The effects of paclobutrazol application on physiological responses, flowering and fruit qualities of longkong (Aglaia dookkoo Griff.)

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