Judul: Study on the Mechanisms of Weed Resistance in Monochoria vaginalis (Burm. f.) C. Presl from Rice Fields Area of West Java toward Methyl Metsulfuron Herbicide
Abstrak: Monochoria vaginalis (Burm. F.) C. Presl merupakan tanaman herba akuatik yang dikenal sebagai gulma paling mengganggu di areal sawah Jawa Barat, Indonesia. Herbisida metil metsulfuron telah lama digunakan pada padi sawah di Jawa Barat dengan intensitas yang cukup tinggi. Namun, kasus resistensi Monochoria vaginalis terhadap herbisida metil metsulfuron di Indonesia belum banyak dilaporkan dan diteliti. Penelitian ini bertujuan untuk (1) mendapatkan informasi mengenai penggunaan herbisida metil metsulfuron di areal padi sawah Jawa Barat, (2) mengklasifikasikan tingkat resistensi Monochoria vaginalis terhadap metil metsulfuron, dan (3) mengidentifikasi mekanisme Target Site Resistance (TSR) pada gen MvALS1 ekotipe Monochoria vaginalis yang resisten. Penelitian dilaksanakan pada bulan Juni 2023 hingga Oktober 2023 di Rumah Kaca Cikabayan dan Laboratorium Bioteknologi Molekuler Tumbuhan 2 IPB. Uji tingkat resistensi dilakukan dengan metode Whole Plant Pot Test menggunakan Rancangan Petak Terbagi (Split Plot Design) dengan 4 ulangan. Petak utama adalah lokasi padi sawah pengambilan benih gulma. Anak petaknya adalah dosis metil metsulfuron: 0, 1, 2, 4, 8, 16, dan 32 g b.a ha-1. Selanjutnya, sekuensing DNA menggunakan metode PCR dilakukan pada semua sampel untuk mengidentifikasi perbedaan basa nukleotida pada gen MvALS1 dari ekotipe resisten. Hasil penelitian menunjukkan bahwa Monochoria vaginalis asal Rawamerta, Karawang menunjukkan tingkat resistensi sedang terhadap metil metsulfuron dengan rasio resistensi 6,00 dan asal Patokbeusi, Subang menunjukkan tingkat resistensi yang rendah terhadap metil metsulfuron dengan rasio resistensi 3,89 dibandingkan Monochoria vaginalis sensitif. Penjajaran basa nukleotida gen MvALS1 menunjukkan bahwa ekotipe M. vaginalis asal Rawamerta dan Patokbeusi mengalami lima substitusi asam amino: Ser-64-Ala, Asp-66-Glu, Asn-240-Asp, Glu-426-Asn, dan Ser-469-Asn dibandingkan dengan sekuen asam amino dengan nomor Genbank AB243613.1. Monochoria vaginalis asal Sukra mengalami tiga substitusi asam amino: Ser-64-Ala, Asp-66-Glu, dan Asn-240-Asp. Studi ini mengkonfirmasi pertama kalinya terjadi substitusi asam amino Ser-64-Ala, Asn-240-Asp, dan Glu-426-Asn pada ekotipe resisten Monochoria vaginalis terhadap metil metsulfuron (inhibitor ALS)., Monochoria vaginalis (Burm. F.) C. Presl is an aquatic herbaceous plant, recognized as the most troublesome weed in rice fields in West Java province, Indonesia. Metsulfuron-methyl has long been used in wetland rice in West Java with a high enough intensity. However, the case of Monochoria vaginalis resistance to metsulfuron-methyl herbicides in Indonesia has not been widely reported and investigated. The study aimed to (1) obtain information about the use of metsulfuron-methyl in West Java rice fields, (2) classify the resistance level of Monochoria vaginalis toward metsulfuron-methyl, and (3) identify Target Site Resistance (TSR) mechanism in the MvALS1 gene of the resistant ecotype of Monochoria vaginalis. Research was conducted from June 2023 until October 2023 at Cikabayan Green House and Plant Molecular Biotechnology Laboratory 2 IPB. The resistance level test of Monochoria vaginalis was performed using the Whole Plant Pot Test method. The experimental design used Split Plot Design with 4 replications. The primary plot was designated for the rice fields where weed seeds were collected. The subplot was the dosage of metsulfuron-methyl: 0, 1, 2, 4, 8, 16, and 32 g a.i ha-1. Following that, all samples were subjected to DNA sequencing using the PCR method to identify mutations in the MvALS1 gene from the resistant ecotype. The result showed that Monochoria vaginalis from Rawamerta, Karawang
Keyword: bioassay, GR50, sekuensing, sulfonilurea, resistensi situs target, sequencing, sulfonylurea, target site resistance

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: Bifurkasi Hopf pada Model Siklus Bisnis Kaldor Kalecki tanpa dan dengan Waktu Tunda
Abstrak: Business cycle model is one of dynamical system models in economic. One of the business cycles model is Kaldor-Kalecki model. Kaldor-Kalecki business cycle model that is written in delayed defferential equations, is a business cycle model that involves gross product and capital stock of a company. In this paper Kaldor-Kalecki business cycle model is analyzed using both nondelay and delay in time of capital stock. By Taylor expansion for the time delayed model, an analysis of stability around the fixed points has been done. Furthermore, by using Hopf bifurcation theorem, it can be shown that there exists periodic orbits and limit cycle. In the nondelayed model, changing the parameter of goods market could lead to the occurrence of Hopf bifurcation and the existence of limit cycle. Similarly, for the delayed model, it has been shown that changing the time delay parameter may result in the occurrence of Hopf bifurcation and limit cycle.
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