Photocontrol of anthocyanin formation in turnip seedlings : VIII. Wave-length dependence.

When irradiated for a period of 48 hours with light of restricted wave-lengths in the red and far-red regions, maximum anthocyanin content in hypocotyls was found at 730 nm; in cotyledons the yield at 716 was almost equal to that at 730 nm.In hypocotyls the effectiveness of 703, 716 and 760 nm light was much increased if plants were transferred to red light after 6 hours. The intermediate wave-length band centred at 703 nm was ineffective when given alone but led to a high yield if followed by red light. When given before far-red light (standard far-red field), 6 hours at 703 nm reduced anthocyanin yield in the same way as red light; when given after 6 hours of far-red, however, 703 nm light did not act like red light to sustain a high rate of anthocyanin synthesis.It is concluded that two reactions are involved in the photocontrol of anthocyanin formation in turnip seedlings.