Judul: Aplikasi pupuk kalsium dan boron untuk mengurangi getah kuning pada buah Manggis (Garcinia mangostana L.)
Abstrak: The yellow sap contamination causes low quality of mangosteen. Yellow sap contamination occurs due to weak cell walls in the fruit. Weak cell walls caused by low calcium and boron. Calcium has a function to strengthen the integrity of the cell wall and boron provide the stability maintenance of the cell wall. This research aims to examine the combination of calcium and boron with a low dose to reduce yellow sap contamination in mangosteen. The research was located in 3 mangosteen orchard in Cigudeg, Citeureup, Sukabumi, and analysis of samples in Post Harvest Laboratory of Bogor Agricultural University in November 2014 to March 2015. The research was designed by Randomized Complete Block Design (RCBD) with one factor of the combination of calcium and boron dose. The treatment consisted of 5 levels that repeated 4 times with each repetition consisted of one tree so that the number of mangosteen tree is 20 trees in each experimental orchard. In each tree, 20 fruits were collected randomly. The combination of fertilizers that used in this research was without fertilizer (control), 1 kg Ca / tree + 0.047 g B / tree, 1 kg Ca / tree + 1.553 g B/ tree, 1.5 kg Ca / tree + 0.047 g B / tree , and 1.5 kg Ca / tree + 1.553 g B / tree. The results of this research indicated that the most effective dose to reduce contamination of yellow sap in mangosteen in three experimental orchard was a dose of 1.5 kg Ca / tree + 1.553 g B / tree. The application of calcium and boron at a dose of 1.5 kg Ca/tree + 1.553 g B/tree significantly reduced scores and percentage of yellow sap contamination on peel and aryl of fruit, and did not affect the physical and chemical quality of mangosteen fruits.
Keyword: Bogor Agricultural University, cell wall, fertilization, fruit quality, mineral nutrient

Judul: Application of calcium and boron for controlling yellow latex contamination on the mangosteen fruits (Garcinia mangostana L.)
Abstrak: Yellow latex originally can be found in all of mangosteen organs, except in the root. When Yellow latex is spilled from its chanenel it will become a serious issue, because it can damage the visual performance of rind and the taste of aryl. Yellow latex contamination in mangosteen occur due to the pressure from the seeds and aril within the time of fruits development, it is also due to the of change of turgor compulsion. The cause of yellow latex bursting is lack of Calcium on the cells epitel membrane. Calcium is important on the developing of membrane’ structure as Ca-pektat in middle lamela. Another element that able to keep the membrane integrity is Boron. In the growth phase, Boron is used on cells division and as regulator for membrane function. The combination of calcium and boron are estimated to affect on controlling of yellow latex contamination in mangosteen. This research was aimed to know the role of calcium and boron application in controlling contamination yellow latex on the mangosteen fruit, Other objectives were to get the best combination calcium and boron in preventing the yellow latex contamination on mangosteen. The research was conducted at the field in Purwakarta West Java, from November 2012 to June 2013. The two factor experiment was designed in a randomized block design with three replications. The rates of calcium were 0.0, 2.5, 5.0, and 7.5 kg/tree. The rates of boron were 0.0, 0.77, 1.55, and 2.32 g/tree. Fertilizer application is done twice, first at 80% anthesis as much as 2/3 of the dose of treatment, and the second giving as much as 1/3 of treatment dose 28 days after the first treatment. Variables measured: (1) Measurement of levels of yellow latex contaminant include: The number of fruit which aryl contaminated with yellow latex, the number of fruit with contaminated pericarp, the number of contaminated aryl segment, score of yellow latex intensity in the aryl and pericarp. (2) the physical properties of the fruit include: fruit weight, pericarp weight, seed weight, aryl weight, edibel portion, longitudinal diameter, transversal diameter, rind hardness, resistance, and observations to the development of pre-harvest fruit diameter. (3) the chemical properties of the fruit are: total soluble solids (TSS), total titrable acid (TTA), nutrient content of Ca, Mg and B in plant tissue and soil, leaf chlorophyll content. Application of dolomite and boron significantly reduce scores and the percentage of yellow latex on the aryl and pericarp, percentage of aryl segment contaminated with yellow latex, increas content of calcium and boron in fruit perikarp. There was interaction between dolomite and boron fertilizer on score and percentage of aryl contaminated with yellow latex. The optimum rate of dolomite and boron to get minimum score and percentage of aryl and pericarp contaminated with yellow latex ranging from 3.7 to 5.0 kg Ca/tree and 0.85 to 1.55 g B2O3/tree. Application of dolomite and boron at 5.0 kg Ca/tree and 1.55 g B2O3/tree can reduce the percentage of fruit which aryl contaminated with yellow latex by 98%, from 66.67% to 1.05%. Fertilizer of boron with a dose
Keyword: doses, leaf tissue, pericarp tissue, gamboge disorder, aryl, pericarp

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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