## 4 Discussion
The results of some studies show a strong negative correlation between the increasing of concentrations of volatile oils apart the pure components limonene and cineole purified from _Eucalyptus globulus_ on seed germination and vigour [27]. Moreover, the increasing doses of _Vicia sativa_ aqueous extracts caused decrease in germination of mungbean and mashbean [28] and the aqueous extracts of some weeds decreased the germination of wheat and chickpea seeds [29]. Nevertheless, the results of this study, at the first glance, seem rather contradictory. For instance, it is obvious that wormwood aqueous herbs extracts in 2.5 and 5% concentrations significantly increased the germination of lettuce seeds (Table 7). A question remains: why is that so? This is a very easy but, at the same time, tough question, considering the fact that all the treatments were performed with the same aqueous extracts, and prepared from the same lots of nettles, wormwood herbs, black cumin, and chia in the same concentrations. The same is true for the seeds of pepper, spinach and lettuce, which also belong to the same lots. Moreover, the experimental conditions, such as moisture and temperature, were completely controlled since the trials were conducted in the same laboratory by the same staff. Besides, the phytochemical analyses of aqueous extracts showed the highest content (above the 1 mg L\({}^{-1}\)) of epicatechin, quinic acid, caffe acid, esculetin and cinnamic acid in chia, and with those compounds kaefforol was additionally detected in aqueous extracts of black cumin and wormwood. With the previously mentioned compounds, gallic acid was detected in content higher than 1 mg L\({}^{-1}\) (Tables 1-3 and S1) in wormwood extracts. On the other hand, in nettle aqueous extracts, there were only two compounds present in concentrations higher than 1 mg L\({}^{-1}\), namely epicatechin and esculetin (Tables 4 and S1). Thus, considering the previously mentioned certain contradiction in the achieved results, it is important to point out that similar results were obtained in some legumes at the beginning of the 1980s and that the authors of that study found the combination of some phenols, gallic acid, \(\beta\)-naphth and gibberellic acid to show no influence on germination but a significant influence on seedling growth [30]. This corresponds with the fact that treatment with 10 mM of gibberellic acid might increase the amino acid and protein synthesis in the cells of the meristems, developing vascular tissues of the embryonic axis and cotyledons in the seeds of _Sinapis arrensis_[31]. Besides, the results of recent studies show that treatment with 2 uM of \(\alpha\)-naphthalene acetic acid cause a high induction of _Stevia rebaudiana_ calluses and increase their biomass [32]. Although, some polyphenic rich medicinal plants cause a decrease in seed germination and seedling growth of many cultivated plants [33]. The physiological role of phenolic substances seemed to be pretty controversial, and the researchers were mostly divided about their importance. Moreover, it was the prevailing opinion that exogenously applied phenols depress the growth of plant tissues, but at the same time, that exogenously applied phenols might modify the growth response to gibberellins and cytokins [34]. It is well known that an increase in seed respiration strictly corresponds to germination process. That includes processes such as glycolysis, the oxidative pentose phosphate pathway, the tricarboxylic cycle and finally oxidative phosphorylation [35; 36]. The treatment of seeds with phenolic compounds strongly correlated to the inhibition of enzymes of glycolysis and the oxidative pentose phosphate pathway, which might be a possible explanation for the decrease in seed germination [37]. According to some authors, the synergistic effect between the phenolic compounds and plant hormones is not excluded. This is because the phenolic acids might show hormone-like activity and consequently be able to act through the plant hormones as biostimulants [38].