# Soybean Germination Response to Algae Extract and a Static Magnetic Field Treatment
## 4 Discussion  
The application of algal extract and pre-sowing treatment of seeds with a static magnetic field can be an alternative choice and supplementation to synthetic chemicals, which can have negative effects on growers, consumers, and the environment. In the literature, the effects of these two factors on soybeans are usually discussed separately. In the present study, their synergistic action was evaluated, which was preceded by the selection of the optimal concentration of algae extract (20%, 40%, 60%, 80%, and 100%), as well as the induction of a static magnetic field (250 and 500 mT) and exposure time (3 and 12 min). The positive effect of _Cladophora glomerata_ extract on the germination of soybean seeds and seedling development may result from the composition of the algal biomass. As shown in a previous review [53], this macroalga can serve as a source of micro- and macroelements (ash from 2.44% to 39.2%), proteins (from 10.7% to 22.5%), carbohydrates (from 58.4% to 61.7%), vitamins A, B\({}_{1}\), B\({}_{2}\), C and E, and other antioxidant molecules, such as polyphenols and pigments-carotenoids, chlorophylls. The examined extract from _Cladophora glomerata_ consists of micro- (Cu-0.1726 mg/L, Mn-1.314 mg/L, Zn-0.2614 mg/L, Fe-4.285 mg/L,) and macroelements (Ca-185.6 mg/L, K-829.7 mg/L, Mg-28.92 mg/L, P-19.87 mg/L, S-220.2 mg/L) [7]. Obtained algal extracts, due to their complex biochemical compositions, have broad effects on plants and can protect them from biotic and abiotic stress, enhance nutrient use efficiency, and stimulate beneficial microbiome of plants [10; 54]. The effect of algal extracts on cultivated plants depends on many factors, such as type of biostimulant (e.g., seaweed species used for production, harvest season of algal material), biostimulant dose or frequency of application, etc. [4; 5; 15]. In the preliminary tests, the selection of the appropriate concentration of the tested preparation for stimulating plant growth is essential. The present study indicates that examined concentrations of _C. glomerata_ extract (20%, 40%, 60%, 80%, and 100%) had no phytotoxic effects on soybean germination and growth. Germination percentages in all experimental groups were higher than in the control group, but 20% and 80% concentrations were outstanding. In our previous study, 20% and 80% extracts of _C. glomerata_ also provided the highest germination ability of carrot seedlings [9]. [PERSON] et al., tested extract obtained from green macroalga--_Enteromorpha intestinalis_--and applied it at different concentrations--20%, 40%, 60%, and 100%--on soybeans [10]. In this case, the highest germination percentage (100%) was observed for 60% extract, whereas the lowest for concentrations, 20% and 100%, were both 40%. In the case of the control group, the germination percentage was only 20% and for the group treated with chemical fertilizer it was 32%. In the present study, the highest content of chlorophyll \(a\) and \(b\), as well as carotenoids was determined for 80% _C. glomerata_ extract. It aligns with the results presented by [PERSON] et al., who observed the increase in the content of chlorophyll \(a\) and \(b\), as well as carotenoids in soybean with the increase in the concentration of _Enteromorpha intestinalis_ extract (20%, 40%, and 60%) and a decrease for the 100% extract [10]. The application of Bozzyme formulation, prepared from _Ascophyllum nodosum_, at a dose of 500 mL/ha significantly influenced the total chlorophyll content in soybean [55]. However, [PERSON] et al., showed that treatment of soybean seeds with commercial preparation of Stimulagro (liquid extract of _Ascophyllum nodosum_) at small doses (0.5, 1.0, and 2.0 g/L) had no effect on the chlorophyll content expressed in SPAD units and was comparable to the control group. The enhancement of the leaf chlorophyll level in plants is a well-known property of algal extracts acting as biostimulants for plant growth [56].