Floral induction in longan (Dimocarpus longan Lour.) trees by low temperature (LT) or potassium chlorate (KClO3) treatment, is supposed to act, at least partially, by their interference with the hormonal concentration and/or export out of leaves. Therefore the effect of LT and KClO3 on hormone concentration and transport rate of leaves was investigated in these experiments. Results of experiments below show that LT-, but not KClO3, treatment considerably increased the leaf export of N6 (Δ2-isopentenyl) adenine/N6 (Δ2-isopentenyl) adenosine (iP/iPA) together with indole acetic acid (IAA). Export rates of Zeatin/Zeatin riboside (Z/ZR) and gibberellins (GA) were very low and often below the detection limit (