Off-season Floral Inducting of Potassium and sodium chlorate in Longan Plantations

Abstract

The effect of potassium chlorate (KCIO3) and sodium chlorate (NaCIO3) application rates at 30, 45, 60 and 75 g/m of canopy diameter were studied on Longan (Dimocapus longan Lour.) cv. Daw in farmers’ orchards in Chiang Mai and Lamphun provinces during 2000-2002. The chemicals were treated at different times, as off-seasom in August and as early season in November to induce flowering of 6 and 15 years old Longan plantations. The studies revealed that both potassium chlorate andsodium chlorate had induced flowering of 6 and 15 years old longan cv. Daw in early and off season. Potassium chlorate at the rate of 75 g/m of canopy diameter induced the highiest flowering at 93.5% when the application was made in August is for 6 years old longan. When every rate was applied in November for 6 and 15 years old longan, the percentage of flowering was not different from each others. The application made in August with higher rates promoted length of panicles and number of fruits/panicle better than lower rates. The application in November for both 6 and 15 years longan, the length of panicle increased but number of fruit/panicle was almost the same. The other characteristics recorded were not different. Sodium chlorates applied in August for 6 and 15 years old longan did not affect the flowering percentage of both years except the second year, the percentage of flowering was up to 97.5 and 92.5 at the rate of application 60 and 75 g/m of canodiameter. All rates of application induced higher flowering than non-treated. There were no difference of size of fruit, thickness of percentage of aril, percent of fruit skin, Brix and juice of fruit from each rate for the application in and August and Novermber.