Struktur anatomi dan sifat fisika-mekanik kayu bitti (Vitex cofassus Reinw) dari hutan rakyat yang tumbuh di Kabupaten Bone dan Wajo Sulawesi Selatan

HAPID, Abdul, Dr. Ir. Sri Nugroho Marsoem, M.Agr

2010 | Tesis | S2 Ilmu Kehutanan

Kayu bitti merupakan salah satu jenis kayu bahan baku utama perahu pinisi. Namun informasi tentang kayu ini masih terbatas dan kayu bitti yang tersedia saat ini adalah kayu berdiameter kecil dari pohon muda. Oleh karena itu perlu dilihat bagaimana sifat dan karateristik. Tujuan dari penelitian ini adalah mengetahui sifat-sifat kayu bitti dari hutan rakyat yang tumbuh di Kabupaten Bone dan Wajo, Sulawesi Selatan. Rancangan yang digunakan adalah rancangan acak lengkap dalam faktorial, dengan faktor tempat tumbuh dan kedudukan radial. Hasil penelitian menunjukkan bahwa Interaksi perlakuan berpengaruh tidak nyata terhadap struktur anatomi dan sifat fisika-mekanika kayu bitti. Faktor tempat tumbuh berpengaruh nyata terhadap penyusutan tangensial dari kondisi segar ke kering tanur. Kedudukan radial berpengaruh nyata terhadap proporsi serabut, panjang serat, tebal dinding serat, berat jenis segar, kering udara dan kering tanur, penyusutan dari kondisi segar ke kering tanur, pengembangan radial dan longitudinal dari kondisi kering tanur ke basah, semua sifat mekanika kayu kecuali MOE. Kayu bitti memiliki Rerata proporsi pembuluh 11,17 – 17,88%, proporsi serabut 57,49 – 70,32%, proporsi jari-jari 10,74 – 19.30% dan proporsi parenkim 5,40 – 8,98%. Dimensi sel yaitu rerata panjang serat 0,86 – 1,44 mm, diameter serat 17,81 – 20,59 μm, diameter lumen 11,93 – 13,86 μm dan tebal dinding serat 2,61 – 4,02 μm. Rerata kadar air segar dan kering udara adalah 59,32 – 110,22% dan 9,66 – 20,82%. Berat jenis segar, kering udara dan kering tanur adalah 0,44 – 0,70, 0,48 – 0,75 dan 0,50 – 0,80. Penyusutan radial, tangensial, longitudinal dan nilai T/R penyusutan dari kondisi segar ke kering tanur secara berurutan 3,64 – 7,44%, 1,79 – 4,32%, 0,18 – 0,49% dan rasio T/R 1,42 – 2,03. Pengembangan radial, tangensial, longitudinal dan nilai rasio T/R pengembangan dari kondisi kering tanur ke kondisi basah berurutan 3,673 – 4,374%, 1,155 – 3,179%, 0,238 – 0,493% dan 1,32 – 3,26. Keteguhan lengkung statik sampai batas proporsi (BP), MOE dan MOR secara berurutan 460,37 – 803,17 kg/cm2, 67,75 – 97,22 (x103 kg/cm2) dan 634,13 – 1046,39 kg/cm2. Keteguhan tekan sejajar serat sampai batas maksimum dan keteguhan tekan tegaklurus serat sampai batas maksimum adalah 331,59 – 529,95 kg/cm2 dan 62,51 – 136,84 kg/cm2. Periode juvenil kayu bitti diperkirakaan berakhir pada bagian 10 cm dari hati.

Bitti Wood is one of the wood species for the main raw material of pinisi boat. However, the information about this wood is limited and bitti wood availablity is in small diameter which is came from young trees. Therefore it is necessary to determine the characteristics and properties of bitti wood. This research had the objectives to find out the anatomical structure and physical-mechanical properties of bitti wood from community forests. The plantation were at Bone and Wajo Distric South Sulawesi. This study applied factorial experiment in completely randomized design. Factors of this research were site and radial position. The results showed that the interaction between the site and radial position had no significant effect to anatomical structure and physical-mechanical properties of bitti wood. Site factor had an effect only on tangential shrinkage of the wood from green to oven-dry condition. Radial position had an effect on proportion of fibers, fiber length, cell-wall thickness, specific gravity (green, airdry and oven-dry condition), shrinkage of the wood from green to oven-dry, swelling (radial and longitudinal) of the wood from oven-dry to wet condition and mechanical properties of bitti wood, except MOE. The bitti wood had an average proportion of vessels 11.17 – 17.88%, fibers of 57.49 – 70.32%, rays of 10.74 – 19.30% and parenchyma of 5.40 – 8.98%. The results of cell dimension measurement were average fiber length of 0.86 – 1.44 mm, fiber diameter of 17.81 – 20.59 μm, lumen diameter of 11.93 – 13.86 μm and cell-wall thickness of 2.61 – 4.02 μm. The average of green and air-dry moisture content were 59.32 – 110.22% and 9.66 – 20.82% respectively. Specific gravity in green, air-dry and oven-dry condition were 0.48 – 0.70, 0.48 – 0.75 and 0.50 – 0.80 respectively. The shrinkage on radial, tangential, longitudinal of the wood from green to ovendry condition were 3.64 – 7.44%, 1.79 – 4.32%, 0.18 – 0.49% and T/R ratio was 1.42 – 2.03. Swelling on radial, tangential and longitudinal of the wood from oven-dry to wet condition were 3.673 – 4.374%, 0,342% respectively and T/R ratio was 1.32 – 3.26. Static bending strength to proportional limit, MOE and MOR were 460.37 – 803.17 kg/cm2, 67.75 – 97.22 (x103 kg/cm2), 634,13 – 1046,39 kg/cm2 respectively. The compression parallel to grain to maximum and compression perpendicular to grain to maximum were 331.59 – 529.95 kg/cm2 and 62.51 – 136.84 kg/cm2. The juvevile wood periode was estimated at 10 cm from pith.

Kata Kunci : Perahu pinisi,Vitex cofassus Reinw,Struktur anatomi,Sifat fisika,mekanika