Review Year around off season flower induction in longan (Dimocarpus longan, Lour.) trees by KClO 3 applications: potentials and problems P. Manochai a , P. Sruamsiri b , W. Wiriya-alongkorn a , D. Naphrom b , M. Hegele c , F. Bangerth c, * a Department of Horticulture, Maejo University, Chiang Mai, Thailand b Department of Horticulture, Chiang Mai University, Chiang Mai, Thailand c Institute of Special Crops and Crop Physiology, University of Hohenheim, 70593 Stuttgart, Germany Received 21 June 2004; received in revised form 5 October 2004; accepted 7 January 2005 Abstract Off season induction of flowering and fruit production is a desirable economical and scientific goal with many subtropical fruit trees. Both objectives have been accomplished by the application of gibberellin biosynthesis inhibitors with mango and a few other fruit trees. Recently the same was achieved with longan trees (Dimocarpus longan, Lour.) after treatment with potassium chlorate. This treatment allows the efficient induction of flowering and fruit production all over the year in an obviously species-specific manner. Experiments are described that investigated several aspects of this KClO 3 treatments, such as methods of application, seasonal effects, reactiveness of different cvs. toward the chemical, influence of leaf age, etc. The results are discussed with respect to the practical application of KClO 3 for off season fruit production, but also under the aspect of its use for more basic investigations into the endogenous regulation of the flowering induction process in perennial fruit trees. # 2005 Elsevier B.V. All rights reserved. Keywords: Flowering induction requirements; Potassium chlorate; Application method; Application time www.elsevier.com/locate/scihorti Scientia Horticulturae 104 (2005) 379–390 * Corresponding author. Tel.: +49 711 459 2354; fax: +49 711 459 2351. E-mail address: fkbang@uni-hohenheim.de (F. Bangerth). 0304-4238/$ – see front matter # 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.scienta.2005.01.004