TY  - JOUR
AU  - Zimmermann, D.
AU  - Westhoff, M.
AU  - Zimmermann, G.
AU  - Geßner, P.
AU  - Gessner, A.
AU  - Wegner, L. H.
AU  - Rokitta, M.
AU  - Ache, P.
AU  - Schneider, H.
AU  - Vásquez, J. A.
AU  - Kruck, W.
AU  - Shirley, St.
AU  - Jakob, P.
AU  - Hedrich, R.
AU  - Bentrup, F.-W.
AU  - Bamberg, E.
AU  - Zimmermann, U.
TI  - Foliar water supply of tall trees: evidence for mucilage-facilitated moisture uptake from the atmosphere and the impact on pressure bomb measurements
JO  - Protoplasma
VL  - 232
SN  - 0033-183X
CY  - Wien
PB  - Springer
M1  - PreJuSER-58849
SP  - 11 - 34
PY  - 2007
N1  - Record converted from VDB: 12.11.2012
AB  - The water supply to leaves of 25 to 60 m tall trees (including high-salinity-tolerant ones) was studied. The filling status of the xylem vessels was determined by xylem sap extraction (using jet-discharge, gravity-discharge, and centrifugation) and by (1)H nuclear magnetic resonance imaging of wood pieces. Simultaneously, pressure bomb experiments were performed along the entire trunk of the trees up to a height of 57 m. Clear-cut evidence was found that the balancing pressure (P(b)) values of leafy twigs were dictated by the ambient relative humidity rather than by height. Refilling of xylem vessels of apical leaves (branches) obviously mainly occurred via moisture uptake from the atmosphere. These findings could be traced back to the hydration and rehydration of mucilage layers on the leaf surfaces and/or of epistomatal mucilage plugs. Xylem vessels also contained mucilage. Mucilage formation was apparently enforced by water stress. The observed mucilage-based foliar water uptake and humidity dependency of the P(b) values are at variance with the cohesion-tension theory and with the hypothesis that P(b) measurements yield information about the relationships between xylem pressure gradients and height.
KW  - Adhesives: metabolism
KW  - Atmosphere: chemistry
KW  - Dehydration
KW  - Glycosaminoglycans: metabolism
KW  - Gravitation
KW  - Magnetic Resonance Spectroscopy
KW  - Plant Leaves: cytology
KW  - Plant Leaves: physiology
KW  - Pressure
KW  - Trees: cytology
KW  - Trees: physiology
KW  - Water: metabolism
KW  - Xylem: physiology
KW  - Adhesives (NLM Chemicals)
KW  - Glycosaminoglycans (NLM Chemicals)
KW  - Water (NLM Chemicals)
KW  - J (WoSType)
LB  - PUB:(DE-HGF)16
C6  - pmid:18176835
UR  - <Go to ISI:>//WOS:000252224200002
DO  - DOI:10.1007/s00709-007-0279-2
UR  - https://juser.fz-juelich.de/record/58849
ER  -