Abstract:

The contents of the flavonoids and endogenous hormones of leaves in Ginkgo biloba phyllome branches were determined during all stages. The results indicated that the abscisic acid (ABA) content was low in the early stage, and got its lower peak in the early July, and rose quickly from the middle of Aug., and reached its highest value in the early Nov., which was consistent with the flavonoids content peak. Typical two-peak curve belonged to the change of ethylene (ETH) concentration, one rested in the early July, the other with a higher value in the late Sep. Cytokinin (CTKs) content was high in the early stage and fluctuated several times with different ranges in the middle-late stage. There was a significant relationship between CTKs and zeatin ribosides(Zrs). Gibberellin (GA) content was high in the early stage, and then went down gradually to reach its lowest value in the middle July, and lower value in the late Sep. apiece. 3-indole acetic acid (IAA) content fluctuated with a large scope, and showed three peaks during the growth and development of the leaves. Of these peaks, the first peak was the highest. It was very helpful for the improvement of the flavonoids synthesis to have higher ETH, ABA, and CTKs/IAA, and lower GA. When IAA/ABA, IAA/ETH, CTKs/ABA, CTKs/ETH, GA/ABA, GA/ETH, IAA/ABA, IAA/ETH, GA/ABA, GA/ETH values were the lowest, the peaks of flavonoids formation could be observed accordingly. The relationship between flavonoids and endogenous hormones in G. biloba leaf was discussed in this paper.

Key words: Ginkgo biloba, Leaf, Endogenous hormone, Flavonoids