Silicon foliage spraying improves growth characteristics, morphological traits, and root quality of Panax ginseng C.A.Mey

Ginseng is a perennial herb used as valuable traditional medicine for more than three thousand years. Ginsenosides are the major group of pharmacologically active components of ginseng, and they are effective against various diseases. Present study was designed to investigate the impact of foliar silicon sprays on growth characteristics, physiological traits, and pharmaceutical quality of 6-year-old ginseng plants. Three different concentrations i.e. 50 mg/L, 100 mg/L, and 200 mg/L of Si was used as foliar treatment. Compared to control, stem hardness was enhanced up to 54% in 100 mg/L treatment followed by 38% in 50 mg/L and 36% in 200 mg/L. SEM analysis showed that the density of epidermal cells was 21-25% higher in Si-treated plants than that in the control plants. Cuticle thickness was found higher in Si treated plants as compared to control. Overall a total of 25%, 38%, and 54% of cuticle thickness and 43%, 49%, and 63% ginseng roots production was observed in plants treated with Si treatment of 50 mg/L, 100 mg/L, and 200 mg/L, respectively. Results suggest that out of three different concentrations of Si treatments, 200 mg/L found to be most effective in overall higher Si content in leaves with thick cuticle and higher root production, 100 mg/L treatment showed high photosynthesis rate followed by stomatal conductance, chlorophyll content and stem hardness. 50 mg/L was found to be least effective. Out of 12 ginsenosides analyzed in 6-year-old ginseng roots, the most common were AP, Rg1, Rb1, and Re. The content of ginsenosides per gram of ginseng roots did not show any significant differences among treatments, but overall, ginsenosides contents were higher in Si-treated plants because of increased root growth triggered by increased Si level. Our study show that the application of aerial sprays with elevated Si levels increases the growth, promotes the physiological and morphological traits and increases the yield of 6-year-old ginseng plants. In addition, this study implied the importance of Si for commercial production of high-quality ginseng roots.