Judul: Growth and Productivity of Sorghum First Ratoon Variety Samurai 1 with the Addition different of Urea Fertilizer and Harvest Ages
Abstrak: Penelitian ini bertujuan mengetahui pertumbuhan dan produktivitas tanaman sorgum manis ratun pertama varietas Samurai 1 dengan perlakuan pemberian dosis pupuk urea dan umur panen yang berbeda. Penelitian dilaksanakan di Unit Pendidikan Penelitian Peternakan (UP3J) Jonggol dan Laboratorium Agrostologi, Ilmu Gizi dan Teknologi Pakan Fakultas Peternakan Institut Pertanian Bogor selama 4 bulan. Rancangan percobaan yang digunakan adalah RAKF (Rancangan Acak Faktorial) dengan pola 3 x 3 dan empat kali ulangan. Penelitian ini terdiri dari 3 perlakuan pemupukan dan 3 perlakuan umur panen. Perlakuan tersebut adalah P1 (pemupukan N 100 kg ha-1), P2 (pemupukan N 200 kg ha-1), P3 (pemupukan N 300 kg ha-1), T1 (umur panen 60 hari), T2 (umur panen 65 hari), T3 (umur panen 65 hari). 70 hari). Data dianalisis dengan analisis varian (ANOVA), jika ada signifikansi dilanjutkan dengan uji Duncan. Peubah yang diamati adalah pertambahan tinggi, diameter, jumlah daun, jumlah anakan, biomassa, berat segar, berat kering, dan nilai brix. Hasil penelitian menunjukkan ada interaksi antara dosis pupuk urea dan umur panen terhadap berat segar total dan berat segar daun. Umur panen berpengaruh nyata terhadap tinggi tanaman, diameter jumlah daun, jumlah anakan, biomassa, berat segar, berat kering oven, dan nilai brix. Pemupukan tidak berpengaruh nyata, tetapi perlakuan pemupukan urea 200 kg ha-1 dan umur panen 70 hari pada sorgum ratun pertama Samurai 1 memiliki nilai tertinggi pada tinggi tanaman, diameter, jumlah daun, jumlah anakan berat kering oven daun, dan batang., This study aimed to evaluate the growth and productivity of the first ratoon sorghum Samurai 1 with the treatment of urea fertilizer doses and different harvest age. The research was conducted at the Jonggol Animal Research Education Unit (UP3J) and the Laboratory of Agrostology, Nutrition Science and Feed Technology, Faculty of Animal Science, Bogor Agricultural University for 4 months. The experimental design used was Factorial Randomized Design (FRD) with a 3 x 3 pattern and four replications. This study consisted of 3 treatments of fertilization and 3 treatments of harvest age. The treatments were P1 (fertilizing 100 kg N ha-1), P2 (fertilizing 200 kg N ha-1), P3 (fertilizing 300 kg N ha-1), T1(harvested at 60 days age), T2 (harvested at 65 days age), T3 (harvested at 70 days age). The data was analyzed by analysis of variance (ANOVA), and if there were any significances, it will be continued with Duncan test. The variables observed were increased in height, diameter, number of leaves, number of tillers, biomass, fresh weight, dry weight, and brix content. The results showed there was an interaction between urea fertilizer dose and harvest age on total fresh weight and leaf fresh weight. Harvest age had a significant effect on plant height, leaf diameter, number of tillers, biomass, fresh weight, oven dry weight, and brix content. Fertilization had no significant effect, but urea fertilization treatment of 200 kg ha-1 and harvest age of 70 days on the first ratoon sorghum Samurai 1 had the highest values on plant height, diameter, number of leaves, number of tillers, oven dry weight of leaves, and stems.
Keyword: growth, harvest age, productivity, sorghum, urea fertilizer

Judul: Growth and Production of Sorghum Varieties of Samurai 1 Second Ratun by Treatment with Urea Fertilizer Dosage and Harvest Age
Abstrak: Sorgum merupakan tanaman serealia yang tumbuh di daerah tropis serta lahan marginal yang tahan terhadap kekeringan. Percobaan ini bertujuan mengevaluasi pertumbuhan dan produksi biomassa varietastanaman sorgum (Sorgum bicolor (L.) Monech) samurai 1 berasal dari turunan benih penjenis pada ratun kedua dengan dosis N dan umur panen. Penelitian ini menggunakan rancangan acak kelompok faktorial dengan 3 taraf urea, yaitu P1 (100 kg urea ha-1 ), P2 (200 kg urea ha-1 ), dan P3 (300 kg urea ha-1 ), dan 3 umur panen, yaitu T1 60 hari setelah panen (HSP), T2 65 HSP dan 70 HSP dengan 4 ulangan kelompok. Hasil penelitian menunjukkan bahwa tidak terdapat perbedaan nyata pada interaksi antar perlakuan terhadap pertumbuhan dan produksi sorgum. Hasil biomassa terbaik sebesar 63,80 ton ha-1 ditunjukkan oleh perlakuan 200 kg urea ha-1 dan 70 HSP. Kesimpulan dari penelitian ini adalah sorgum Samurai 1 yang dipupuk 200 kg urea ha-1dan dipanen pada umur 70 HSP menghasilkan pertumbuhan dan produksi biomassa tertinggi., Sorghum is a cereal plant that growsin the tropics and marginal landsthat are resistant to drought. This experiment was aimed to evaluate the growth and biomass production of the samurai 1 (Sorghum bicolor (L.) Monech) harvested at derivative time at second regrowing ratoon combined with N. This study used a factorial randomized design with 3 levels of urea, namely P1 (100 kg urea ha-1 ), P2 (200 kg urea ha-1 ), and P3 (300 kg urea ha-1 ), and 3 harvest if time, namely T1 60 days after harvest (DAH), T2 65 DAH and 70 DAH with 4 replicate groups. The results showed that there was no significant difference in the interaction between treatments on growth and production of sorghum. The best biomass yield of 63.80 tons ha-1 was indicated by the treatment of 200 kg urea ha-1 and 70 DAP. The conclusion of this study was that Samurai 1 sorghum fertilized with 200 kg urea ha1 and harvested at 70 DAP resulted in the highest growth and biomass production.
Keyword: Harvest age, production, sorghum, urea

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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