Judul: Efektivitas Fungi Mikoriza Arbuskula (FMA) dalam Memperbaiki Produktivitas Rumput Gajah (Pennisetum purpureum Schum.) Berdasarkan Periode Pemanenan
Abstrak: The use of arbuscular mycorrhizal fungi (AMF) was expected to be an alternative environmentally friendly technology and efficiency of fertilizer to increase the productivity of forage. This study was aimed to determine the level of production of elephant grass (Pennisetum purpureum Schum.) inoculated by AMF and fertilizer dose reduction based on different harvesting period. This research used Completely Randomized Factorial Design with 2 treatments and 3 replications. The first treatment was fertilizer: P0 (control), P1 (100% fertilizer dose), and P2 (50% fertilizer dose and inoculated by AMF). The second factor was the interval of harvest H30 (30th day of harvest), H50 (50th day of harvest, and H60 (60th day of harvest). Variables measured were plant height increment of each week, the production of dry weight on the first harvesting period, the production of dry weight on second harvesting period, and percent of infection AMF. It can be concluded that the P2H60 treatment with 10 grams of AMF inoculation and fertilizer dose 50% (SP36 75 kg/ha, KCl 75 kg/ha, manure 2 ton/ha, and urea 100 kg/ha) on 60th day of harvest elephant grass get the best production, either the first and second periods and more effective and efficient use of fertilizer.
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Judul: Efektivitas Teknik Perbanyakan Fungi Mikoriza Arbuskula dari Spora Tunggal dengan Tanaman Centrosema pubescens dan Pueraria javanica.
Abstrak: Limited availability of forage was caused by few constraints, like dry season, limited land, low productivity of forage, and cultivation management which is not optimal. Arbuscular Mycorrhizal Fungi (AMF) is one of microorganism that can be used to solve that problems. AMF needs host plant for its growth. This research aimed to evaluate the efectivity of multiply technique from a single spore by host plant Centrosema pubescens and Pueraria javanica. The treatment of this research is the difference kind of AMF that being used to roots inoculation. P1= Gigaspora margarita, P2= Acaulospora tuberculata, P3= Glomus etinucatum. Parameters in this research are percentage of growth plants, succeded infection precentage, the amount of spores and root infection. Result shows that the most effective AMF from single spore are Acaulospora tuberculata and Glomus etinucatum with the host plant Centrosema pubescens. Pueraria javanica only effective to growth of Acaulospora tuberculata.
Keyword: Pueraria javanica, AMF, Arbuscular Mycorrhizal Fungi, biofertilizer, Centrosema pubescens, forage availabity

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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