Judul: Isolasi Bakteri Endofit dari Tanaman Kehutanan dan Potensinya untuk Pengendalian Meloidogyne spp. pada Tanaman Tomat
Abstrak: Meloidogyne spp. is one of the main constraints of tomato production in Indonesia. Endophytic bacteria as a biocontrol agents is an alternative for controlling nematodes. The objective of this study was to isolate endophytic bacteria from forest plants and to evaluate its potential for controlling Meloidogyne spp. on tomato (Lycopersicon esculentum Mill.). Endophytic bacteria were isolated from mahoni (Swietenia mahogany Jacq), trambesi (Albizia saman (Jacq.) Merr.), gaharu (Aquilaria malacensis), and meranti (Shorea sp.) with surface sterilization method using 70% alcohol, 4% NaOCl and steril water. The bacterial strain were cultured on tryptic soy agar (TSA) for two days. In vivo testing to determine the effect of bacteria for suppressing of nematode galls was conducted in the greenhouse with seed treatment. The result showed there are thirty three isolates of endophytic bacteria were isolated from the root of forest plant. twenty two isolates are negative reaction and eleven isolates are positif reaction after hypersensitive test using tobacco plant. Two isolates of endophytic bacteria MSJ1H and TSS1D were able to reduce gall number. Based on high plant indicator, soaking seed treatment with endophytic bacteria were able to increase the high of tomato plants.
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Judul: Isolasi Bakteri Endofit dan Penguj ian Potensinya untuk Mengendalikan Nematoda Meloidogyne spp. pada Tanaman Tomat (Lycopersicon esculentum Mill.)
Abstrak: Penelitian ini bertujuan untuk mengisolasi dan menguji bakteri endofit yang berasal dari tanaman tomat dan cabai untuk mengendalikan nematoda Meloidogyne spp. serta mengetahui pengaruhnya terhadap pertumbuhan tanaman. Bakteri endofit diisolasi dari pertanaman tomat dan cabai yang berasal dari daerah Bogor dan Malang. Isolasi bakteri endofit dengan menggunakan metode sterilisasi permukaan dan homogenisasi jaringan. Sterilisasi permukaan jaringan menggunakan ethanol 80 % dan NaOCl 3 % dan 1,5 %. Bakteri yang didapat selanjutnya dimurnikan dan disimpan dalam media Trytic Soy Broth (TSB) yang dicampur dengan glycerin 20 % pada suhu -79°C sebagai stok. Pengujian bakteri endofit dilakukan secara in vitro dan in vivo. Pengujian in vitro bertujuan untuk melihat pengaruh kultur filtrat bakteri endofit terhadap ketahanan hidup larva Meloidogyne spp., sedangkan uji in vivo bertujuan untuk melihat pengaruh sel bakteri yang diinokulasikan pada tanaman terhadap pertumbuhan tanaman dan pembentukan puru akar yang disebabkan oleh Meloidogyne spp. pada tanaman tomato Uji in vivo dilakukan dirumah kaca Institut Pertanian Bogor dengan metode perlakuan tanah dan perlakuan benih. Hasil uji in vitro menunjukkan bahwa perlakuan isolat bakteri endofit berpengaruh terhadap tingkat ketahanan hidup larva Meloidogyne spp.. Hasil uji di rumah kaca menunjukkan bahwa perlakuan bakteri endofit pada tanaman tomat dapat menekan pembentukan puru akar yang disebabkan oleh Meloidogyne spp. Identifikasi isolat bakteri uji dilakukan dengan melihat karakteristik koloni bakteri dan dengan beberapa pengujian yaitu uji gram (KOH 3 %), pewarnaan gram, uji bakteri tahan panas dan uji flourescent. Hasil identifikasi menunjukkan isolat bakteri uji yang digunakan adalah dari genus Bacillus sp. dan bakteri Pseudomonas flourescent.
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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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