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Gewählte Publikation:

Losso, A; Beikircher, B; Damon, B; Kikuta, S; Schmid, P; Mayr, S.
(2017): Xylem Sap Surface Tension May Be Crucial for Hydraulic Safety
PLANT PHYSIOL. 2017; 175(3): 1135-1143. FullText FullText_BOKU

Abstract:
The surface tension (gamma) of xylem sap plays a key role in stabilizing air-water interfaces at the pits between water-and gas-filled conduits to avoid air seeding at low water potentials. We studied seasonal changes in xylem sap gamma in Picea abies and Pinus mugo growing at the alpine timberline. We analyzed their vulnerability to drought-induced embolism using solutions of different gamma and estimated the potential effect of seasonal changes in gamma on hydraulic vulnerability. In both species, xylem sap gamma showed distinct seasonal courses between about 50 and 68 mN m(-1). Solutions with low gamma caused higher vulnerability to drought-induced xylem embolism. The water potential at 50% loss of hydraulic conductivity in P. abies and P. mugo was -3.35 and -3.86 MPa at gamma of 74 mN m(-1) but -22.11 and -22.09 MPa at 45 mN m(-1). This indicates up to about 1 MPa seasonal variation in 50% loss of hydraulic conductivity. The results revealed pronounced effects of changes in xylem sap gamma on the hydraulic safety of trees in situ. These effects also are relevant in vulnerability analyses, where the use of standard solutions with high gamma overestimates hydraulic safety. Thus, gamma should be considered carefully in hydraulic studies.
Autor/innen der BOKU Wien:
Kikuta Silvia
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