## 4 Discussion  
Products containing amino acids are used as stimulants mainly on fruit crops, but research results [23; 24; 25] indicate that this method is also effective on forage grasses [26; 27]. Application of amino acids to agricultural and horticultural crops increases the yield. Studies on soybean (_Glycine max_) conducted by [PERSON] et al. [28] showed that they positively improved the parameters of shoot growth and fresh weight, as well as the seed yield. [PERSON] et al. [29] found that they significantly increased plant height, stem diameter, and the yield of fresh and dry matter of roselle (_Hibiscus sabdariffa_) leaves. Moreover, their beneficial effect on potato (_Solanum tuberosum_) was also reported, increasing plant height, vegetative growth and dry matter yields [23]. According to [PERSON] et al. [30], foliar use of amino acid mixtures increased the productivity of tomato (_Solanum lycopersicum_), and, according to [PERSON] et al. [24], the same treatment increased the content of dry matter, chlorophylls, carbohydrates and polysaccharides in broad bean (_Vicia fab_). Amino acids can affect the content of other compounds in plants. [PERSON] et al. [31] found that the use of glutamine on onion (_Allium cepa_) increased the total content of amino acids, but also of soluble sugars and phenolic compounds. In contrast, [PERSON] et al. [32] reported that amino acids increased the transcription of genes involved in the transport of nitrates, ammonium, phosphates, magnesium, and iron. According to [PERSON] et al. [33], leaves sprayed with amino acid liquid fertilizer and liquid biological fertilizer (amino acid liquid fertilizer mixed with _Bacillus amyloliquefaciens_ SQR9) increased cowpea (_Vignu unguiculata_) yields, compared to control. In the present studies, the amino acid product increased, compared to control, the content of phosphorus, potassium, calcium, magnesium, and sodium in _Poa pratensis_ absolutely dry matter. Studies by [PERSON] et al. [34] showed that under the influence of amino acid preparations the content of nitrogen, phosphorus and potassium in strawberry (_Fragaria ananassa_) leaves increased significantly, compared to control. In contrast, studies by [PERSON] et al. [35] and [PERSON] et al. [36] comparing the effects of different levels of amino acids showed no significant differences in K content. [PERSON] et al. [24] studied the effects of amino acids on salinity tolerance and found that they significantly improved the K+:Na+ ratio in leaf tissues. At the same time, the content of N, P, K, Mg, and Ca in leaves increased and sodium concentration significantly decreased. In effect, when K+ content increased and Na + content decreased, salinity tolerance increased. In turn, the exact mechanisms triggered by the other biostimulant, i.e., Ti, are difficult to determine, also because this chemical element can improve the health of plants, but they can grow and develop well without it [37; 38]. Several hypothetical theories about the mechanism of Ti action in plants have been proposed in the literature. Some theories suggest that the biological effects of Ti are based on inducing the plant's defence mechanism against Ti; a low dose of this element strengthens defence mechanisms, while high (toxic) \begin{table}
\begin{tabular}{c c c c c c} \hline
**Biostimulant** & **Cut** & **Control** & **Ti** & **Amino Acids** & **Amino Acids + Ti** \\ \hline \multicolumn{6}{c}{Cut I} \\ \hline Control & & 0 & 2.957 & 5.017 & 6.74 \\ \hline Ti & & 1.179 & 0 & 2.489 & 4.293 \\ Amino acids & Cut II & 2.502 & 1.604 & 0 & 3.021 \\ Amino acids + Ti & & 2.988 & 2.024 & 1.646 & 0 \\ \hline \multicolumn{6}{c}{All three cuts jointly} \\ \hline Control & & 0 & 3.243 & 6.654 & 8.594 \\ \hline Ti & & 5.337 & 0 & 3.457 & 5.395 \\ Amino acids & Cut III & 9.643 & 4.313 & 0 & 1.994 \\ Amino acids + Ti & & 11.491 & 6.241 & 2.175 & 0 \\ \hline \end{tabular}
\end{table} 
Table 4: The values of the Mahalanobis distances for all pairs of biostimulant treatments in cut I, cut II, cut III, and all three cuts jointly.