Influence of different LED lamps on the production of phenolic compounds in common and Tartary buckwheat sprouts

Lights are very important source of photosynthesis for plant growth and development. Blue and red lights among visible regions are the most useful for the photosynthesis. Recent advancements of light-emitting diodes (LEDs) technologies provide abundant opportunities to study the relationship between plant metabolites and different light sources. The objectives of this study were to evaluate the effects of various LEDs such as red (R), blue (B), red + blue (R + B) lamps on the levels of phenolic compounds such as chlorogenic acid, C-glycosylflavone (orientin, iso-orientin, vitexin, iso-vitexin), rutin and quercetin in seed sprouts of common and Tartary buckwheats at 9 and 12 days after sowing (DAS). Plant growth was significantly influenced at 12 DAS by LED lamps. Their values were higher under B LED light in common buckwheat sprouts, and R LED light in Tartary buckwheat sprouts. Phenolic compounds were significantly affected only at 9 DAS by R LED light in common buckwheat sprouts, but there is no effect on of Tartary buckwheat sprouts by different LED lamps. Total phenolic contents in common buckwheat sprouts were significantly differ, and as mean as follows [9 + 12 DAS] 36.02 > 34.12 > 33.12 mg g(-1) DW under R, RB and B LEDs, respectively; in contrast, there were no differences in mean values of Tartary buckwheat sprouts. In particular, rutin values in Tartary buckwheat sprouts were documented 82% (ca. 29 mg g(-1) DW) of the total phenolic compounds; but only 14% (5 mg g(-1) DW) in common buckwheat sprouts. These results indicated that the levels of phenolic compounds in common buckwheat sprouts tend to increase by the application of R LED at 9 DAS, but no differences in Tartary buckwheat sprouts. (C) 2014 Elsevier B.V. All rights reserved.