Foliar Application of Selenium under Nano Silicon on Artemisia Annua: Effects on Yield, Antioxidant Status, Essential Oil, Artemisinin Content and Mineral Composition

The unique biological properties of A. annua have stimulated the research on its cultivation in different regions of the world. In this study, the effect of the Se and nano-Si supply on the yield, biochemical characteristics and mineral content of A. annua was investigated. Growth stimulation and a significant increase in the antioxidant status were recorded under Se and nano-Si foliar application. A decrease in the number of essential oil components and significant changes in the essential oil amount and composition led to significant phenophase shifts: nano-Si significantly stimulated eucalyptol and artemisia ketone accumulation and decreased germacrene D production, whereas Se demonstrated the opposite effect. A joint Se and nano-Si supply significantly decreased the camphor content and increased artemisia ketone and artemisinin levels by 1.3–1.5 times. Se/Si supplementation affected the macro- and microelements content, causing either a redistribution of leaves/stems elements (Al, Li and Zn) or a significant decrease in Ca, Mg, K, B, Cu, Fe and Mn concentrations in leaves, with no signs in growth inhibition or a decrease in the photosynthetic pigments content. The biofortification of A. annua with Se singly or in combination with nano-Si resulted in the synthesis of products with a Se content of as much as approximately 16% of the daily adequate Se consumption level (ACL) when using 5 g day−1 as a spice, or 36% of ACL when using 50 mL of tea infusion (1:2, v/w). The results indicated a high possibility of Se and nano-Si application toward the regulation of A. annua growth, biochemical characteristics (including essential oil and artemisinin) and mineral content.