## 3 Results
### Changes in Antioxidant Activity, Content of Secondary Metabolites and Minerals in Harvested Seeds  
Harvested seeds were used to examine the effects of seed treatments on antioxidant activity, content of total phenolic compounds, minerals and secondary metabolites specific for buckwheat. Changes induced in the radical scavenging activity and the total amount of phenolic compounds in seed extracts are presented in Figure 5.  
Both the radical scavenging activity and the total amount of phenolic compounds in the control seeds of 'VB Vokiai' was slightly lower (12% and 9%, respectively) in comparison to the control of 'VB Nojai' seeds (Figure 5). The treatment-induced changes in radical scavenging activity were cultivar dependent: for 'VB Nojai' the only observed effect was a negligible (2%) increase in radical scavenging activity in the CP7 group, whereas CP5 decreased this activity by 20% in 'VB Vokiai' seeds, and CP7 and EMF15 treatments enhanced radical scavenging activity (by 10% and 18%, respectively). CP but not EMF treatments reduced the content of the total phenolic compounds in 'VB Vokiai' seeds (CP5 by 24% and CP7 by 15%), in contrast to 'VB Nojai' seeds, where the amount of total phenolic compounds was reduced by EMF treatments (EMF15 by 19%, EMF10 by 9%) more so than by the CP treatment (CP5 by 7%). There was no correlation found between changes induced in the radical scavenging activity and the content of the total phenolic compounds in buckwheat seeds. The analysis of the content of mineral elements has revealed certain cultivar-dependent differences in the mineral content of the control seeds (Figure 6). The content of K and Fe in 'VB Vokiai' seeds was (by 8.6% and 28%, respectively) smaller, and the content of Zn by 30% larger compared to 'VB Nojai' seeds, while the amounts of calcium, magnesium, sodium, and copper were similar. Figure 4: Morphometric parameters of buckwheat plants and seed yield measured 14 weeks afterowing in experimental field plots. (**a**) 'VB Vokiai’ parameters and seed yield; (**b**) 'VB Nojai’ parameters and seed yield. The means \(\pm\) standard errors are presented (\(n\) = 21–28). Different lowercase letters indicate significant differences (\(p\) < 0.05; [PERSON]’s LSD test). Figure 5: Radical scavenging activity and amount of total phenolic compounds in the harvested seeds of buckwheat. (**a**) radical scavenging activity in 'VB Vokiai’ and 'VB Nojai’ seeds; (**b**) content of total phenolic compounds in 'VB Vokiai’ and 'VB Nojai’ seeds. The means \(\pm\) standard errors of three replicates are presented (\(n\) = 3). Different lowercase letters indicate significant differences (\(p\) < 0.05; [PERSON]’s LSD test). Treatment-induced changes in seed mineral content were also significantly different for the two buckwheat cultivars. A slight increase (4-9%) in K content was observed in VB 'Vokiai' seeds after treatment with CP5, CP7 and EMF15, but the only effect in 'VB Nojai' was a 3% decrease of K content in the EMF15 group. The amount of Ca in 'VB Nojai' seeds was not affected by stressors, but in 'VB Vokiai' seeds CP5 reduced Ca content by 17%. There was no change in the amount of Mg and Na in 'VB Vokiai' seeds, while in 'VB Nojai' EMF15 increased the content of Mg by 8%; Na was increased by 15% in the CP7 group but significantly decreased by EMF10 and EMF15 (17% and 36%, respectively). The effect of stressors on Fe content in 'VB Vokiai' seeds was particularly significant: Fe amount increased by 49%, 36% and 54% for CP7, EMF10 and EMF15, respectively. However, no positive effects on Fe content were observed in 'VB Nojai' seeds; on the contrary, Fe content decreased by 11% in the CP7 group. Treatments did not change Cu content in seeds of both cultivars. CP treatments did not have an effect on the amount of Zn in seeds of both cultivars, whereas the effects of EMF treatments were the opposite: EMF10 treatment decreased Zn amount by 24% in 'VB Vokiai' seeds, and increased it in 'VB Nojai' seeds (by 19% in the EMF10 group and 37% in the EMF15 group).