Judul: Penentuan dosis pemupukan N, P dan K pada budidaya katuk (Sauropus androgynus (L.) Merr.)
Abstrak: The objective of the research was to determine optimum rate of N, P, and K fertilizer for katuk (Sauropus androgynus (L.) Merr.) production. Experiments were conducted at vegetables garden Darmaga Field Unit University Farm, Bogor Agricultural University from May to December 2010. Treatments were N, P and K fertilizer at rate of 0%, 50%, 100%, 150% and 200% of fertilizer recommendation (100% N = 100 kg N.ha-1, 100% P = 135 kg P2O5.ha-1, 100% K = 135 kg K2O.ha-1). One hundred percent P, 50 % N, and 50 % K were applied before planting, while 25% N and 25% K were applied at 3rd and 6th week after planting. This experiment used randomized completely block design with four replications. Plot size was 5 m x 1.5 m. Katuk cuttings were planted in double rows per plot, with plant spacing of 50 cm x 25 cm. Results showed that N application had no effect on vegetative growth but increased on yield with a linear response pattern. P fertilizer application increased on plant height but had no effect on yields. K fertilizer treatment effected on yield with quadratic respon pattern. Multi-nutrient response approach was not applicable to this experiment, but the results of K fertilization treatment could be used to determine the maximum dose of fertilizer. Based on these formulated, equation was y=-0.0012x2+0.2529x+68.059 for K2O. The optimum rate for K was 105 kg K2O.ha-1.
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Judul: Effect of Fertilization Dosage on Growth and  Production of Katuk (Sauropus androgynus) Cuttings Using Fertigation Through  Drip Irrigation
Abstrak: Keberadaan tanaman indigenous dapat menambah pilihan jenis sayuran sebagai konsumsi masyarakat. Salah satu tanaman yang masuk dalam tanaman indigenous adalah katuk. Untuk menunjang pertumbuhan tanaman katuk yang maksimal diperlukan adanya aplikasi pemupukan dan penyiraman yang efisien. Penelitian ini bertujuan mengetahui dosis pemupukan yang optimal pada budidaya katuk. Kegiatan penelitian dilaksanakan mulai bulan November 2022 hingga April 2023 di Kebun Percobaan Leuwikopo. Percobaan dilakukan dengan metode rancangan kelompok lengkap teracak sebanyak tiga kali ulangan. Penelitian terdiri dari faktor tunggal yaitu dosis pupuk N, P, dan K dengan lima taraf dosis (0%, 50%, 100%, 150%, 200%). Hasil penelitian menunjukkan bahwa pengaruh dari pemupukan tidak memberikan respon yang nyata, kecuali pada peubah tinggi cabang pada umur tanaman 10-13 MST. Meskipun tidak berpengaruh nyata, terdapat indikasi bahwa bobot basah, bobot daun, dan produktivitas total akan meningkat seiring peningkatan dosis pupuk yang diberikan., The existence of indigenous plants can increase the choice of vegetables for public consumption. One of the indigenous plants is katuk. To support the maximum growth of katuk plants, efficient fertilization and watering applications are needed. This study aims to determine the optimal dose of fertilization in katuk cultivation. Research activities were carried out from November 2022 to April 2023 at the Leuwikopo Experimental Garden. The experiment was conducted using a randomized complete group design method with three replications. The research consisted of a single factor, namely the dose of N, P, and K fertilizers with five dose levels (0%, 50%, 100%, 150%, 200%). The results showed that the effect of fertilization did not give a real response, except for the variable of branch height at plant age 10-13 weeks after planting. Although not significantly affected, there are indications that wet weight, leaf weight, and total productivity will increase as the dose of fertilizer applied increases.
Keyword: indigenous vegetables, inorganic fertilizer, productivity

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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