Judul: Abundance and Potency of Endophytic Fungi to Suppress Yellow Leaf Curl Disease in Chilli Pepper (Capsicum annuum L.).
Abstrak: Incidence of yellow leaf curl diseases caused by Pepper yellow leaf curl begomovirus (PepYLCV) has become a major problem in chilli pepper growing area, especially in Java and Sumatra since early 2000. Disease incidence in the field may reach 20 % to 100% and the disease was obviously recognized by its unique symptoms involving bright yellow mosaic, mottle, curling, and stunting. A research was conducted to explore the potency of endophytic fungi as an alternative strategy to suppress PepYLC disease. Research activities consisted of 3 parts, i.e. (1) Isolation of endophytic fungi collected from chilli pepper plants at endemic area in Sleman, Yogyakarta; (2) Pathogenicity assay using chilli pepper seeds, and (3) Efficacy of selected endophytic fungi to suppress disease incidence. The result showed that diversity of endophytic fungi isolated from unsymptomatic plants were significantly higher than those from infected plants. There were 19 isolates of species identified from unsymptomatic plants; whereas 13 isolates from infected plants. Based on pathogenicity assay using 17 selected isolates, the endophytic fungi could be differentiated into 2 groups, i.e. pathogenic (13 isolates) and non-pathogenic (4 isolates). Further screening of non-pathogenic isolates showed that 4 isolates might have a potential as plant growth promoting fungi (PGPF) and 2 isolates, identified as Cercospora nicotianae and Pleosporaceae, might be recommended as bio-control agent. Endophytic fungi isolated in this study having potency as biocontrol agent was taken from low abundance population C. nicotianae was singleton and has potency as biocontrol agent for PepYLC disease.
Keyword: biocontrol agens, geminivirus, yellow leaf curl

Judul: Endophytic Fungi in the Control of Pathogen Fusarium oxysporum in Chili Plants (Capsicum annuum L.)
Abstrak: Chili (Capsicum annuum L.) is an important crop which has economic value. Cultivation of chili has a risk due to attack by pathogens. Alternative effort that can be used is using endophytic fungi as biological agents. Endophytic fungi are fungi that live in plant tissue. Many endophytic fungi are able to produce antibiotic compounds that active against bacteria and pathogenic fungi. The antimicrobial compounds produced are able to protect plant from infections. This study aims to determine endophytic fungi which has potential to control Fusarium oxysporum. Literature study begins with collect data from related book and scientific journal. the writing stage consists of several stages, are problem formulating, collecting data, analysing data, and giving conclusion with suggesting. The study shows that endophytic fungi can control F. oxysporum growth. The most effective endophytic fungus on in vitro are, Mucor sp. (73,4%), Neoscytalidium sp. (73,09%), Rhizopus sp. (69,6%), Helicomyces spp. (68,5%), and Penicillium sp. (66,4%). In vivo showed that Penicillium sp. can inhibit the growth of F. oxysporum in chili with a disease severity percentage of 2,78%.
Keyword: alternative, biological agents, potencial

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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