## 3 Results and Discussion
### Surface Imaging Using an Optical Microscope and SEM
(**a**) Control (water); (**b**) PAW 5\({}^{\prime}\); (**c**) PAW 20\({}^{\prime}\). Figure 7: SEM images of _Beta vulgaris_ at 1000\(\times\) magnification. (**a**) Control (water); (**b**) PAW 5\({}^{\prime}\); (**c**) PAW 20\({}^{\prime}\). Previous studies with the GAD reactor indicated that high concentrations of NOx can be generated in the gas phase and further transported to the liquid phase, where compounds such as H2O2 also appear through secondary reactions [50]. In the case of PAW treatment of seeds, these compounds can cause an increase in germination, e.g., through H2O2 accumulation [48; 49]. The increase in germination may also be related to other effects of plasma treatment on seeds, such as surface etching and increased water absorption [67; 68; 69], or inactivation of harmful organisms [70; 16; 71]. Many of these effects can also affect seeds through active particles found in PAW, e.g., via H2O2 activating the catalase enzyme for the synthesis of new proteins [26], increases in chlorophyll content [72], the cracking of hard seeds, thus allowing them to absorb moisture [73] or the enhancement of nitrogen contents in the seeds through adsorption, diffusion and trapping of RNS produced in plasmas [74]. Their effect can not only be an increase in germination, but also an increase in the quality of the plants grown and their levels of disease tolerance [75; 76]. We speculate that the results of seeds' imbibition in PAW, especially with the presence of RONS and low pH, changed the osmotic potential and made the seed surface more prone to structural changes. On the basis of the results, it can be concluded that when using the same reactor and the same treatment conditions, the results largely depend on the type of treated seeds. In the case of _Beta vulgaris_, the effect of PAW treatment is evident in both the change of microflora, germination parameters and surface structure of the tested seeds. Due to the higher rate of germination (\(G_{EN}\)), sprouts of greater length were obtained in addition to a larger fraction of germinated seeds. Because of the relatively small decontamination effect of fungi whose specific species were restricted or stimulated, the gradual increase in treatment efficiency with increasing treatment time may be related to the change in surface structure observed via optical and scanning electron microscopy. In the case of _Daucus carota_, characterized by other types of fungi, a complete reduction in _Alternaria radicina_ and _Trichoderma harzianum_ species, which were not removed during the classical decontamination method with sodium hypochlorite, can be observed. Compared to the control, significantly better germination and sprout length parameters were obtained even for shortest time, but these were still worse than the results obtained for traditional treatment with NaOCl. In combination with the overall better decontamination effect of sodium hypochlorite, it can be thought that for carrot seeds, the decisive influence on germination was connected with fungi on the surface, which is better removed by the traditional method. However, the use of PAW may still offer a competitive alternative due to the ecology and economy of plasma treatment with the investigated device, for which only electricity and commonly available air are needed. PAW can be also generated in larger quantities in devices of different constructions [77; 78; 79], which can further improve the cost factor.