Judul: Effectiveness of Organic Pesticides in Controlling Leaf Spot Disease caused by Nigrospora sphaerica on Red Ginger (Zingiber officinale var Rubrum)
Abstrak: Seiring dengan kondisi pandemic COVID-19 permintaan masyarakat akan jahe merah meningkat secara pesat khususnya di Jawa Barat. Peningkatan permintaan jahe merah belum dapat diimbangi dengan peningkatan produksi jahe merah. Salah satu faktor yang mendorong terjadinya penghambatan yaitu banyaknya Organisme Pengganggu Tanaman (OPT) yang dapat menyebabkan kegagalan produksi jahe merah. Sementara itu pada komoditi jahe merah kemampuan daya hambat pestisida organik Liqcoris 15% dalam mengendalikan bercak daun yang disebabkan oleh fungi patogen belum dilaporkan. Penelitian bertujuan mengidentifikasi secara morfologi fungi patogen Nigrospora sphaerica, mengetahui apakah Nigrospora sphaerica merupakan fungi patogen penyebab bercak daun pada tanaman jahe merah (Zingiber officinale var Rubrum) serta menganalisis efektivitas pemberian pestisida organik Liqcoris dengan konsentrasi 15%. Penelitian ini dilaksanakan di laboratorium Biosistem Lanskap Manajemen (BLM), laboratorium Fitopatologi dan rumah kaca SEAMEO BIOTROP Bogor, Jawa Barat pada bulan Agustus 2022-Februari 2023. Berdasarkan hasil penelitian, Nigrospora sphaerica berhasil direidentifikasi secara morfologi memiliki koloni berwarna putih, abu-abu terang hingga berwarna gelap dan konidia berbentuk bulat dan hitam. Hasil identifikasi morfologi diperkuat oleh hasil identifikasi molekuler penelitian sebelumnya. Nigrospora sphaerica merupakan fungi patogen penyebab penyakit bercak daun pada tanaman jahe. Aplikasi penyemprotan pestisida organik Liqcoris konsentrasi 15% ke daun efektif menghambat penyakit bercak daun yang disebabkan oleh Nigrospora sphaerica dari intensitas penyakit 14,84% menjadi menurun menjadi 12,94 % dengan persentase penurunan 12,80% setelah 3 minggu pemberian aplikasi.
Keyword: leaf spot, Liqcoris organic pesticide, Nigrospora sphaerica

Judul: Pengaruh Pemupukan Anorganik (N, P, K) dan Potensi Limbah Sereh Wangi sebagai Bahan Organik terhadap Pertumbuhan dan Produksi Jahe Gajah (Zingiber officinale Rosc.).
Abstrak: Exports of ginger from Indonesia in the last three years has declined because the quality of the ginger can not meet world market competitiveness. Suboptim cultivation techniques become a constraint in the development of the ginger plant coupled with the excessive use of synthetic chemical fertilizers that causes low soil capacity. The development of environmentally friendly technology to reduce the use of synthetic chemical fertilizers is expected to address the development problems of the ginger plant. Cultivation systems based on the utilization of in-situ organic materials such as waste of lemongrass (cymbopogon citratus) is widely available in the surrounding area of the ginger plant need attention so that the empowerment of local input and medicinal needs can be realize. The research aims to determine the effect of some several of organic materials and inorganic fertilizers (N, P, K) on the growth and production of young ginger, and weed growth. The research conducted at Bogor Agricultural University, Experimental Station, Cikabayan, Darmaga, Bogor, started September 2011 to April 2012 and used a split-plot design. The main plot consisted of organic materials consisting of granules (20 ton / ha), Cymbopogon citratus compost buried in soil (20 t / ha), Cymbopogon citratus compost mulch (20 t / ha) and without organic fertilizer as controls. Sub plot are inorganic fertilizer consisted of ½ doses (N, P, K), 1 doses (N, P, K), 2 doses (N, P, K) and without inorganic fertilizer. Organic materials and inorganic fertilizer did not significantly affect the growth component of ginger. Plants treated with ½ doses of inorganic fertilizer showed the highest dry weight of rhizomes and significantly different with 2 doses and plant resistance to disease is 54,98%. Combined treatment of lemongrass compost buried in soil and inorganic fertilizer showed the higest dry weight of total weeds, but combined treatment of lemongrass compost mulch and inorganic fertilizer showed the lowest dry weight of total weeds. Lemongrass can be used as the source of organic fertilizer and herbicid, depending on the method used and treatment.
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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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