Judul: Antagonistic Activity of Dark Septate Endophyte against Fusarium sp. Isolated from Wilted Chili Plants
Abstrak: Cabai (Capsicum annuum L.) merupakan salah satu komoditas pertanian yang bernilai tinggi, namun produktivitasnya seringkali terkendala oleh serangan layu fusarium. Beberapa kultur cendawan dark septate endophyte (DSE) dilaporkan dapat menekan pertumbuhan Fusarium spp., namun potensi DSE sebagai agen biokontrol layu fusarium pada cabai belum banyak diteliti. Dalam penelitian ini, dua isolat DSE (S51 dan Cladosporium sp. KSP1) dievaluasi potensi antagonisnya terhadap Fusarium penyebab layu bibit cabai. DSE diuji patogenisitasnya untuk mengonfirmasi bahwa DSE tersebut bukan patogen pada cabai. Sebanyak dua strain Fusarium sp. asal tanaman cabai dengan gejala layu fusarium diseleksi patogenisitasnya pada tanaman cabai berusia 2 minggu. Fusarium sp. yang menunjukkan sifat patogenisitas tinggi dipilih untuk uji antagonis dengan DSE. Hasil penelitian menunjukkan Fusarium sp. strain F1 memiliki patogenisitas yang paling tinggi pada bibit cabai. Inokulasi DSE pada benih cabai membuktikan DSE tidak memengaruhi daya kecambah cabai. Panjang tajuk serta panjang akar bibit cabai ini tidak berbeda nyata dengan kontrol, sehingga kedua strain DSE dinyatakan bersifat non-patogenik. Kedua strain DSE dapat menghambat pertumbuhan Fusarium sp. strain F1 secara in vitro dengan persentase penghambatan antara 18 – 23%. Penelitian lebih lanjut tentang efektifitas DSE dalam menghambat perkembangan gejala layu diperlukan sebelum DSE dinyatakan sebagai agen potensial pengendali layu fusarium pada cabai., Chili (Capsicum annuum L.) is a high-value commodity, but its productivity is often constrained by fusarium wilt attacks. The dark septate endophyte (DSE) have been reported to inhibit the growth of Fusarium spp., however the potential of DSE as a biocontrol agent for fusarium wilt in chili has not been investigated. In this study, two DSE strains (S51 and Cladosporium sp. KSP1) were evaluated for their antagonistic potential against Fusarium isolated from chili with wilt symptom. DSE was tested for pathogenicity to determine its virulence on chili plants. Two strains of Fusarium sp. that were obtained from wilted chili plants were examined for its pathogenicity on 2-weeks-old chili seedling. Fusarium which showed high pathogenicity was evaluated through antagonist test against DSE. The results showed that Fusarium sp. strain F1 has the highest pathogenicity. Both DSE strains had no effect on chili germination and were found to be non-pathogenic as shoot and root length of chili seedlings did not differ significantly from those of control. Both DSE were able to inhibit the growth of Fusarium sp. F1 in vitro about 18 to 23%. Further research is needed to determine the effectiveness of DSE in suppressing the development of wilt symptoms in chili plants.
Keyword: antagonist test, biocontrol agent, chili seedling, fusarium wilt, pathogenicity

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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