Exogenous application of plant growth regulators increased the total flavonoid content in Taraxacum officinale Wigg

The effects of plant growth regulators (PGRs) were studied on growth, total flavonoid, gibberellins (GA) and salicylic acid (SA) contents of Taraxacum officinale (dandelion), a widely used medicinal plant in Korea. All the four PGRs used; gibberellic acid (GA₃), kinetin (Kn), salicylic acid (SA) and ethephon (2-chloroethylphosphonic acid) were applied at the rates of 0.5 and 1.0 mM. GA₃ markedly enhanced fresh shoot weight, while 0.5 mM of kinetin application significantly enhanced dry root mass as compared to control. SA enhanced both shoot and root attributes, while ethephon decreased plant growth. Endogenous bioactive GA₁ and GA₄ content and SA content enhanced with the application of GA₃, SA and kinetin, but declined with ethephon. The flavonoid content of dandelion significantly increased with SA treatment, but was not altered with the application of other PGRs. The current study demonstrated the favorable effect of GA₃, kinetin and SA on growth, bioactive GAs, SA and flavonoid contents of dandelion. These investigations offered interesting information as PGRs were never tested for plant growth and development of dandelion. It also reports the presence of both early C-13 hydroxylation and non C-13 hydroxylation pathways of GA biosynthesis in dandelion for the first time.