Judul: National Rice Production and Bacterial Leaf Blight Disease in District of Indramayu, West Java
Abstrak: Padi (Oryza sativa) merupakan tanaman pangan penting di berbagai negara di dunia termasuk Indonesia. Produksi padi Indonesia mengalami fluktuasi yang dipengaruhi oleh berbagai faktor seperti alih fungsi lahan, agro-klimat, dan organisme pengganggu tanaman. Salah satu penyakit penting padi adalah hawar daun bakteri (HDB) oleh Xanthomonas oryzae pv. oryzae. Upaya pengendalian penyakit tersebut antara lain penggunaan varietas tahan, kultur teknis, hayati dan kimiawi. Penelitian ini bertujuan menggambarkan produksi padi secara nasional dan intensitas penyakit HDB pada tanaman padi di Kabupaten Indramayu, Jawa Barat. Data produksi padi tingkat nasional, provinsi dan kabupaten diakses secara daring dari website Badan Pusat Statistik, kegiatan lapangan meliputi pengumpulan data usaha tani dan produksi padi melalui wawancara dengan petani, pengamatan gejala dan intensitas penyakit di petak sawah contoh milik petani. Produksi padi nasional pada periode tahun 2011-2021 menunjukkan peningkatan selama tujuh tahun pertama, kemudian menurun dalam tiga tahun terakhir secara nyata. Pada periode waktu yang sama Provinsi Jawa Barat sebagai produsen padi nasional terbesar ketiga juga menunjukkan penurunan produksi. Indramayu merupakan kabupaten penghasil padi utama di Jawa Barat juga memiliki produksi yang berfluktuasi yang dipengaruhi produksi tahunan di kecamatan-kecamatan utama. Penyakit HDB di lahan pengamatan contoh Kabupaten Indramayu menunjukkan intensitas beragam antar varietas padi. Insidensi penyakit pada padi varietas Ciherang adalah 79,4% yang lebih rendah daripada Mekongga (83%) dan varietas Kebo Putih (92%). Sementara itu, severitas penyakit dari yang terendah adalah varietas Ciherang, local dan Mekongga berturut-turut 24,07, 35,11 dan 83%. Varietas Ciherang memiliki tingkat ketahanan terhadap HDB lebih baik daripada dua varietas lainnya., Rice (Oryza sativa) is an important food crop in various countries in the world, including Indonesia. Indonesian rice production fluctuates, which is influenced by various factors such as land conversion, agro-climate, and plant pest organisms. One of the important diseases of rice is bacterial leaf blight (BLB) by Xanthomonas oryzae pv. oryzae. Efforts to manage the disease include the use of resistant varieties, technical, biological and chemical control techniques. This study aims to describe the national rice production and the intensity of HDB disease in rice plants in Indramayu Regency, West Java. Data on rice production at the national, provincial and district levels is accessed online from the website of the Central Statistics Agency (BPS), field activities include collecting data on farming and rice production through interviews with farmers, observing symptoms and intensity of disease in sample rice fields belonging to farmers. National rice production in the 2011-2021 period showed an increase for the first seven years, then decreased significantly in the last three years. In the same period of time, West Java Province as the third largest national rice producer also showed a decline in production. Indramayu is the main rice producing district in West Java and also has fluctuating production which is influenced by annual production in the main sub-districts. BLB disease in the sample observation area of Indramayu District showed varying intensity between rice varieties. The incidence of disease in Ciherang rice varieties was 79.4% which was lower than Mekongga (83%) and Kebo Putih varieties (92%). Meanwhile, the disease severity from the lowest was ‘Ciherang’, ‘local’ and Mekongga varieties, respectively 24.07, 35.11
Keyword: Disease incidence, disease severity, production fluctuation, variety resistence, Xanthomonas oryzae pv, oryzae

