Enhancement of Growth Characteristics and Biological Activities in Astragalus membranaceus Using Artificial Light Sources

Abstract

We investigated the effects of light emitting plasma (LEP) and red, blue, green, and white light emitting diode (LED) artificial light sources on plant growth characteristics and antioxidant activities in Astragalus membranaceus B. The highest germination rate (91.33 ± 2.08%) was produced by growth under red LED light. Root growth under LEP light was superior to that under the other light treatments. We measured antioxidant activity using a 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, and determined the total phenol and flavonoid contents and tyrosinase inhibitory activity in response to the various light treatments. Antioxidant activities were 53.6% as the highest level of activity under LEP light. Growth under LEP light also produced the highest total phenolic and flavonoid contents of 36.05 and 5.94 mg/mL, respectively. Extracts from plants grown under LEP light caused the highest inhibition of tyrosinase activity with inhibition of 35.37, 61.87 and 65.49%, respectively, for extract concentrations of 100, 500, and 1000 μg/mL compared with other artificial light treatments. These results suggest that LEP light may be an important artificial light source for the enhancement of plant growth and biological activity and indicate the importance of further study of the use of LEP light sources for agricultural production.