Effects of light quality and intensity on growth, related enzymes activity, and components of Polygala tenuifolia / 中草药

ABSTRACT

Objective To study the growth physiology and components of Polygala tenuifolia under different light quality and intensity, and provide theoretical basis for the artificial cultivation, yield improvement, and increasing the target composition of P. tenuifolia. Methods Using P. tenuifolia shoots as the experimental material, four kinds of ights (white, yellow, red, and blue) as light quality, the light intensity was set at 100, 300, and 500 μmol/(m2∙s) to determinate the plant height, root length, leaf length, leaf width, malondialdehyde (MDA) content, antioxidant enzyme activity, and secondary metabolite content in P. tenuifolia after 30 d of illumination. Results Under the red light, P. tenuifolia had the highest plant height, the longest root length and leaf length, and the largest biomass. Under the yellow light, the MDA content was the lowest, and the MDA content was the highest under white light. The activities of SOD, POD, and CAT were significantly increased under red and blue light. The highest content of total flavonoids, total phenols, and 3,6'-disinapoyl sucrose under blue light. Different light qualities had no significant effect on the content of polygalaxanthone III. The biomass of plant height and the 3,6’-disinapoyl sucrose content were the highest under the light intensity of 300 μmol/(m2∙s). P. tenuifolia had the longest roots under the light intensity of 500 μmol/(m2∙s), and the content of MDA and the activities of POD, SOD, and CAT increased with the increase of light intensity. Conclusion Red light has the strongest promoting effect on the roots of P. tenuifolia. Red and blue light significantly increases the activity of POD, SOD, and CAT. Blue light promotes the accumulation of total flavonoids, total phenols, and 3,6’-disinapoyl sucrose. The light intensity of 500 μmol/(m2∙s) has the strongest promoting effect on the roots of P. tenuifolia, and the activities of POD, SOD, and CAT in leaves were higher. Different light qualities had no significant effect on the contents of total flavonoids, total phenols, and polygalaxanthone III. The light intensity of 300 μmol/(m2∙s) promotes the accumulation of 3,6’-disinapoyl sucrose.