A non-invasive probe for online-monitoring of turgor pressure changes under field conditions

Abstract

An advanced non-invasive, field-suitable and inexpensive leaf patch clamp pressure probe for online-monitoring of the water relations of intact leaves is described. The probe measures the attenuated output patch clamp pressure, P(p), of a clamped leaf in response to an externally applied input pressure, P(clamp). P(clamp) is generated magnetically. P(p) is sensed by a pressure sensor integrated into the magnetic clamp. The magnitude of P(p) depends on the transfer function, T(f), of the leaf cells. T(f) consists of a turgor pressure-independent (related to the compression of the cuticle, cell walls and other structural elements) and a turgor pressure-dependent term. T(f) is dimensionless and assumes values between 0 and 1. Theory shows that T(f) is a power function of cell turgor pressure P(c). Concomitant P(p) and P(c) measurements on grapevines confirmed the relationship between T(f) and P(c). P(p) peaked if P(c) approached zero and assumed low values if P(c) reached maximum values. The novel probe was successfully tested on leaves of irrigated and non-irrigated grapevines under field conditions. Data show that slight changes in the microclimate and/or water supply (by irrigation or rain) are reflected very sensitively in P(p).

A non-invasive plant-based probe for continuous monitoring of water stress in real time: a new tool for irrigation scheduling and deeper insight into drought and salinity stress physiology

“…The measuring principle of the magnetic turgor pressure probe (ZIM-probe, ZIM Plant Technology GmbH, Hennigsdorf, Germany) is quite simple (Figure 1): a small three-dimensional leaf patch is used as an "artificial sensing compartment" for measuring relative changes of turgor pressure in the entire leaf tissue , Westhoff et al 2009a). This requires that the stomata of the patch are closed and that the patch is in hydraulic contact with its surrounding.…”

“…The non-invasive leaf patch clamp pressure probe (so-called ZIM-probe) recently introduced by Zimmermann and co-workers , Westhoff et al 2009a) has apparently overcome the impasse in measuring continuously the temporal and spatial dynamics of plant water relations in real time both and with high precision under laboratory and field conditions. The probe measures relative changes in leaf turgor pressure, i.e.…”

Distribution and function of epistomatal mucilage plugs

“…5 in Zimmermann et al 2007a). Both techniques measure changes in turgor pressure in the low pressure range as shown recently (Westhoff et al 2009). …”

“…turgor pressure) was measured online using the non-invasive leaf patch clamp pressure probe. The principle of the probe and the theoretical background of the parameter measured by the probe are described in details elsewhere (Zimmermann et al 2008;Westhoff et al 2009). Briefly, the leaf is positioned in the space between the two planar circular pads of the probe.…”

Advanced techniques using the plant as indicator of irrigation management

“…This occur because it is a robust, easy-touse method, through which producers can receive the information about the water needs of their plants by wireless telemetry, mobile network and internet, and can thus precisely adjust both the moment of irrigation and the amount of water to be applied. WESTHOFF et al (2009) state that the probe potential for measuring changes in leaf turgor pressure, for long periods, is demonstrated by measurements in several crops under different climate and irrigation conditions. These authors concluded that ZIM-probe can be used as an early warning system of water stress beginning and that the probe gives way to a more appropriate form of measuring crop water demand, both in the field and in the greenhouse.…”