© 2008 The Author(s).
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RESEARCH PAPER |
A novel, non-invasive, online-monitoring, versatile and easy plant-based probe for measuring leaf water status
1Abteilung für Biophysikalische Chemie, Max-Planck-Institut für Biophysik, Max-von-Laue-Str. 3, D-60439 Frankfurt a. M., Germany
2Lehrstuhl für Biotechnologie, Universität Würzburg, Biozentrum, Am Hubland, D-97074 Würzburg, Germany
3Institut für Pflanzenphysiologie, Universität Salzburg, Hellbrunnerstrasse 34, A-5020 Salzburg, Austria
* To whom correspondence should be addressed. E-mail: Dirk.Zimmermann{at}mpibp-frankfurt.mpg.de
A high-precision pressure probe is described which allows non-invasive online-monitoring of the water relations of intact leaves. Real-time recording of the leaf water status occurred by data transfer to an Internet server. The leaf patch clamp pressure probe measures the attenuated pressure, Pp, of a leaf patch in response to a constant clamp pressure, Pclamp. Pp is sensed by a miniaturized silicone pressure sensor integrated into the device. The magnitude of Pp is dictated by the transfer function of the leaf, Tf, which is a function of leaf patch volume and ultimately of cell turgor pressure, Pc, as shown theoretically. The power function Tf=f(Pc) theoretically derived was experimentally confirmed by concomitant Pp and Pc measurements on intact leaflets of the liana Tetrastigma voinierianum under greenhouse conditions. Simultaneous Pp recordings on leaflets up to 10 m height above ground demonstrated that changes in Tf induced by Pc changes due to changes of microclimate and/or of the irrigation regime were sensitively reflected in corresponding changes of Pp. Analysis of the data show that transpirational water loss during the morning hours was associated with a transient rise in turgor pressure gradients within the leaflets. Subsequent recovery of turgescence during the afternoon was much faster than the preceding transpiration-induced water loss if the plants were well irrigated. Our data show the enormous potential of the leaf patch clamp pressure probe for leaf water studies including unravelling of the hydraulic communication between neighbouring leaves and over long distances within tall plants (trees).
Key words: Irrigation, leaf patch clamp pressure, liana, Tetrastigma voinierianum, transfer function, turgor pressure, turgor pressure probe
These authors contributed equally to this work and share first authorship. Received 25 February 2008; Revised 23 May 2008 Accepted 27 May 2008