ANALISIS POTENSI PRODUKSI BENIH, PENANGANAN DAN KARAKTERISTIK PERTUMBUHAN BIBIT KEPUH (Sterculia foetida Linn.) SEBAGAI SALAH SATU SUMBER BIOFUEL

Nurhasybi, Prof. Dr. Ir. Mohammad Na’iem, M.Agr.Sc.

2012 | Tesis | S2 Ilmu Kehutanan

Kepuh (Sterculia foetida Linn.) merupakan salah satu jenis potensial untuk dikembangkan sebagai sumber biofuel terbarukan, karena memiliki sebaran tumbuh yang luas, pertumbuhan yang cepat, dan kandungan minyak biji yang tinggi. Tujuan penelitian ini adalah untuk mengetahui potensi produksi benih, kandungan minyak benih, mendapatkan teknik penanganan benih, dan karakteristik pertumbuhan bibit kepuh. Pengunduhan buah kepuh dilaksanakan pada 6 (enam) daerah yaitu Kupang, Mataram, Bali, Tuban, Cirebon, dan Bogor. Berdasarkan karakteristik sebarannya, pendugaan potensi produksi benih dilakukan dengan pendekatan produksi benih per pohon. Morfologi buah dan benih dari setiap asal benih dikorelasikan dengan curah hujan dan ketinggian tempat tumbuhnya. Uji biokimia dan rendemen minyak dilakukan untuk setiap asal benih. Teknik penanganan benih yang dilakukan meliputi penentuan masak fisiologi, pengeringan, penyimpanan, dan teknik perkecambahan. Penentuan kriteria mutu bibit siap tanam didekati melalui karakteristik pertumbuhan bibit. Hasil penelitian menunjukkan morfologi buah dan benih kepuh berbeda nyata antar populasi, namun tidak berkolerasi nyata dengan curah hujan dan ketinggian tempat asal benih tersebut. Benih kepuh yang berasal dari daerah lebih kering (Bali dan Nusa Tenggara) dengan curah hujan lebih sedikit cenderung memiliki kadar minyak yang lebih tinggi. Potensi produksi benih kepuh berkorelasi positif dengan diameter, tinggi, dan lebar tajuk pohon. Model pendugaan potensi produksi benih adalah : Pb = -8733,311 + 195,602Tp + 13,339Dp + 673,658Lb, R² = 0,563, dimana : Pb = produksi benih (butir), Tp = tinggi pohon (m), Dp = diameter pohon (cm), dan Lb = lebar tajuk (m). Masak fisiologi benih kepuh dicirikan dengan warna kulit buah hijau kemerahan hingga merah dengan warna kulit benih coklat tua hingga hitam. Benih kepuh dapat dikategorikan sebagai benih intermediate. Benih dapat disimpan pada kadar air awal mendekati 10 % pada ruang DCS (dry cold storage), ruang AC dan ruang kamar selama 4 bulan. Perkecambahan benih dilakukan dengan cara merendam benih dalam H2SO4 pekat selama 10 menit dan dikecambahkan pada media campuran pasir dan cocopeat (1 : 1 v/v). Perakaran yang panjang dan indeks kekokohan bibit mendekati 7 berperan penting pada pertumbuhan bibit kepuh setelah ditanam di lapangan. Kriteria bibit kepuh siap tanam dapat dicirikan dengan tinggi lebih dari 40 cm dan diameter pangkal batang lebih dari 4 mm.

Kepuh (Sterculia foetida Linn.) is a potential tree species to be developed as renewable energy resource because of fast growing species that covers large area, its seed contains quite high oil that is considered to be appropriate for biodiesel raw material. The objective of this research is to find out the potential seed production, oil content in seed from several population, seed handling and growing seedling character. Seed collection and field survey on potential seed production was conducted in six areas including Kupang, Mataram, Bali, Tuban, Cirebon, dan Bogor. The prediction of potential seed production was approached by seed production in individual tree. Fruit and seed morphology from different areas was correlated with rainfall and altitude. Biochemical test and oil contain in seed was conducted in every location of seed collection. The seed handling including determination of seed maturation, seed drying, seed storage and seed germination. Criterion of seedling quality for planting was approached through seedling growth character. The results indicated that fruit and seed morphology was significantly different among seed sources but was not significantly correlated with rainfall and altitude of the seed collection areas. The seed sources in dry areas (Bali and Nusa Tenggara) tend to have higher oil content. Model of potential seed production was Pb = -8733,311 + 195,602Tp + 13,339Dp + 673,658Lb, R² = 0,563, remarks : Pb = seed production (grains), Tp = tree height (m), Dp = stem diameter (cm), and Lb = tree crown size (m). The physiological maturity of seed was determined by fruit color from green reddish to red and the seedcoat color from dark brown to black. Kepuh seed was cathegorized as intermediate seed. The seed can be dried until 10 % in moisture content and can be stored for 4 months in dry cold storage (DCS) room, Air Conditioned room and ambient room. Pre-treatment before seed sowing can be conducted by soaking the seed in concentrated H2SO4 for 10 minutes. The root length and seedling sturdiness quotient as much as 7 (seven) was an important factor of kepuh seedling for planting in the field. The best seedling criterion for planting was the initial height more than 40 cm and diameter more than 4 mm.

Kata Kunci : kepuh, kriteria bibit siap tanam, produksi benih, penanganan benih