Synergistic effects of selenium and zinc on Bletilla striata (Thunb.) Reichb. F. growth and polysaccharide antioxidation.

Selenium (Se) is a beneficial trace element for plants, while zinc (Zn) is a vital micronutrient. Bletilla striata (Thunb.) Reichb. F. is widely recognized as a medicinal herb. In this study, Se and Zn were introduced to determine the medicinal properties of B. striata. The plant's biomass, polysaccharides, Se and Zn contents, and the antioxidant properties of polysaccharide solutions were all examined. A notable increase in polysaccharide synthesis in B. striata tubers was observed following the application of 0.2 kg ha^-1 of Se, and 1.0 kg ha^-1 of Zn, either individually or in combination. Se and Zn content in polysaccharides were 3.33 to 3.77 mg kg^-1 and 82.82 to 121.78 mg kg^-1, at 1.0 kg ha^-1 Se and 10.0 kg ha^-1 Zn treatments, respectively. These values were 2.1-3.1 times and 1.8-2.8 times higher than those observed in control samples. Polysaccharide antioxidation has resulted in an increase in antioxidant activity as the concentration of polysaccharide solutions increased. The largest scavenging of 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radicals and the most excellent reducing power of the polysaccharide solutions were observed when a mixture of Se and Zn was applied at a rate of 1.0 kg ha^-1 and 10.0 kg ha^-1. The individual application of Se at 1.0 kg ha^-1 and Zn at 10.0 kg ha^-1 also resulted in significant DPPH radicals scavenging and reduced power. These data suggested that Se-Zn enriched B. striata is a new source of Se and Zn supplementation and an antioxidant resource.