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: The Treatment of Leaf-Fruit Ratio and Foliar Fertilizer on the Quality of Abiu Fruit (Pouteria caimito Radlk.)
Abstrak: Abiu (Pouteria caimito Radlk.) is a plant belong to the Sapotaceae family that can be consumed fresh, processed and as herbal products. Abiu has 72 types of bioactive compounds found in its fruit with an area percentage of >1%. The purpose of this research aimed to (1) determine the effect of the treatment of leaf-fruit ratio on the quality of abiu fruit, (2) determine the effect of leaf fertilizer on the quality of abiu fruit, and (3) determine the interaction of the treatment of leaf-fruit ratio with the concentration of leaf fertilizer on quality of abiu fruit. The research was conducted at Balungbang Jaya, Bogor city, West Java Province, from July 2022 to November 2022. This research used a split plot factorial Randomized Complete Block Design (RCBD) that consisted of 3 replications, the main plot was leaf-fruit ratio, namely 45 leaves : 1 fruit and 30 leaves : 1 fruit which was carried out on tertiary branches of plants, and sub plot is the concentration of foliar fertilizer which consistsed of 1, 2, and 3 g L-1. The fertilizer applied to each treatment was dissolved in a concentration of grams per liter of water. The number of plants in the research was 18 trees. The research results showed that the leaf-fruit ratio and foliar fertilizer improved the quality of abiu fruit, which was indicated by a trend of increasing fruit quality, although it did not show a significant difference. The difference between Leaf-fruit ratio 45:1 versus 30:1 and foliar fertilizer increased the horizontal and vertical diameter of fruit at 4 – 9 weeks after anthesis and the weight of abiu fruit with a percentage range below 10%. Total Dissolved Solids (TDS) is 12.22% and the Total Dissolved Solids/Total Titratable Acidity (TDS/TTA) ratio is 6.42% if the ratio is 45:1 compared to the ratio 30:1. Application of foliar fertilizer increased fruit weight by 10.74%, TDS by 10.94%, and TDS/TTA ratio by 18.42%. The interaction between leaf-fruit ratio and foliar fertilizer had a significant effect on TTA, but had no significant effect on the internal and external quality of abiu fruit.
Keyword: Leaf fruit ratio, Abiu, Pupuk daun, Bioactive compounds, Sapotaceae, tertiary branch, total titratable acidity

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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