Effects of Light Quality on Growth and Accumulation of Flavonoids Compounds of Ginkgo biloba Seedlings

Purpose To explore the effects of red and blue light on the growth and flavonoids accumulation of Ginkgo biloba seedlings.

Methods Three kinds of light quality, including red light, blue light, red+blue mixed light, and white light (CK) used as a control, were set with the 1-year old G. biloba seedlings as material. Flavonoid content, flavonoid yield per plant, enzymes related to flavonoid synthesis, and total flavonoid reducing capacity of G. biloba seedling were measured at the 3rd, 6th, 9th and 12th week of treatment, and the growth indexes were measured at the 12th week.

Results Under light quality treatment, total biomass of G. biloba seedlings was lower than CK, seedling height increased significantly under blue light treatment, and the ground diameter was less affected by light quality. Among the enzymes related to flavonoid synthesis, the activities of phenylalnine ammonialyase (PAL) and cinnamic acie 4-hydroxylase (C4H) were increased under red+blue mixed light and blue light treatment, while the activity of 4-coumaric acid coA ligase (4CL) was only increased under red light treatment. The content of flavonoids (quercetin, kaempferol, isorhamnetin, total flavonoid), flavonoid yield per plant, and total flavonoid extract reducing capacity were extremely significantly affected by light quality, and the flavonoid yield and total reducing capacity of flavonoid extract were showed that blue light and red+blue mixed light treatments were higher than CK and red light treatments, that is, blue light and red+blue mixed light were beneficial to the accumulation of flavonoid and the improvement of antioxidant capacity. With the extension of treatment time, the change trend of flavonoids in the early stage (3-6 weeks) was higher than that in the late stage (9-12 weeks), and the maximum value generally appeared in the 6th week.

Conclusion Red+blue mixed light and blue light treatments promote the accumulation of flavonoids and related enzymes activities of G. biloba seedlings, while red light treatment is on the contrary. The light quality treatment time of G. biloba for leaves is suitable for six weeks.