## 2 Materials and Methods
### Design of the Pot Experiment and Characteristics of PGRs
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**PGR Title** & **Stimpo** & **Regoplant** & **Charkor** \\ \hline Standard & TU U 20.2-31168762-005:2012 & TU U 20.2-31168762-006:2012 & TU U 24.2-03563790-041-2001 \\  & [51] & [52] & [53] \\ Content & Natural & & Synthetic \\  & Promotes accelerated cell & division, rhyzogenesis, development of & Accelerates cell division, rhizogenesis, development of \\  & division and the development & symbiotic microflora in the root & symbiotic microflora in the root \\  & of a powerful root system, & system, intensification of & system, enhances \\ Mode of action & increases the leaf area and & photosynthetic activity and & photosynthetic activity and \\  & chlorophyll content, reduces & development of leaf surface, & development of leaf surface, \\  & phytotoxic action of pesticides, & enhances host plant tolerance to & decrease in phytotoxic action of \\  & enhances host plant tolerance to & pesticides, enhances host plant & \\  & pathogenic organisms & & \\  & PGR emitism C: emitism C: & & PGR emitism C: emitism C: \\  & metabolic product of & metabolic product of & metabolic product of \\  & _Cylindrocarupon_ & _Cylindrocarupon_ & _Cylindrocarupon_ \\  & _obtusiusculum_—analogues of & _obtususculum_—analogues of & _obtusususculum_—analogues of \\ Composition & phytothormones of auxin, & phytothormones of auxin, & phytothormones of auxin, \\  & cytokinin nature, saturated and & cytokinin nature, saturated and & \\ unsaturated fatty acids, amino acids, carbohydrates & unsaturated fatty acids, amino & \\  & Natural complex aversectin C, & carbohydrates & \\  & a metabolic product of & & 2,6-Dimethylpyridine-N- \\  & actinomycetes & actinomycetes & \\  & boric acid, copper sulphuric & _Streptomyces avernylilis_. & \\  & acid (II) 5-water, ammonium, & & \\  & molybdenum acid, manganese & & \\  & (II) chloride 4-water, & & \\  & potassium iodide & & \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Characteristics of PGRs used for the treatment of \(M.\times\)_siganteus_ (adapted from [16; 36] and [[http://www.agrobiotech.com.ua](http://www.agrobiotech.com.ua)]([http://www.agrobiotech.com.ua](http://www.agrobiotech.com.ua)), accessed on 10 November 2021). Charkor, Regoplant and Stimpo are widely utilized in Ukraine and surrounding countries for improving the development and biomass production of different agricultural plants, including first-generation energy crops: barley, wheat, sugar beet, fruits, and vegetables [6; 7; 8; 50]. Recently, Stimpo and Regoplant obtained Organic Standard certification and can be used in organic agriculture [54]. The type of \(M\). \(\times\)_giganteus_ treatment with selected PGRs was chosen based on their function type [6; 9; 51; 52; 53; 55]. The composition of Charkor includes chemically synthesized analogues of phytohormones, i.e., 2,6-Dimethylpyridine-N-oxide and 1-naphthylacetic acid; these substances are plant root initiators/ stimulators. Charkor was successfully utilized when green and woody cutting seedlings of fruit and ornamental trees, shrubs, flowers, and medicinal plants were treated. Hence, Charkor's standard application method involves the soaking of vegetative plant parts in a water solution of this substance before planting; spraying biomass during vegetation is not utilized in the case of Charkor. The recommended concentration (Table 3) of Charkor in the water solution used to treat vegetative parts before planting is between 0.1% and 4%; the recommended exposition time is between 2 and 20 h. Following these recommendations, \(M\). \(\times\)_giganteus_ rhizomes were soaked in a Charkor water solution with concentrations of 0.1% and 0.4% and an exposure time of 12 h. In the control experiment, rhizomes were soaked in distilled water without PGR at the same exposition time. Regoplant and Stimpo do not have chemically synthesized analogues of plant hormones and, unlike Charkor, they are not characterized with a strong root initiation effect.