Judul: Inventarisasi Penyakit Tanaman Padi (Oryza sativa L.) di Kecamatan Lubuk Basung dan Tanjung Raya, Kabupaten Agam, Sumatra Barat
Abstrak: Tanaman padi merupakan salah satu komoditas pangan penting di dunia. Penurunan produksi padi di Indonesia dan khususnya Sumatra Barat disebabkan oleh beberapa faktor penyakit tanaman seperti cendawan, bakteri, virus, dan nematoda. Berbagai macam penyakit yang mengancam produksi komoditas tanaman pangan telah dilaporkan termasuk komoditas tanaman padi. Patogen dapat merusak bagian tertentu atau bahkan seluruh organ tanaman. Faktor lingkungan menjadi salah satu penyebab pemencaran penyakit pada tanaman padi. Tujuan dari penelitian ini mengamati dan melakukan penghitungan kejadian dan keparahan penyakit tanaman padi di Kecamatan Lubuk Basung dan Tanjung Raya, Kabupaten Agam, Sumatra Barat. Penelitian akan dilaksanakan dalam lima tahap yaitu wawancara petani, penentuan tanaman contoh, penghitungan insidensi dan keparahan penyakit, penghitungan produksi padi, serta analisis data. Penyakit tanaman padi yang ditemukan yaitu hawar daun bakteri (Xanthomonas oryzae pv oryzae), blas (Pyricularia oryzae), hawar daun pelepah (Rhizoctonia solani), pucuk putih (Aphelenchoides besseyi), bercak cokelat sempit (Cercospora oryzae), dan busuk bulir bakteri (Burkholderia glumae). Hasil penelitian menunjukkan bahwa seluruh lahan pengamatan ditemukan penyakit tanaman padi dengan lahan LB1, LB3, LB5, TR2, TR3, TR5 rata rata menunjukkan insidensi dan keparahan penyakit yang tinggi dibandingkan lahan pengamatan lainnya., Rice Plant is one of the most important food commodities in the world. The decline in rice production in Indonesia and especially West Sumatra is caused by several plant disease factors such as fungi, bacteria, viruses, and nematodes. Various diseases that threaten the production of food crop commodities have been reported, including rice commodities. Pathogens can damage certain parts or even entire plant organs. Environmental factors are one of the causes of the spread of disease in rice plants. The purpose of this study was to observe and calculate the incidence and severity of rice disease in Lubuk Basung and Tanjung Raya, Agam, West Sumatra. The research will be carried out in five stages, farmers interview, determining sample plants, calculating disease incidence and severity, calculating rice production, and analyzing data. Rice plant diseases found were bacterial leaf blight (Xanthomonas oryzae pv oryzae), blast (Pyricularia oryzae), sheath blight (Rhizoctonia solani), white tip (Aphelenchoides besseyi), narrow brown spot (Cercospora oryzae), and bacterial grain rot (Burkholderia glumae). The results showed that all of the observed rice plant diseases were found with LB1, LB3, LB5, TR2, TR3, TR5 fields on average showing a high incidence and severity of disease compared to other observation fields.
Keyword: dispersal, pathogen, rice production

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: 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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