Effects of Artemisia argyi and tartary buckwheat ( Fagopyrum tataricum ) straw extracts on selenium accumulation in watercress ( Nasturtium officinale )

Selenium-enriched vegetables have high nutritional value and good flavor, which are beneficial to human health. To improve the selenium uptake of watercress, a pot experiment was conducted to study the effects of selenium combined with 400-fold diluted extracts of Artemisia argyi and tartary buckwheat (Fagopyrum tataricum) straw on its growth and selenium accumulation. Both extracts promoted root and shoot biomass, increased leaf chlorophyll and carotenoid contents, and enhanced POD activity. Compared with single selenium treatment, A. argyi straw extract raised root and above-ground selenium accumulation by 46.38% and 16.69%, while tartary buckwheat extract increased it by 39.10% and 5.41%. Their combined treatment increased selenium accumulation by 47.28% and 19.64%. The correlation analysis showed that the selenium content in the roots and above-ground parts of watercress had a positive correlation with the biomass of watercress, chlorophyll content, carotenoid content, and POD activity. In conclusion, the two extracts can promote watercress growth and selenium enrichment, and their combined application achieves a better effect.