Noree Ismaal and Sayan Sdoodee

pp. 455 - 466

Abstract

Flowering induction by physical methods of root pruning and limb strangulation to alleviate the
incidence of biennial fruit-bearing in longkong were investigated. The experiment was conducted at the
Department of Plant Science, Faculty of Natural Resources, Prince of Songkla University, Hat Yai, Songkhla
Province, from December, 2001 to November, 2002. In the root-pruning trial, twelve 6-year-old longkong
trees were used. Each tree was grown in 1 m³ soil volume. The experiment was arranged in a completely
randomized design having 4 treatments in 3 replications. The treatments were: (1) control, (2) cutting 1 side
30 cm from the stem at 30 cm depth, (3) cutting 1 side 20 cm from the stem at 30 cm depth, and (4) cutting
2 sides 30 cm from the stem at 30 cm depth. In the limb strangulation experiment, six 6-year-old longkong
trees were used. Again, each tree was grown in 1 m³ soil volume and the experiment was arranged in a completely randomized design. The treatments were: (1) control, (2) limb strangulation 2 months before bloom,
and (3) limb strangulation 1 month before bloom. All treatments were done on one plant with 6 replications
(one plant per replicate). The root-pruning methods decreased diurnal water use and a physiological response as compared with the control. All three root-pruning treatments induced flowering; however, only the
trees cut on 1 side, 30 cm from the stem at 30 cm depth, stimulated flower-bud elongation. Similarly, the
limb strangulation treatments resulted in decreased water use and physiological response as compared with
the control. Both limb strangulation methods induced flowering, but strangulation at 1 month before bloom
was more effective in the flower-bud development.