Long-term xylem pressure measurements in the liana Tetrastigma voinierianum by means of the xylem pressure probe

Benkert, R.; Jian-jun, Zhu; Zimmermann, G.; Türk, Roman; Bentrup, Friedrich‐Wilhelm; Zimmermann, U.

doi:10.1007/bf00197348

Cited by 24 publications

(46 citation statements)

References 53 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…This is particularly obvious if the tension gradients between 1 m and 5 m are considered. Root pressure together with stem pressure (Kramer 1983, Braun 1984 can explain these findings (for a more detailed discussion, see Benkert et al 1995).…”

Section: Discussionmentioning

confidence: 91%

“…Additionally, the rapid dissipation of pressure pulses applied via displacement of the metal rod of the probe (see below), as well as the movement of dyes injected into the transpiration stream (data not shown) provide further evidence that a conducting vessel has been probed (cf. Balling and Zimmermann 1990, Zimmermann et al 1993, Benkert et al 1995. The construction and function of the cell turgor pressure probe has been described elsewhere (Zimmermann et al 1969;Zimmermann 1978Zimmermann , 1989.…”

Section: Pressure Probe Measurementsmentioning

confidence: 99%

“…Direct measurements of the xylem pressure in the liana Tetrastigma voinierianum with the xylem pressure probe have revealed (Benkert et al 1995) that negative pressures develop during the day time. Their magnitude depended on the weather conditions.…”

Section: Introductionmentioning

confidence: 98%

“…A conclusive answer to the question how water is lifted from the roots to the foliage of a tall tree can only be found through further measurements under various environmental conditions. The previous probe measurements on T. voinierianum were performed in early spring under conditions of a tropical greenhouse at heights of 1 m and 5m (Benkert et al 1995). In the present communication, we report on long-term xylem pressure measurements recorded during summer and autumn up to heights of 9.5 m. The local light intensity, the temperature, and the relative humidity were measured simultaneously in order to identify the relevant environmental parameter(s) responsible for the observed local changes in xylem pressure and to reveal the propagation of the latter in the xylem conduit.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Diurnal changes in xylem pressure and mesophyll cell turgor pressure of the lianaTetrastigma voinierianum: The role of cell turgor in long-distance water transport

et al. 1999

View full text Add to dashboard Cite

Summary. Long-term xylem pressure measurements were performed on the liana Tetrastigma voinierianum (grown in a tropical greenhouse) between heights of 1 m and 9.5 m during the summer and autumn seasons with the xylem pressure probe. Simultaneously, the light intensity, the temperature, and the relative humidity were recorded at the measuring points. Parallel to the xylem pressure measurements, the diurnal changes in the cell turgor and the osmotic pressure of leaf cells at heights of 1 m and 5 m (partly also at a height of 9.5 m) were recorded. The results showed that tensions (and height-varying tension gradients) developed during the day time in the vessels mainly due to an increase in the local light intensity (at a maximum 0.4 MPa). The decrease of the local xylem pressure from positive, subatmospheric or slightly above-atmospheric values (established during the night) to negative values after daybreak was associated with an almost ] : 1 decrease in the cell turgor pressure of the mesophyll cells (on average from about 0.4 to 0,5 MPa down to 0.08 MPa). Similarly, in the afternoon the increase of the xylem pressure towards more positive values correlated with an increase in the cell turgor pressure (ratio of about 1 : 1). The cell osmotic pressure remained nearly constant during the day and was about 0.75-0.85 MPa between 1 m and 9,5 m (within the limits of accuracy). These findings indicate that the turgor pressure primarily determines the corresponding pressure in the vessels (and vice versa) due to the tight hydraulic connection and thus due to the water equilibrium between both compartments. An increase in the transpiration rate (due to an increase in light intensity) results in very rapid establishment of a new equilibrium state by an equivalent decrease in the xylem and cell turgor pressure. From the xylem, cell turgor, and cell osmotic pressure data the osmotic pressure (or more accurately the water activity) of the xylem sap was calculated to be about 0.35-0.45 MPa; this value was apparently not subject to diurnal changes. Con-*Correspondence and reprints: Institut fiir Pflanzenphysiologie, Universit~t Salzburg, Hellbrunnerstral3e 34, A-5020 Salzburg, Austria. E-mail: friedrich.bentrup @ sbg.ac.at sidering that the xylem pressure is determined by the turgor pressure (and vice versa), the xylem pressure of the liana could not drop toin agreement with the experimental results -less than -0.4 MPa, because this pressure corresponds to zero turgot pressure.

