Effects of Copper Compounds on Phenolic Composition of the Common and Tartary Buckwheat Seedlings

Food producers actively seek effective seed-coating agents to ensure optimal antimicrobial protection and/or nutritional support for young plants. In this context, our study aimed to investigate the impact of various copper compounds on the germination and early growth stages of two important crops, common and Tartary buckwheat. Microparticles (MPs) and nanoparticles (NPs) of copper oxide (CuO) were selected as potential seed treatment agents and compared to Cu salt in a comprehensive germination assay. The results indicated that seed germination remained unaffected by the tested copper compounds after eight days, while there was a significant reduction in seedlings fresh weight and root length. Treated common buckwheat seedlings exhibited extreme increases in all tested phenolic metabolites, even at low concentrations of Cu compounds. In contrast, in Tartary buckwheat seedlings, the already higher concentrations of flavonoids and tannins were mostly slightly decreased. Considering all the results, CuO NPs emerged as the most severe form of Cu, while CuO MPs may have the highest potential for applications in agriculture and food sciences. This finding has implications for producers seeking seedlings enriched in beneficial phenolic compounds for human health, as well as for farmers aiming to boost the antioxidative system of plants to mitigate stress.