Judul: Identifikasi Organisme Pengganggu Tanaman Gandum (Triticum aestivum L.) di Kuningan dan Bogor, Provinsi Jawa Barat
Abstrak: The development of wheat crops in Indonesia has been struggling to fulfill domestic needs which increase over time. Information about plant pest organisms which attack introduced (SO9) and IPB bred strain (Kasifbey) wheat is one of the main constraints to maintain production capacity of the wheat crops. Therefore, this research needs to be performed. The aim of this research is to find out information about the plant pest organisms on the SO9 and Kasifbey wheat. Observations on the crops have been conducted at the two places cultivation: in Leuwimalang village, Cisarua Subdistrict, Bogor District (705 m above sea surface) and in Cilimus village, Cilimus Subdistrict, Kuningan District (418 m above sea surface) West Java Province. Symptoms of the plant pest organisms which appear on the crops were observed. Subsequently, the extent and intensity of the pest attacks on the crops were quantified. Finally, the samples of the diseased crops and insects were identified at the laboratory using determination key identification. The insects which found on the wheat crops are some species of the Lepidoptera caterpillars and several species of aphids (Hemiptera: Aphididae), species of Oxya sp. (Orthoptera: Acrididae), Nezara viridula (Hemiptera: Pentatomidae), Leptocorisa oratorius (Hemiptera: Alydidae), white grub larvae (Coleoptera: Scarabaeidae), and stem borer. Pathogens which are found on the wheat crops: Fusarium sp., Helminthosporium sp., Phoma sp., Curvularia sp., and Alternaria sp.. The dominant pest in each location are different. The Oxya sp. is a dominant pest in Kuningan and attacks 100% of the sample area of the SO9 and Kasifbey wheat crops. On the other hand, Mythymna unipuncta is a dominant pest in Cisarua with more than 50% attacked area. Diseases of the wheat crops at both location are mostly caused by the Helminthosporium sp. with 100% diseases incidence. The Kasifbey is more frequently attacked by insects and pathogens than the SO9.
Keyword: Helminthosporium sp., Mythymna unipuncta, Triticum aestivum, Oxya sp., Wheat

Judul: Potential Disease Problem of Wheat Grain in Indonesia
Abstrak: Gandum (Triticum aestivum L.) merupakan tanaman serealia yang banyak dibudidayakan di daerah subtropis dan menjadi makanan pokok di dunia. Indonesia saat ini melakukan pengembangan gandum dan menghadapi beberapa kendala, salah satunya karena penyakit bulir gandum. Penelitian ini bertujuan memberikan informasi mendalam tentang penyakit bulir gandum oleh cendawan yang berpotensi menjadi masalah pada pertanaman gandum di Indonesia. Analisis berdasarkan hasil Pest Risk Analysis (PRA) patogen berupa potensi masuk, menetap, berkembang, dan dampak ekonomi yang ditimbulkan oleh penyakit bulir gandum. Informasi juga meliputi pentingnya penyakit tersebut, bioekologi patogennya, potensi penyakit tersebut menjadi masalah pada pertanaman gandum di Indonesia berdasarkan segitiga penyakit, dan potensi pengendaliannya. Penyakit bulir gandum yang berpotensi menjadi masalah pada pertanaman gandum di Indonesia yaitu yaitu scab/ hawar malai (Fusarium graminearum, F. culmorum, F. avenaceum, F. equiseti, F. acuminatum, F. trincictum, F. poae, F. camptoceras, F. moniliforme, F. longipes, F. sambucinum, F. nivale, F. sporotrichoides, F. chlamydosporum, F. semitectum, F. oxysporum, dan F. solani), black point/bintik hitam (Alternaria alternata, A. triticina, Cladosporium cladosporioides, Curvularia lunata, C. pallescens, Phoma glomerata, Helminthosporium sorokiniana, dan H. sativum), bercak Septoria (Septoria tritici dan S. nodorum), blast (Pyricularia oryzae dan P. graminis tritici), karnal bunt (Tilletia indica), common bunt (T. tritici dan T. laevis), dan ergot (Claviceps purpurea) dengan hasil PRA keseluruhan tergolong sedang. Walaupun baru diidentifikasi hingga genus, patogen bulir gandum yang sudah dilaporkan ada di Indonesia adalah Fusarium sp., Helmintsporium sp., Phoma sp., Curvularia sp., dan Alternaria sp., Wheat (Triticum aestivum L.) is a cereal crop that is widely cultivated in subtropical areas and wheat is the main staple food in the world. Indonesia is currently developing wheat production and is facing several obstacles, one of which is due to wheat grain diseases. This study aims to provide in-depth information about fungal grain disease which is a potential problem in wheat cropping in Indonesia. The analysis is based on the results of the Pest Risk Analysis (PRA) of pathogens in the form of the potential of entry, establishment, spread, and the economic impact of wheat grain diseases. This information includes the importance of the diseases, the bioecology of the pathogens, the potential for the diseases to become a problem in wheat cropping system in Indonesia based on the disease triangle, and the potential to control them. Grain diseases that have the potential to become a problem in wheat production in Indonesia are scab/ panicle blight (Fusarium graminearum, F. culmorum, F. avenaceum, F. equiseti, F. acuminatum, F. trincictum, F. poae, F. camptoceras, F. moniliforme, F. longipes, F. sambucinum, F. nivale, F. sporotrichoides, F. chlamydosporum, F. semitectum, F. oxysporum, and F. solani), black point/ black spot (Alternaria alternata, A. triticina, Cladosporium cladosporioides, Curvularia lunata, C. pallescens, Phoma glomerata, Helmintshosporium sorokiniana, and H. sativum), Septoria spot (Septoria tritici and S. nodorum), blast (Pyricularia oryzae and P. graminis tritici), karnal bunt (Tilletia indica), common bunt (T. tritici and T. laevis), and ergot (Claviceps purpurea) with moderate PRA results. Although still identified to the genus level, the pathogens of wheat grain diseases that have been reported in Indonesia are Fusarium sp., Helmintsporium sp., Phoma sp., Curvularia sp., and Alternaria sp.
Keyword: bioecology, control, disease triangle, fungi, Pest Risk Analysis

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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