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: Pelapisan Benih dengan Bacillus subtilis AB89 dan Tokoferol untuk Mempertahankan Viabilitas Benih Padi Hibrida Selama Penyimpanan
Abstrak: This research aims to evaluate the effect of seed coating by Bacillus subtilis AB89 and Tocopherol on viability of hybrid rice seeds during storage. Experimental design is used a Nested Design randomized complete. The main plot is period of seed storage consisting of six standards are: P0 = 0 weeks, P1 = 3 weeks, 6 weeks = P2, P3 = 9 weeks, 12 weeks = P4, and P5 = 15 weeks with seed coating as a subplot consisting of three levels, namely: C0 = control (without coating), C1 = polymer + isolates Bacillus subtilis AB89, C2 = polymer tocopherol + 500 ppm . Seeds used in this research is hybrid rice varieties DG-1, SL-8, and Intani2. Seed moisture content fluctuated during storage, but the seed coating treatment showed a lower water content values than the control. The results showed that treatment of seed coating and without coating capable maintaining viability of hybrid rice seed varieties both DG-1, SL-8 and Intani 2 until 15 weeks period of seed storage . Coating by Bacillus subtilis AB89 on DG-1 varieties increased the speed of grown, cumulative germination percentage and dry weight normal seedling until 15 weeks period of seed storage. Coating by tocopherol 500 ppm on SL-8 varieties has the highest value of the maximum growth potential and increased the highest maximum growth potential on Intani 2 varieties.
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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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