Judul: Penggunaan Bakteri Kitinolitik untuk Mengendalikan Penyakit Akar Putih pada Bibit Karet (Hevea brasiliensis).
Abstrak: Karet merupakan salah satu tanaman industri yang memiliki peran penting sebagai komoditas ekspor. Salah satu jenis penyakit yang paling merugikan pada perkebunan karet yaitu penyakit jamur akar putih (JAP). Pengendalian hayati menggunakan bakteri kitinolitik merupakan salah satu alternatif dalam pengendalian tanaman. Penelitian ini bertujuan untuk mengetahui kemampuan beberapa isolat bakteri kitinolitik untuk mengendalikan penyakit akar putih pada bibit karet. Penelitian dilakukan pada bulan Mei sampai Desember 2017. Pengujian dilakukan dalam dua tahap yakni in vitro dan in planta. Bakteri kitinolitik yang diuji adalah E.TB7, R.T.B2, E.T.C4, E.T.B5, NAP05, NAP21, dan fungisida Anvil 50 EC sebagai pembanding. Pengujian secara in vitro dilakukan dengan metode dual culture. Variabel yang diamati adalah zona hambatan dan abnormalitas hifa. Pengujian secara in planta dilakukan dengan menggunakan bibit tanaman karet yang diinokulasi oleh Rigidoporus lignosus. Bakteri kitinolitik dengan kepadatan 108 cfu/ml diaplikasikan dengan cara menyiram 100 ml/tanaman secara merata. Tingkat keparahan penyakit diukur 60 hari setelah inokulasi. Bakteri kitinolitik E.T.C4 dan E.T.B7 mampu menekan keparahan penyakit akar putih.
Keyword: dual culture, in planta, Rigidoporus lignosus, pengendalian hayati

Judul: Eksplorasi Bakteri Lisis sebagai Agens Pengendalian Hayati Penyakit Akar Putih (Rigidoporus lignosus (Kloztch) Imazeki) pada Tanaman Karet.
Abstrak: The hevea rubber (Hevea brasiliensis) is one of the important commodity in Indonesia for export purposes. One of the obstacles to be limiting in the production of hevea rubber is white root fungus disease caused by Rigidoporus lignosus. The purpose of this study was to explore and select a lysis bacteria from hevea rubber rhizosphere which have the potential as biological control agent of the disease. This research had been conducted in laboratory Wish, Dramaga, Bogor and laboratory Mycology, Departement of plant protection, faculty of agriculture, IPB on December 2014 until March 2015. Of the 251 isolates obtained in this study, 118 isolates on has the ability as cellulolytic, 68 isolates are cellulolytic and chitinolytic, and 65 isolates did have both of these properties. Out of the isolates that have lysis properties, 147 (79%) were not pathogenic based on the hypersensitivity test in tobacco plants. Among of those non-pathogenic isolates, 30 isolates could inhibit the radial growth R. lignosus in vitro testing. Based one the score of lysis index, inhibition zone, and growth inhibition, 13 isolates might be potential as biological control agents of R. lignosus.
Keyword: antagonis, kitinolitik, selulolitik, Rigidoporus lignosus

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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