## 2 Materials and Methods
### Electrical Measurements  
To measure the complex parameters (impedance), a device based on the AD5933 precision converter chip (Analog Devices, Inc., Wilmington, MA, USA) and ATmega328 controller (Microchip Technology, Chandler, AZ, USA) has been developed in Prokhorov General Physics Institute of the Russian Academy of Sciences (GPI RAS) (Figure 2). Unlike the analogues [21; 22], this device has an automatic calibration function that contains an electromagnetic relay and a 68-k\(\Omega\) resistor. Special forceps with nickel-plated contacts make it possible to use them on trees with a trunk diameter of up to 46 mm (Figure 3). The device outputs the measurement result in the form of numbers proportional to the real and imaginary components of the current flowing through the plant tissues.  
A complete picture of the impedance measurements can be obtained in a wide frequency range, where for each frequency, the active and reactive components of the impedance are calculated. The measurements allowed us to obtain the dependence of the impedance on the frequency of the voltage applied to the sample. The data were recorded in the frequency ranges of 2 kHz-10 kHz in 1 kHz increments and 20 kHz-100 kHz in 10 kHz increments. The device was pre-calibrated by connecting the outputs of the AD5933 to the resistor via a relay, and then measurements were made of completed grafts of pear Otradnenskaya. The contacts were attached to the tree 5 cm above and 5 cm below the grafting union. The data obtained during calibration of the device were processed in the ATmega328 microcontroller according to a special algorithm for converting complex num  
\begin{table}
\begin{tabular}{c c c c c c c} \hline
**Exposure Time** & **Electrical** & **[O2] (uM)** & **(pH)** & **Redox (mV)**, & **NO3\({}^{-}\) (mM)**, & **H2O2 (mM)** \\ \hline
45 & 25.1 \(\pm\) 1.2 * & 262 \(\pm\) 8 & 8.4 \(\pm\) 0.2 & 601 \(\pm\) 26 * & 22.15 \(\pm\) 0.98 & 7.04 \(\pm\) 0.68 * \\ \hline \end{tabular}  
* Deviation from control (\(p\) \(<\) 0.05).  
\end{table}
Table 1: Physicochemical characteristics of PTS obtained from 10% NaCl solution after 45 min of exposure.  
Figure 1: Photo of the “CAPKO” device for a CAP generation.  
bers, and the result was transmitted from the controller to the PC via the RS 232 interface. The results are presented in tabular form including frequency, actual current value, and imaginary current value.  
Figure 3: Measuring the electrical impedance of the grafting zone 6 months after grafting: 1, 2—electrodes located at a distance of 100 \(\pm\) 5 mm from each other.  
Figure 2: A device for determining the complex resistance (impedance).  
The measurement was carried out on young pear trees before and after planting them in the ground, within 4 months. The clamps of the device were attached to the bark of the rootstock and scion through a membrane layer that provided electrical conductivity between the solutions, but prevented their mutual diffusion; these non-woven membranes were moistened with a 5% solution of sodium bicarbonate in distilled water. The measurements of each plant were carried out in triplicate.  
To assess the dynamics of the fusion of the scion and the rootstock, measurements of the electrical impedance were carried out in the area above and below the grafting site. Measurements were started 7 days after grafting and carried out once a week for 4 months after grafting. The electrodes were placed at a distance of 100 \(\pm\) 10 mm from each other, as shown in Figure 3.  
In addition to this, a group of the experimental young trees were treated with CAP immediately after grafting, and another group of the experimental young trees were soaked with PTS solution.