The effect of photo-irradiation on the growth and ingredient composition of young green barley ( Hordeum vulgare)

Abstract

We clarified that photo-irradiation of young green barley from three different light sources, natural light, 100% red light-emitting diodes (R-LEDs), and a mixture of 90% red-LEDs + 10% blue-LEDs (RB-LEDs), had significantly different results in growth degree (weight and height) and in components of young green barley. Barley that has sprouted for 15 days after germination did not show any apparent difference in height in response to irradiation by the three tested light sources, but by the 20th day of sprouting the height showed a positive effect by R-LEDs irradiation. By 15 days of sprouting the barley had achieved the heaviest weight by natural light irradiation, while the barley irradiated by R-LEDs had made remarkable progress at 20 days of sprouting. On the other hand, the irradiation by RB-LEDs showed a suppressive tendency after 15 days or more. The amino acid content, as indicated by dry weight conversion, was greatest in the barley irradiated by RB-LEDs, followed by R-LEDs, and natural light, which showed that LEDs irradiation is effective. In addition, four cyanogenic glucosides were isolated, identified, and quantified, as they are components frequently assessed in barley research. With regard to vitamin E, R-LEDs irradiation increased γ-tocopherol. Our results indicate that irradiation by LEDs would be effective for the enhancement of the functionality of young green barley.