Judul: Karakteristik Dan Pengelolaan Lahan Budidaya Tanaman Krisan (Chrysanthemum Sp.) Di PT. Agrobumi Puspa Sari Sukabumi
Abstrak: Study was carried out at PT. Agrobumi Puspa Sari Selabinta Sukabumi. Aim of this study were to foccused on chrysanthemum land management and different characteristics of grass field, ex-paddy field, ex-unirrigated field and exchrysanthemum plantation in order to improve cultivation system of chrysanthemum. Oral and written information about land management of chrysanthemum cultivation including propagation, land preparation, planting, maintenance (dead seedlings replacing, watering, fertilizing, radiation addition, pest and disease controlling, bud elimination) and harvesting were recuperated. Soil characteristics in this study were pH, exchangeable AI, K, Ca, Mg, Na, Cation Exchange Capacity (CEC), organic-C, total N, available P and micro elements (Fe, Mn, Zn, and Cu).
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Judul: Keanekaragaman Hama dan Penyakit pada Tanaman Krisan (Chrysanthemum spp.)
Abstrak: Ornamental plants are horticultural commodities which have great market demand because of their beauty and aesthetics. One of the important ornamental plants in the world is chrysanthemum. The purpose of this observation was to know the variety of insect pest and pathogen, and also know about intensity and severity on different plant age. Data were collected though interview with farmers and direct observations in the fields. Identification of insect pests and pathogen were conducted in the laboratory. The result showed that diseases found in the fields were white rust (Puccinia horiana), black rust (Puccinia chrysanthemi), fusarium (Fusariumoxysporium), downy mildew, powdery mildew (Oidium chrysanthemi), leaf blight (Helminthosporium sp.), dwarf (Chrysanthemum stunt viroid), pythium (Pythium spp.), and grey mould (Botrytis cinerea). Pests found in chrysanthemum were whitefly (Bemisia tabaci Gennadius.), leaf miner (Lyriomiza huidobrensis Blanchard.), aphids (Aphis gossypii Glover. and Macrosiphoniella sanborni Gillete.), armyworm (Spodoptera litura Fabricius.), dan thrips (Thrips parvispinus Karny.). Insect pests and pathogens management conducted by farmers were organic fertilize rountinely, removing diseased leves, weed control, and pesticide application.
Keyword: plant age, plant pathogen, insect pest, chrysanthemum, ornamental plants

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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