Judul: Pelapisan Benih menggunakan Bakteri Probiotik untuk Mempertahankan Viabilitas Benih Jagung Manis (Zea mays saccharata Sturt.) selama Penyimpanan
Abstrak: This research aims to evaluate the effect of seed coating by Bacillus subtilis, Serratia marcescens, and Fluorescent Pseudomonads to sweet corn seed (Zea mays saccharata Sturt.) during storage. Research was conducted on nested plot design (Nested Design) with the main plot was the storage period ( 0, 3, 6, 9, 12, 15, 18, 21, and 24 week), and the subplot was the coating treatment ( control, Bacillus subtilis, Serratia marcescens, and Fluorescent Pseudomonads). Interaction of seed coating treatment and seed storage period showed significant effect to seed germination, seed vigour index, dry weight normal seedling, seed moisture content, and population of bacteria. The dry weight normal seedling of seed that was coated by bacteria showed the better dry weight normal seedling result than control seeds. Bacillus subtilis can maintain the seed germination up to 64.0%. Serratia marcescens can maintain the seed germination up to 60.0%, while control seed only have 56.7% seed germination. Based on seed germination result seed coating using Bacillus subtilis and Serratia marcescens are the treatment that more potential to be developed. Bacillus subtilis bacteria showed the best ability to survive until 24 week storage period. The population on Bacillus subtilis until 24 week storage period is 14.2 × 104 cfu g-1.
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Judul: Aplikasi Bakteri dalam Perlakuan Seed Coating untuk Mempertahankan Viabilitas dari Benih Cabai (Capsicum annuum L.) yang Sehat
Abstrak: This research was conducted to study the effect of seed coating using Bacillus subtilis, Pseudomonas group fluorescens and Serratia marcescens toward the viability of undiseased chilli seed (Capsicum annuum L.) during storage. This study used nested design with three replications. The main plot is storage period (0, 3, 6, 9, 12, 15, 18, 21 and 24 weeks) and the subplot is seed coating treatment with bacteria (Bacillus subtilis, Pseudomonas group fluorescens, Serratia marcescens and control). Chilli seed IPB C5 still have a good viability until 24 weeks, showed from the percentage of germination that is 77.3%. Control and coating used bacteria treatment showed unsignificant difference on germination, vigour index, growth rate and normal seedling dry weight. The bacteria as coater were still alive until 24 weeks of storage periode with population 5.89 x 104 cfu g-1 for Pseudomonas group fluorescens, 4.79 x 104 cfu g-1 for Bacillus subtilis and 1.70 x 104 cfu g-1 for Serratia marcescens.
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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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