Induction of flowering in longan in the Mekong delta, Vietnam
In the Mekong delta, besides some local longan cultivars (Long, Giong, and Xuong Com Vang - XCV) which are able to flower naturally in the on season, the others, e.g., E-Daw and Tieu Da Bo TDB requires induction techniques to commence flowering. The common techniques used include branch girdling, collar drenching with KClO3, and the integration of the two mentioned methods. Floral induction techniques on longan varies depending on the season of cropping and cultivars. Leaf age at the time of application of chemical is also an important factor affecting longan flowering. The three cultivars, viz., Long, TDB and XCV, are usually induced for flowering when leaves turn to light green (35-40 days old); meanwhile, the suitable leaf age for floral induction on E-Daw is 40-45 days old. Long flowers naturally or manually via branch girdling (2-3 mm width). For XCV, flowering is induced by KClO3 collar drenching at the concentration of 24-36 g m‑1 canopy diameter (c.d.) combined with branch girdling (2-3 mm width), The same method with different KClO3 concentration (20-40 g m‑1 c.d.) and girdling width (0.5-1.0 mm) was applied on TDB. On the other hand, only collar drenching of KClO3 (40-60 g/g m‑1 c.d.) was found enough for flowering of E-Daw.
Hau, T.V. and Hieu, T.S. (2020). Induction of flowering in longan in the Mekong delta, Vietnam. Acta Hortic. 1293, 193-202
potassium chlorate, cincturing, 'E-Daw', leaf age