## 3 Results  
All the observed traits had normal distribution. The results of the MANOVA indicated that effects of biostimulants (Wilk's \(\lambda\) = 0.1983; \(F\) = 3.78; \(p\) < 0.0001) and cuts (Wilk's \(\lambda\) = 0.0042; \(F\) = 74.32; \(p\) < 0.0001) were significantly different regarding all the six quantitative traits. According to those results, the interaction between biostimulants and cuts was not significant for macronutrient content ([PERSON]'s \(\lambda\) = 0.487; \(F\) = 0.69; \(p\) = 0.905), but it was significant for the dry matter yield (Table 1). ANOVA indicated that the main effects of biostimulants and cuts were significant for all examined traits (Table 1). The studies showed that the use of biostimulants significantly affected the chemical composition of the _Poa prtenensis_ meadow. The weighted average of macronutrient content ranged from 1.586 to 2.424 g P kg\({}^{-1}\) DM; from 10.90 to 18.78 g K kg\({}^{-1}\) DM; from 6.098 to 9.622 g Ca kg\({}^{-1}\) DM; from 2.024 to 3.726 g Mg kg\({}^{-1}\) DM; from 0.289 to 0.518 g Na\(\cdot\)kg\({}^{-1}\) DM. (Table 3). The biostimulants used on their own had the greatest impact on the content of phosphorus and magnesium, while combined application resulted in higher calcium content in the meadow vegetation. Plants treated with combined application of both stimulants contained, on average, 15% more calcium than control ones. According to nutritional standards, good quality forage should contain at least 3.0 g P kg\({}^{-1}\) DM; 17-20 g K kg\({}^{-1}\) DM; 7.0 g Ca kg\({}^{-1}\) DM; 2.0 g Mg kg\({}^{-1}\) DM and 1.5-2.5 g Na kg\({}^{-1}\) DM [22]. The studies also revealed significant correlation between the dry matter yield and macronutrient content. The yield was positively significantly correlated with the content of P (0.810), K (0.825) and Na (0.821), and negatively with the content of Ca (\(-\)0.496) and Mg (\(-\)0.680). The annual dry matter yield was correlated with the mean content of P (0.563), K (0.778), Ca (0.669) and Mg (0.741). Figure 2 shows the variability of the dry matter yield and content of six macroelements of the control and three biostimulant treatments in terms of the first two canonical variables. In the graph, the coordinates of the point for particular biostimulant treatments are the values for the first and second canonical variables, respectively. The first two canonical variables accounted for from 97.47% (cut II) to 99.98% (all three cuts) of the total multivariate variability between the individual biostimulants. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline  & & \multicolumn{2}{c}{**Dry**} & & & & & & \\
**Source of Variation** & **d.f.** & **Matter** & **P** & **K** & **Ca** & **Mg** & **Na** \\  & & & & & & & & & \\ Block & 3 & 0.046 & 0.022 & 1.450 & 3.175 & 0.196 & 0.0002 \\ Biostimulant & 3 & 1.863 *** & 0.099 *** & 6.631 *** & 2.867 ** & 0.299 *** & 0.005 * \\ Cut & 2 & 39.08 *** & 1.944 *** & 171.8 *** & 24.19 *** & 7.823 *** & 0.155 *** \\ Biostimulant \(\times\) cut interaction & 6 & 0.586 ** & 0.004 & 0.238 & 0.057 & 0.018 & 0.0002 \\ Residual & 33 & 0.167 & 0.016 & 0.314 & 0.327 & 0.033 & 0.001 \\ \hline \hline \end{tabular}  
* \(p<0.05\); ** \(p<0.01\); ** \(p<0.001\); ** \(p<0.001\); df—degrees of freedom.  
\end{table} 
Table 1: Mean squares from two-way analysis of variance for six observed traits.