Judul: Effects of Plant Density and Nodes Cutting on Sweetpotato (Ipomoea batatas L.) Growth and Yield in Polybag in Context of Urban Farming
Abstrak: Ubi jalar (Ipomoea batatas L.) memiliki potensi dalam pertanian perkotaan. Stek mini dapat menurunkan kebutuhan bahan tanam. Kerapatan tanam yang lebih tinggi dapat meningkatkan efisiensi lahan. Penelitian ini bertujuan untuk menentukan jumlah buku bibit dan kerapatan tanam yang optimal bagi pertanian kota yang efisien. Penelitian dilakukan antara Mei - Oktober 2021 di Setu, Tangerang Selatan. Penelitian dirancang dengan split plot-rancangan kelompok lengkap teracak (SP-RKLT). Faktor pertama adalah jumlah buku bibit dengan taraf 2, 4, dan 6 buku. Faktor kedua adalah kerapatan tanam dengan 1, 2, dan 3 stek per polybag. Hasil menunjukkan bahwa bibit dengan buku yang lebih banyak memiliki pertumbuhan batang, daun, dan buku awal yang lebih baik sampai 8 MST. Perlakuan 1 stek per polybag memberikan pertumbuhan akhir individu tinggi namun perlakuan 2 dan 3 stek per polybag memberikan pertumbuhan per polybag dan hasil umbi yang paling tinggi., Sweet potato (Ipomoea batatas L.) has potential for efficient urban farming. Mini cutting can reduce plant material needs. High plant density can lead to more efficient land use. This research aims to deduce the most optimal node cutting and plant density for efficient urban farm. Research was done from May to October 2021 in Setu, Tangerang Selatan. This research is designed with split-plot randomized complete block design (SP-RCBD). First factor is node cutting with treatment 2, 4, and 6 node each cutting. Second factor is plant density with treatment 1, 2, and 3 cutting each polybag. Result shows that cutting with more node have better early growth until 8 weeks after planting. Plant density of 1 plant per polybag gives best individual plant late growth while 2 and 3 plant per polybag give better per polybag growth and tuber yield.
Keyword: jumlah buku bibit, kerapatan tanam, pertanian kota, polybag, ubi jalar, node cuttings, plant density, sweet potato, urban farming

Judul: The Effect Number of internodes and Time of Shoots Cutting and Number of Shoots Cut on The Productivity of Sweet Potatoes (Ipomea batatas L.) Clone Ase Kapas.
Abstrak: Ubi jalar (Ipomea babatas L.) merupakan salah satu tanaman sumber karbohidrat yang ada di Indonesia. Sistem budidaya tanaman yang kurang baik menyebabkan tidak maksimalnya produktivitas dari tanaman ubi jalar. Penelitian ini bertujuan mengetahui pengaruh jumlah buku dan waktu pemotongan pucuk pucuk dan jumlah pucuk yang di potong terhadap produktivitas ubi jalar (Ipomea batatas L.) klon Ase Kapas. Perlakuan buku dengan tiga taraf yaitu lima, enam dan tujuh buku sedangkan perlakuan pemotongan pucuk dengan lima taraf yaitu pemotongan dua pada bulan kedua, pemotongan dua pada bulan ketiga, pemotongan enam pada bulan kedua, pemotongan enam pada bulan ketiga dan tidak dipotong. Hasil penelitian menunjukkan perlakuan pemotongan pucuk dan jumlah buku tidak berpengaruh terhadap bobot, diameter, panjang dan jumlah umbi. Perlakuan tujuh buku berpengaruh terhadap parameter vegetatif tanaman., Sweet potato (Ipomea babatas L.) is one of carbohydrate sources in Indonesia. The poor crop cultivation system causes the productivity of the sweet potato crop is not maximal. This research aim to determine the effect number of internode and time of shoots cutting and number of shoots cut on the productivity of sweet potato (Ipomea batatas L.) clone Ase Kapas. The treatment of the internodes was three levels, namely five, six and seven segments, while the treatment of the shoot cutting was five levels, namely cutting two in the second month, cutting two in the third month, cutting six in the second month, cutting six in the third month and no cutting. The results showed that shoot cutting and internodes treatments had no effect on weight, length diameter and number of tubers. The treatment of seven segments had an effect on the vegetative parameters of the plant.
Keyword: Cutting, internodes, productivity, shoot, vegetative

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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