Judul: Comparison of Arthropod Diversity in Organic and Non Organic Rice in Cawitali, Tegal Regency
Abstrak: Keanekaragaman artropoda sangat penting dalam menyusun dan membentuk suatu agroekosistem. Salah satu contoh agroekosistem yang baik adalah sistem pertanaman padi organik yang memiliki keanekaragaman artropoda yang cukup tinggi karena bebas pestisida. Tujuan penelitian ini adalah untuk mempelajari dan mendapatkan informasi mengenai peran, kelimpahan dan kekayaan artropoda pada tanaman padi organik dan non organik, Penelitian dilakukan pada bulan Februari sampai July 2023 di Cawitali, salah satu daerah di Kabupaten Tegal yang memproduksi padi organik. Penelitian menggunakan metode sungkup plastik dan pitfall trap pada 10 petak (ulangan) padi organik dan non organik berukuran 10 m x 10 m, pada area pematang sawah dipasang 2 buah pitfall trap dan penyungkupan plastik dilakukan pada 5 titik/rumpun padi. Identifikasi dan sortasi artropoda dilakukan di Laboratorium Pengendalian Hayati, Departemen Proteksi Tanaman, Fakultas Pertanian, IPB University. Hasil penelitian didapatkan 1646 individu artropoda selama periode pengamatan. Pada lahan padi organik didapatkan 739 individu (12 ordo, 55 famili, 69 morfospesies), sedangkan pada padi non organik berjumlah 907 individu (11 ordo, 50 famili, 64 morfospesies). Kelimpahan individu lebih banyak ditemukan pada padi non organik, sementara padi organik memiliki kekayaan jenis yang lebih tinggi. Secara keseluruhan keanekaragaman tertinggi ada pada padi organik dimana memiliki nilai indeks Shanon-Wienner, Evenness, dan Simpson lebih tinggi dibandingkan padi non organik. Padi organik memiliki keanekaragaman artropoda yang tinggi, sehingga peluang keberhasilan pengendalian hayati lebih tinggi., Arthropod diversity is an essential part of an agroecosystem. One example of a good agroecosystem is organic rice because it generally has a fairly high arthropod diversity due to absence of pestisides. The purpose of this research was to study and obtain information on the role, abundance and richness of arthropods in organic and non organic rice plants. The research was conducted from February to July 2023 in Cawitali, one of the areas in Tegal Regency that produces organic rice. Insect were sampled using plastic hoods and pitfall traps methods on 10 organic and non organic rice plots (as replicates) of 10 m x 10 m, 2 pitfall traps were installed in each plots, and plastic hoods were placed at 5 points/rice clumps. Arthropod Identification and sorting were carried out at the Biological Control Laboratory, Department of Plant Protection, Faculty of Agriculture, IPB University. The results of the study obtained 1646 arthropod individuals during the observation period. In organic rice fields, there were 739 individuals (12 orders, 55 families, 69 morphospecies), while in non-organic rice there were 907 individuals (11 orders, 50 families, 64 morphospecies). The abundance of individuals is more found in non-organic rice, while organic rice has a higher species richness. Overall, the highest diversity is in organic rice which has higher values of Shanon-Wienner, Evenness, and Simpson indices than non-organic rice. Organic rice has high arthropod diversity, so the chances of successful biological control are higher.
Keyword: agroekosistem, kekayaan, kelimpahan

Judul: Population of Plant-hoppers and Spiders in Biointensive and Conventional Rice Croping
Abstrak: Padi merupakan salah satu tanaman serelia penting yang digunakan sebagai makanan pokok sebagian besar penduduk dunia. Padi tergolong dalam tanaman pangan berupa rumput berumpun dan memiliki kemampuan beradaptasi yang tinggi pada berbagai kondisi lingkungan. Penelitian bertujuan mengetahui perbandingan populasi hama wereng dan populasi laba-laba pada pertanaman padi biointensif dan konvensional di Kampung Darim, Kecamatan Terisi, Kabupaten Indramayu, Provinsi Jawa Barat. Metode penelitian yang digunakan adalah metode pengamatan langsung dilakukan dengan menetapkan titik pengamatan secara terpilih yang mewakili bagian tengah lahan sawah dengan ukuran 10 m x 10 m. Pada setiap lahan sawah ditentukan 100 grid pengamatan, grid pengamatan berukuran 1 m2. Data diolah dan dianalisis menggunakan aplikasi Microsoft excel 2013. Hasil penelitian menunjukkan bahwa populasi wereng lebih tinggi pada lahan pertanaman padi dengan perlakuan biointensif, populasi laba-laba lebih tinggi pada lahan pertanaman padi dengan perlakuan biointensif. Spesies yang ditemukan yaitu Araneus inustus, Neoscona theisi, Atypena adelina, Pardosa pseudoannulata, Tetragnathidae sp., Oxyopes javanus, dan Harmochirus sp. Dominasi spesies yang ditemukan yaitu Atypena adelina baik pada lahan dengan perlakuan biointensif maupun konvensional. Famili yang mendominasi pada pada lahan dengan perlakuan biointensif maupun konvensional adalah Famili Araneidae., Rice is one of the important cereal crops which is used as a staple food for most of the world's population. Rice is classified as a food crop in the form of clump grass and has high adaptability to various environmental conditions. This study aims to determine the comparison of planthopper populations and spider populations in biointensive and conventional rice plantations in Darim Village, Terisi District, Indramayu Regency, West Java Province. The research method used is a direct observation method carried out by determining selected observation points that represent the middle of the rice field with a size of 10 m x 10 m. In each rice field, 100 observation grids are determined, the observation grid is 1 m2 in size. The data was processed and analyzed using the Microsoft Excel 2013 application. The results showed that the planthopper population was higher on rice plantations with biointensive treatment, the spider population was higher on rice plantations with biointensive treatment. The species found were Araneus inustus, Neoscona theisi, Atypena adelina, Pardosa pseudoannulata, Tetragnathidae sp., Oxyopes javanus, and Harmochirus sp. The dominant species found was Atypena adelina both on land with biointensive and conventional treatment. The family that dominates on land with biointensive and conventional treatment is the Araneidae family.
Keyword: dominasi, keragaman, musuh alami

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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