Judul: The Effect of Urea Fertilization and Varieties on Maize (Zea mays L.) Plants in Terms of Biomass and Seed Production
Abstrak: Jagung merupakan tanaman pangan yang mempunyai peran strategis dalam pembangunan pertanian dan perekonomian nasional. Produktivitas jagung sangat ditentukan oleh mutu genetik varietas yang ditanam dan pemupukan yang tepat. Kegiatan penelitian ini bertujuan mengetahui pengaruh pemupukan berbagai dosis pupuk urea terhadap dua varietas jagung yang ditanam melalui produksi biomassa dan biji. Penelitian dilakukan pada Januari hingga Mei 2023 di Kebun Percobaan Leuwikopo Departemen Agronomi dan Hortikultura, Institut Pertanian Bogor, Dramaga, Bogor, Jawa Barat. Penelitian dilaksanakan menggunakan rancangan petak terbagi dalam rancangan kelompok lengkap teracak dengan tiga kali ulangan. Perlakuan terdiri dari 2 faktor yaitu varietas dan dosis pupuk urea. Varietas sebagai petak utama dan dosis pupuk urea sebagai anak petak. Dua varietas jagung, BISI 18 (hibrida) dan Bisma (komposit) ditanam dan dipupuk dengan dosis urea 0, 175, 350, dan 525 kg ha-1 . Peningkatan dosis urea hingga 525 kg ha-1 secara linier meningkatkan total bobot kering, bobot tongkol dengan kelobot, bobot tongkol tanpa kelobot, diameter tongkol, bobot biji per tongkol, dan bobot biji per plot. Tinggi tanaman, jumlah daun, diameter batang, panjang tongkol, dan nilai SPAD menunjukkan respon kuadratik dengan dosis urea optimum masing-masing 461,25, 435, 350, 435 dan 518 kg ha-1 . Dosis urea 439,25 kg ha-1 merupakan dosis optimum untuk mencapai produktivitas tinggi pada kedua varietas tersebut., Maize is a food crop that has a strategic role in the development of agriculture and the national economy. Maize productivity is largely determined by the genetic quality of the varieties planted and proper fertilization. This research activity aims to determine the effect of fertilizing various doses of urea fertilizer on two varieties of corn grown through the production of biomass and seeds. The research was conducted from January to May 2023 at the Leuwikopo Experimental Garden, Department of Agronomy and Horticulture, IPB University, Dramaga, Bogor, West Java. The research used a split-plot design in a completely randomized group design with three replications. The treatment consisted of 2 factors, variety and dose of urea fertilizer. The variety is the main plot and the dosage of urea fertilizer is the sub-plot. Two maize varieties, BISI-18 (hybrid) and Bisma (composite) were grown and fertilized with urea doses of 0, 175, 350, and 525 kg ha-1 . The increasing urea dose up to 525 kg ha-1 linearly increased the total dry weight, ear weight with husks, ear weight without husk, ear diameter, seed weight per ear, and weight of seed per plot. Plant height, number of leaves, stem diameter, cob length, and SPAD values showed a quadratic response with optimum urea doses of 461.25, 435, 350, 435, and 518 kg ha-1 , respectively. The urea dose of 439.25 kg ha-1 is the optimum dose to achieve high productivity for both varieties.
Keyword: ear weight, ear diameter, optimum dose, productivity, total dry weight

Judul: The Effect of N Doses Fertilizer and Varieties on Corn Growth and Production in Saturated Soil Culture in Rice Fields
Abstrak: Jagung (Zea mays L.) merupakan komoditas pangan kedua setelah beras yang berperan sebagai sumber karbohidrat. Peningkatan konsumsi jagung perlu diseimbangi dengan peningkatan produktivitas. Penelitian bertujuan mengetahui pengaruh dosis pupuk N dan varietas terhadap pertumbuhan dan produksi jagung pada budidaya jenuh air di lahan sawah. Penelitian menggunakan rancangan percobaan RKLT dengan dua faktor yaitu varietas dan dosis pupuk N. Faktor varietas terdiri atas dua taraf yaitu jagung Sukmaraga dan Pioneer 27. Faktor dosis pupuk N terdiri atas 0 kg N ha-1, 90 kg N ha-1, 135 kg N ha-1, dan 180 kg N ha-1. Hasil penelitian menunjukkan bahwa faktor varietas menunjukkan hasil yang berbeda di awal pertumbuhan yaitu pada karakter tinggi tanaman, diameter batang, dan jumlah daun, serta bobot basah akar. Selain itu terdapat perbedaan pada komponen hasil yaitu pada karakter diameter tongkol, jumlah baris biji per tongkol, dan bobot 100 biji. Dosis N 180 kg N ha-1 memberikan hasil terbaik untuk semua karakter pertumbuhan dan produksi namun tidak berbeda nyata dengan dosis N 135 kg N ha-1. Tidak terjadi interaksi antara faktor varietas dan dosis N., Corn (Zea mays L.) is the second food commodity after rice which acts as a carbohydrate source. Increased consumption of corn needs to be balanced with productivity. This study aims to determine the effect of N fertilizer dosage and varieties on the growth and production of maize in saturated soil culture in paddy fields. This study used an Randomized Complete Block design (RCBD) with two factors, namely the variety and dose of N fertilizer. Variety factors consisted of two levels, namely Sukmaraga and Pioneer 27. The dosage factor for N fertilizer consisted of 0 kg N ha-1 , 90 kg N ha-1, 135 kg N ha-1, and 180 kg N ha-1. The results of this study indicated that the variety factor showed different results at the character of plant height, stem diameter, number of leaves, and root wet weight,the ear diameter, number of seed rows per ear, and the weight of 100 seeds. The N dose of 180 kg N ha-1 gave the best results for all growth and production characters but was not significantly different from the N dose of 135 kg N ha-1. There was no interaction between the variety factor and the N dose.
Keyword: Nitrogen dose, Pioneer 27, Saturated soil culture, Sukmaraga

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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