## 4 Discussion  
Seed color formation is genetically regulated. The color of red clover seeds is determined by two gene loci [38], and yellow seed coats are homozygous recessive at both, while a dominant allele at either locus imparts a light purple color and dominant alleles at both loci result in dark purple seed coats. It has been determined that the pleiotropic gene locus controls the dormancy and pigment traits in red rice by regulating ABA and flavonoid biosynthetic pathways, respectively [39]. The relationship between seed germination and coat color was reported for legumes, e.g., physical dormancy (often called hard seededness) correlates with the amount of phenolic pigments and dark seed color [21]. In contrast to  
Figure 4: Morphometric parameters of red clover seedlings grown in rhizboxes 5 weeks after sowing. Seedlings were grown from yellow (**a**) and dark purple (**b**) seeds. Mean values \(\pm\) standard error are presented. The number of seedlings in the experimental group was \(n=\) 19–23. * Significantly different from the control group (\(p\leq 0.05\)); # significantly different from seedlings growing from control yellow seeds (\(p\leq 0.05\)). previous studies [30; 31], we did not obtain a clear difference in germination kinetics of yellow seeds compared to dark purple or brown seeds of red clover (Table 1); at least the germination of 'Arimaiciai' cultivar seeds was not dependent on seed color in the control group. However, the effects of seed treatments with CP and EMF on germination and seedling growth were dependent on seed color. Germination of yellow seeds was stimulated by both durations of CP (CP5, CP7) and EMF (EMF10, EMF15) treatments, while brown seeds germinated faster only in CP but not in EMF-treated groups. The response of dark purple seeds was intermediate between yellow and brown seeds (EMF15 did not stimulate germination), and the extent of stimulation was lower compared to that in yellow seeds. One of the possible explanations for such differences may be related to the content of pigments as well as other phenolics in seeds of different color. It has been established that production of hydrogen peroxide and other ROS species plays a key role in activation of germination processes so that insufficient amounts of H\({}_{2}\)O\({}_{2}\) may cause delay in germination [40; 41]. We have demonstrated that changes in germination of Norway spruce seeds induced by CP and EMF are related to modulated production of H\({}_{2}\)O\({}_{2}\) in germinating seeds [26]. Therefore, it is possible to hypothesize that treatment induced changes in H\({}_{2}\)O\({}_{2}\) generation in brown and dark purple seeds are \"shielded\" due to higher amount of ROS scavengers compared to yellow seeds (having less pigments). Different effects of CP on germination of color morphs may be related also to different absorption of CP generated UV light in seeds of different color. Low-temperature non-equilibrium CP in the air at a low pressure used in our study generates radiation in a spectral range from UV (220 nm) up to near infrared (1100 nm) [32]. A weak UV radiation in the range of 220-350 nm is attributed to the molecular bands of oxygen-based and nitrogen-based species (NO, OH) formed in air plasma. Thus, CP-treated seeds were exposed to UVC, UVB, and UVB radiation and the effects of UV radiation on seed germination cannot be excluded. However, the reports on the effects of UV on germination are controversial [42]. Despite numerous reports on stimulation of seed germination by UVB and UVA (when UV is applied without CP), some studies present evidences that contribution of UV radiation to the effects of CP treatments on germination is negligible [43]. Phytochromes are light sensing molecules involved in the control of plant germination and morphogenesis [44]. Plant cells perceive UV-B radiation by the photoreceptor UVR8 which is well studied in Arabidopsis thaliana [45]; however, the information on the amount of UVR8 on red clover seeds of different color is not available.