Judul: Fungal Identification of Colletotrichum sp. from Red Chili (Capsicum annuum L.) Seeds and its Elimination Technique with Electroteraphy
Abstrak: Anthracnose is one of the important diseases in chili plants. The antrachnose fungus is also known to be seed-borne. Control measures applied to the seed phase is an effective strategy to reduce initial number of inoculum and the risk of transmission during planting. Electrotherapy shows potential as an alternative for controlling pathogens associated with seeds. This study aims to identify the fungus isolated from chilies with anthracnose symptom and to eliminate the pathogen from its seeds using electrotherapy technique without reducing the quality of seeds. The fungal colony on PDA was white, colony diameter rate at 3.71 mm per day. The hyphae was septate and branched, bearing cylindrical conidia with one of the edges tapered and aseptate, conidia length around 5.69 -9.78 µm and widths ranging from 2.30-3.19 µm. PCR amplification using a specific primer of Colletotrichum acutatum CaInt-2/ ITS4 showed DNA band size of ± 490 bp. Nucleotide analysis of PCR amplicon employing universal primers ITS5/ITS4 showed that CRSB isolates had 100% homology using contig results and 99.8% using forward fragments with nucleotide isolates Colletotrichum sp. in GenBank. Electrotherapy of healthy seeds and fungal with a DC 12 V 1 A electric current and 0.5 M NaCl concentration results in a treatment window at 20-25 minutes electrotherapy which can reduce the number of fungal colonies, but can maintain seed viability remains high. Electrotherapy for infected seeds at 20 and 25 minutes showed that seed viability was not so different., Antraknosa merupakan salah satu penyakit penting pada tanaman cabai. Cendawan penyebab antraknosa diketahui dapat bersifat terbawa benih. Pengendalian patogen yang diterapkan pada fase benih menjadistrategi yang efektif untuk menekan patogen ini sejak dini sehingga dapat mengurangi risiko penularan saat penanaman. Elektroterapi menunjukkan potensi sebagai alternatif untuk mengendalikan patogen terbawa benih. Penelitian ini bertujuan mengidentifikasi cendawan dari buah cabai bergejala antraknosa dan mengeliminasi patogen dari benih tersebut dengan teknik elektroterapi tanpa menurunkan kualitas benih. Koloni cendawan pada media PDA berwarna putih dengan pertumbuhan koloni 3.71 mm per hari, hifa bersekat dan bercabang, konidia silindris dengan salah satu ujungnya meruncing dan tidak bersekat, panjang konidia 5.69-9.78 µm dan lebar 2.30-3.19 µm. Amplifikasi PCR menggunakan primer spesifik Colletotrichum acutatum CaInt-2/ITS4 menunjukkan pita DNA berukuran ± 490 pb. Analisis nukleotida hasil amplifikasi PCR dengan primer universal ITS5/ITS4 menunjukkan isolat CRSB memiliki homologi 100% menggunakan hasil contig dan 99.8% menggunakan fragmen forward dengan nukleotida isolat Colletotrichum sp. yang ada pada GenBank. Elektroterapi benih sehat dan suspensi cendawan dengan arus listrik DC 12 V 1 A serta konsentrasi NaCl 0.5 M menghasilkan treatment window pada waktu elektroterapi 20-25 menit yang dapat menurunkan jumlah koloni cendawan, tetapi dapat mempertahankan viabilitas benih tetap tinggi.
Keyword: Era Lutfi, Antraknosa, Colletotrichum, Benih cabai, Elektroterapi

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: 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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