Noree Ismaal and Sayan Sdoodee

pp. 691 - 700

Abstract

Ways of alleviating the incidence of alternate bearing in longkong by flowering induction using a
chemical method (paclobutrazol ) were investigated at an experimental plot of the Department of Plant
Science, Faculty of Natural Resources, Prince of Songkla University, Hat Yai campus, Songkhla Province
between December, 2001 and November, 2002. Twelve 10-year-old longkong trees grown in the experimental
plot were used. The experiment was arranged as a completely randomized design in 4 treatments with 3
replications. The treatments were 1) control, 2) 1 g pt^-1 of paclobutrazol application 3) 2 g pt^-1 of paclobutrazol
application and 4) 4 g pt^-1 of paclobutrazol application. It was found that all paclobutrazol applications
decreased plant water use, physiological responses (leaf water potential, stomatal conductance and chlorophyll
fluorescences) and leaf nitrogen content, compared with the control. Paclobutrazol application increased
flowering, fruit setting and fruit qualities. Paclobutrazol application of 4 g pt^-1 gave a higher number of floral
buds/plant than the other treatments. Paclobutrazol application of 1 g pt^-1 gave higher fruit/cluster and fruit
weight/cluster than the other treatments. Paclobutrazol application significantly increased total soluble solids,
but there was no effect on titratable acidity. It was also noted that the paclobutrazol application increased
peel thickness.