Judul: Mycobiota on chilli fruits: their effect on colletotrichum capsici, causing anthracnose
Abstrak: Colletotrichum capsici merupakan cendawan patogen penyebab antraknosa pada berbagai buah tropis, terutama pada buah cabai. Penggunaan agens kontrol biologi merupakan alternatif pengendalian penyakit pascapanen pada produk hortikultura. Penelitian ini bertujuan untuk menguji potensi antagonistik mikobiota pada buah cabai terhadap C. capsici. Cendawan patogen dan cendawan uji diisolasi dari buah cabai merah besar var. Imperial-308 dan Hibrida F1 Maraton yang diperoleh dari 3 pasar tradisional di Kotamadya Bogor. Isolasi C. capsici menghasilkan 4 isolat. Colletotrichum capsici CPB I.1 memiliki patogenisitas tertinggi pada buah cabai merah besar var. IPB Perbani. Isolasi cendawan uji dilakukan dengan menggunakan metode pengenceran serial yang dilanjutkan dengan metode cawan tuang menghasilkan 14 isolat, terdiri atas 7 isolat cendawan berfilamen dan 7 isolat khamir. Uji antagonisme dilakukan dengan menggunakan metode oposisi langsung pada media Potato Dextrose Agar (PDA) menghasilkan 4 isolat cendawan antagonis yang menyebabkan persentase hambatan pertumbuhan lebih dari 70% terhadap C. capsici CPB I.1, yaitu 3 isolat cendawan berfilamen (Plectosphaerella cucumerina, isolat MF 2, dan Aspergillus flavus) dan 1 isolat khamir (Issatchenkia orientalis). Dua cendawan antagonis (P. cucumerina dan I. orientalis) tidak menyebabkan penyakit pada buah cabai var. IPB Perbani, sehingga berpotensi sebagai agens kontrol biologi., Colletotrichum capsici is a pathogenic fungus causing anthracnose on various tropical fruits, especially chilli fruit. Biological control agents have been used as an alternative to control postharvest diseases. This study aims to examine the antagonistic potential of mycobiota on chilli fruit against C. capsici. Pathogenic fungus and test fungi were isolated from red chilli fruits var. Imperial- 308 and Hibrida F1 Maraton collected from 3 traditional markets in Municipality of Bogor. Four isolates of C. capsici were obtained from red chilli fruits infected by anthracnose. Colletotrichum capsici CPB I.1 showed the highest pathogenicity on red chilli fruits var. IPB Perbani. Fourteen isolates of test fungi were obtained from healthy red chilli fruits using serial dilution method, followed by pour plate method. They consisted of 7 filamentous fungi and 7 yeast isolates. Test of antagonism using direct opposition method on PDA obtained 4 antagonist fungal isolates which inhibited the growth of C. capsici CPB I.1 more than 70%. They consisted of 3 filamentous fungi (Plectosphaerella cucumerina, isolate MF 2, and Aspergillus flavus) and 1 yeast (Issatchenkia orientalis). Two isolates of antagonist fungi (P. cucumerina and I. orientalis) did not cause any diseases of chilli fruits var. IPB Perbani, consequently they can be used as biocontrol agents. Keywords: anthracnose, chilli fruit, Colletotrichum capsici, mycobiota
Keyword: antraknosa, buah cabai, Colletotrichum capsici, mikobiota

Judul: Keefektifan Kitosan dan Aktinomiset dalam Pencegahan Busuk Antraknosa (Colletotrichum capsici (Syd.) Butler & Bisby) Buah Cabai Merah
Abstrak: Anthracnose due to Colletotrichum capsici is one disease that can decrease the quantity and quality of chillies production in Indonesia. Chitosan and actinomycetes are now widely used in controlling various plant diseases. The objectives of this research have been designed to evaluate the effectiveness of chitosan and two isolates of actinomycetes in preventing anthracnose on red chilli. In vitro test was conducted through baiting poisonous methods, while in vivo test has been done by solution coating of chitosan, isolate actinomycetes of APS5 and APS12, and their combination on the red chilli. The experiment had been done in a completely randomized design with 4 replications. The variables observed were the diameter growth of fungal colonies C. capsici, relative prevention growth, disease severity, and the rigidity of red chilli. The results of in vitro experiment showed that the concentration suspension of APS12, APS5, and APS512 (10%) were effective in suppressing the growth of C. capsici with 57%-72% of relative prevention growth. In vivo experiment showed that the coating of 1% CT, CTAPS5, CTAPS12 could reduce disease severity of C. capsici and lengthen the shelf life of red chilli until 10 days.
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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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