Judul: Dominance of Weed Upon Several Character of The Palm Environment and Its Potential Resistance to Herbicide glyphosate
Abstrak: Pengendalian gulma secara kimiawi pada lahan sawit secara berulang dalam jangka waktu yang lama dapat menyebabkan terjadinya potensi resistensi pada gulma. Tujuan penelitian adalah mengetahui gulma dominan pada karakter lingkungan yang berbeda dan mengetahui potensi resistensi terhadap herbisida glifosat. Benih gulma diambil dari Perkebunan Kelapa Sawit Jonggol IPB-Cargill Singasari, Kecamatan Jonggol, Bogor, Jawa Barat. Penelitian dilaksanakan pada bulan Januari sampai September 2020. Metode yang dilakukan dalam penelitian ini ada dua, yaitu identifikasi gulma dominan dan pengujian resistensi. Gulma dominan diidentifikasi dengan cara melakukan analisis vegetasi pada tiga blok terpilih dan dihitung berdasarkan nilai NJD. Gulma dominan yang didapat yaitu Eleusine indica. Pengujian resistensi dilakukan dengan melakukan penanaman dan pengaplikasian herbisida glifosat pada gulma dominan (E.indica) untuk menentukan tingkat resistensi herbisida glifosat. Nisbah resistensi dihitung dari nilai perbandingan Lethal Dose50 gulma resisten dengan gulma sensitif. Hasil penelitian menunjukkan bahwa keragaman gulma pada blok 1, 2, dan 5 didominasi oleh famili Poaceae. Jenis gulma yang mendominasi pada lahan curam (22.00%) dan intensitas cahaya rendah (1,135.20 x 1000 lux) yaitu spesies Ottochloa nodosa dan jenis gulma yang mendominasi pada lahan landai (14.86%) hingga datar (8.00%) dan intensitas cahaya sedang (1,427.60 x 1000 lux) hingga tinggi (1,979.00 x 1000 lux) yaitu gulma spesies E. indica. Perbedaan gulma dominan ini di pengaruhi oleh intensitas cahaya dan kemiringan (topografi) lahan. Perbedaan karakteristik tersebut menunjukkan adanya potensi resistensi gulma E. indica pada Blok 5 yang ditunjukkan dengan nilai Lethal Time50 sebesar 1.53 hari, Lethal Dose50 sebesar 5.35, dan nilai N, Weeds chemical control on palm oil estate over a long period of time can lead to weeds resistance. The purpose of the study was to reveal the dominant weeds in some environmental characters and to know the potential resistance to glyphosate herbicides. Weed seeds were taken from Jonggol Oil Palm Plantation IPB-Cargill Singasari, Jonggol Subdistrict, Bogor, West Java. The research was carried-out from January to September 2020. The research began with vegetation analysis to identify the dominant weeds in each selected block. Weeds was identied and calculated. Dominant weeds was defined by the highest Summed Dominance Ratio (SDR) Then the dominant weed was chosen to be tested for its resistance to glyphosate herbicides. The dominant weed seed, namely Eleusine indica, were planted in plastic pots 15 cm x 9 cm size containing as much as 20 seeds in each pot. At the age of 14 days after planting or after the appearance of 3 leaves various glyphosate herbicides dose was applied. Weeds dominant on the slope of ramps (14.86%), i.e Block 2, up to flat (8.00%) i.e Block 5, and medium light intensity (1,427.60 x 1000 lux) to high (1,979.00 x 1000 lux) was Eleusine indica, while the dominant weed on a steep slope (22.00%) 1.e. Block 1, and low light intensity (1,135.20 x 1000 lux) was Ottochloa nodosa species. Those different in characteristics also revealed the potential of Eleusine indica resistance. Proved in Block 5 shown by LT50 values of 1.53, LD50 of 5.35, and NR values in the range of 2 – 6 indicating the occurrence of low resistance.
Keyword: Dosis, Eleusine indica, Kimiawi, Pengendalian, Vegetasi

Judul: Dominance of Weeds and The Potential of Resistance to Glyphosate Herbicides in Guava Plantation
Abstrak: Gulma pada pertanaman jambu kristal harus dikendalikan untuk mengurangi kompetisi. Pengendalian gulma menggunakan herbisida berbahan aktif yang sama secara terus menerus dapat menyebabkan gulma menjadi resisten terhadap herbisida. Pengujian resistensi gulma bertujuan melihat status gulma dominan yang berada pada pertanaman jambu kristal sehingga strategi pengendalian dapat dilakukan. Identifikasi gulma dominan menggunakan analisis vegetasi pada 4 blok menggunakan metode kuadrat. Setiap blok diambil 5 titik contoh dengan kuadran. Gulma dominan ditentukan berdasarkan Nisbah Jumlah Dominansi (NJD). Biji gulma dominan pada percobaan pertama diambil dari kebun ATP secara acak pada tiap blok sebanyak 20 titik yang kemudian ditanam sebanyak 25 bibit ke polybag setelah disemai. Gulma disemprot dengan herbisida dengan 9 taraf dosis yaitu kontrol 0 g.ha-1(D0), 60,75 g.ha-1(D1), 121,5 g.ha-1(D2), 243 g.ha-1(D3), 486 g.ha-1(D4), 972 g.ha-1(D5), 1.944 g.ha-1(D6), 3.888 g.ha-1(D7), dan 7.776 g.ha-1(D8) sebanyak 3 ulangan. Gulma kemudian dipanen dan dihitung % kematiannya. Hasil penelitian menunjukan bahwa gulma dominan di kebun ATP adalah Cyperus kyllingia. Tiap blok kebun jambu kristal memiliki nisbah resistensi yang berbeda dengan blok 4 yang tertinggi yaitu sebesar 2,129 (resistensi rendah)., Weeds in guava plantation must be controlled to reduce competition. Weed control using the same active ingredient herbicide continuously can cause weeds resistant. Weed resistance testing aimed to see the status of dominant weeds in guava plantations so that weed control strategies can be carried out. Dominant weeds identification used vegetation analysis in 4 blocks using the quadrant method. Each block was taken 5 sample points with a quadrant. Dominant weeds was determined based on the Sum Dominancy Ratio (SDR). The dominant weed seeds in the first experiment were taken from the ATP IPB field by taking ramdomly 20 points from each blocks, which were then planted as many as 25 seedlings into polybags after sowing. Weeds were sprayed with the glyphosate herbicide with 9 dose levels, namely control 0 g.ha-1(D0), 60.75 g.ha-1(D1), 121.5 g.ha-1(D2), 243 g.ha-1(D3), 486 g.ha-1(D4), 972 g.ha-1(D5), 1,944 g.ha-1(D6), 3,888 g.ha-1(D7), and 7.776 g.ha-1 (D8) with 3 replications. Weeds were then harvested and the %mortality was calculated. The results showed that the dominant weed in ATP field was Cyperus kyllingia. Each block had a different resistance ratio to glyphosate. Block 4 had the highest resistance ratio, which was 2.129 (low resistance).
Keyword: analisis vegetasi, dosis, ESPS, LD50

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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