Judul: Efektivitas Isolat Rhizobium Dalam Meningkatkan Pertumbuhan Semai Akasia (Acacia Crassicarpa A. Cunn. Ex Benth)
Abstrak: Dalam kurun waktu 20 tahun terakhir, HTI Pulp telah berkembang dengan pesat. Pada tahun 2002, HTI Pulp tercatat mempunyai luas sebesar 1.3 ha. Spesies-spesies tanaman HTI Pulp yang sering ditanam merupakan tanaman yang mampu tumbuh cepat seperti Acacia cracicarpa dan A. Mangium. Adapun salah satu faktor terpenting yang menentukan kesuksesan program HTI Pulp yaitu ketersediaan bibit akasia yang sehat. Oleh karena itu, penggunaan strain Rhizobium yang sesuai dan efektif merupakan faktor penting untuk menghasilkan bibit akasia yang sehat. Penggunaan inokulan Rhizobium tersebut dapat mengurangi biaya produksi pembibitan dan juga pencemaran lingkungan yang disebabkan oleh penggunaan pupuk N inorganik. Penelitian ini bertujuan untuk menyeleksi isolat Rhizobium yang efektif dalam meningkatkan pertumbuhan A. crassicarpa yaitu tinggi dan bobot kering tanaman. Disamping itu, penelitian ini juga bertujuan untuk mengetahui kadar dan serapan N, P dan K serta aktivitas nitrogenase. Penelitian ini dilakukan di Rumah Kaca, Laboratorium Biologi Tanah dan Laboratorium Kimia dan Kesuburan Tanah Departemen Ilmu Tanah dan Sumberdaya Lahan, Fakultas Pertanian, IPB. Digunakan tanah podsolik merah kuning (Ultisol) yang belum pernah diolah sebagai media pertumbuhan. Tanah tersebut berasal dari Stasiun Penelitian Hutan Haurbentes , Jasinga yang bersifat masam dengan tingkat kesuburan yang rendah. Salah satu tanah tersebut dilakukan sterilisasi dengan autoklaf dan juga pengapuran untuk menaikkan pH 6.5. Isolat Rhizobium yang digunakan dalam penelitian ini merupakan hasil isolasi bintil akar A. crassicarpa berumur 4 tahun yang tumbuh pada tanah gambut di kawasan HTI RAPP Pelalawan, Pangkalan Kerinci, Riau. Isolat tersebut yaitu Rh Ac-1; Rh Ac-2; Rh Ac-3; Rh Ac-4; Rh Ac-5; Rh Ac-6; Rh Ac-7; Rh Ac-8; Rh Ac-9 dan Rh Ac-10. Digunakan dua perlakuan blanko yaitu (1) tanpa inokulasi isolat Rhizobium dan tanpa pemupukan N inorganik, (2) tanpa inokulasi isolat Rhizobium tetapi dipupuk 45 ppm N inorganik. Jumlah perlakuan sebanyak 12 dengan 3 ulangan, sehingga total satuan percobaan sebanyak 60. Digunakan Rancangan Acak Lengkap (RAL) yang dilanjutkan dengan Analisys of Variances (ANOVA) dengan uji lanjut Duncan Multiple Range Test (DMRT) taraf 5%. Hasil penelitian menunjukkan bahwa diperoleh 3 isolat Rizobium dari 10 isolat yang diuji sangat nyata meningkatkan pertumbuhan A. crassicarpa (tinggi dan bobot kering tanaman) dan kadar N serta serapan N dan K. Ketiga isolat tersebut yaitu Rh Ac-1, Rh Ac-5 dan Rh Ac-4. Perlakuan isolat Rh Ac-1 menghasilkan Bobot Kering Akar 191% dan serapan K sebesar 136% terhadap Blanko. Disamping itu, perlakuan isolat Rh Ac-5 menghasilkan tinggi sebesar 56% dan Rh Ac-4 menghasilkan bobot kering tanaman bagian atas sebesar 84% terhadap Blanko. Pengaruh inokulasi isolat Rh Ac-1, Rh Ac-4 dan Rh Ac-5 terhadap pertumbuhan bibit A. crassicarpa setara dengan penggunaan pupuk 45 ppm N inorganik dan lebih baik dari pada yang tidak diinokulasi. Ketiga isolat tersebut mampu berkompetisi dengan Rhizobium indegenus.
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Judul: Penggunaan Rhizobium Dan Mikrob Pelarut Fosfat (MPF) Untuk Memperbaiki Pertumbuhan Bibit Akasia (Acacia mangium dan Acacia crassicarpa)
Abstrak: The increasing of paper raw material requirement is caused by the development of raw material. Therefore, it is needed a method to produce a high quality and quantity of paper. Acacia is one of paper raw material. To increase the growth of acacia seed, an effective usage of Rhizobium and Phosphate Solubilizing Microbe (pSM) seedling inoculant is one of strategies to produce good acacia seeds. The Rhizobium and Phosphate Solubilizing Microbe seedling inoculant can reduce anorganic fertilizer usage and increase the growth of acacia seed. The aims of this research were to select Rhizobium which has an ability to fix atmosphere N2 air and local Phosphate Solubilizing Microbe in dissolving phosphate, also to test the ability of those isolates in increasing the growth of acacia seedling. This research was conducted in the Soil Biotechnology Laboratory, Department of Soil and Land Resource Science, Faculty of Agriculture, Bogor Agricultural University and RAPP greenhouse (Pelalawan and Pangkalan Kerinci R&D Nursary) in Riau. Plant media is cocopit. The experiment consisted of 15 Rhizobium treatments isolated from peat soil, which was planted with A. crassicarpa, and mineral soil, which was planted with A. mangium; 16 Phosphate Solubilizing Microbe treatments taken from peat and mineral soil with 5 replications . The research resulted 2 Rhizobium isolates from IS tested isolates, which could increase the growth of A. crassicarpa effectively, those were Rh Ac S and POS-RIS, and 2 Phosphate Solubilizing Microbe from 16 tested isolates, those were BPF 4 and FPF S. While on A. mangium, there were 2 isolated out of 15 Rhizobium isolates which could increase the A. mangium growth effectively, those were M32-M33-R2N and M45-R2N; also 3 isolates out of 16 Phosphate Solubilizing Microbe, those were M32-BP3, FRK2, and M33-FP2. The characteristic of effectiveness could be seen from the plant height, the amount of leaves, the dry root wight, the dry plant weight, the diameter of bar and the root compactness; so that the usage of Rhizobium inokulan, Rh Ac 5 and P05-RIS equal to the usage of 0.1 kgll Monopotassiumphosphate fertilizer and better than control. Meanwhile the usage of MPF, BPF 4 and FPFS equal to the usage ofO.SI1 kg of Osmocote fertilizer and better than control.
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Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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