Judul: Identification of Phenolic Compound from Different Accessions of Cyperus rotundus L. and the Effect on Germination of Borreria alata (Aubl.) DC
Abstrak: Teki (Cyperus rotundus L.) adalah salah satu gulma yang sangat penting di dunia karena kemampuannya dalam menekan produktivitas tanaman dan sulit untuk dikendalikan. Selain menghambat pertumbuhan tanaman, teki juga dapat menghambat pertumbuhan gulma lain sehingga dapat digunakan sebagai alat manajemen gulma. Teki mengandung senyawa alelokimia, salah satu senyawa yang banyak ditemukan berasal dari golongan fenol. Kelimpahan senyawa fenol diduga dipengaruhi oleh faktor lingkungan antara lain perbedaan tempat tumbuh. Karena kemampuan adaptasi teki yang tinggi, diduga kandungan senyawa fenol teki dari aksesi yang berbeda serta kemampuannya dalam menekan pertumbuhan gulma lain juga berbeda-beda., Purple nutsedge (Cyperus rotundus L.) is one of the important weeds in the world because of its ability to suppress the production of crops and difficult to control. C. rotundus residues can suppress the growth of others weeds. C. rotundus contains allelochemical compound such as phenolic compounds. The abundance of phenolic compounds were affected by environmental factor such as different growth location. Because of the adaptation ability of C. rotundus, there are assumption that the content of phenolic compound of C. rotundus from different accessions and the ability to suppress the growth of other weeds also have the different.
Keyword: Allelopathy, bioherbicide, organic farming, purple nutsedge, weed management

Judul: Studi Potensi Alelopati Teki (Cyperus rotundus L.) sebagai Bioherbisida untuk Pengendalian Gulma Berdaun Lebar
Abstrak: This research was conducted at Seed and Technology Laboratory of IPB, Cikabayan Greenhouse, Darmaga, Bogor and Regional Health Laboratory, Jakarta from July 2011 until May 2012 to study the potency of allelochemical compounds from Cyperus rotundus L. as bioherbicide for broadleaf weed control (Asystasia gangetica, Borreria alata and Mimosa pigra). The research consisted of 3 experiments. The objective of the first experiment was to study breaking treatment of seed dormancy for Asystasia gangetica, Mimosa pigra and Borreria alata. The weed treatment were soaked in 50 0C warm water for 24 hours, soaked in 90 0C hot water and embedded in soil for 4 days and control. The result showed that burrying Borreria alata seed in the soil for 4 days, soaking Mimosa pigra seed in hot water could be used as dormancy breaking treatments. No dormancy breaking treatment needed for Asystasia gangetica. The second experiment was conducted to study the influence of C. rotundus extracts on pre-emergence of broadleaf weed. The treatments used 0.5, until 4.5 kg/L with interval 0.5 kg/L concentration of extract (C. rotundus biomass with aquadest). The third experiment was conducted to determine the effect of C. rotundus extracts, mixed with fresh and dried C. rotundus biomass with soil, mulched of fresh and dried C. rotundus biomass, compost and flour of C. rotundus to weed growth and developmentand soybean. The experiment was using completely randomized design in observation of germination and randomized block design in weed growth. The result showed that 1.0 kg/L concentration of C. rotundus extract caused lower weed seed germination but have no effect on soybean germination. Applications of C. rotundus biomass have no effect on the growth and development of weed and soybean. Application of C. rotundus extract 1.0 kg/L potentially can be used as pre-emergence bioherbicide.
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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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