Judul: The Difference in Weed Dominance in Various Years of Pruning in Tea Plant (Camellia sinensis L. (O.) Kuntze) at Wonosari, PTPN XII, Malang
Abstrak: PTPN XII Kebun Wonosari merupakan perusahaan perkebunan negara yang memiliki kebun teh seluas 549,72 ha. Kegiatan magang dilaksanakan di Kebun Wonosari pada bulan Januari–April 2021. Tujuan magang meningkatkan pengalaman dan keterampilan secara teknis dan manajerial serta menganalisis sistem perbedaan dominansi gulma berbagai umur pangkas. Pengamatan meliputi perbedaan dominansi gulma setiap afdeling, manajemen struktur pengendalian gulma, metode pengendalian gulma, alat pengendalian gulma, jenis herbisida, dosis herbisida, waktu aplikasi herbisida, efisiensi metode pengendalain gulma, tenaga kerja penyemprotan herbisida, dan laju penutupan gulma setelah semprot. Hasil pengamatan menunjukkan gulma dominan di Kebun Wonosari yaitu (Peperomia pellucida (L.) Kunth) dan (Borreria alata L.). Koefisien komunitas setiap afdeling pada berbagai umur pangkas cenderung heterogen. Metode pengendalian gulma secara kimiawi lebih efisien dibandingkan dengan manual. Laju penutupan gulma setelah semprot meningkat karena biji gulma terus tumbuh., PTPN XII Wonosari plantation is a state-owned plantation company that has 549.72 ha of tea plantation. The apprenticeship was performed in Wonosari plantation from January to April 2021. The apprentice aims are to improve the technical and managerial experience and skills as well as to analyzes the differences of weed dominance at various prune ages. The observations included the difference of weed dominance for each afdeling, the management of weeds control structure, the weeds control method, the weeds control tools, the herbicides, the dose of herbicides, the time of herbicide application, the efficiency of the weeds control method, the labor of herbicide spraying, and the weeds cover rates after spraying. The result showed that there were two dominant weed species in Wonosari plantation, which are (Peperomia pellucida L) and (Borreria alata L.). The community coefficient of every afdeling on a variety of prune ages tends to be heterogeneous. The method was chemically more efficient compared to the manual for controlling the weeds. The rate of weeds covering after spraying increased as the weed seeds keep growing.
Keyword: community coefficient, crop age, cover rate, weed dominance

Judul: Pengelolaan Pemangkasan Tanaman Teh (Camellia sinensis (L.) O. Kuntze) di Kebun Wonosari, PTPN XII, Malang, Jawa Timur
Abstrak: Pemangkasan merupakan kegiatan pemeliharaan tanaman teh yang sangat penting untuk meningkatkan jumlah dan kualitas hasil pada tanaman teh. Kegiatan magang secara umum bertujuan meningkatkan pengetahuan, memperoleh pengalaman kerja, dan meningkatkan keterampilan mengenai aspek teknis dan manajemen perkebunan teh, secara khusus bertujuan mempelajari pengelolaan pemangkasan melalui analisis aspek-aspek pemangkasan yang meliputi pemenuhan kriteria pemangkasan, pelaksanaan pemangkasan, dan pasca pemangkasan. Kegiatan magang dilaksanakan pada Januari hingga April 2021 di Kebun Wonosari, PTPN XII, Malang. Magang dilakukan secara langsung dengan mengikuti aspek teknis dan manajerial teh di lapangan dan tidak langsung dengan mengambil data sekunder dari arsip perusahaan. Kegiatan magang dilakukan untuk mempelajari pengelolaan pemangkasan dengan melihat pengaruh ketinggian tempat dan penggunaan alat pangkas yang berbeda. Pengamatan yang dilakukan untuk mengetahui hal tersebut yaitu dengan mengamati pemangkasan di Afdeling Wonosari (950-1200 m dpl) dan Afdeling Gebug Lor (1200-1450 m dpl) masing-masing 3 nomor kebun dan setiap nomor kebun diambil 15 tanaman contoh. Pengamatan juga dilakukan pada penggunaan alat pangkas manual dan mekanis di Afdeling Wonosari masing-masing 3 nomor kebun dan setiap nomor kebun diambil 15 tanaman contoh. Kegiatan magang telah meningkatkan keterampilan sebagai tenaga pemangkas dengan prestasi kerja sebesar 0,004 ha HK-1. Hasil pengamatan menunjukkan pelaksanaan pemangkasan berdasarkan tinggi dan diameter tanaman masing-masing 137,9 cm dan diameter 142,3 cm sudah memenuhi kriteria pangkas, persentase pucuk burung 64,25% kurang dari kriteria pangkas 70%, dan pati akar belum memenuhi kriteria pangkas. Penggunaan alat pangkas mekanis banyak meninggalkan cabang berdiameter kurang dari 1 cm, alat manual banyak meninggalkan cabang berdiameter 1-1,99 cm. Pertumbuhan tunas lebih cepat di Afdeling Wonosari yang berarti semakin rendah tempat, pertumbuhan tunasnya semakin cepat. Keterampilan pemangkas dipengaruhi oleh umur dan lama kerja, tidak dipengaruhi tingkat pendidikan. Pelaksanaan dan realisasi pemangkasan tidak selalu sesuai dengan rencana. Pengelolaan sisa pangkasan dilakukan dengan meletakkan serasah pangkasan di atas perdu yang telah dipangkas dan diturunkan setelah kering., Pruning is important tea plant maintenance activity to increase quantity and quality of yields on tea plants. This internship generally aimed to increase knowledge, gain work experience, improve skills regarding technical and manajerial of tea plantations and spesifically aimed to study the management of pruning through analysis of pruning aspects which include pruning criteria, pruning implementation, and post-pruning. Internship activities were held in January to April 2021 at Wonosari Plantation, PTPN XII, Malang. The internship was carried out directly by participating in the technical and managerial aspects of tea in the field and indirectly by taking secondary data from the company archives. The internship aimed to learn about pruning management, especially the effect of altitude and the use of different pruning tools. Therefore, observations were made by observing pruning in Afdeling Wonosari (950-1200 m asl) and Afdeling Gebug Lor (1200-1450 m asl) each with 3 garden numbers and 15 sample plants each. Observations were also made on the use of manual and mechanical pruning tools in Afdeling Wonosari, each with 3 garden numbers and 15 plant samples for each garden number. The internship activity has increased skills as a pruner with a work performance of 0,004 ha HK-1. The results showed that the height was 137,9 cm and diameter was 142,3
Keyword: pruning tools, branch damage, branch composition, root starch, planting year

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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