Judul: Salah satu kendala dalam budidaya anggrek Phalaenopsis di daerah tropis adalah rendahnya ketahanan terhadap penyakit busuk lunak. Penyakit ini disebabkan oleh bakteri patogen Dickeya dadantii. Penggunaan varietas tahan atau resisten merupakan salah satu alternatif pengendalian yang dapat diandalkan dan merupakan salah satu solusi yang tepat untuk mengatasi kendala tersebut. Varietas tahan dapat diperoleh melalui evaluasi dan seleksi ketahanan tanaman dengan menginokulasikan penyakit, namun seleksi ketahanan bukan sesuatu hal yang mudah dilakukan karena terkait dengan penyebaran dan penularan penyakit serta membutuhkan waktu yang lama dalam seleksi. Cara yang digunakan untuk mengatasinya adalah penggunaan marka molekuler, yang dapat mempersingkat waktu seleksi dalam memperoleh tanaman yang resisten. Serangkaian kegiatan penelitian dilakukan untuk mengembangkan metode evaluasi respon ketahanan anggrek Phalaenopsis terhadap infeksi bakteri D. dadantii, mengevaluasi respon ketahanan genotipe anggrek Phalaenopsis terhadap infeksi D. dadantii, mengisolasi dan mengkarakterisasi gen Pto asal 20 genotipe anggrek Phalaenopsis, dan mengembangkan marka SNAP (Single Nucleotide Amplified Polymorphism) pada 32 genotipe anggrek Phalaenopsis berbasis gen Pto.
Abstrak: Salah satu kendala dalam budidaya anggrek Phalaenopsis di daerah tropis adalah rendahnya ketahanan terhadap penyakit busuk lunak. Penyakit ini disebabkan oleh bakteri patogen Dickeya dadantii. Penggunaan varietas tahan atau resisten merupakan salah satu alternatif pengendalian yang dapat diandalkan dan merupakan salah satu solusi yang tepat untuk mengatasi kendala tersebut. Varietas tahan dapat diperoleh melalui evaluasi dan seleksi ketahanan tanaman dengan menginokulasikan penyakit, namun seleksi ketahanan bukan sesuatu hal yang mudah dilakukan karena terkait dengan penyebaran dan penularan penyakit serta membutuhkan waktu yang lama dalam seleksi. Cara yang digunakan untuk mengatasinya adalah penggunaan marka molekuler, yang dapat mempersingkat waktu seleksi dalam memperoleh tanaman yang resisten. Serangkaian kegiatan penelitian dilakukan untuk mengembangkan metode evaluasi respon ketahanan anggrek Phalaenopsis terhadap infeksi bakteri D. dadantii, mengevaluasi respon ketahanan genotipe anggrek Phalaenopsis terhadap infeksi D. dadantii, mengisolasi dan mengkarakterisasi gen Pto asal 20 genotipe anggrek Phalaenopsis, dan mengembangkan marka SNAP (Single Nucleotide Amplified Polymorphism) pada 32 genotipe anggrek Phalaenopsis berbasis gen Pto., One of the obstacles in a Phalaenopsis orchid cultivation in tropical regions is the low resistance to soft rot disease. The disease is caused by pathogenic bacteria Dickeya dadantii. Using resistant varieties is one of alternative control to do and is one of the appropriate solutions to overcome these obstacles. Resistant varieties can be obtained through the evaluation and selection of plant resistance by inoculating disease, but is not an easy thing to do because it can spread and transmission the disease and requires long time in the selection. Using molecular markers could shorten the time of selection to obtain resistant plants. A series of research activities were carried out to developed evaluation method of Phalaenopsis orchid resistance response to bacterial infections D. dadantii, evaluated respons of Phalaenopsis resistance to infection D. dadantii, isolated and characterized the Pto gene from 20 genotypes Phalaenopsis, and developed SNAP markers in 32 genotypes Phalaenopsis based on Pto gene.
Keyword: Soft rot, Disease resistance, Pto gene, Molecular markers, SNAP, Plant resistance, Genetic diversity, Gene

Judul: Pertumbuhan dan Ketahanan terhadap Penyakit Busuk Lunak pada Anggrek Phalaenopsis dengan Pemupukan dan Asam Salisilat.
Abstrak: Maintaining is one of the important processes in Phalaenopsis plants cultivation to get high quality plants. Practically, it is aimed to promote plant grow quickly, healthy and free of diseases. One of main disease on Phalaenopsis is soft rot which caused by Dickeya dadantii bacteria. The use of resistant varieties, application of NPK fertilizers and salicylic acid for growth and resistance are alternatives that can be used to prevent the disease. The purposes of this study were to analyze the Phalaenopsis orchid resistance to soft rot diseases that caused by D. dadantii, determine the effect of NPK fertilizer and salicylic acid concentration as well as the interaction between them for growth and resistance to soft rot diseases caused by D. dadantii. The experiments were conducted at the Bacterial Plant Laboratory, Department of Plant Protection and Greenhouse Leuwikopo, Bogor Agriculture University and plastic house Alam Sinar Sari Dramaga, Bogor, Indonesia. The treatments used for the first experiment were five Phalaenopsis hybrids, namely Phal. KHM 205, Phal. KHM 1126, Phal. KHM 1318, Phal. AMP 17, and Phal. KHM 2249. Phal. amabilis and Phal. amboinensis used as control. Phalaenopsis hybrids used in the second experiment were Phal. KHM 1318 and Phal. KHM 205. The first factor was NPK concentration (0, 1000 and 2000 ppm) and the second one was the concentration of salicylic acid (0, 5 and 10 ppm). The resistance test on some genotype of Phalaenopsis to D. dadantii showed that all Phalaenopsis hybrid had the symptoms of soft rot disease. Phal. KHM 2249 which had the lowest number of leaves reduction and the highest number of life plants after infection was indicated as resistance genotype relatively compared to others in the experiment. The resistance could be came from highest peroxidase activity, low leaf thickness and water content that were not appropriate for pathogen development. The results in the second experiment showed that NPK fertilizer increased growth of Phal. KHM 1318 and Phal. KHM 205. NPK fertilization 1000 and 2000 ppm showed the same effects on all growth variables. Salicylic acid did not have significant effect in improving plant growth. The increased of NPK concentrations reduced plant resistance to soft rot disease which could be seen from increasing of disease symptoms area and the number of fallen leaves and decreasing of the number of life plants after soft root infection on both genotype. Salicylic acid application on Phal. KHM 1318 could not improve plant resistance to soft root although it increased peroxidase activities. Adversely on Phal. KHM 205, salicylic acid could decreased disease symptom area but did not increased peroxidase activity.
Keyword: D. dadantii, leaf thickness, leaf water content, PAL, peroxydase

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: