Abstract. Putro GS, Marsoem SN, Sulistyo J, Hardiwinoto S. 2020. The growth of three teak (Tectona grandis) clones and its effect on wood properties. Biodiversitas 21: 2814-2820. Various clones of superior teak (Tectona grandis L. f.) trees have recently been introduced in several land conditions. A study was conducted on three different clones of superior teak known as Jati Unggul Nusantara (JUN) growing in Paliyan, Gunungkidul, Yogyakarta, Indonesia. Two different ages of those clones were observed their growth rate and its wood properties. Strip plot design was applied to the treatment of tree age (five and eight-year-old) and clone types (D14, F35, and F21 clones). Tree growth was measured on 300 trees, meanwhile, annual growth rate and wood properties were measured on 18 trees. The result showed that at five-year-old as well as eight-year-old, the D14 clone has the best growth performance with diameter of 14.6 ± 1.80 cm and 20.5 ± 2.54 cm and height of 9.8 ± 1.72 m and 15.2 ± 2.13 m respectively. The growth rate negatively correlated with temperature and had no significant correlation to the precipitation. Different clones and tree age significantly affect the variability of fiber length, green specific gravity, and heartwood proportion. The clone of D14 produced the highest-fiber length, green specific gravity, and heartwood proportion (1.111mm; 0.50 and17.7%) at five-year-old trees and (1.156 mm; 0.54 and 49.0%) at eight-years-old.

Increasing the growth rate of teak trees is carried out to shorten the tree harvest rotation and reduce the deficit of teak timber supply, while maintaining the superiority of wood properties. The study was conducted to study the nature offive-year-oldJUNTeak wood in three classes of tree diameter and radial position of the trunk.This study employed a completely randomized design arranged in factorial combinations of the treatments of radial positions and diameter classes consisting of large (18-22 cm), medium (14-18 cm) and small (10-14 cm) stem diameters, andthe radial position of wood on the trunk based on the tree's ring. Three samplesof trees werefelled for each stem diameter classso that totally nine trees were used in this study. The testing of the physical properties of wood and the measurement of fiber dimensions were conducted using British Standards 373 and the IAWA method, respectively. The results showed that the diameter of the tree and the radial position of the wood had a significant effect on all parameters observed (fiber dimension and physical properties of wood), except the fiber diameter. The tree growth rate had a negative correlation with fiber length (-0.67), fiber wall thickness (-0.65), air-dry moisture content (-0.91) and air dry specific gravity (-0.86), and had a positive correlation with fiber diameter (0.61) and greenwater content (0.78). According to the pattern of wood properties in the radial direction, JUN wood harvested at the age of five was categorized as juvenile wood.This wood is acceptable as furniture and lightweight construction material.