Judul: Sortation and Electrotherapy of Rice Seeds that Carry Xanthomonas oryzae pv. oryzae and Burkholderia glumae
Abstrak: Padi merupakan tanaman pangan utama dan sumber karbohidrat penting di Indonesia. Jumlah konsumsi beras di Indonesia semakin meningkat, sedangkan produksi padi menunjukkan grafik yang fluktuatif. Keberadaan patogen pada kulit benih, embrio, dan endosperm benih dapat menurunkan mutu benih padi. Deteksi bakteri terbawa benih padi dilakukan melalui uji Gram menggunakan KOH 3% dan pewarnaan bakteri serta uji hipersensitivitas menggunakan tanaman indikator tembakau. Bakteri Burkholderia glumae dan Xanthomonas oryzae pv. oryzae ditemukan pada padi varietas Inpari 42, Ciherang, dan Pandan Wangi di Desa Sukaresmi, Kecamatan Tamansari Kabupaten Bogor. Perlakuan sortasi benih padi tanpa gejala dari yang bergejala memberikan mutu benih lebih baik yaitu bobot 1000 butir, viabilitas dan pertumbuhan padi. Benih padi bergejala memiliki bobot 1000 butir, viabilitas dan pertumbuhan padi yang lebih rendah dari pada sampel padi tanpa gejala atau sampel campuran tanpa gejala dan bergejala. Perlakuan elektroterapi dengan parameter arus listrik 12 V DC dan 1 A selama 30 menit dalam larutan elektrolit NaCl 1 M berpengaruh nyata terhadap daya kecambah benih bergejala pada varietas Inpari 42, tetapi tidak berpengaruh nyata terhadap benih varietas Ciherang dan Pandan Wangi. Perlakuan elektroterapi pada benih bergejala berpengaruh terhadap panjang tajuk tanaman varietas Ciherang, tetapi tidak berpengaruh terhadap panjang tajuk tanaman Inpari 42 dan Pandan Wangi., Rice is the main food crop and an important source of carbohydrates in Indonesia. The amount of rice consumption in Indonesia is increasing, while rice production shows a fluctuating graph. Rice production is affected by the physiological, physical, and genetic quality of its seeds. The presence of pathogens in the part of including coat, embryo, and seed endosperm can reduce seed quality. The bacteria carried by rice seeds was detected through Gram test using KOH 3% and Gram staining and hypersensitivity reaction (HR) test using tobacco as indicator plants. Bacteria Burkholderia glumae and Xanthomonas oryzae pv. oryzae were found in rice varieties Inpari 42, Ciherang, and Pandan Wangi in Sukaresmi Village, Tamansari District, Bogor Regency. The sortation treatment gave symptomless rice seed samples better seed quality, namely weight of 1000 grains, viability, and seedling growth than those symptomatic seed samples. Symptomatic rice seeds have a lower weight of 1000 grains, seed viability, and plant growth than symptomless seed samples or mixed samples of both symptomless and symptomatic seeds. Electrotherapy treatment including electric current at 12 V DC, 1 A for 30 minutes in 1 M NaCl electrolyte solution significantly affects the germination of symptomatic seeds of the Inpari 42 variety but does not significantly affect the seeds of the Ciherang and Pandan Wangi varieties. Electrotherapy treatment on symptomatic seeds affects the length of the plant crown of the Ciherang variety but does not affect the length of the plant crown of the Inpari 42 and Pandan Wangi varieties.
Keyword: Electric current, Seed-borne bacteria, Seed treatment, Seed viability

Judul: Sortation and Electrotherapy of Rice Seed Variety Inpari 42 that Detected to Contain Grain Rot and Leaf Blight Bacterial Pathogen
Abstrak: Burkholderia glumae penyebab penyakit busuk bulir bakteri dan Xanthomonas oryzae pv. oryzae penyebab penyakit hawar daun bakteri merupakan patogen terbawa benih penting pada padi. Upaya pengendalian secara mekanik dan fisik pada benih merupakan alternatif yang perlu dikaji. Penelitian ini bertujuan mengetahui pengaruh sortasi sebagai perlakuan mekanik dan elektroterapi sebagai perlakuan fisik pada benih padi varietas Inpari 42 yang diperoleh dari lot benih lapangan terhadap viabilitas benih. Penelitian ini meliputi pengamatan penyakit dan pengambilan sampel benih padi di suatu lahan sawah milik petani di Kabupaten Bogor. Pengujian kesehatan benih, isolasi dan identifikasi bakteri serta perlakuan sortasi dan elektroterapi dilaksanakan di Laboratorium Bakteriologi Tumbuhan, Departemen Proteksi Tanaman, Fakultas Pertanian, Institut Pertanian Bogor. Berdasarkan karakterisasi morfologi dan uji biokimia, fisiologi, serta reaksi hipersensitivitas, bakteri yang diisolasi dari benih teridentifikasi sebagai B. glumae dan X. oryzae pv. oryzae. Berbagai waktu elektroterapi yang diaplikasikan pada benih yang disortasi menunjukkan hasil yang berbeda nyata pada beberapa peubah respon dan menunjukkan hasil yang lebih baik daripada kontrol pada hampir semua peubah respon. Sortasi benih memberikan perbaikan potensi hasil pada viabilitas benih. Benih tanpa sortasi dan sortasi benih tidak bergejala memberikan hasil yang lebih baik daripada benih gejala. Perlakuan sortasi benih dan elektroterapi tidak berpengaruh terhadap jumlah tanaman yang tumbuh. Namun, perlakuan elektroterapi dengan arus listrik 12 V, 1 A dalam larutan elektrolit NaCl 0,5 M pada durasi berbeda dan sortasi benih memberikan pengaruh yang lebih baik terhadap panjang tajuk selama 5 MST., Burkholderia glumae and Xanthomonas oryzae pv. oryzae which causes bacterial grain rot and leaf blight of rice, respectively, are important seed-borne pathogen in rice. Mechanical and physical control attempts on seeds are an alternative that needs to be studied. This study aims to find out the effects of sortation as mechanical treatment and electrotherapy as physical treatment on Inpari 42 rice seeds obtained from field seed lot on seed viability. The study included the observation of diseases and sampling of rice seeds in a field in the Bogor district. Seed health tests, isolation and identification of bacteria, sorting and electrotherapy treatments were carried out at the Laboratory of Plant Bacteriology, Department of Plant Protection, Faculty of Agriculture, Bogor Agricultural University. Based on morphological characterization and biochemical, physiological, and hypersensitivity tests, the obtained bacteria were indicated as B. glumae and X. oryzae pv. oryzae. The amount of time of electrotherapy applied to sorted seeds showed difference result on some response variables and showed better responses than controls on almost all response variables. Seed sorting provides potential improvements in seed viability. Seeds without sortation and symptomless seeds sub-lot sample showed better results than symptomatic seeds. Sortation of seed and electrotherapy treatments applying electric currents with 12 V, 1 A in 0,5 M NaCl electrolyte at different amount of time gave no significant effect on the number of growing crops. However, electrotherapy gave a better effect on shoot length for five weeks after planting.
Keyword: Arus listrik, Burkholderia glumae, patogen terbawa benih, viabilitas benih, Xanthomonas oryzae pv. oryzae, electric current, seed-borne pathogen, seed viability

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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