Judul: Evaluasi Produksi Bibit Sengon (Paraserianthes falcataria (L.) Nielsen) di Persemaian Rumpin
Abstrak: Pemerintah menargetkan untuk membangun 30 pusat persemaian. Salah satu persemaian yang dibangun adalah Persemaian Rumpin di Kabupaten Bogor yang memproduksi berbagai jenis bibit tanaman kehutanan, seperti adalah sengon. Penilaian mutu bibit perlu dilakukan untuk mendapatkan standar mutu bibit, namun belum ada kajian mengenai penilaian mutu bibit sengon di Persemaian Rumpin. Penelitian ini bertujuan mengevaluasi proses produksi, kondisi, dan mutu bibit sengon di Persemaian Rumpin. Prosedur penelitian meliputi proses produksi bibit sengon, penilaian mutu bibit sengon, perhitungan indeks kekokohan, penetapan standar mutu bibit sengon, dan analisis data. Proses produksi bibit sengon dimulai dari pengadaan benih, penyiapan media tanam, penaburan dan perkecambahan benih, pemeliharaan bibit sengon di daerah naungan, dan pemeliharaan bibit sengon di daerah terbuka. Hasil penelitian menunjukkan bahwa kondisi bibit sengon memiliki nilai persyaratan umum 87% dan rata-rata persyaratan khusus 84,75%. Mutu bibit sengon yang didapatkan adalah Mutu Kedua (D) dan dianggap tidak lulus uji, sehingga perlu dilakukan perbaikan kualitas bibit.
Keyword: production, quality, seedlings, sengon

Judul: Identification and Disease Severity of Dieback Disease on Sengon Seedlings in Persemaian Permanen Dramaga Bogor
Abstrak: Sengon merupakan salah satu komoditas tanaman kehutanan yang digemari masyarakat. Sehingga pengadaan semai sehat di persemaian sangat penting dilakukan dalam upaya mencapai keberhasilan tanam. Namun, sengon sangat rentan terhadap beberapa penyakit. Salah satu penyakitnya yaitu penyakit mati pucuk di persemaian. Penelitian ini bertujuan menghitung kejadian penyakit dan keparahan penyakit mati pucuk pada semai sengon di Persemaian Permanen Dramaga Bogorserta mengidentifikasi jenis patogen penyebab penyakit mati pucuk pada semai sengon. Metode pengambilan data dilakukan menggunakan metode sensus dan skoring. Selain itu, proses identifikasi dilakukan di bawah mikroskop cahaya dengan perbesaran 40x10. Analisis data dilakukan menggunakan analisis deskriptif. Persentase kejadian penyakit dan keparahan penyakit mati pucuk pada semai sengon berturut-turut sebesar 10,809% dan 73,764% yang mana keparahan penyakit dinyatakan berat. Berdasarkan hasil identifikasi, cendawan Rhizoctonia sp. diduga sebagai penyebab penyakit mati pucuk pada semai sengon., Sengon is one of the forestry plant commodities favored by the community. So that the provision of healthy seedlings in the nursery is significant to achieve successful planting. However, sengon is very susceptible to several diseases. One of the diseases is dieback in the nursery. This study aims to calculate the incidence and severity of shoot death in sengon seedlings in Persemaian Permanen Dramaga Bogor and identify the types of pathogens that cause dieback in sengon seedlings. Methods of data collection carried out using the census and scoring methods. In addition, the identification process carried out under a light microscope with a magnification of 40x10. Data analysis performed using descriptive analysis. The percentage of disease incidence and dieback severity in sengon seedlings were 10.809% and 73.764%, where the severity of the disease is declared as severe. Based on the identification results, the fungus Rhizoctonia sp. is suspect as the cause of dieback in sengon seedlings.
Keyword: dieback, disease severity, nursery, Rhizoctonia sp., sengon

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.
Keyword: