Judul: Identification of Target-site Resistance to Glyphosate on Eleusine indica (L.) Gaertn. from Jonggol Oil Palm Plantation, Bogor, West Java
Abstrak: Resistensi glifosat dapat terjadi melalui mekanisme target-site resistance (TSR) dengan adanya mutasi pada gen target herbisida yaitu 5-enolpiruvil-sikimat-3-fosfat sintase (EPSPS). Penelitian ini bertujuan mengidentifikasi mekanisme TSR yang berkaitan dengan TIPS mutation pada spesies Eleusine indica yang telah dilaporkan resisten di kebun kelapa sawit asal Jonggol, Bogor, Jawa Barat. Analisis bio-assay dilakukan menggunakan Rancangan Kelompok Lengkap Teracak (RKLT) faktor tunggal yaitu dosis herbisida dengan 8 taraf dosis dan 3 ulangan. Banyaknya satuan percobaan adalah 24 satuan percobaan setiap blok. Percobaan dimulai dengan pengambilan biji E. indica resisten pada Blok II dan Blok V. Biji gulma E. indica ditanam pada pot dengan cara disebar. Gulma yang telah tumbuh dipelihara dengan melakukan penyiangan, penyiraman, dan seleksi pertumbuhan agar seragam. Aplikasi glifosat dilakukan saat gulma berdaun 4 menggunakan delapan taraf dosis yaitu 0, 1/8x, 1/4x, 1/2x, x, 2x, 4x, 8x dengan x adalah dosis rekomendasi, sehingga dosis herbisida glifosat adalah 0, 121,5, 243, 486, 972, 1944, 3888, dan 7776 g ha-1. Volume semprot yang digunakan adalah 400 L ha-1. Persentase kerusakan gulma diperoleh dari biomasa tanaman kemudian analisis regresi dilakukan untuk memperoleh LD50 dan nisbah resistensi. Biotipe E. indica asal Kebun Jonggol Blok V memiliki LD50 sebesar 1737 g ha-1 dengan status resistensi penurunan sensitivitas dan nisbah resistensi 2,343. Blok II masih berstatus sensitif dengan nisbah resistensi 1,588 dan nilai LD50 sebesar 1177,30 g ha-1. Identifikasi TSR dilakukan dengan isolasi dan amplifikasi gen penyandi EPSPS dari DNA genom E. indica asal kebun kelapa sawit Jonggol sebagai biotipe resisten dan asal pinggir jalan kampus IPB Dramaga sebagai biotipe sensitif. Hasil runutan basa nukleotida disejajarkan menggunakan algoritma MUSCLE dan visualisasi hasil penjajaran menggunakan Geneious Prime. Hasil pensejajaran basa nukleotida menunjukkan tidak adanya titik mutasi penyebab resistensi glifosat pada rentang basa 979 sampai dengan 1280 gen penyandi EPSPS. Nilai LD50 yang tinggi pada pada Blok V mengindikasikan adanya potensi resistensi akibat perbedaan basa nukleotida pada titik lain dari gen EPSPS maupun mekanisme non-target-site resistance (NTSR)., Target-site resistance (TSR) to glyphosate is caused by mutation in targeted gene namely 5-enolpyruvyl-shikimate-3-phosphate synthase (EPSPS). This research was aimed to identify TSR mechanism assosiated with TIPS mutation in Eleusine indica biotypes from Oil Palm Plantation in Jonggol which was reported resistant recently. Bio-assay analysis was conducted using a single-factor Randomized Completely Block Design (RCBD), namely herbicide dose with 8 dose levels and 3 replications. The number of experimental units was 24 experimental units per block. The experiment began with the collection of resistant E. indica seeds in Block II and Block V. E. indica seeds were planted in pots by spreading. Weeds that had grown were maintained by weeding, watering, and selecting for uniform growth. Glyphosate application was carried out when the weeds were 4-leafed using eight dose levels, namely 0, 1/8x, 1/4x, 1/2x, x, 2x, 4x, 8x with x being the recommended dose, so that the herbicide dose of glyphosate was 0, 121.5, 243, 486, 972, 1944, 3888, and 7776 g ha-1. The spray volume used was 400 L ha-1. Percentage of weed damage was obtained from plant biomass then regression analysis was conducted to obtain LD50 and resistance ratio. E. indica
Keyword: bio-assay, EPSPS, LD50, resistance index, sequencing

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: 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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