Judul: Response of Three Varietas Water Spinach (Ipomea reptans  Poir) to Increased NPK Fertilization
Abstrak: Kangkung darat (Ipomea reptans Poir) merupakan komoditas hortikultura yang banyak dibudidayakan dan digemari karena waktu panennya yang cepat dan mudah dibudidayakan. Namun seiring berjalannya waktu produksi tanaman kangkung terus menurun setiap tahunnya. Penggunaan pupuk majemuk dan pemilihan varitas unggul merupakan salah satu solusi dan alternatif untuk meningkatkan produksi dan efisiensi budidaya. Penelitian ini bertujuan mendapatkan informasi interaksi dan respon tiga varietas kangkung terhadap pemberian dosis pupuk NPK yang berbeda pada pertumbuhan dan hasil. Penelitian ini dilakukan pada bulan April hingga Mei 2024 di Desa Cikura, Kabupaten Banjarnegara, Jawa Tengah. Penelitian ini menggunakan rancangan kelompok lengkap teracak dengan dua faktor dosis dan varietas yang terdiri atas tiga ulangan. Faktor pertama yaitu dosis pemupukan dengan 4 taraf dosis pemupukan yaitu 0 NPK, 0,5 g tan-1 NPK, 1 g tan-1 NPK, dan 1,5 g tan-1. Faktor kedua yaitu varietas menggunakan 3 varietas komersil yaitu Bangkok LP-1, Rajawali, dan Serimpi. Hasil penelitian menunjukkan bahwa dosis pupuk 1,5 g tan-1 mampu meningkatkan tinggi tanaman, jumlah daun dan berat segar tanaman. Varietas Bangkok LP-1 dapat meningkatkan pertumbuhan dan hasil tanaman kangkung. Hasil penelitian menunjukan tidak terdapat interaksi yang nyata antara dosis pupuk NPK dan tiga varietas kangkung terhadap pertumbuhan dan hasil tanaman kangkung, Water spinach (Ipomea reptans Poir) is a horticultural plant widely cultivated and favored due to its quick harvest time and ease of cultivation. Bu, as time goes by, water spinach production continues to decline every year. The use of compound fertilizers and the selection of superior varieties are among the solutions and alternatives to increase production and cultivation efficiency. This study aims to determine the effect of NPK fertilizer dosage on the growth and yield of three varieties of water spinach (Ipomea reptans Poir). The research was conducted from April to May in Cikura Village, Banjarnegara Regency, Central Java. This study used a randomized complete group design with two factors, dose and variety, consisting of three replications. The first factor is the fertilizer dose with 4 levels of fertilizer dose namely 0 NPK, 0.5 g tan-1 NPK, 1 g tan-1 NPK, dan 1.5 g tan-1. The second factor is the variety using 3 commercial varieties, namely Bangkok LP-1, Rajawali, and Serimpi. The research results showed that a fertilizer dose of 1.5 g tan-1 was able to increase plant height, number of leaves and fresh weight of plants. The Bangkok LP-1 variety can increase the growth and yield of kale plants. The results of the research showed that there was no real interaction between the dose of NPK fertilizer and the three varieties of kale on the growth and yield of kale plants.
Keyword: Bangkok LP-1, dosage, interaction

Judul: Effect of Organic Fertilizer on Evapotranspiration, Water Use Efficiency, Growth and Yield of Red Spinach (Amaranthus tricolor) and Water Spinach (Ipomoea reptans)
Abstrak: Pemenuhan permintaan tanaman hortikultura dapat dilakukan melalui peningkatan produksi dengan mengetahui faktor iklim khususnya curah hujan, evapotranspirasi, serta kadar air tanah. Peningkatan produktivitas juga dapat dilakukan dengan pemberian pupuk organik pada tanaman. Penelitian bertujuan mengetahui pengaruh pupuk organik terhadap evapotranspirasi, efisiensi pemakaian air, pertumbuhan, dan hasil bayam merah (Amaranthus tricolor) dan kangkung (Ipomoea reptans). Percobaan dilakukan pada tanaman bayam merah dan tanaman kangkung secara terpisah. Kedua percobaan disusun dengan Rancangan Acak Kelompok (RAK) yang terdiri dari 3 perlakuan, yaitu tanpa pupuk: 0 ton ha-1 (P1), pupuk kandang: 10 ton ha-1 (P2) dan pupuk kompos organik: 10 ton ha-1 (P3) dengan 3 ulangan. Hasil penelitian menunjukkan bahwa pemberian perlakuan pupuk pada bayam merah memberikan pengaruh terhadap tinggi tanaman, jumlah daun, panjang akar, panjang daun, koefisien evapotranspirasi, kebutuhan air tanaman, serta efisiensi pemakaian air. Bobot segar tanaman bayam tertinggi yaitu 1866,7 g/3m2 dengan perlakuan pemberian pupuk kandang. Perlakuan pupuk pada kangkung berpengaruh pada tinggi tanaman, bobot segar sampel, bobot kering sampel, efisiensi pemakaian air, kadar air tanah. Pemberian pupuk organik juga memberikan pengaruh pada berat basah dan berat kering, khususnya pemberian pupuk kandang yang memiliki bobot segar paling tinggi yaitu 2166,7 g/3m2., Fulfilling the demand for horticultural crops can be done through increasing production by knowing climatic factors, especially rainfall, evapotranspiration, and soil water content. Increased productivity can also be done by applying organic fertilizer to plants. Research aims determine the effect of organic fertilizer on evapotranspiration, water use efficiency, growth, and yield of red spinach (Amaranthus tricolor) and water spinach (Ipomoea reptans). The experiment was carried out on red spinach and water spinach separately. Both experiments were arranged in a Randomized Block Design (RBD) consisting of 3 treatments, namely without fertilizer:0 ton ha-1 (P1), manure: 10 ton ha-1 (P2), and organic compost: 10 ton ha-1 (P3) with 3 replicates. The results showed thatfertilizer treatment on red spinach has an effect on plant height, number of leaves, root length, leaf length, evapotranspiration coefficient, plant water requirements, and water use efficiency. The highest fresh weight of spinach plants was 1866.7 g/3m2 with the treatment of manure. Fertilizer treatment on water spinach affects plant height, sample fresh weight, sample dry weight, water use efficiency, soil moisture content. The application of organic fertilizer also has an effect on the wet weight and dry weight, especially the application of manure which has the highest fresh weight of 2166.7 g/3m2.
Keyword: Compost, Evapotranspiration, Growth, Manure, 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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