Ascent of sap
From Wikipedia, the free encyclopedia
The ascent of sap in the xylem of plants is movement of water from root to the crown. Due to the difficulty of directly measuring large negative pressures in living plants, the dominant theory (cohesion-tension) has received some criticism. Other theories, not generally accepted by the plant physiology community, include:
- vital theory
- root pressure theory
- CP theory (The compensating-pressure theory).
In spite of some debate on the subject, the overwhelming circumstantial evidence strongly supports the cohesion-tension theory.
[edit] References
- Xylem Structure and the Ascent of Sap, 2nd ed. by Melvin T. Tyree and Martin H. Zimmermann (ISBN 3-540-43354-6)
- "On the Ascent of Sap" by Henry H. Dixon and J. Joly. Philosophical Transactions of the Royal Society of London. B, Vol. 186, pp. 563-576. (1895)
- "The Cohesion-Tension Theory" by Angeles G, Bond B, Boyer JS, Brodribb T, Brooks JR, Burns MJ, Cavender-Bares J, Clearwater M, Cochard H, Comstock J, Davis SD, Domec J-C, Donovan L, Ewers F, Gartner B, Hacke U, Hinckley T, Holbrook NM, Jones HG, Kavanagh K, Law B, López-Portillo J, Lovisolo C, Martin T, Martínez-Vilalta J, Mayr S, Meinzer FC, Melcher P, Mencuccini M, Mulkey S, Nardini A, Neufeld HS, Passioura J, Pockman WT, Pratt RB, Rambal S, Richter H, Sack L, Salleo S, Schubert A, Schulte P, Sparks JP, Sperry J, Teskey R, Tyree M. New Phytologist, Vol. 163:3, pp. 451–452. (2004)