Judul: National Rice Production and its Important Disease Intensity in Sukabumi District
Abstrak: Produksi beras sebagai sumber pangan pokok ditingkatkan untuk memenuhi kebutuhan masyarakat Indonesia yang jumlah penduduknya selalu meningkat. Produksi padi di Indonesia berfluktuasi karena berbagai faktor abiotik dan biotik, termasuk hama dan penyakit. Produksi beras nasional Indonesia meningkat selama periode 2011-2017, kemudian menurun secara signifikan pada 2018-2020. Penurunan produksi beras juga terjadi di lima provinsi penghasil beras terbesar yaitu Jawa Tengah, Jawa Timur, Jawa Barat, Sulawesi Selatan, dan Sumatera Selatan pada periode 2018-2021. Petani padi di Kecamatan Jampangkulon dan Cibitung Kabupaten Sukabumi menerapkan cara budidaya dan pengelolaan OPT secara konvensional, yaitu mengandalkan pupuk kimia dan pestisida sintetik. Penyakit penting yang ditemukan pada padi varietas lokal, Trisakti dan IR64 dari pengamatan lapangan di Kabupaten Sukabumi adalah bercak daun lonjong atau blas jamur oleh Pyricularia oryzae dan hawar daun bakteri oleh Xanthomonas oryzae pv. oryzae. Insidensi penyakit P. oryzae mencapai 100% pada ketiga varietas dengan tingkat severitas berkisar 60,7-66,7% pada daun dan 52,3-60% pada malai, sedangkan hawar bakteri menyebabkan insidensi 76,7-93,3% dan severitas 33,0- 64,4%. Varietas padi lokal paling tahan terhadap P. oryzae dibandingkan dua varietas lainnya, sedangkan Trisakti relatif lebih tahan penyakit hawar daun bakteri. Varietas IR64 paling rentan terhadap kedua penyakit tersebut dibandingkan dengan varietas lainnya. Berdasarkan analisis usahatani dan rasio keuntungan terhadap biaya (rasio B/C), varietas yang paling menguntungkan berturut-turut adalah lokal, IR64 dan Trisakti. Kata kunci: Rasio B/C, Xanthomonas oryzae pv. oryzae, Pyricularia oryzae, insidensi, severitas, fluktuasi produksi padi, Rice production as a staple food source is increased to meet the needs of the Indonesian people, whose population is always increasing. Rice production in Indonesia fluctuates due to various abiotic and biotic factors, including pests and diseases. Indonesia's national rice production increased during the 2011-2017 period, then decreased significantly in 2018-2020. The decline in rice production also occurred in the five largest rice producing provinces, namely Central Java, East Java, West Java, South Sulawesi and South Sumatra in the period 2018-2021. Rice farmers in Jampangkulon and Cibitung Subdistricts, Sukabumi Regency, apply conventional methods of cultivating and managing pests, which rely on chemical fertilizers and synthetic pesticides. The important diseases found in local rice varieties, Trisakti and IR64 from field observation in Sukabumi District were fungal oval leaf spot or blast by Pyricularia oryzae and bacterial leaf blight by Xanthomonas oryzae pv. oryzae. The incidence of disease by P. oryzae reached 100% in the three varieties with severity ranging from 60.7-66.7% on leaves and 52.3-60% on panicles, while bacterial blight caused incidence of 76.7-93.3% and severity 33.0-64.4%. The local rice variety was most resistant to P. oryzae than the other two varieties, while Trisakti was relatively most resistant to bacterial leaf blight. The IR64 variety was the most susceptible to both diseases compared to the other varieties. Based on the analysis of farming and benefit- cost ratio (B/C ratio), the most profitable varieties were local one, followed by IR64 and Trisakti, respectively. Keywords: B/C ratio, Xanthomonas oryzae pv. oryzae, Pyricularia oryzae, incidence, severity, rice production fluctuation
Keyword: B/C ratio, Xanthomonas oryzae pv. oryzae, Pyricularia oryzae, incidence, severity, rice production fluctuation

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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