## 3 Results and Discussion
### Effect of Soil Salinity on Biomass Yield and Sodium Content in F. arundinacea
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{3}{*}{**Plots**} & \multirow{3}{*}{\begin{tabular}{c} **Fresh** \\ **Biomass** \\ **Yield** \\ **(kg\(\cdot\)m\({}^{-2}\))** \\ \end{tabular} } & \begin{tabular}{c} **Biomass** \\ **Loss** \\ **after Air-** \\ **Drying** \\ **(\%)** \\ \end{tabular} & \begin{tabular}{c} **Air-Dry** \\ **Biomass** \\ **Yield** \\ **(g\(\cdot\)m\({}^{-2}\))** \\ \end{tabular} & \begin{tabular}{c} **Moisture** \\ **Content in** \\ **Fresh** \\ **(g\(\cdot\)m\({}^{-2}\))** \\ \end{tabular} & \
\begin{tabular}{c} **Moisture** \\ **Content in** \\ **Fresh** \\ **Biomass** \\ **(\%)** \\ \end{tabular} &
\begin{tabular}{c} **Moisture** \\ **Content in** \\ **Air-Dry** \\ **Biomass** \\ **(\%)** \\ \end{tabular} \\ \hline FA\_1 & 2.05 & 68.73 & 641.10 & 578.37 & 71.79 & 9.79 \\ FA\_2 & 1.75 & 69.84 & 527.85 & 474.11 & 72.91 & 10.18 \\ FA\_3 & 2.05 & 70.56 & 603.53 & 541.16 & 73.60 & 10.34 \\ FA\_4 & 2.75 & 74.09 & 712.50 & 636.76 & 76.85 & 10.63 \\ FA\_5 & 2.25 & 71.20 & 648.08 & 576.76 & 74.37 & 11.01 \\ FA\_6 & 2.55 & 71.15 & 735.57 & 655.43 & 74.30 & 10.90 \\ FA\_7 & 2.55 & 70.71 & 746.95 & 663.96 & 73.96 & 11.11 \\ FA\_8 & 2.90 & 68.88 & 902.48 & 807.67 & 72.15 & 10.51 \\ \hline Mean \(\pm\) & \multirow{2}{*}{2.36 \(\pm\) 0.37} & 70.64 \(\pm\) & 689.76 \(\pm\) & 616.78 \(\pm\) & 73.74 \(\pm\) & 10.56 \(\pm\) \\ \cline{1-1} \cline{3-4} SD & & 1.58 & 105.41 & 93.35 & 1.48 & 0.42 \\ \cline{1-1} \cline{3-4} V [\%] & 15.68 & 2.23 & 15.28 & 15.13 & 2.00 & 3.99 \\ \hline \hline \end{tabular}  
* SD—standard deviation, V—variability coefficient (n = 8 study plots).  
\end{table} 
Table 1: Biomass yield of _F. arundinacea_ on experimental plots in the field cultivation. Figure 1: Second year of tall fescue field cultivation (May 2021). On experimental plots in the field cultivation of _F. arundinacea_, the concentration of salts in plants and soil was determined (Table 2). The average content of sodium ions in the above-ground plant parts of tall fescue was high and amounted to 6.51 mg\(\cdot\)g\({}^{-1}\) of dry matter. However, in individual experimental plots, it ranged widely from 2.45 to 8.66 mg\(\cdot\)g\({}^{-1}\) of dry matter. Similarly, the soil salinity (expressed as sodium chloride equivalent) remained high, though variable, from 0.70 to 6.85 g\(\cdot\)L\({}^{-1}\) with a variability coefficient of 51.55%. Our research showed a strong negative correlation between soil salinity and air-dry biomass yield of _F. arundinacea_. At the lowest content of NaCl in the soil (0.70 g\(\cdot\)L\({}^{-1}\)), tall fescue yield was 902.48 g\(\cdot\)m\({}^{-2}\), while at the highest soil salinity (more than 5.50 g\(\cdot\)L\({}^{-1}\)), it decreased to 527.85-641.10 g\(\cdot\)m\({}^{-2}\) (Figure 2). The negative effect of salinity on tall fescue yield has been shown by two field experiments conducted in Turkey. The average dry matter yield from three consecutive years of _F. arundinacea_ cultivation at one cut was 5.94 and 4.59 Mg\(\cdot\)ha\({}^{-1}\) for non-saline and highly saline soil, respectively [41]. In the second experiment, a gradual decrease in the yield of tall fescue was obtained during irrigation with water having an increased salt content [42]. Similar observations were obtained for experiments in pots. Dry weight yield of _F. arundinacea_ 'Fawn' for the first cut reached 41.08, 28.64, 13.08 and 11.96 g\(\cdot\)m\({}^{-2}\) for non-saline control and irrigation of water with 4000, 8000 and 12,000 ppm of NaCl, respectively [43].