Judul: Isolation of Trichoderma from chili farming and its potential in degrading carbendazim fungicides
Abstrak: Cabai merupakan salah satu komoditas hortikultura penting di Indonesia yang dibutuhkan dalam kehidupan sehari-hari dan memiliki nilai ekonomis tinggi. Kebutuhan terhadap cabai terus meningkat sejalan dengan meningkatnya jumlah penduduk dan industri yang membutuhkan bahan baku cabai, namun produksi cabai tidak stabil dan dapat mengalami penurunan. Pada budidaya cabai terdapat beberapa faktor yang dapat menurunkan hasil produksi, salah satunya adalah adanya serangan hama dan penyakit tanaman. Para petani menanggulangi permasalahan hama dan penyakit tanaman tersebut dengan menggunakan pestisida kimia, salah satunya adalah karbendazim. Karbendazim (metil 2-benzimidazol karbamat) adalah fungisida berspektrum luas yang bekerja secara sistemik untuk mengendalikan berbagai macam cendawan patogen pada tanaman. Keberadaan karbendazim dalam tanah dapat mempengaruhi populasi mikroorganisme dalam tanah dan menjadi salah satu cemaran fungisida yang terdeteksi dalam makanan, tanah, dan air. Karbendazim memiliki persistensi lingkungan jangka panjang, oleh karena itu diperlukan mikroorganisme yang kompeten dan kompetitif secara ekologis untuk bioremediasi tanah dan reservoir air yang terkontaminasi, yaitu Trichoderma. Beberapa spesies Trichoderma memiliki enzim yang dapat mendegradasi xenobiotik dalam tanah. Penelitian ini bertujuan untuk menyeleksi, mengisolasi dan mengkarakterisasi spesies Trichoderma yang tumbuh pada tanah yang terpapar fungisida dan berpotensi mampu mendegradasi fungisida berbahan aktif karbendazim. Sepuluh isolat Trichoderma diisolasi dari dua lokasi perkebunan cabai yang diberi perlakuan fungisida berbasis karbendazim secara teratur, dengan kadar residu karbendazim dalam tanah 0,110 ̶ 0,119 ppm. Berdasarkan Analisis filogenetik menggunakan marka ITS, tujuh isolat (S1T1, S1T5, S2T1, S2T2, S2T3, S2T4, dan S2T5) sebagai T. asperellum, sedangkan tiga isolat (S1T2, S1T3, dan S1T4) diidentifikasi sebagai T. hamatum. Trichoderma asperellum S1T1 dan S2T3 menunjukkan toleransi terhadap karbendazim hingga 20 ppm dengan laju pertumbuhan diameter maksimum masing-masing 0,22 cm/hari dan 0,20 cm/hari. Penambahan kedua strain pada tanah dengan yang dikontaminasi 0,05 ̶ 1 ppm karbendazim, meningkatkan degradasi karbendazim sebesar 3% ̶ 11 % ., Chili is one of important horticultural commodities in Indonesia, which is needed in daily life and has high economic value. The need for chilies continues to increase in line with the increasing population and industries that need chili raw materials, but chili production is unstable and can experience a decline. In chili cultivation there are several factors that may reduce production, one of which is the presence of pests and plant diseases. The farmers tackle the problem of pests and plant diseases with chemical pesticides, one of which is carbendazim. Carbendazim (methyl 2-benzimidazol carbamate) is a broad-spectrum fungicide that works systemically to control various kinds of pathogenic fungi in plants. The presence of carbendazim in the soil can affect the microbiome in the soil and be recognized as contaminants in food, soil and water. Carbendazim has long-term environmental persistence, therefore a competent and ecologically competitive microorganism is needed for bioremediation of contaminated soil and water reservoirs, namely Trichoderma. Some Trichoderma species have enzymes that can degrade xenobiotics in soil. This study aims to screen, isolate and characterize Trichoderma species that have the potential to thrive in soil exposed to fungicides and are capable of degrading the fungicide carbendazim. Ten Trichoderma isolates were obtained from two chili plantation locations regularly treated with carbendazim-based fungicides, resulting in residual carbendazim levels of approximately 0.110 ̶
Keyword: Bioremediation, carbendazim residue, fungal identification, fungicide tolerance, soil

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: 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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