## 3 Results and Discussion
### Pot Experiments
A decrease of this value (in proportion to the quantum efficiency) indicates a reduction of PSII efficiency [34; 35]. Phosphorus deficiency could be one of the factors contributing to the reduction of PSII maximum quantum efficiency. The recorded values of the F\({}_{\mathrm{V}}\)/F\({}_{\mathrm{m}}\) ratio in the maize leaves of the control objects were 0.753 and below the optimal value (Tables 3 and 4). In foliar fertilized plants, the values of the F\({}_{\mathrm{V}}\)/F\({}_{\mathrm{m}}\) ratio increased compared to the control. However, the dependents were not statistically significant relative to the applied dose of foliar fertilizer. A different relationship was observed in the case of soil fertilization, where F\({}_{\mathrm{V}}\)/F\({}_{\mathrm{m}}\) values in fertilized facilities were higher than in the control, but the values of this parameters decreased with the increase of the applied fertilization dose (Tables 3 and 4). A much more sensitive ratio is F\({}_{\mathrm{V}}\)/F\({}_{\mathrm{0}}\). This ratio contains the same basic information but exhibits higher values and a higher dynamic range than F\({}_{\mathrm{V}}\)/F\({}_{\mathrm{m}}\). The ratio F\({}_{\mathrm{V}}\)/F\({}_{\mathrm{0}}\) shows higher amplitude under stress conditions, since it immediately reflects all changes of F\({}_{\mathrm{V}}\) and/or F\({}_{\mathrm{0}}\)[36]. As shown in Tables 3 and 4, the values of the F\({}_{\mathrm{V}}\)/F\({}_{\mathrm{0}}\) ratio increased significantly with the increase in the dose of foliar and soil fertilizer applied in comparison with the control. However, as is the case of the F\({}_{\mathrm{V}}\)/F\({}_{\mathrm{m}}\) ratio, the F\({}_{\mathrm{V}}\)/F\({}_{\mathrm{0}}\) ratio increased proportionally to the dose of foliar fertilizer. A different relationship was observed in a case of soil fertilization. \begin{table}
\begin{tabular}{c c c c c} \hline \multirow{2}{*}{**Object**} & **Intensity of Photosynthesis Net (PN)** & **Transpiration Rate** & **Stomatal** & **Intercellular CO2** \\  & **Photosynthesis Net (PN)** & **(E)** & **Conductance (g\({}_{\mathrm{S}}\))** & **Concentration (C\({}_{\mathrm{I}}\))** \\ \cline{2-5}  & \(\mu\)mol(CO2)m-2s-1 & **mmol(H2O)m-2s-1 & **mmol m-2s-1** & **mmol L-1** \\ \hline Control & 14.4 \({}^{\mathrm{a}}\)\(\pm\) 0.1 & 2.11 \({}^{\mathrm{a}}\)\(\pm\) 0.05 & 0.07 \({}^{\mathrm{a}}\)\(\pm\) 0.002 & 45 \({}^{\mathrm{a}}\)\(\pm\) 0.5 \\ \hline Sf\_1 & 17.9 \({}^{\mathrm{c}}\)\(\pm\) 0.2 & 2.61 \({}^{\mathrm{c}}\)\(\pm\) 0.01 & 0.12 \({}^{\mathrm{c}}\)\(\pm\) 0.003 & 71 \({}^{\mathrm{c}}\)\(\pm\) 0.5 \\ \hline Sf\_2 & 17.2 \({}^{\mathrm{b}}\)\(\pm\) 0.1 & 2.49 \({}^{\mathrm{b}}\)\(\pm\) 0.05 & 0.09 \({}^{\mathrm{b}}\)\(\pm\) 0.002 & 62 \({}^{\mathrm{b}}\)\(\pm\) 0.5 \\ \hline Sf\_3 & 16.1 \({}^{\mathrm{b}}\)\(\pm\) 0.1 & 2.34 \({}^{\mathrm{ab}}\)\(\pm\) 0.03 & 0.08 \({}^{\mathrm{b}}\)\(\pm\) 0.001 & 58 \({}^{\mathrm{b}}\)\(\pm\) 0.7 \\ \hline \end{tabular}  
* Means values with the same lower case are not statistically significant according to the T-Tukey test (\(\alpha\) = 0.05). F\({}_{\mathrm{f}}\)\({}_{\mathrm{1}}\), FF\({}_{\mathrm{2}}\), and FF\({}_{\mathrm{3}}\)—object with foliar fertilizer applied in doses of 1, 2, and 4 kg ha\({}^{-1}\), respectively, Sf\({}_{\mathrm{1}}\), Sf\({}_{\mathrm{2}}\), and Sf\({}_{\mathrm{3}}\)—object with soil fertilizer applied in doses of 30, 40, and 60 kg ha\({}^{-1}\), respectively.  
\end{table} 
Table 2: Mean values of gas exchange parameters in maize leaves, depending on the dose of soil fertilization (n = 10). The indicator PI (performance index) describes the effective energy amount processed by PSII [37]. In the conducted experiment, a significant difference of PI value was observed with relation to applied fertilizer dose. In the case of other parameters, PI values decreased with an increased dose of applied fertilizer. It should be noted that this value is still significantly higher compared to the control (Tables 3 and 4). Deficiencies in particular elements disrupt the normal functioning of the photosynthetic apparatus.