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 Nutsedge (Cyperus rotundus L.) as Bioherbicide to Control Some Weed Species in Lowland Rice
Abstrak: Lahan tanaman padi di Indonesia yang luas masih belum bisa mencukupi kebutuhan pangan dalam negeri. Salah satu faktor penyebabnya adalah persaingan antara tanaman padi dan gulma. Inovasi yang dapat diterapkan dalam pengendalian gulma adalah aplikasi bioherbisida. Bioherbisida yang digunakan adalah bioherbisida dari senyawa alelopati yang dihasilkan tumbuhan. Senyawa alelopati dapat menekan bahkan mematikan tumbuhan lain di sekitarnya. Salah satu tumbuhan yang dapat dimanfaatkan untuk menjadi bahan baku bioherbisida adalah gulma teki (Cyperus rotundus L.). Penelitian ini bertujuan untuk mengetahui efektivitas bioherbisida berbahan baku teki pada lahan pertanaman padi sawah. Rancangan percobaan yang digunakan adalah rancangan kelompok lengkap teracak (RKLT) faktor tunggal dan tiga ulangan. Perlakuan terdiri dari kontrol (P0), pengendalian manual (P1), bioherbisida granul 22,5 kg tepung ha-1(P2), bioherbisida granul 45 kg tepung ha-1(P3), bioherbisida granul 67,5 kg tepung ha-1(P4), bioherbisida larutan 45 kg tepung ha-1(P5), herbisida pratumbuh Oksifluorfen 2 l ha-1(P6). Hasil percobaan menunjukan bahwa aplikasi bioherbisida teki formulasi granul dosis 67,5 kg ha-1dapat menekan pertumbuhan gulma Ludwigia octovalvis, Pistia stratiotes, dan Paspalum distichum dibandingkan dengan perlakuan tanpa penyiangan di lahan pertanaman padi. Aplikasi bioherbisida teki dapat meningkatkan hasil panen dan tidak menimbulkan fitotoksisitas terhadap tanamanpadi. Kata kunci : alelopati, bioherbisida, gulma, padi sawah, teki, Competition between weeds and rice is one of factors that decreasing rice productivity. An innovation that can be applied in weed control is the application of bioherbicides. The bioherbicide is usualy made of allelopathic compounds produced by plants. Allelopathic compounds can suppress some weeds. One of the plants that can be used as raw material for bioherbicides is nutsedge weed (Cyperus rotundus L.). The objective of the research was to determine the effectiveness of bioherbicide made from nutsedges (Cyperus rotundus L.) in rice fields. The experiment was designed as randomized complete block design with single factor and three replications. The treatments were without weeding (P0), manual weeding (P1), granule bioherbicide from nutsedge 22,5 kg ha-1(P2), 45 kg ha-1(P3), 67,5 kg ha-1(P4), solution bioherbicide 45 kg ha-1(P5), and Oxyfluorfen herbicide 2 l ha-1(P6). The results of the experiment showed that the application of bioherbicide with granule formulations at 67,5 kg ha-1could suppress the growth of Ludwigia octovalvis, Pistia stratiotes, and Paspalum distichum weeds compared to the without weeding treatment. The application of bioherbicide made from nutsedge could increase crop yields and did not cause fitotoxicity to rice plants. Keywords: allelopathy, bioherbicide, lowland rice, sedge, weed
Keyword: allelopathy, bioherbicide, lowland rice, sedge, weed

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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