Judul: Bakteri Sebagai Agens Pengendalian Hayati Rigidoporus microporus, Penyebab Penyakit Busuk Akar Putih Pada Tanaman Karet
Abstrak: Rigidoporus microporus adalah penyebab penyakit busuk akar putih (BAP) yang paling merusak di perkebunan karet seluruh dunia, termasuk di Indonesia. R. microporus sangat sulit dikendalikan karena dapat bertahan hidup di dalam tanah sebagai saprofit dan menjadi sumber inokulum. Kolonisasi R. microporus pada perakaran tanaman karet menyebabkan akar hitam, membusuk, rapuh, dan mudah patah, sedangkan pada infeksi lanjut menyebabkan kematian pada tanaman karet. Pemanfaatan bakteri sebagai agens pengendalian hayati (APH) berpotensi menekan perkembangan infeksi R. microporus karena menghasilkan enzim hidrolitik pendegradasi dinding sel, sedangkan senyawa antibiotik yang disekresikannya dapat menghambat kolonisasi dan menekan intensitas penyakit BAP pada tanaman karet. Bakteri APH, juga bermanfaat sebagai pemacu pertumbuhan tanaman, yaitu meningkatkan ketersediaan nutrisi bagi tanaman dan mensintesis fitohormon. Penelitian bertujuan (1) memperoleh isolat bakteri APH hasil seleksi yang aman, mempunyai aktivitas lisis dan antibiosis terhadap R. microporus; (2) mengetahui pengaruh metabolit antifungal isolat bakteri APH dalam menghambat pertumbuhan R. microporus dan jenis senyawa yang dihasilkan; (3) mengetahui potensi isolat bakteri APH sebagai pemacu pertumbuhan tanaman; (4) mengevaluasi keefektifan isolat bakteri APH dalam menekan kolonisasi R. microporus pada bibit karet; dan (5) mengidentifikasi isolat bakteri APH melalui pendekatan morfologi dan molekuler. ...
Keyword: mycelial abnormalities, hydrolytic enzymes, Rigidoporus microporus, diffusible organic compounds, volatile organic compounds

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.
Keyword: