## 3 Results
### Physiological Indicators of Yield
The highest value of the initial fluorescence was observed during the full flowering phase in 2018, which was characterized by average air temperatures and a significant lack of precipitation during this period. In contrast, the lowest value of this parameter was recorded in 2019, which experienced a relatively humid period and the highest average air temperature during the potato flowering period (Table 3). The Fm (maximum fluorescence of chlorophyll) is measured using the Kautsky test after irradiating the plant with intense light. Fm reflects the fluorescence of chlorophyll with full reduction of the electron acceptors in PSII. All factors of the experiment significantly influenced the value of this physiological indicator. A significant difference was observed in the influence of beneficial microorganisms for both the 10-min and 15-min exposures, with increases of 5.77% and 6.39%, respectively, compared to the control group. Genetic characteristics of the tested cultivars played a significant role in determining the maximum fluorescence efficiency. Among them, two mid-early cultivars, 'Oberon' and 'Satina', exhibited the highest values, while the remaining cultivars in the same homogeneous group did not show significant differences (Table 4). The maximum fluorescence of chlorophyll was also significantly influenced by the meteorological conditions in the years of the study. In the first two years, a similar value of Fm was obtained. In 2019, with a wet period during flowering, the highest value of this indicator was obtained (Table 3). \begin{table}
\begin{tabular}{c c c c} \hline \hline \multicolumn{2}{c}{**Experimental Factors**} & \multicolumn{1}{c}{**Dry Matter (\%)**} & \multicolumn{1}{c}{**Starch (\%)**} \\ \hline Pre-planting & \begin{tabular}{c} Control object \\ Exposition I * \\ Exposition II ** \\ \end{tabular}  & 20.2 a & 15.2 a \\ \cline{2-4}  & \begin{tabular}{c} Composition I ** \\ Exposition II ** \\ \end{tabular}  & 20.4 a & 15.4 a \\ \cline{2-4}  & \begin{tabular}{c} HSD *** \\ \end{tabular}  \(p_{\leq 0.05}\) & ns *** & ns *** \\ \hline \hline \multirow{8}{*}{Cultivars} & \begin{tabular}{c} ’Denar’ \\ ’Bellaroas’ \\ ’Gwiazda’ \\ ’Ignacy’ \\ ’Owacia’ \\ ’Vineta’ \\ ’Finezja’ \\ \end{tabular}  & 16.3 a & 12.4 a & 18.0 a & 13.8 a \\  & \begin{tabular}{c} ’Bellarosa’ \\ ’Gwiazda’ \\ ’Ignacy’ \\ ’Owacia’ \\ ’Vineta’ \\ ’Finezja’ \\ \end{tabular}  & 16.5 a & 13.3 a & 13.3 a \\  & \begin{tabular}{c} ’Ignacy’ \\ ’Owacia’ \\ ’Vineta’ \\ ’Finezja’ \\ \end{tabular}  & 18.0 a & 13.6 a & 13.8 a \\  & \begin{tabular}{c} ’Vineta’ \\ ’Satina’ \\ ’Tajfun’ \\ ’Jelly’ \\ ’Mondee’ \\ ’Syrena’ \\ ’Kuras’ \\ \end{tabular}  & 18.0 a & 13.8 a & 13.8 a \\ \cline{2-4}  & \begin{tabular}{c} ’Synena’ \\ ’Kuras’ \\ \end{tabular}  & 18.0 a & 13.8 a & 13.8 a \\ \cline{2-4}  & \begin{tabular}{c} ’Déeron’ \\ ’Satina’ \\ ’Tajfun’ \\ ’Jelly’ \\ ’Mondee’ \\ ’Syrena’ \\ \end{tabular}  & 18.0 a & 13.6 a & 13.8 a \\  & \begin{tabular}{c} ’Kuras’ \\ \end{tabular}  & 18.0 b & 13.8 a & 13.8 a \\  & \begin{tabular}{c} ’Déeron’ \\ ’Satina’ \\ ’Tajfun’ \\ ’Jelly’ \\ ’Mondee’ \\ ’Syrena’ \\ \end{tabular}  & 18.0 a & 13.6 a & 13.3 a & 13.6 a \\  & \begin{tabular}{c} ’Mowacia’ \\ ’Vineta’ \\ ’Finezja’ \\ \end{tabular}  & 18.0 a & 13.8 a & 13.8 a & 13.3 a \\  & \ \begin{tabular}{c} ’Déeron’ \\ ’Satina’ \\ ’Tajfun’ \\ ’Jelly’ \\ ’Mondee’ \\ ’Syrena’ \\ \end{tabular}  & 18.0 a & 13.6 a & 13.6 a & 13.8 a \\  & \begin{tabular}{c} ’Mowacia’ \\ ’Vineta’ \\ ’Finezja’ \\ \end{tabular}  & 19.3 a & 13.8 a & 13. Fo/Fm is the ratio of the quiescent fluorescence (Fo) to the maximum fluorescence (Fm). This ratio, known as Fo/Fm, is a measure of Photosystem II (PSII) efficiency and reflects the photosynthetic activity of plants. A higher Fo/Fm ratio indicates enhanced photosynthesis efficiency and PSII function. The application of EM significantly influenced this indicator at both exposure times (10 and 15 min) by 7.93% and 6.21%, respectively, compared to the control group.