Judul: The Effect of Melaleuca and Tumeric Essential Oils in Impending the Growth of Rhizoctonia sp. in Vitro
Abstrak: Tanaman yang terserang penyakit dapat merugikan berbagai aspek, salah satunya dapat menurunkan kualitas tanaman. Penggunaan pestisida nabati merupakan salah satu solusi untuk mencegah serangan penyakit. Penelitian ini bertujuan mengetahui daya hambat dan konsentrasi minyak atsiri yang bekerja optimal. Pengamatan dilakukan dengan menggunakan minyak atsiri kayu putih, minyak atsiri kunyit, dan kombinasi keduanya dengan konsentrasi 1%, 3%, dan 5% pada media PDA dan media PDB. Hasil penelitian ini dianalisis dengan rancangan acak lengkap faktorial dan uji lanjutan apabila berpengaruh nyata. Hasil pengamatan menunjukkan minyak atsiri yang optimal sebagai penghambat pertumbuhan patogen adalah minyak atsiri kunyit konsentrasi 3% dan minyak atsiri kombinasi konsentrasi 5%.
Keyword: Deuteromycota, eucalyptus, factorial complete randomized design, turmeric, vegetable pesticides

Judul: The Effect of Turmeric Essential Oil in the Growth of Rhizoctonia sp. in Vitro
Abstrak: Rhizoctonia sp. merupakan salah satu cendawan patogen yang sering menyebabkan kerusakan tanaman di persemaian dimana penyebarannya sangat luas. Pengendalian hayati yang ramah lingkungan merupakan salah satu solusi untuk menekan penyebarannya. Minyak atsiri memiliki kandungan bahan aktif sebagai alternatif mengurangi ketergantungan kimia sintetik yang kurang ramah lingkungan. Penelitian ini bertujuan untuk menganalisis pengaruh minyak atsiri kunyit dalam menghambat pertumbuhan patogen Rhizoctonia sp. secara in vitro. Penelitian ini menggunakan metode pemberian minyak atsiri kunyit dengan beberapa konsentrasi yaitu 1%,5%,10% dan kontrol pada media PDA dan PDB. Pengamatan selanjutnya dilakukan secara makroskopis dan mikroskopis. Hasil penelitian menunjukkan bahwa nilai hambat tertinggi terdapat pada perlakuan kunyit 10%. Efektivitas pengendalian patogen Rhizoctonia sp. dipengaruhi oleh tingkat konsentrasi dan kandungan bahan aktif dalam minyak atsiri., Rhizoctonia sp. is one of the pathogenic fungi that often cause damage to plants in nurseries, where its spread is widespread. Environmentally friendly biological control is needed. Essential oils contain active ingredients as an alternative to reduce dependence on less environmentally friendly synthetic chemicals. This study aimed to analyze the effect of turmeric essential oil in the growth of Rhizoctonia sp. pathogen in vitro. The study applied turmeric essential oil at various concentrations, namely 1%, 5%, 10%, and a control, on PDA and PDB media, followed by macroscopic observations. The results showed that the highest controlling value was observed in the 10% turmeric concentration on both PDA and PDB media. The results of the study indicated that the highest inhibitory effect is observed in the 10% turmeric treatment. The effectiveness of controlling the Rhizoctonia sp. pathogen was influenced by the concentration level and active ingredients present in the essential oil.
Keyword: Essential Oil, in vitro, pathogen, Rhizoctonia sp., turmeric

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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