Judul: Native Arbuscular Mycorrhiza Colonization in Seedling Root of Dogfruit (Archidendron pauciflorum) Planted as Seed-ball in Greenhouse and Field
Abstrak: Mikoriza arbuskula (MA) merupakan simbiosis mutualisme antara cendawan dan tumbuhan, termasuk jengkol (Archidendron pauciflorum). Jengkol dimanfaatkan sebagai sumber pangan dan pakan hewan di hutan. Penanaman bibit jengkol pada lahan revegetasi dengan kemiringan tajam berbahaya bagi pekerja, sehingga penanaman dengan seed-ball diperlukan dalam revegetasi lahan pasca tambang. Penelitian ini bertujuan mempelajari kemampuan cendawan MA lokal dalam mengkolonisasi bibit jengkol yang ditanam sebagai seed-ball di rumah kaca dan lapangan untuk tujuan revegetasi. Seed-ball dibuat dengan menggunakan tiga tipe sumber inokulum cendawan mikoriza arbuskula (CMA), yaitu kontrol tanpa CMA, inokulum hutan alam, dan inokulum stockpile. Seed-ball jengkol dirawat di rumah kaca dan ditanam di lapangan. Semua bibit yang ditanam di rumah kaca tidak membentuk kolonisasi MA sedangkan bibit yang ditanam di lapangan seluruhnya terkolonisasi oleh MA termasuk perlakuan kontrol dengan kolonisasi 2% – 16%. Pada tanaman di rumah kaca, perlakuan inokulasi meningkatkan tinggi tanaman, jumlah daun, jumlah anak daun, jumlah cabang, dan lebar daun. Pada tanaman di lapangan, inokulasi tidak berpengaruh terhadap seluruh parameter pertumbuhan tanaman. Terdapat dua spesies spora MA pada semua perlakuan dan lokasi yaitu Glomus sp. 1 dan Glomus sp. 2. Jenis CMA yang paling mendominasi adalah Glomus sp. 2., Arbuscular mycorrhiza (AM) is a mutualistic symbiosis between soil fungi and plants, including dogfruit (Archidendron pauciflorum). Dogfruit is used for food and animal feed. Planting dogfruit seedlings on revegetation land with a sharp slope is dangerous to workers, seed-ball planting is recommended for revegetation of post-mining. The research aimed to study the ability of the native AM fungi to colonize dogfruit seedlings grown as a seed-ball in greenhouse and field for revegetation purposes. The seed-ball was made using three types of fungal inoculum sources, namely control without AM fungi, natural forest, and stockpile inoculums. The seed-ball grown in greenhouse and field. All seedlings in greenhouse did not colonized by mycorrhiza, whereas all seedling grown in field formed mycorrhizal symbiosis with colonization value was 2% – 16%. Inoculation increased plant height, number of leaves, number of leafleat, number of branches, and leaf width in greenhouse. In field, inoculation had no effect on plant growth. There were two types of AM spores found in all treatments, Glomus sp. 1 and Glomus sp. 2. Glomus sp. 2 is the dominant species of AM fungi in all treatments.
Keyword: Arbuscules, plant height, revegetation, stockpile, vesicles

Judul: Diversity and Colonization of Arbuscular Mycorrhizal Fungi (AMF) in Trapping Culture Martabe, North Sumatra
Abstrak: Cendawan Mikoriza Arbuskula (CMA) adalah kelompok cendawan mikoriza yang bersimbiosis secara mutualisme dengan akar tanaman. Studi mengenai keanekaragaman CMA pada ekosistem hutan di wilayah tropis Indonesia masih terbatas dan eksplorasi CMA secara langsung dari rizosfer alami sering diperoleh hasil yang relatif rendah. Penelitian ini bertujuan mendapatkan informasi mengenai keragaman dan kolonisasi CMA pada rizosfer hutan Martabe, Sumatra Utara melalui kultur trapping. Penelitian dilakukan dengan membuat kultur trapping menggunakan tanaman Sorghum vulgare dan Mucuna bracteata masing-masing sebanyak 3 ulangan. Keragaman spesies CMA diketahui dengan mengisolasi dan mengidentifikasi spora berdasarkan karakteristik morfologi kemudian dilakukan penghitungan persentase kolonisasi. Sebanyak 18 spesies CMA berhasil diperoleh yang terdiri dari genus Glomus, Gigaspora, dan Acaulospora. Keragaman spesies CMA didominasi oleh genus Glomus. Jumlah spesies CMA tertinggi ditemukan pada tanaman Mucuna bracteata sedangkan jumlah spora terbanyak ditemukan pada tanaman Sorghum vulgare. Persentase kolonisasi CMA pada akar tanaman Sorghum vulgare dan Mucuna bracteata masing-masing sebesar 42,81% dan 51,06% yang ditandai dengan terdapatnya struktur berupa arbuskula, hifa eksternal dan internal, titik penetrasi serta vesikula. Kedua jenis tanaman tersebut termasuk dalam tanaman adaptif yang dapat bersimbiosis dengan CMA., Arbuscular Mycorrhizal Fungi (AMF) is a mutualism symbiosis between mycorrhizal fungi and plant roots. Studies of AMF diversity in Indonesian tropical forests still need to be expanded, and exploration of AMF directly from the natural rhizosphere often has relatively low results. This study aims to obtain information on the diversity and colonization of AMF in forest rhizosphere Martabe, North Sumatra, through trapping culture. The research was carried out by making trapping cultures using Sorghum vulgare and Mucuna bracteata plants with three replications each. The diversity of AMF species is known by isolating and identifying the spores based on morphological characteristics and then calculating the percentage of colonization. A total of 18 AMF species were obtained, consisting of genera Glomus, Gigaspora, and Acaulospora. The species diversity of CMA is dominated by the genera Glomus. The highest number of AMF species was found in Mucuna bracteata, while the highest number of spores was found in Sorghum vulgare. The percentage of AMF colonization on Sorghum vulgare and Mucuna bracteata was 42.81% and 51.06%, indicated by the presence of arbuscules, external and internal hyphae, penetration points, and vesicles. Both types of plants are included in adaptive plants that can be in symbiosis with AMF.
Keyword: Akar, Hutan, Indonesia, Rizosfer, Spora, Forests, Indonesian, Rhizosphere, Roots, Spores

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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