Judul: Pengaruh Chitosan dan Gammated Chitosan terhadap Pertumbuhan dan Ketahanan Planlet Anggrek Phalaenopsis amabilis terhadap Penyakit Busuk Lunak.
Abstrak: Phalaenopsis amabilis atau yang lebih dikenal dengan sebutan aggrek bulan, merupakan salah satu spesies yang paling terkenal dalam genus Phalaneopsis. Anggrek Phalaenopsis ini bahkan sempat menduduki rangking atas dalam perdagangan tanaman anggrek, karena harganya yang relatif terjangkau dan keindahan bunganya. Salah satu kendala dalam produksi anggrek Phalaenopsis di Indonesia adalah kurang tepatnya teknik budidaya yang diterapkan dan rentannya sebagian besar Phalaenopsis terhadap penyakit busuk lunak. Chitosan merupakan salah satu bahan organik yang banyak dilaporkan dapat menginduksi ketahanan tanaman terhadap patogen. Aktivitas chitosan ditentukan oleh tingkat polimerisasinya. Iradiasi sinar gamma pada chitosan dilaporkan mempengaruhi aktivitas chitosan. Penelitian ini bertujuan mempelajari pengaruh chitosan dan chitosan yang telah diiradiasi (gammated chitosan) terhadap pertumbuhan dan ketahanan tanaman anggrek Phalaenopsis amabilis terhadap infeksi bakteri patogen busuk lunak. Perlakuan chitosan diberikan dengan cara menyiram larutan perlakuan pada media aklimatisasi. Perlakuan diaplikasikan dengan 5 taraf konsentrasi yaitu kontrol (tanpa chitosan), chitosan 15 ppm dan 30 ppm; serta Gammated chitosan 15 ppm dan 30 ppm. Tanaman dibagi ke dalam 3 kelompok (ulangan) berdasarkan tinggi tanaman menjadi kelompok kecil (panjang daun terpanjang < 3 cm), sedang (panjang daun terpanjang 3 – 6 cm), dan besar (panjang daun terpanjang > 9 cm). Perlakuan chitosan maupun gammated chitosan dapat meningkatkan persen hidup tanaman namun tidak meningkatkan pertumbuhan tanaman. Seluruh tanaman yang diuji dalam infeksi dengan bakteri patogen busuk lunak menunjukkan gejala busuk lunak. Perlakuan chitosan 30 ppm, gammated chitosan 15 dan 30 ppm cenderung menekan intensitas penyakit dibandingkan dengan kontrol hingga 18 jam setelah infeksi (JSI) namun secara umum belum efektif meningkatkan ketahanan anggrek Phalaenopsis terhadap penyakit busuk lunak. Aktivitas enzim peroksidase cenderung lebih tinggi pada perlakuan gammated chitosan dan paling tinggi pada konsentrasi gammated chitosan 30 ppm.
Keyword: aktivitas peroksidase, diameter gejala busuk lunak, persen hidup, intensitas penyakit, tingkat ketahanan

Judul: Pertumbuhan Anggrek Phalaenopsis amabilis pada Perlakuan Chitosan dan Asam Salisila
Abstrak: Phalaenopsis orchid plant vegetative growth is influenced by environmental condition such as light, temperature, and humidity. Certain organic material affected on the growth, development and plant resistance to pests and diseases, including chitosan and salicylic acid. The objective of this research was to test the application of organic compound chitosan and salicylic acid on the growth of Phalaenopsis amabilis. This research was arranged in a randomized completely design with organic compound as a single factor. There were six treatment, 3 ppm chitosan, chitosan 6 ppm, 5 ppm salicylic acid, salicylic acid 10 ppm and 3 ppm chitosan + 5 ppm salicylic acid. Each treatment was repeated five times with 3 plantlets per bottle. Organic compound were mixed in ½ MS in vitro medium and planlets were transfered to the treatment medium and cultured in the tissue culture laboratory for four weeks. Planlets subsequently were acclimatizated to spaghnum ii moss medium in greenhouse. Treatment were continued by spraying of organic compound to planlets every two weeks. The results of the experiment showed that the best treatment of organic compound, was chitosan 3 ppm. This is showed by length of youngest leaf and percentage growth of plant on treatment of chitosan 3 ppm.
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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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