Judul: Effectiveness of a Bioherbicide Based on Purple Nutsedge (Cyperus rotundus L.) in Suppressing Weed Growth in Upland Rice Cultivation
Abstrak: Salah satu masalah dalam budidaya padi gogo adalah terjadinya kompetisi dengan gulma sehingga dapat menghambat pertumbuhan dan menurunkan produksi. Pengendalian gulma menggunakan herbisida pra tumbuh sintetik dapat berdampak buruk bagi ekosistem pertanian. Bioherbisida berbahan baku umbi teki (Cyperus rotundus L.) berpotensi untuk mengendalikan gulma pada tanaman padi gogo. Penelitian ini bertujuan memperoleh informasi tentang efektivitas bioherbisida berbahan dasar umbi teki bentuk granul dalam menekan pertumbuhan gulma dan pengaruhnya terhadap tanaman padi gogo. Percobaan disusun dalam Rancangan Kelompok Lengkap Teracak (RKLT) faktor tunggal dengan delapan perlakuan yaitu: tanpa penyiangan (P1), penyiangan manual sebanyak 2 kali pada 3 dan 6 MST (P2), bioherbisida formulasi granul 22,5 kg ha-1 (P3), bioherbisida formulasi granul 45 kg ha-1 (P4), bioherbisida formulasi granul 67,5 kg ha-1 (P5), bioherbisida formulasi granul 90 kg ha-1 (P6), bioherbisida formulasi larutan 67,5 kg ha-1 (P7), herbisida sintetis oksifluorfen (P8). Hasil Percobaan menunjukkan bahwa aplikasi bioherbisida berbahan baku umbi teki formulasi granul dengan dosis 22,5 – 90 kg ha-1 dan larutan 67,5 kg ha-1 sangat efektif menekan gulma golongan daun lebar spesies C. diffusa, A. sessilis, C. nodiflora, C. benghalensis, dan C. rutidosperma. Bioherbisida dengan formulasi granul dan formulasi larutan pada tingkat dosis yang diuji tidak efektif menekan gulma golongan rumput spesies R. exaltata dan gulma golongan teki spesies C. rotundus. Bioherbisida berbahan baku umbi teki tidak menyebabkan gejala fitotoksisitas pada tanaman padi gogo. Aplikasi bioherbisida berbahan baku umbi teki dengan formulasi granul dosis 90 kg ha-1 menghasilkan produksi gabah kering panen tertinggi, yakni 453,2 kg ha-1., One of the problems in upland rice cultivation is weed competition, which can lead to stunted growth and reduced production. Weed control using synthetic pre-emergent herbicides can pose threats to agricultural ecosystems. Bioherbicides made from purple nutsedge (Cyperus rotundus L.) are potential for weed control in upland rice. This research aims to obtain information about the effectiveness of bioherbicides made from purple nutsedge in granular formulation in suppressing weed growth and its impact on upland rice. The experiment was arranged in a single-factor Randomized Complete Group Design (RKLT) with eight treatments: no weeding (P1), manual weeding twice at 3 and 6 WAP (P2), granular bioherbicide formulation 22.5 kg ha-1 (P3), granular bioherbicide formulation 45 kg ha-1 (P4), granular bioherbicide formulation 67.5 kg ha-1 (P5), granular bioherbicide formulation 90 kg ha-1 (P6), solution bioherbicide formulation 67.5 kg ha-1 (P7), synthetic Oxyfluorfen herbicide (P8). The result of the experiment demonstrate that applying bioherbicide made from purple nutsedge in granular formulation with doses ranging from 22.5 – 90 kg ha-1 and a solution of 67.5 kg ha-1 was effectively suppressed some broadleaf weeds including C. diffusa, A. sessilis, C. nodiflora, C. benghalensis, and C. rutidosperma species. Bioherbicides with granular formulations and solution formulations with the tested dose levels were found ineffective in suppressing grass weeds R. exaltata species and sedges weeds C. rotundus species. Bioherbicides made from purple nutsedge did not induce phototoxicity symptoms in upland rice. Applying bioherbicide made from purple nutsedge in a granular formulation at a dose of 90 kg ha-1 resulted in the highest dry grain production at 453.2 kg ha-1.
