Judul: Potensi Bakteri Rhizosfer sebagai Pupuk Hayati pada Persemaian Tanaman Sengon (Paraserianthes falcataria).
Abstrak: Biological fertilizer is one of alternative fertilizer from nitrogen fixing bacteria for albizia. The aim of this research was to utilize rhizosfer bacteria from forest soil as biological fertilizer for albizia nursery (Paraserianthes falcataria). Growing media for albizia seedling was polybag filled of acid soil from Jasinga (Ultisol type) with pH 4.7 and peat with ratio 2:1. Rhizosfer bacteria used in the study was Burkholderia cepacia with isolate codes L6.5 and L10.1. Streak quadrant results showed rhizosfer bacteria had coccus form, was not absorb pink color, and had convex elevation. Rhizosfer bacteria isolate L6.5 and L10.1 that were added with ½ N from NPK fertilizer for albizia nursery showed similar influence with fertilization using NPK dosage as recommended. NPK fertilizer with ½ N dosage that was added to rhizosfer bacteria showed influences at root length, lateral root amount, crown length, wet weight, dry weight, and nodule amount compared with control.
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Judul: Penggunaan Rhizobium dan bakteri pelarut fosfat pada tanah mineral masam untuk memperbaiki pertumbuhan bibit sengon (Paraserianthes falcataria (L.) Nielsen)
Abstrak: The main problem of acid soil is the availability of nutrients and high exchangeable A1 content. Soil acidity will reduce many legum plant growth, decrease number of rhizobia and nodule initiation and inhibit the function and growth of ndule. Based on these problems, the experiment was cmducted to obtain the acid and A1 tolerant strain of Rhizobium isolated from sengon nodules, and to obtain the effective strain of Rhizobium in fixing atmospheric nitrogen, and phosphate solubilizing bacteria in increasing P availability, thus support plant growth. The study was focused on three aspects: ( I ) Research on Rhizobim consist of (a) collection of Ahitobiurn strains from sengon nodules, (b) screening Rhizobium toward acidity and high concentration of Al, (c) screening Rhizobium based on their ability to fix nitrogen, (d) marking the selected Rhizobim with antibiotic, and screening the resistant mutants, (e) assesing the effectiveness of the selected Rhizobim on acid soil in greenhouse; (2) Research on phosphate solubilizing bacteria, consist of (a) isolation of phosphate solubilizing bacteria, (b) selection of phosphate solubilizing bacteria in dissolving P from rock phosphate and Alms in liquid medium and acid soil, (c) identification of selected phosphate solubilizing bacteria, (d) determination of organic acid produced by selective phosphate solubilizing bacteria, (e) assessing the effectiveness of selected phosphate solubilizing bacteria in greenhouse; (3) winmulation between Rhizobim and phosphate solubilizing bactetia in greenhouse and field experiments., Permasalahan yang utama dari tanah masam adalah cadangan unsur hara kesuburan tanah yang rendah, kandungan Al dapat ditukar tinggi, dan mempunyai kapasitas retensi P yang tinggi. Kemasaman tanah pada tanaman leguminosa akan menyebabkan terganggunya pertumbuhan tanaman, jumlah rhizobia dan pembentukan bintil akar berkurang serta terhambatnya fungsi dan perkembangan bintil.
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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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