Article info.

ABSTRACT

Received 20 Mar 2018
Revised 08 Jun 2018

Accepted 29 Mar 2019

This review was aimed to focus on the management techniques relating to flowering and fruit setting phenology of longan (Dimocarpus longan L.) and rambutan (Nephelium lappaceum L.). For longan, there are three common cultivars grown in the Mekong Delta, namely, ‘Tieu Da Bo’, ’Xuong Com Vang’ and ‘E-daw’ (originated from Thailand). Their characteristics of flowering and fruit development are relatively different. The crop season of ‘Tieu Da Bo’ cultivar, from floral induction to harvesting, occurs within only 7.5-8.0 months, since the trees only need two leaf flushes before being able to be induced for flowering. As for the ‘Xuong Com Vang’ cultivar, three leaf flushes should be completed prior to the floral induction. Fruit development of ‘E-daw’ cultivar is relatively long, within 4.0-4.5 months. Therefore, the crop season of ‘Xuong Com Vang’ and ‘E-daw’ usually extends to almost 12 months. The most common flowering induction technique applied on longan is collar drenching of KClO₃ alone (‘E-daw’) or in combination with branch girdling (‘Tieu Da Bo’ and ‘Xuong Com Vang’). KClO₃ doses and time of application vary depending on the cultivar treated and crop season. For rambutan, the three popular cultivars grown in the Mekong Delta include ‘Rongrien’ (originated from Thailand), ‘Nhan’, and ‘Java’. The latter is recently the most popular cultivar, and its crop season duration is about 9.5-10 months. The duration from fruit set to harvest is 14-16 weeks. Off-season floral induction on rambutan is implemented via the drainage of irrigation ditch combined with plastic mulching covering the growing bed. Another method is to spray Paclobutrazol onto the canopy when color of the third leaf flush is light green (50-60 day-old). To improve fruit set, foliar application of 1-Naphthaleneacetic acid (NAA) is recommended. The chemical, 30 ppm, can be sprayed to a few inflorescences possessing about 30% of blooming flower. In addition, immature fruit drop can also be reduced by the foliar application of NAA 20 – 40 ppm when fruit sized is 4-5 cm approximately.

Keywords

‘E-daw’, floral induction, fruit set, ‘Java’, ‘Rongrien’, ‘Tieu Da Bo’, ‘Xuong Com Vang’

Cited as: Hau, T.V. and Hieu, T.S., 2019. Longan and rambutan in the Mekong Delta, Vietnam: A review of technologies to improve flowering and fruit setting. Can Tho University Journal of Science. 11(1): 7-23.