Judul: Potensi Seduhan Vermikompos untuk Pengendalian Penyakit Karat Daun (Puccinia arachidis Speg.) pada Tanaman Kacang Tanah (Arachis hypogaea L.)
Abstrak: One of important disease in groundnuts is leaf rust disease that caused by P. arachidis Speg. The effectiveness of vermicompost tea derived from worm castings was tested against the rust in groundnut leaf. The objective of this research was investigating the potency of vermicompost tea as controlling agent against the rust in groundnut leaf. The test was performed to observe (1) possibility of phytotoxin action in vermicompost tea against the plants, (2) effect of vermicompost tea in germination of P. arachidis uredospores in vitro, (3) ability of vermicompost tea to suppress growth of the rust disease in vivo. Vermicompost tea was tested in two preparations including aerated vermicompost tea and non-aerated vermicompost tea at concentrations 12.5, 25, 50, 75, and 100% respectively. This concentrations were applied both in germination test and the rust growth test. Results showed that aerated vermicompost tea and nonaerated vermicompost tea are not phytotoxin to the tested groundnuts and able to suppress uredospores germination and the rust growth by P. arachidis.
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Judul: Potensi Kitosan dan Agens Antagonis dalam Pengendalian Penyakit Karat (Phakopsora pachyrhizi Syd.) Kedelai
Abstrak: The soybean rust disease (Phakopsora pachyrhizi Syd.) is the most important disease of soybean and may cause 90% yield loss. The ability to spread rapidly, present of alternative hosts, and the rapid changes of P.pachyrhizi virulence are the causal of the difficulty to control the disease. This study is to evaluate potential uses of chitosan, Trichoderma harzianum, Bacillus subtilis, and chitosan-Streptomyces sp. combination to control the rust disease in two soybean lines. The experiments were conducted using a complete randomized factorial design (4x2) with three replications. Plant developments, disease incidence and severity of rust infection were observed. The studies have shown that all treatments have significantly suppressed soybean rust disease incidence and severity in both soybean lines compared to that of control. The use of T.harzianum has found the most effective and efficient in suppressing disease severity and in increasing plant vegetative growth with no phytotoxic effect.
Keyword: T.harzianum., Streptomyces sp, rust disease, chitosan, B.subtilis

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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