# Soybean Germination Response to Algae Extract and a Static Magnetic Field Treatment
## 4 Discussion
Examined extracts from _Cladophora glomerata_ had no statistically significant effect on soybean dry mass as compared to the control group, but the highest values were obtained for concentrations 20% (3.52 g) and 100% (3.66 g). [PERSON] et al., who tested an extract from _Ascophyllum nodosum_ at much smaller doses of 0.5, 1.0, and 2.0 g/L on soybean also did not observe an effect on soybean dry mass [56]. Algal-based biostimulants are efficient, not only in germination tests performed under controlled conditions, but also under real field conditions. [PERSON] et al., showed that among tested concentrations of extracts prepared from red seaweed (_Kappaphycus alvarezii_ at 2.5, 5.0, 7.5, 10, 12.5, and 15%), the last concentration used as a foliar spray provided the highest grain yield (by 57% as compared to the control) of soybean grown under rainfed conditions [4]. [PERSON] and [PERSON] also confirmed that the application of extract from _Ascophyllum nodosum_ greatly influenced grain, straw, and total biological yield (grain + stover yield) [55]. Seaweed extracts are used in agriculture as a foliar spray or also as a soil drench to stimulate seedling rooting [15]. In the present study, root length in all experimental groups (except 80%) was higher than in the control group and the best results were obtained for the 60% extract. The response of the soybean to the _Cladophora glomerata_ extract was consistent with that observed in the work of [PERSON] et al., where root length increased with an increase in _Enteromorpha intestinalis_ extract concentration (20%--4.5 cm, 40%--5.0 cm, 60%--6.6 cm) and decreased for 100% extract--5.2 cm; however, all values were higher than in the control group [10]. [PERSON] et al., tested the effects of different concentrations of water-soluble marine algal extracts (from 10\({}^{-2}\) g/mL to 10\({}^{-13}\) g/mL) including the green algae--_Ulva fenestrata_ and _Codium fragile_--on the root growth in soybean seedlings and concentrations of 10\({}^{-2}\) g/mL exerted an inhibitory effect [16]. For _Codium fragile_, the highest stimulatory effect on root length was noted for the concentrations of 10\({}^{-5}\) g/mL and roots were longer by 18.0% than the control roots [15]. Promotion of soybean root growth is crucial because it enables to obtain seedlings that mature in fewer days after sowing and avoid damage caused by soil pathogens [16]. Algal extracts used as biostimulants of plant growth are known to increase soybean length. [PERSON] et al., observed that the application of 100% extract from the green algae, _Enteromorpha intestinalis_ (among tested concentrations of 20%, 40%, and 60%), had the greatest effect on shoot length (5.7 cm), which was 63% higher than in the control group. In the present study, comparable results were obtained for 20% (14.4 cm), 60% (14.1 cm), and 80% (14.6 cm) extracts [10]. In the work of [PERSON] et al., the greatest soybean height was measured for the highest tested concentrations of _Kappaphycus alvarezii_ extract (15% among others 2.5%, 5.0%, 7.5%, 10%, 12.5%) and was 16.8% higher than in the control group [4]. [PERSON] et al., and [PERSON] also paid attention to another property of algal biostimulants, that they can increase the uptake of nutrients by soybeans, probably due to enhanced root growth (confirmed in this study) and also can enhance the effectiveness of fertilizers [4,55]. In a previous study, we confirmed that carrot seeds treated with an extract from _Cladophora glomerata_ were biofortified with macro- Ca, K, Mg, and S, and microelements Cu, Fe, Mn, and Zn [9]. There are also examples of the influence of much lower concentrations of the tested biostimulants on the growth and development of soybean in the literature. The presented data are inconsistent, which means that for each type of biostimulant, preliminary tests should be carried out to select the optimal concentrations.