Judul: The Effect of Leaf Pruning on the Productivity of Three Cowpea Varieties (Vigna unguiculata L. Walp.)
Abstrak: Pemangkasan daun menjadi salah satu upaya yang dapat dilakukan untuk meningkatkan produktivitas kacang tunggak. Penelitian ini bertujuan mengetahui waktu terbaik pemangkasan daun dalam memperoleh produktivitas paling optimal. Penelitian dilaksanakan di Desa Tangkil, Kecamatan Citeureup, Bogor, dari bulan April hingga Juli 2017. Penelitian ini menggunakan rancangan kelompok lengkap teracak (RKLT) dengan dua faktor yaitu varietas (petak utama) dan waktu pemangkasan (anak petak) yang disusun pada petak terbagi (split plot) dengan empat ulangan. Petak utama adalah tiga varietas tanaman kacang tunggak, yaitu KT-2, KT-6, dan KT-8. Anak petak adalah waktu pemangkasan daun, yaitu 4 MST, 6 MST, 8 MST, dan 10 MST. Hasil penelitian menunjukkan pemangkasan daun berpengaruh nyata terhadap peningkatan jumlah polong, bobot kering polong, dan bobot biji kacang tunggak. Komponen hasil paling optimal didapatkan pada tanaman dengan perlakuan pemangkasan tua, yaitu minggu ke 8 dan 10. Pemangkasan minggu ke 8 menunjukkan hasil paling optimal dalam peubah umur berbunga, jumlah tandan bunga, jumlah bunga, jumlah polong, bobot kering polong, dan bobot biji. Pemangkasan pada minggu ke 10 menunjukkan hasil paling optimal dalam peubah jumlah daun, bobot 100 biji, dan indeks panen. Varietas KT-8 menunjukkan hasil paling optimal pada peubah jumlah daun, jumlah tandan bunga, jumlah bunga, jumlah polong, bobot kering polong, bobot biji, dan indeks panen, Leaves pruning is one of the efforts that can be done to increase the productivity of cowpea. The experiment aimed to determine the best time to prune the leaves in obtaining the most optimal productivity. The experiment was conducted at Tangkil Village, Citeureup, Bogor, from April to July 2017. The experiment was arranged in split plot randomized block design with four replications and two factors. The main plot was variety of cowpea consisted of KT-2, KT-6, and KT-8. The subplot was pruning time consisted of 4 MST, 6 MST, 8 MST, and 10 MST. The result showed that leaf pruning significantly affected the increase of number of pods, weight of dry pods, and weight of cowpea grains. The most optimal yield component was obtained in plants with old pruning treatment (8 MST and 10 MST). Pruning at week 8 showed the most optimal result in the variables of flowering age, number of flower bunches, number of flowers, number of pods, weight of dry pods, and weight of grains. Pruning at week 10 showed the most optimal results in variables of number of leaves, weight of 100 grains, and harvest index. KT-8 showed the most optimal results on the variable number of leaves, number of flower bunches, number of flowers, number of pods, weight of dry pods, weight of grains, and harvest index.
Keyword: harvest index, KT-8, pruning time, sink source, southern pea

Judul: Impact of N, P, K Fertilization and Pruning to Increase Cowpea (Vigna unguiculata L.) Seed Production and Quality
Abstrak: Penelitian bertujuan mengidentifikasi untuk memperoleh pengaruh pemupukan N, P, K dan pemangkasan terhadap peningkatan produksi dan mutu benih kacang tunggak (Vigna unguiculata L.). Penelitian menggunakan rancangan perlakuan Split Plot dalam Rancangan Kelompok Lengkap Teracak (RKLT), masing-masing dengan tiga ulangan. Petak utama adalah pemangkasan yang terdiri dari tanpa pangkas (P0) dan pangkas (P1), sedangkan anak petak adalah tiga dosis pupuk N, P, K yang terdiri dari D1 (Urea 100 kg ha-1, SP-36 200 kg ha-1, KCl 150 kg ha-1), D2 (Urea 100 kg ha-1, SP-36 250 kg ha-1, KCl 175 kg ha-1), dan D3 (Urea 100 kg ha-1, SP-36 275 kg ha-1, KCl 200 kg ha-1). Pemupukan N, P, K dan pemangkasan tidak berpengaruh terhadap karakter vegetatif yaitu daya tumbuh, jumlah cabang, dan tinggi tanaman, serta komponen produksi seperti produksi petak-1, jumlah polong tanaman-1, bobot benih tanaman-1, jumlah benih polong-1, bobot polong tanaman-1, dan bobot 1000 butir benih, namun berpengaruh nyata terhadap interaksi bobot 1000 butir benih. Kedua perlakuan juga berpengaruh nyata pada komponen mutu benih seperti daya berkecambah, indeks vigor, dan Berat Kering Kecambah Normal (BKKN), tetapinamun tidak berpengaruh nyata terhadappada kecepatan tumbuh dan potensi tumbuh maksimum. Secara umum, perlakuan tersebut dapat diterapkan untuk meningkatkan mutu benih dalam produksi benih kacang tunggak., This study investigated the effect of N, P, K fertilization and pruning treatment to increase cowpea yield and seed quality. The experiment was arranged in a split-plot with a randomized complete block design, with three replications. The main plot was pruning treatment, i.e. pruning and control, while the subplot was three fertilizer doses of N, P, K i.e. 100 kg ha-1 Urea – 200 kg ha-1 SP-36 – 150 kg ha-1 KCl (D1), 100 kg ha-1 Urea – 250 kg ha-1 SP-36 – 175 kg ha-1 KCl (D2), and 100 kg ha-1 Urea – 275 kg ha-1 SP-36 – 200 kg ha-1 KCl (D3). N, P, K fertilization and pruning treatment didn’t affect to vegetative characters such as seed germinated in the field, branches number, and plant height. Both treatments also didn’t affect yield components such as yields plot-1, pods number plant-1, seeds weight plant-1, seeds number pod-1, pods weight plant-1, and 1000 seeds weight, but significantly affected interaction of the 1000 seeds weight. A significant effect of both treatments was observed on seed quality such as seed germination, vigor index, and normal seedling’s dry weight, however, didn’t affect other character such as germination speed and maximum growth potential. Generally, the treatments could be applied to increase the seed quality in cowpea seed production.
Keyword: cowpea, fertilizer dose, seed viability, pruning, cultivation technique

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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