Evaluasi Kualitas Pertumbuhan dan Karakteristik Kayu Jati (Tectona grandis L. f.) Unggul Nusantara Umur 4 Tahun

Abstract

INTRODUCTION. The lack of better quality of wood supply recently has resulted in the barrier of wood industry development in Indonesia. To overcome the above problem many community forests had been establishing by people using selected wood species. One of them is Jati (Tectona grandis) Unggul Nusantara (JUN) plantation belongs to Koperasi Perumahan Wanabakti Nusantara (KPWN) with teak as the main species. These stands were planted using tree spacing of 3 m by 3 m for the rotation of 5 years. To ensure these woods qualities were similar to those of the conventional teak, growth quality and wood properties have to be studied well. The aim of the study was to evaluate growth quality and wood characteristics of 4 year-old JUN by measuring the diameter and height of the trees and by studying wood physic properties and fiber morphology. MATERIALS AND METHOD. The main material used was increment core of 4 year-old of JUN extracted from the stem from the nine selected trees representing the diameter of the stands (small, medium and big) at dbh level using increment borer (ø 5 mm). From each sample tree, 2 pieces of increment core were extracted oppositely: one for wood physical measurement (moisture content at green condition/green MC, wood density and specific gravity/SG); and the other for fiber morphology measurement (fiber length and cell wall thickness). Both of them were measured radially (from pith to the bark). All measurements were carried out using procedural standard of Faculty of Forestry IPB. Demarcation between juvenile- and mature wood portions was evaluated using fiber length and wood density from pith to the bark. Effect of stem diameter and growth ring number was evaluated using t-student at the 95% confidence interval. Data processing was conducted with SPSS 13. RESULT AND DISCUSSIONS. It showed that growth quality of JUN was varied. Average value of diameter and height was 13.45 cm and 6.92 m, respectively. Growth rate of diameter and height was fast. They are around 3.36 cm and 1.73 m per year, respectively. It also showed that green MC, density, SG, fiber length and cell wall thickness of each group were varied. Average value of green MC was 112.27% (small tree), 127.53% (medium) and 146.35% (big); wood density was 0.99 g/cm3 (small), 1.02 g/cm3 (medium) and 1.09 g/cm3 (big); SG was 0.47 (small), 0.45 (medium) and 0.45 (big); fiber length was 741.15 μm (small), 845.52 μm (medium) and 833.30 μm (big), while wall thickness was 3.06 μm (small), 3.20 μm (medium) and 3.17 μm (big). Statistical analysis showed that green MC and wood density are influenced by diameter, while SG, fiber length and cell wall thickness are not. The bigger the diameter, the greater the green MC and the wood density. Based on its SG, the wood of JUN was classified into Strength Class of III. The result also showed that growth ring has no effect on the all parameters studied, except in case of SG on medium tree group and fiber length on small tree group. Generally, SG and fiber length tended to increase from pith to the bark. The border between juvenile- and mature wood could not determine yet since the average value of wood density and fiber length was tended to increase radially. It indicates that the JUN studied has no mature wood portion yet.