Judul: Cendawan Mikoriza Arbuskula pada Sawo Duren (Chrysophyllum cainito) di Kampus IPB Darmaga
Abstrak: Arbuscular mycorrhizal fungi (AMF) are soil fungi that symbiosis with the plant roots. Research about AMF on fruit plants are rarely reported. The objectives of this research are to identify AMF spore and to detect the structure of arbuscular mycorrhiza (AM) on star apple. AMF spore was isolated from the star apple rhizosphere soil following the wet sieving and decanting method and centrifugation, and then identified based on shape, color, size, and spore wall ornamentation. The AM structure was observed on colored root using trypan blue. The result of the research showed that AMF was associated with star apple. The structures of AM in the roots of star apple were internal hyphae, coiled hyphae, and vesicles. The percentage of AM infection in the star apple’s root was 12-31 %. The AMF spores found in the star apple rhizosphere were Acaulospora bireticulata, A. scrobiculata, Ambispora cf. fecundisporum, Funneliformis cf. geosporum, Glomus cf. aggregatum, Glomus cf. microaggregatum, Glomus sp. 1, and Glomus sp. 2.
Keyword: Acaulospora, Ambispora, arbuscular mycorrhiza, Chrysophyllum cainito, Funneliformis, Glomus

Judul: Cendawan Mikoriza Arbuskula pada Kecapi (Sandoricum koetjape) di LIPI Cibinong
Abstrak: Research on the association of arbuscular mycorrhizal fungi (AMF) with plants fruits are still rarely done and kechapi (Sandoricum koetjape) is one of the plants that has not been studied. This study aims to identify AMF and arbuscular mycorrhiza structures on kechapi. Spores isolated from the rhizosphere soil samples of kechapi and pot culture. Spores were isolated by wet sieving and decanting method followed by centrifugation then later identified. Observations of arbuscular mycorrhiza structure on roots done by staining using trypan blue then observed structures of arbuscular, coiled hyphae, internal hyphae, and vesicles. The result showed that the percentage infection of roots of kechapi is 36-50%, and the structures of infections in roots of kechapi were coiled hyphae, internal hyphae, and vesicles. The genera of AMF assosiated with kechapi were Acaulospora, Funneliformis, Gigaspora, and Glomus
Keyword: Sandoricum koetjape, Glomus, Gigaspora, Funneliformis, arbuscular mycorrhizal fungi, Acaulospora

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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