show abstract

Section: Discussionmentioning

confidence: 91%

Section: Pressure Probe Measurementsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Diurnal changes in xylem pressure and mesophyll cell turgor pressure of the lianaTetrastigma voinierianum: The role of cell turgor in long-distance water transport

et al. 1999

View full text Add to dashboard Cite

show abstract

“…in the liana T. voinierianum, Benkert et al, 1995 ;Zimmermann et al, 1995a,b ;Thu$ rmer et al, 1999 ;and in sugarcane and crop plants, F. Thu$ rmer et al, unpublished data ;Schneider et al, 1997a,b ;Wegner & Zimmermann, 1998).…”

Section: mentioning

confidence: 99%

Diurnal changes in xylem pressure of the hydrated resurrection plant Myrothamnus flabellifolia: evidence for lipid bodies in conducting xylem vessels

et al. 1999

View full text Add to dashboard Cite

The resurrection plant Myrothamnus flabellifolia has the ability to recover from repeated prolonged and extreme desiccation cycles. During the dry state the inner walls of the xylem vessels seemed to be covered, at least partly, by a lipid film as shown by Sudan III and Nile Red staining. The lipid film apparently functioned as an ' internal cuticle ' which prevented the adjacent parenchyma ray cells from complete water loss. The hydrophobic nature of the inner xylem walls was supported by the finding that benzene ascended as rapidly as water in the xylem of dry Myrothamnus branches. On watering, numerous lipid bodies were found in the water-conducting vessels, presumably formed from the lipid film and\or from lipids excreted from the adjacent living cells into the vessels. The presence of lipid bodies within the vessels, as well as the hydrophobic properties of the inner xylem walls, could explain the finding that the xylem pressure of hydrated, well watered plants (measured both under laboratory and field conditions with the xylem pressure probe) never dropped below c. k0.3 MPa and that cavitation occurred frequently at low negative xylem pressure values (k0.05 to k0.15 MPa). The xylem pressure of M. flabellifolia responded rapidly and strongly to changes in relative humidity and temperature, but less obviously to changes in irradiance (which varied between 10 and c. 4000 µmol m −# s −" ). The morphological position of the stomata in the leaves could explain the extremely weak and slow response of the xylem pressure of this resurrection plant to illumination changes. Stomata were most abundant in the furrows, and were thus protected from direct sunlight. Simultaneous measurements of the cell turgor pressure in the leaf epidermal cells (made by using the cell turgor pressure probe) revealed that the xylem and the cell turgor pressure dropped in a ratio of 1 : 0.7 on changes in the environmental parameters, indicating a quite close hydraulic connection and, thus, water equilibrium between the xylem and cellular compartments. An increase in irradiance of c. 700 µmol m −# s −" resulted in a turgor pressure decrease from 0.63 to 0.48 MPa. Correspondingly, the cell osmotic pressure increased from 1.03 to 1.22 MPa. From these values and by assuming water equilibrium, the osmotic pressure of the xylem sap was estimated to be 0.25-0.4 MPa. This value seems to be fairly high but may, however, be explained by the reduction of the water volume within the vessels due to the floating lipid bodies.

show abstract

Salinity: Environment - Plants - Molecules

Läuchli¹,

Lüttge²

2002

143

View full text Add to dashboard Cite

Long-term xylem pressure measurements in the liana Tetrastigma voinierianum by means of the xylem pressure probe

Cited by 24 publications

References 53 publications

Diurnal changes in xylem pressure and mesophyll cell turgor pressure of the lianaTetrastigma voinierianum: The role of cell turgor in long-distance water transport

Diurnal changes in xylem pressure and mesophyll cell turgor pressure of the lianaTetrastigma voinierianum: The role of cell turgor in long-distance water transport

Diurnal changes in xylem pressure of the hydrated resurrection plant Myrothamnus flabellifolia: evidence for lipid bodies in conducting xylem vessels

Salinity: Environment - Plants - Molecules

Contact Info

Product

Resources

About