Agriculture Reference
In-Depth Information
called undersampling and results in aliasing. The maximum sample rate is
specified in samples per second, and not in hertz.
Ag/AgCl electrodes were prepared from Teflon-coated silver wire (A-M
Systems) according to the method of Ksenzhek and Volkov (1998). The
Ag/AgClelectrodeswereidentical;oneelectrodeisreferredtoastheref-
erence electrode, and the other as the working electrode. The reference
electrode(-)wasinsertedinthestemorrootofasoybean,whereasthe
working electrode (+) was inserted in the stem or a leaf of a soybean. The
potential difference between the working electrode and the reference elec-
trodeisreferredtoasthevariationpotentialintheplant.Themechanism
of generation of a variation potential is not clear. Variation potentials mea-
sured in green plants, trees, and fruits typically have amplitudes from 20
to 140 mV.
24.5
Light-Induced Electrophysiological Signaling in Plants
The soybean was irradiated in direction A shown in Fig. 24.1 with white
light in a Faraday cage for 2 days with a 12 h : 12 h light-to-dark photoperiod
prior to conducting the experiments. Action potentials are not generated
when the lights are turned off and on (Fig. 24.2).
After 1−2 min of irradiation, a change in the direction of irradiation
from direction A to direction B generates action potentials in soybean
Fig. 24.2.
Potential difference between two Ag/AgCl electrodes in the stem of soybean under
irradiation (
on
)andinthedark(
off
).Thedistancebetweentheelectrodeswas5cm.Thesoil
was preliminarily treated with water every day. The volume of soil was 0.5 L. The frequency
of scanning was 50,000 samples/s
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