeable membrane; (b) sugars are actively loaded in one region and unloaded at another; (c) the sieve pores are unblocked so that the sieve tube hydraulic conductivity is high (around 4 centimeters2 second-1 bar-1); (d) the sugar concentration is kept high (around one molar in the source region); and (e) the average sap velocity is kept low (around 20-50 centimeters hour-1). The dimensions of sieve cells in several species of plants are reviewed and sieve tube hydraulic conductivities are calculated; the values range from 0.2 to 20 centimeters2 second-1 bar-1. For long distance pressure-flow to occur, the hydraulic conductivity of the sieve cell membranes must be about 5 {\texttimes} 10-7 centimeters second-1 bar-1 or greater.},
issn = {0032-0889},
URL = {http://www.plantphysiol.org/content/54/4/589},
eprint = {http://www.plantphysiol.org/content/54/4/589.full.pdf},
journal = {Plant Physiology}
}