Judul: The Effect of NPK Fertilizer Dosage (15:15:15) on Yield and Quality of Abiu Fruit (Pouteria caimito)
Abstrak: Tanaman abiu berasal dari daerah hulu Amazon yang tergolong dalam famili Sapotaceae. Tanaman abiu berpotensi untuk dikembangkan di Indonesia. Pemupukan untuk peningkatan produksi dan kualitas buah merupakan salah satu upaya mengembangkan abiu. Tujuan penelitian adalah mengetahui pengaruh pemberian berbagai dosis pupuk NPK (15:15:15) terhadap hasil dan kualitas buah abiu. Penelitian dilaksanakan di Balumbang Jaya, Bogor Barat dan Laboratorium Pascapanen, Departemen Agronomi dan Hortikultura, IPB pada bulan Februari sampai Juni 2018. Rancangan percobaan yang digunakan adalah rancangan kelompok lengkap teracak (RKLT) satu faktor berupa dosis pupuk yaitu 500 g/tanaman, 1000 g/tanaman, dan 1500 g/tanaman. Setiap perlakuan diulang tiga kali, setiap ulangan terdiri atas dua tanaman. Dosis pupuk NPK pada taraf 1500 g/tanaman menghasilkan kualitas buah abiu yang lebih baik dengan bobot buah utuh (184,96 g) dan bobot daging buah (102,24 g) yang nyata lebih tinggi dibandingkan perlakuan lainnya. Dosis pupuk NPK pada taraf 500 g/tanaman, 1000 g/tanaman, 1500 g/tanaman tidak memberikan pengaruh nyata terhadap kekerasan buah baik kulit maupun daging, bobot kulit, bobot dan jumlah biji, edible portion, total padatan terlarut, total asam tertitrasi, kandungan vitamin C dan jumlah buah panen., The abiu plant originated from the upper Amazon region which belongs to the Sapotaceae family. Abiu plants has the potential to be developed in Indonesia. Fertilization to improve fruit production and its quality is one of the efforts to develop abiu fruit. This study aims to determine the effect of various doses of NPK fertilizer (15:15:15) on the yield and quality of abiu fruit. The research was carried out in Balumbang Jaya, Bogor Barat and Post Harvest Laboratory, Department of Agronomy and Horticulture, IPB from February to June 2018. The experimental design used was a randomized complete group design (RCGD) one factor in the form of doses fertilizer is 500 g/plant, 1000 g/plant, and 1500 g/plant. Each treatment was repeated three times, each replication consisted of two plants. The NPK fertilizer dosage at the level of 1500 g/plant resulted in better quality abiu fruit with, intact fruit weight (184,96 g) and fruit flesh weight (102,24 g) which were significantly higher than other treatments. The dose of NPK fertilizer at a level of 500 g/plant, 1000 g/plant, 1500 g/plant did not give a significant effect in the form of fruit hardness, fruit skin weight, weight and number of seeds, fruit flesh, total soluble solids, total titratable acidity and content of vitamin C and number of fruit harvested.
Keyword: fertilization, fruit quality, production, sapotaceae

Judul: Optimizing Active Compund of Pesticides and Spraying Intervals to Increase the Quality of Abiu Fruit (Pouteria caimito Radlk.).
Abstrak: Abiu merupakan buah tropika yang berasal dari Amazon. Abiu berpotensi untuk dikembangkan di Indonesia karena kaya nutrisi dan manfaat. Kecacatan kulit buah abiu menjadi masalah yang umum dijumpai. Penelitian ini bertujuan mempelajari pengaruh pengaplikasian beberapa jenis bahan aktif pestisida dan interval penyemprotan serta interaksiknya terhadap kualitas buah abiu. Penelitian dilakukan di kebun buah abiu dan Laboratorium Pascapanen Departemen Agronomi dan Hortikultura, Fakultas Pertanian IPB. Rancangan yang digunakan adalah rancangan kelompok lengkap teracak dua faktor dengan tiga ulangan. Faktor pertama adalah jenis bahan aktif pestisida, yaitu mankozeb+streptomisin sulfat (P1), benomil (P2), dimetoat (P3), klorpirifos (P4), dan kontrol (P5). Faktor kedua adalah interval penyemprotan, yaitu 1x2 minggu (V1), 1x1 minggu (V2), dan 2x1 minggu (V3). Perlakuan jenis bahan aktif pestisida berpengaruh nyata terhadap kemulusan buah abiu. Bahan aktif benomil tidak memberikan pengaruh berbeda nyata dengan bahan aktif dimetoat dan klorpirifos. Benomil mempertahankan kemulusan sebesar 73,88%, dimetoat 71,33%, dan klorpirifos 65,77%. Interval penyemprotan dan interaksi keduanya tidak berbeda nyata terhadap kemulusan buah. Kedua perlakuan tidak berpengaruh nyata terhadap perkembangan buah, kelunakan, bobot, volume, PTT, TAT, dan vitamin C., Abiu is a tropical fruit from Amazon. It has potential to be developed in Indonesia. Imperfections that found in abiu’s skin are commonly problem. This study aims to determine the effect of several active compund pesticides, spraying intervals, and their interaction on the quality of abiu fruit. The research was conducted at abiu field and The Postharvest Laboratory of Agronomy and Horticulture Department, Faculty of Agriculture IPB. The experimental design used was a factorial completely randomized block design with three replications. The first factor is the active compound of pesticides, namely mancozeb+streptomycin sulfate (P1), benomyl (P2), dimethoate (P3), chlorpyrifos (P4), and control (P5). The second factor is spraying intervals, namely 1x2 week (V1), 1x1 week (V2), and 2x1 weeks (V3). The active compound of pesticides did significantly affect the fruit smoothness. Benomyl didn’t give significantly affect than dimethoat and chlorpyrifos. Benomyl gave 73,88% in maintaining the smoothness abiu fruit, dimethoat at 71,33%, and chlorpyrifos at 65,77%. The spraying interval and its interaction with the active coumpund treatments didn’t significantly affect the fruit smoothness.Both treatments had no significant effect on fruit development, firmness, weight, volume, TSS, TAT, and vitamin C variables.
Keyword: Abiu, Active compound of pesticides, Fruit quality, Spraying intervals

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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