Judul: Plant Parasitic Nematodes on Rice (Oryza sativa L.) in Medan Selayang District, Medan City, North Sumatra
Abstrak: Medan Selayang is one of the districts in Medan City, North Sumatra, and one of the rice production centers in Medan City. One of the problems faced regarding rice cultivation in Medan Selayang is disease caused by plant parasitic nematodes. Monitoring the presence of plant parasitic nematodes must be carried out to determine plant disease control strategies. This research examines a genus of plant parasitic nematodes on rice in Medan Selayang District, Medan City, North Sumatra. The research was carried out from January to March 2023 and carried out in seven stages: Survey and collecting samples from a rice field that exhibits symptoms of nematode infection. Extraction of parasitic nematodes in soil samples using the flotation-centrifugation method. Extraction of parasitic nematodes in root samples using the mist chamber method. Counting the number of parasitic nematodes. Making semi-permanent parasitic nematode preparations. Identifying the morphology of parasitic nematodes. Plant parasitic nematodes community analysis. Six genera of plant parasitic nematodes were identified from soil and root samples: Meloidogyne, Hirschmanniella, Tylenchus, Helicotylenchus, Criconemoides, and Criconemella. The dominant plant parasitic nematodes in the soil samples were Helicotylenchus (6.6/100 g of soil), while Meloidogyne dominated the roots (25/5 g of roots).
Keyword: Helicotylenchus, Meloidogyne, morphology identifications, nematodes

Judul: Nematoda Parasit Padi Sawah Di Kecamatan Terisi Kabupaten Indramayu
Abstrak: Paddy is plant producing staple food in Indonesia. The effort to increase paddy productivity face several handichapes, one of them is root parasitic nematodes. Nematodes are important parasite of paddy plant, because they can attack all parts of the plant including roots, stems, leaves, and panicles. Nematode infection causes various symptoms, such as plant stunting, leaf chloroses, root knot, and root rot. Research aimed to detect and identify parasitic nematode of paddy was conducted at paddy field selected from three villages of Terisi sub district, Indramayu District, West Java. Root samples were picked from plants taken from healthy-, area between healthy and infected-, and infected part of the plantation. The root samples were incubated in a mist chamber for nematode extraction. Part of the sample was stained for nematode detection. Identification of nematodes was based on the morphological characters. The parasitic nematodes of paddy found were Hirschmaniella, Pratylenchus, Helicotylenchus and Meloidogyne.
Keyword: root nematode., Meloidogyne, Hirschmaniella

Judul: Best Difference Equation Aproximation to Duffing 's Equation
Abstrak: Persamaan Duffing merupakan persamaan yang sering muncul sebagai model masalah sistem ayun mekanis atau pada masalah rangkaian listrik. Umumnya penyelesaian persamaan ini secara numerik memberikan hampiran dengan gala! yang tinggi, seperti dengan metode Runge-Kutta. Tulisan ini mengkonstruksi suatu persamaan beda untuk menghampiri persamaan Duffing tersebut. Penyelesaian dari persamaan beda ini melibatkan fungsi-fungsi eliptik Jacobi. Berdasarkan penyelesaian ini diperoleh basil bahwa penyelesaian hampirannya persis sama dengan penyelesaian analitiknya. Penyelesaian analitik yang diperolehjuga melibalkan fungsi-fungsi eliptik Jacobi.
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