EFFECTS OF LIGHT INTENSITY AND POTASSIUM CHLORATE ON PHOTOSYNTHESIS AND FLOWERING IN 'DO' LONGAN

This study was conducted to investigate the effects of light intensity and potassium chlorate (KClO₃) on photosynthesis and flower induction, when applied on leaves of two year old grafted 'Do' longan, grown in 20 L pots filled with soil during February-April 2002, at Lampang Agricultural Research and Training Center. The experimental design employed a 2 x 3 factorial in CRD with 4 replications. The first factors were the levels of shading; 0 and 50%. The second factors were the soil-drench KClO₃ application, foliar spray KClO₃ application and untreated. The results showed that there was no difference in the change of the efficiency of photosystem II (Fv/Fm). The non-shading longan trees gave higher net CO₂ assimilation rate, transpiration rate and stomata conductance rate than the 50%-shading longan trees. The non-shaded longan trees conferred the least time of terminal bud break and the longan trees treated with soil-drench KClO₃ and foliar spray KClO₃ provided flowering while the untreated longan trees gave shoot growth instead. However, there was no interaction between the two factors studied.