Judul: Keefektifan Fungi Mikoriza Arbuskular dan Gliocladium fimbriatum dalam Mencegah Busuk Pangkal Batang (Botryodiplodia theobromae) pada Jeruk
Abstrak: Nowaday, in Indonesia, stem rot (Botryodiplodia theobromae) is the most important disease on citrus which may cause 200 555 tonnes yield loss of its production. The high disease severity may cause the death of citrus plant. Some studies have reported the succesfull of biocontrol agents in controlling several diseases especially soilborne disease. Therefore, the aimed of the study was to evaluate the effectiveness of Fungi Mycorrhiza Arbuscular (FMA), Gliocladium fimbriatum, and their combinations to prevent stem rot disease on citrus seedlings (Citrus nobilis). Fungi Mikoriza Arbuskular (FMA), as well as G. fimbriatum mass culture has infested in the rizosphere of citrus seedlings. Artificial inoculation of B.theobromae has done by wounding technics of the basal stem citrus seedlings 15 cm of soil surface. The observations of experiments were latent period, disease incidence, severity incidence, infection rate, and FMA association (%). Fungi Mycorrhiza Arbuscular, Gliocladium fimbriatum, and their combinations are effective and efficient in reduced the disease severity and improved plant vigor.
Keyword: stem rot., Fungi Mycorrhiza Arbuscular (FMA, Gliocladium fimbriatum, citrus, Botryodiplodia theobromae

Judul: Peran Mikoriza Arbuskular, Kitosan, Dan Trichoderma Harzianum Dalam Pengendalian Penyakit Busuk Pangkal Batang (Botryodiplodia Theobromae Pat.) Pada Tanaman Jeruk
Abstrak: Saat ini, penyakit busuk batang yang disebabkan oleh Botryodiplodia theobromae Pat. telah dilaporkan sebagai penyakit penting pada tanaman jeruk. Beberapa penelitian telah melaporkan keberhasilan agens hayati dalam mengendalikan beberapa penyakit terutama penyakit tular tanah. Oleh karena itu, dilakukan kajian yang bertujuan untuk mengevaluasi keefektifan mikoriza arbuskular, kitosan, Trichoderma harzianum, dan kombinasinya untuk mengendalikan penyakit busuk batang pada bibit jeruk. Hasil uji in vitro dalam cawan petri menunjukkan bahwa T.harzianum dapat menghambat pertumbuhan B. theobromae hingga 96.35% dalam 5 hari. Hasil uji in planta menunjukkan perlakuan tunggal mikoriza arbuskular, kitosan, T. harzianum dan kombinasinya dapat menekan keparahan penyakit (16% - 27%) serta meningkatkan kekuatan pada bibit jeruk. Tingkat keparahan penyakit yang tinggi (38.89%) terjadi pada perlakuan kontrol tanpa menggunakan agens hayati maupun kitosan pada 63 hari setelah inokulasi (hsi), dengan periode laten 19.8 hsi. Perlakuan mikoriza arbuskular pada 63 hsi memperlihatkan tingkat asosiasi mikoriza pada akar mencapai 37.12%. Perlakuan tunggal mikoriza arbuskular dan T.harzianum, kombinasi mikoriza arbuskular dengan kitosan, serta kombinasi T.harzianum dengan kitosan merupakan perlakuan yang efektif dan efisien dalam mengendalikan penyakit busuk pangkal batang pada bibit jeruk.
Keyword: Botryodiplodia theobromae, busuk pangkal batang, jeruk, mikoriza arbuskular, Trichoderma harzianum.

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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