Judul: Perlakuan Benih dan Bibit Cabai (Capsicum annuum L.) dengan Rizobakteri Meningkatkan Pertumbuhan Tanaman dan Menurunkan Kejadian Penyakit Busuk Phytophthora
Abstrak: Penggunaan rizobakteri dalam mengendalikan penyakit busuk phytophthora merupakan salah satu pilihan ramah lingkungan daripada menggunakan fungisida. Penelitian ini bertujuan untuk mengetahui pengaruh perlakuan benih dan bibit menggunakan agen hayati yang dapat meningkatkan pertumbuhan tanaman dan menurunkan kejadian penyakit busuk phytophthora. Penelitian ini terdiri atas tiga percobaan dengan menggunakan rancangan acak lengkap. Percobaan pertama (in vitro) terdiri atas sepuluh taraf perlakuan yaitu tujuh macam konsentrasi metalaksil, dua metode aplikasi rizobakteri, dan kontrol. Percobaan kedua (persemaian) menggunakan tiga taraf perlakuan terhadap benih yaitu merendam benih dalam larutan metalaksil 800 ppm, suspensi rizobakteri ST116B, atau larutan ekstrak kentang (PDA) sebagai kontrol. Percobaan ketiga (rumah kaca) menggunakan rancangan acak lengkap dua faktor dengan faktor pertama (pemberian metalaksil atau rizobakteri) tersarang pada faktor kedua (kondisi tanah yaitu tanah diinokulasi atau tidak diinokulasi P. capsici). Metalaksil 800 ppm dan isolat rizobakteri ST116B secara in vitro dapat menghambat pertumbuhan P. capsici. Perlakuan benih dengan isolat rizobakteri ST116B dapat menurunkan tingkat kejadian penyakit busuk phytophthora dari 61,9% menjadi 9,5%. Perlakuan benih dengan rizobakteri ST116B dengan atau tanpa perlakuan bibit meningkatkan tinggi tanaman dan jumlah daun dibandingkan kontrol negatif pada kondisi tanah tanpa inokulasi P. capsici. Artinya, rizobakteri ST116B dapat berperan sebagai antagonis P. capsici sekaligus PGPR.
Keyword: metalaksil, PGPR, Phytophthora capsici, vigor benih

Judul: Perlakuan Benih Cabai (Capsicum annuum L.) dengan Rizobakteri untuk Mengendalikan Phytophthora capsici, Meningkatkan Vigor Benih, dan Pertumbuhan Tanaman
Abstrak: Rhizobacteria seed treatment was an alternative way instead of using chemicals to combat plant disease. The objectives of this research were (1) to select rhizobacteria isolates which inhibiting Phytophthora capsici growth; and (2) to study the effect of seed treatment using rhizobacteria on P. capsici growth, seed vigor and plant growth of hot pepper. This research consisted of three experiments, all experiments were arranged in completely randomized design using one factor. The first experiment consisted of 24 levels of rhizobacteria i.e. 23 isolates of rhizobacteria and P. capsici isolate (control). The second experiment (on the seedbed) consisted of five levels of seed treatments i.e. ST116B rhizobacteria, ST156 rhizobacteria, E3 rhizobacteria, metalaxyl, and control. The third experiment (in the green house) consisted of six levels of seed treatments i.e. ST116B rhizobacteria, ST156 rhizobacteria, E3 rhizobacteria, metalaxyl, positive control, and negative control. Results of in vitro experiment showed that three of 23 isolates tested i.e. ST156, ST116B, and E3 obstructed P. capsici growth. Seed treatments using ST116B, ST156, and E3 rhizobacteria increased seed vigor (vigor index). The best seed treatment increasing plant growth (number of leaves) and potentially controlling phytophthora blight disease was using ST116B rhizobacteria
Keyword: phytophthora blight disease, metalaxyl, dual culture

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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