Long term measurement of the xylem potential by unpolarizable electrode via liquid junction

Okamoto, Hisashi; Hasuike, Shin-ichiro; Masaki, Nobuyuki; Shinobe, Tetsuji

doi:10.1007/bf02346014

Cited by 2 publications

(2 citation statements)

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“…Reliability of this procedure was verified by the experiments using Vigna embryo, and then pine seedlings as model systems (Okamoto et al 1994). Further support for field application of this system is shown in Fig.…”

Section: Theorymentioning

confidence: 95%

“…The electronic system (impedance converter of gain 1, with input resistance of 10Qohm) was the same as reported formerly (Okamoto et al 1994). The TRP was introduced via the pair of unpolarizable electrodes into the input terminal of this converter whose output was recorded automatically by a 6-channel dot-print type recorder Model 436006 61000 (Yokogawa Electric Corporation, Tokyo) at a chart speed of 1 mm/hr.…”

Section: Devicementioning

confidence: 99%

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Long Term Measurement of the Trans-Root Electric Potential in a Persimmon Tree in the Field

Okamoto

Masaki²

1999

J Plant Res

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A convenient system via a perfect liquid junction was developed for measuring the trans-root electric potential (TRP) of a tree in the field. This system enabled continuous measurement of the TRP of an old kaki tree (Diospym kaki, Japanese persimmon), which showy clear diurnal oscillation throughout two successive years. The level of the TRP on the average for every ten days had two minima (ca. -70mv) in mid winter and mid summer, and two maxima (ca. -30 mv) in October and May. A regular seasonal change in the amplitude of the oscillation was observed, it was at its maximum (ca. 70 mv) in early spring just before the sprouting of new leaves, and at its minimum (ca. 10 mv) during summer and early autumn when leaves were fully expanded. The relationship between the TRP, water transport and rainfall is discussed. change -Trans-root electric potential -Tree root Continuous recording of trans-root electric potential (TRP) of trees in the field is needed by researchers of arboridulture to diagnose the physiological state of root systems in situ. Also, in the field of earth science, availability of trees as sensors for the earth electric potential (or current) has been investigated (Ito 1997(Ito , lwamoto 1991. In previous measurements of bioelectric potential of trees in the field, direct contact with metal wires has been used in most cases to induce the electric potential difference between the plants and soil (e.g. Toriyama and Matteucig 1992). However, such conventional methods often cause serious errors because of the irregular polarization that occurs across the interface between the metal and the liquid phase of a plant body. Sometimes the observed potential exceeds the ordinary level of membrane potential in plant cells, i.e. over -300 mV (e.g. It0 1997). Although these results could partly reflect a change in the bioelectric potential of multicellular plants, Abbreviations: ERG, electro-radiccigram; V, , membrane potential across organ surface; Vpx, membrane potential across xylem/ symplast interface; V,, electric potential of the bulk phase surrounding the surface of an organ; V, or V, , xylem electric potential with respect to V, (when applied to plant roots, it is often called TRP, trans-root electric potential), N.B. Vx=Vw -Vpx, the difference between the two membrane potentials.they are obviously overlapping with other electric phenomena. The most reliable results can not be obtained without a pair of unpolarizable electrodes and a perfect liquid junction which connects these electrodes with the plant and the earth. For these purposes, a simple and reliable system for continuous measurement was devised and tested on one kaki tree in a garden setting. Materials and Methods Plant MaterialA kaki tree (Diospyros kaki Thunb. ex Murray cultivar, jiro), whose trunk diameter is about 28cm (planted just on the northside of the Mori Laboratory of Plant Physiology) was used for this experiment. DeviceAs shown in Fig. 1, an experimental system for continuous recording of TRP over years in the field was developed. The...

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Section: Theorymentioning

confidence: 95%

Section: Devicementioning

confidence: 99%