Kadar Ekstraktif dan Sifat Warna Kayu Jati Plus Perhutani Umur 11 Tahun dari KPH Ngawi

Abstract

Pemanfaatan kayu jati dari pohon umur muda meningkat disebabkan adanya kesenjangan permintaan dengan ketersediaan kayu. Perhutani menanam pohon Jati Plus Perhutani (JPP) dengan karakteristik cepat tumbuh untuk meningkatkan produksi kayu jati. Pembiakan secara vegetatif ini diduga bisa berpengaruh terhadap sifat-sifat kayu. Kadar ekstraktif menjadi penting mengingat hubungannya dengan keawetan alami kayu dan sifat warna kayu. Penelitian ini bertujuan untuk mengetahui variasi kadar ekstraktif dan warna pada arah radial dan longitudinal kayu JPP. Sampel kayu diambil dari tiga pohon JPP berumur 11 tahun di KPH Ngawi. Faktor yang diamati terdiri dari arah longitudinal (pangkal, tengah, ujung); dan radial (gubal, teras terluar, teras terdalam). Kayu diekstrak secara berurutan dengan pelarut toluena, etanol, air panas pada alat soklet. Kadar fenolat total diuji dengan metode Folin-Ciocalteu untuk ekstrak toluena. Pengukuran sifat warna menggunakan sistem CIEL*a*b*. Hasil menunjukkan bagian pangkal memiliki kadar ekstrak terlarut etanol tertinggi, tetapi memiliki kadar fenolat total relatif rendah. Nilai kecerahan (L*) lebih tinggi di bagian ujung dibandingkan dengan bagian tengah dan pangkal sedangkan nilai kemerahan (a*) relatif tinggi di bagian pangkal. Secara nyata, ekstrak terlarut toluena, ekstrak terlarut etanol, dan kadar fenolat total di bagian gubal berbeda nyata dengan bagian teras dan terdapat perbedaan antara teras terluar dan teras terdalam pada kadar esktraktif terlarut toluena dan kadar ekstraktif terlarut etanol. Berdasarkan variasi radial, warna lebih gelap di bagian teras terluar dibandingkan bagian lainnya. Kadar ekstraktif terlarut air panas memiliki hubungan yang nyata (r = -0,72) dengan nilai L* di bagian gubal. Pada bagian teras, nilai L* memiliki hubungan negatif dengan kadar ekstrak terlarut etanol (r = -0,70), kadar ekstraktif terlarut air panas (r = -0,52), dan kadar ekstraktif total (r = -0,78). Secara nyata, nilai a* memiliki hubungan negatif (r = -0,58) dengan kadar fenolat total. Relatif rendahnya kadar ekstraktif dibandingkan umur dewasa serta tidak seragamnya sifat warna pada arah longitudinal perlu menjadi perhatian dalam pemanfaatan kayu JPP umur muda. Extractives Content and Colour Properties of 11-year-old Perhutani Superior Teakwood from Ngawi Forest Management UnitAbstractThe utilization of young teak wood had increased due to the gap in demand and the supply of raw materials. To meet the high demand, Perhutani had planted the fast growing of superior teakwood (Jati Plus Perhutani/JPP). This vegetative reproduction may affect the wood properties. Extractive content is important considering its relationship with the natural durability of wood and colour properties. The purpose of this study was to find out the effect of radial and longitudinal directions on extractives content and colour properties from JPP. The JPP wood samples (11 years) were located in Ngawi Forest Management Unit. The observed factors were vertical (bottom, center, top) and radial (sapwood, outer heartwood, inner heartwood) directions. Wood extracts were obtained by successive extraction (toluene, ethanol, and hot water) in a soxhlet. Total phenolic content was also determined by Folin-Ciocalteu method in toluene soluble extract. Colour properties were determined by CIEL*a*b* system. The result showed that vertical direction had significant effect as the bottom part showed the highest value in ethanol extract content but it had lower value in total phenolic content. Brightness (L*) value was comparatively high at the top part, while redness (a*) value was high at the bottom part. The levels of toluene, ethanol, and total extract content had a significant different between sapwood and heartwood as well as between outer heartwood and inner heartwood. Based on radial direction, the colour was darker in outer heartwood compared to the other parts. The correlation degree between the values of hot water extract and L* was significant (r = -0.72) in sapwood part. In heartwood, the correlation between ethanol, hot water, and total extract contentwith L* values were negative (r = -0.70; -0.52; -0.78, respectively). The correlation between a* value and total phenolic content was moderately significant (r = -0.58). The comparatively low content of extractive compared to mature woods as well as inhomogeneity of colour properties in vertical position should be noticed for young JPP wood utilization.