Prasith Hadloh and Sayan Sdoodee

pp. 615 - 625

Abstract

A pruning trial was established to investigate the effect of canopy manipulation on growth and yield of mangosteen under field conditions at The-Pha research station, Songkhla province. Forty 7-year-old
mangosteen trees were used and the study designed as randomized complete blocks with 4 treatments in 10 replicates. The treatments were as follows: 1. control or no-pruning (T1), 2. cutting upper one along one side
of each tier of branches along the main stem (T2), 3. cutting one tier of branches with the upper tier along the main stem remaining (T3) and 4. top-cutting at 3-meter plant height (T4). It was found that 1 year after
pruning, the trees in T2 exhibited highest relative plant height and longest branch length after pruning (6.63 m /4 month and 35.31 cm /4 month, respectively). First-year bearing was found only in T1 and T4, and the
fruit yields in T1 and T4 were (3.13 and 2.31 kg/tree, respectively). It was remarkable that light transmission through plant canopy in T4 gave the highest photosynthetically active radiation PAR (48.55%), but T1 the
lowest PAR (2.46%). Thus, the plant growth in T4 was greater than in T1, and the mangosteen trees in T4 also exhibited high root proliferation. From the result, it is suggested that canopy manipulation of T4 is an appropriate method.