Keyword: pertanian berkelanjutan, alelopati, pra tumbuh, lahan kering

Judul: Effectiveness of Granular Bioherbicide Based on Purple Nutsedge (Cyperus rotundus L.) in Various Forms and Sizes for Weed Control in Upland Rice Cultivation.
Abstrak: Aplikasi bioherbisida berbasis umbi teki menjadi salah satu alternatif untuk mengurangi dampak persaingan gulma yang lebih ramah lingkungan. Penelitian ini bertujuan menguji keefektifan bioherbisida butiran berbasis umbi teki (Cyperus rotundus L.) 67,5 kg ha-1 dalam berbagai bentuk dan ukuran untuk mengendalikan gulma pada budidaya padi gogo serta pengaruhnya terhadap pertumbuhan padi gogo. Percobaan disusun menggunakan Rancangan Kelompok Lengkap Teracak (RKLT) faktor tunggal dengan dua belas perlakuan, yaitu: tanpa penyiangan (P0), penyiangan manual (P1), bioherbisida butiran bulat besar (P2), bioherbisida butiran bulat sedang (P3), bioherbisida butiran bulat kecil (P4), bioherbisida butiran bulat sangat kecil (P5), bioherbisida butiran silindris besar (P6), bioherbisida butiran silindris sedang (P7), bioherbisida butiran silindris kecil (P8), bioherbisida butiran silindris sangat kecil (P9), bioherbisida tepung 67,5 kg ha-1 (P10), herbisida sintetis Oksifluorfen 480 g ha-1 (P11). Hasil percobaan menunjukkan bahwa aplikasi bioherbisida butiran pada berbagai bentuk dan ukuran efektif menekan pertumbuhan gulma golongan daun lebar hingga 4 MSA. Aplikasi bioherbisida berbasis umbi teki tidak menimbulkan gejala fitotoksisitas terhadap pertumbuhan padi gogo. Aplikasi terbaik bioherbisida butiran pada perlakuan bioherbisida butiran sangat kecil baik bentuk bulat maupun silindris yang efektif menekan pertumbuhan gulma total dan gulma dominan Alternanthera sessilis dan Mimosa pudica, serta dapat meningkatkan pertumbuhan dan hasil padi gogo., The application of bioherbicide based from purple nutsedge can be one alternative to reduce the impact of weed competition that is more environmentally friendly This study aims to test the effectiveness of granular bioherbicide on nutsedge (Cyperus rotundus L.) 67.5 kg ha-1 in various shapes and sizes to control weeds in upland rice cultivation and its effect on upland rice growth. The experiment was designed using a random complete block design (RKLT) single factor with twelve treatments, namely: no weeding (P0), manual weeding (P1), large round granular bioherbicide (P2), medium round granular bioherbicide (P3), small round granular bioherbicide (P4), very small round granule bioherbicide (P5), large cylindrical granular bioherbicide (P6), medium cylindrical granular bioherbicide (P7), small cylindrical granular bioherbicide (P8), very small cylindrical granular bioherbicide (P9), powdery bioherbicide 67.5 kg ha-1 (P10), synthetic herbicide Oxifluorfen 480 g ha-1 (P11). The result of experiment that the application of granular bioherbicides in various forms and sizes effectively suppresses the growth of broadleaf weeds up to 4 weeks after treatment. The application of bioherbicide based from purple nutsedge didn’t cause phytotoxicity symptoms to upland rice growth. The best application of granular bioherbicide in the treatment of very small granular bioherbicide both round and cylindrical forms that effectively suppress total weed growth and dominant weeds Alternanthera sessilis and Mimosa pudica, and improving the growth and yield of upland rice.
Keyword: allelopathy, biological control, efficiency, environmentally friendly, sustainable agriculture

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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