Objective  Effects of silicon on the growth and functional ingredients accumulation of Anoectochilus roxburghii were studied for the herbal crop quality improvement.

  Method  Plants of Hong Xia, A. roxburghii (Wall.) Lindl, were supplied with concentrations of silicon at 0, 0.175, 0.350, 0.525, 0.700, and 0.875 mmol·L⁻¹ in a hydroponic experiment for 30 d. Effects of the treatments on the plant physiology and functional ingredients contents were monitored.

  Result  Silicon addition promoted the growth of A. roxburghii. The relative growth rate under the supplementations of 0.175 to 0.700 mmol·L⁻¹ silicon was more than 7 times that of control. The chlorophyll content, chlorophyll index, and nitrogen balance index (NBI) all rose with increasing silicon to peak at 0.525 mmol·L⁻¹ and followed by a decline (P＜0.01), while the flavonoid decreased significantly to its lowest under 0.875 mmol·L⁻¹ (P＜0.01) and the peroxidase activity significantly increased more than 2 to 3 times that of control (P＜0.01). At high concentration of silicon (i.e., 0.700 mmol·L⁻¹), the accumulation of total flavonoids was 71.45%, and polysaccharides 116.65%, higher than those of control (P＜0.01).

  Conclusion  Presence of silicon was beneficial for the growth of A. roxburghii. At an addition rate of 0.525 mmol·L⁻¹ during the vegetative growth period and 0.700 mmol·L⁻¹ in later stage, a maximized accumulation on flavonoids and polysaccharides could be realized.