The 2010 ASHS Annual Conference

One hundred miles of natural Rhododendron (Baili Rhododendron) in western Guizhou (China) attracted thousands of visitors during their spring flower season. To extend their flowering duration and bring more visitors to this natural wonder, growth regulators, GA₃, Ethephon, Daminozide, and 2,4-D, with various concentrations were sprayed on Rhododendron agastum Balf. et Smith (charming rhododendron) for one or five times since November. Plants received GA₃ at 200 and 400 mg·L^-1 flowered 10 and 14 days earlier, but no effect on the flowering duration. If sprayed GA₃ for five times, flower initiation were significantly earlier and flower duration was significantly extended. Ethephone did not have significant influence on the blossom. The combined applications of GA₃ and 2,4-D could promote the flowering duration for more than one week. The number of flowers increased as the GA₃ concentration went up and reached 140 flowers per plant at 400 mg/L. GA₃ promoted the growth and elongation of cells. To increase the number of flowers and extend the flowering period, GA3 could be sprayed five times on the natural communities of Rhododendron agastum from November. The applications should improve florescence and better promote Baili Rhododendron as one of the popular tour destinations in Guizhou, China.