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Electromagnetic Parameters
correlation between phase angle and dry weight of the root system and showed that a non-destructive
measurement of phase angle has the potential to replace the destructive and time-consuming measurement of root dry weight (Figures 12.3 and 12.4).
Postic and Doussan (2016) compared various electrical methods to estimate root mass. The parallel measurement using a clamp as a stem electrode of capacitance and a hand-held LCR meter at
an alternating current gave the most reliable results. They found that the frequency of the AC current used plays a role in the accuracy of the outcome.
Benada (2017) described his investigations on variable resistance in wheat plants as a starting point for considering the nature of variable disease resistance of cereals against obligate
FIGURE 12.3 Correlation between gram dry root weight per plant (X-axis) and phase angle (Y-axis).
FIGURE 12.4 Simple LCR meter (a) and voltmeter (b) used for measurements of cucumber plants in pots.
(c) The grounding probe and (d) a crocodile clamp on a needle inserted into the stem at the plant base.