Judul: Studi Resistensi Gulma Daun Lebar Padi Sawah terhadap Herbisida Golongan Sulfonilurea di Sentra Produksi Padi Jawa Barat
Abstrak: Herbisida merupakan metode pengendalian gulma yang paling banyak digunakan oleh petani namun, penggunaan herbisida secara intensif diduga menyebabkan gulma menjadi resisten. Penelitian ini bertujuan untuk memperoleh informasi mengenai gulma dominan pada padi sawah serta status resistensi gulma. Penelitian diawali dengan analisis vegetasi di lima kecamatan di Karawang dan Subang yang menjadi daerah sentra produksi padi di Jawa Barat. Pengambilan sampel dilakukan di 45 titik di Subang dan 29 titik di Karawang dengan menggunakan kuadran berukuran 1 m x 1 m. Penelitian dilanjutkan dengan penanaman tiga jenis gulma terpilih (L. octovalvis, S. zeylanica, M. vaginalis) yang diberi perlakuan herbisida metil metsulfuron dan penoksulam. Penelitian dilaksanakan pada bulan Januari hingga Mei 2020 di Rumah Kaca Percobaan Cikabayan, IPB University. Percobaan disusun menggunakan rancangan kelompok lengkap teracak dengan empat ulangan. Faktor pertama adalah asal gulma yaitu biji gulma yang terpapar herbisida (Karawang dan Subang) dan tidak terpapar herbisida (Bogor), faktor kedua adalah dosis herbisida, untuk metil metsulfuron terdiri dari 8 taraf yaitu 0, 2.5, 5, 10, 20, 40, 80 dan 160 gha-1. Dosis penoksulam terdiri dari 8 taraf yaitu 0, 50, 100, 200, 400, 800, 1600, dan 3200 ml ha-1. Hasil penelitian menunjukkan bahwa S. Zeylanica dan M. vaginalis dari Karawang dan Subang dan L. octovalvis dari Subang mengalami resistensi rendah terhadap metil metsulfuron, sedangkan L. octovalvis dari Karawang masih sensitif terhadap metil metsulfuron. L. octovalvis, S. Zeylanica, dan M. vaginalis asal Karawang dan Subang masih sensitif terhadap herbisida penosulam., Farmers most commonly used herbicides for weed control in rice however intensive use of herbicides suspected can lead to resistant weeds. The objective of this study was to obtain information about the weed dominant at lowland rice and the status of weed resistance. The research was started with vegetation analysis at five sub-districts in Karawang and Subang, known as two rice production central areas in West Java. Sampling was carried out at 45 points in Subang and 29 points in Karawang using 1 m x 1 m quadrant. The study was continued by planting three selected weeds (i.e., L. octovalvis, S. zeylanica, M. vaginalis) applied with methyl metsulfuron and penoxsulam herbicides. This research was conducted from January to Mei 2020 at Cikabayan Experimental Greenhouse, IPB University. The experiment was arranged in a randomized complete block design with four replications. The first factor was the origin of weed seeds, namely exposed weeds (Karawang and Subang) and not exposed to herbicides (Bogor), the second factor was the rate of the herbicide, for methyl metsulfuron consists of 8 rates, i.e., 0, 2.5, 5, 10, 20, 40, 80 and 160 gha-1. The dose of penoxsulam consisted of 8 doses, namely 0, 50, 100, 200, 400, 800, 1600, and 3200 mlha-1. The results showed that S. zeylanica and M. vaginalis from Karawang and Subang and L. octovalvis from Subang indicated as low resistance to methyl metsulfuron, while L. octovalvis from Karawang was still sensitive to methyl metsulfuron. L. octovalvis, S. zeylanica, and M. vaginalis from Karawang and Subang were still sensitive to penoxsulam herbicides.
Keyword: herbicide, resistance, rice production center, weed, sulfonylurea

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: Penentuan Nilai Eigen dan Vektor Eigen dari Matriks Tridiagonal 2-Toeplitz dengan Pendekatan Polinomial Chebyshev
Abstrak: The eigenvalues and eigenvectors of a matrix can be determined by finding its characteristic polynomials. The characteristic polynomials of a tridiagonal 2-Toeplitz matrix is shown to be closely connected to polynomials which satisfy the Chebyshev recurrence relationship. If the order of the matrix is odd, then the eigenvalues are found explicitly in terms of the Chebyshev zeros and the eigenvectors are found in terms of the polynomials satisfying the recurrence relationship. For even ordered matrices, the situation is more complicated. The problem in these cases is that although the Chebyshev recurrence formula is still applied, its initial values are not generating Chebyshev polynomials
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