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) OR 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.