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: Keefektifan Cendawan Endofit untuk Menekan Infeksi Chilli veinal mottle virus pada Tanaman Cabai (Capsicum annuum L.)
Abstrak: Chillipepper is an important horticultural commodity in Indonesia because of it’s economics and consumption value. Infection of Chilli veinal mottle virus (ChiVMV) is a constraint to chillipepper production. This research is conducted to evaluate the potency of 3 isolates of endophytic fungi (H1, H5, and H12) to suppress ChiVMV infection and to improve growth of chillipepper. The endophytyic fungi was applied through seed treatment and leaf spray on chillipepper variety TM88. Virus inoculation was done mechanically and virus detection was conducted using Double Antibody Sandwich ELISA (DAS ELISA). Experiment was conducted using randomized complete design with 4 treatments of endophytic fungi i.e. fungi isolate H1, H5, aH12, and without endophytic fungi each with 3 replication. Observation was made for disease incidence, plant height, and root volume. Data analysis was conducted using ANOVA followed by Duncan test at 5%. ELISA absorbance value indicated that treatment of endophytic fungi (H1, H5, and H12) can suppress ChiVMV, although the disease incidence is still high. Endophytic fungi isolate H5 tends to improve plant growth showed by its potency to increase plant height up to 4 weeks after planting.
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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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