Judul: Potensi Kitosan, Khamir, Aktinomiset dan Kombinasinya dalam Menghambat Busuk Antraknosa (Colletotrichum gloeosporioides (Penz.) Sacc.) Buah Jambu Kristal
Abstrak: Anthracnose due to C. gloeosporioides is one of important disease on crystal guava during storage. Biological control using chitosan, yeast, actinomycetes and their combination are a promising alternative to control postharvest diseases of fruits. The study has been designed to evaluate the potencial of chitosan, yeast, actinomycetes and their combination in suppressing crystal guava anthracnose. In vitro evaluated has been done by poisoning tests methods and in vivo evaluated has been done by coating a solution of chitosan, suspension of yeast, suspension of actinomycetes and their combination on the crystal guava. The result of in vitro test showed that suspension of YP, APS5, and their combination are more effective in suppressing C. gloeosporioides than experiments with using metabolit only. The result of in vivo test with inoculation pathogen showed that severity disease of YP+APS5sus, YPsus, CT, APS5sus, CT+APS5sus, and CT+YPsus are smaller or significantly different with control. The coating of solution CT, suspension of APS5 and CT+APS5 on crystal guava are most effective to maintained fruits rigidity and extending the shelf life of crystal guava.
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Judul: Keefektifan Kitosan dan Aktinomiset dalam Pencegahan Busuk Antraknosa (Colletotrichum capsici (Syd.) Butler & Bisby) Buah Cabai Merah
Abstrak: Anthracnose due to Colletotrichum capsici is one disease that can decrease the quantity and quality of chillies production in Indonesia. Chitosan and actinomycetes are now widely used in controlling various plant diseases. The objectives of this research have been designed to evaluate the effectiveness of chitosan and two isolates of actinomycetes in preventing anthracnose on red chilli. In vitro test was conducted through baiting poisonous methods, while in vivo test has been done by solution coating of chitosan, isolate actinomycetes of APS5 and APS12, and their combination on the red chilli. The experiment had been done in a completely randomized design with 4 replications. The variables observed were the diameter growth of fungal colonies C. capsici, relative prevention growth, disease severity, and the rigidity of red chilli. The results of in vitro experiment showed that the concentration suspension of APS12, APS5, and APS512 (10%) were effective in suppressing the growth of C. capsici with 57%-72% of relative prevention growth. In vivo experiment showed that the coating of 1% CT, CTAPS5, CTAPS12 could reduce disease severity of C. capsici and lengthen the shelf life of red chilli until 10 days.
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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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