Judul: Pertumbuhan dan Produksi Ubi Kayu (Manihot esculenta Crantz) pada Sistem Tumpang Sari dengan Bengkuang (Pachyrhizus erosus L.).
Abstrak: Produksi ubi kayu di Indonesia mengalami peningkatan produksi 10 tahun terakhir dari 19,32 juta ton pada tahun 2005 menjadi 21,79 juta ton pada tahun 2015. Luas areal panen turun dari 1,21 juta ha menjadi 949 ribu ha. Lahan produktif di Indonesia semakin berkurang dari tahun ke tahun. Produksi tanaman mengarah pada lahan marjinal dengan hara atau kesuburan yang rendah. Peningkatan produksi dan perbaikan hara perlu dilakukan, salah satunya dengan penanaman ubi kayu secara tumpang sari dengan tanaman kacang-kacangan. Penelitian ini bertujuan mengetahui pertumbuhan dan produksi beberapa varietas ubi kayu pada sistem tumpang sari dengan bengkuang. Tiga varietas ubi kayu (Mangu, Gajah dan Adira 1) ditanam monokultur dan tumpang sari dengan bengkuang. Varietas berpengaruh terhadap pertumbuhan ubi kayu seperti tinggi tanaman, diameter batang, jumlah daun segar, jumlah daun gugur, bobot basah dan kering daun gugur. Ubi kayu pada sistem tanam tumpang sari mempunyai tinggi tanaman dan diameter batang yang lebih besar. Perlakuan sistem tanam tumpang sari meningkatkan jumlah umbi pertanaman, bobot basah dan kering brangkasan dan varietas adira mempunyai bobot basah dan kering tertinggi. Sistem tanam tumpang sari antara ubi kayu dan bengkuang tidak mampu meningkatkan produktivitas ubikayu. Hasil umbi ubi kayu terbesar terdapat pada varietas Mangu yaitu 4,27 kg tanaman-1 atau 34,16 ton ha-1 Interaksi varietas dan sistem tanam tidak menghasilkan pengaruh terhadap pertumbuhan dan produksi ubi kayu maupun bengkuang. Penanaman ubi kayu secara tumpang sari mampu menaikkan nilai unsur hara N, P, K dan Al., Productivity of cassava in Indonesia increased in last 10 years from 19,32 million ton hectare-1 in 2005 to 21,79 million ton hectare-1 in 2015. However the cassava field decreased from 0.949 to 1.21 million ha. Productive land in Indonesia is decreasing almost every year. Planting in the marjinal land with low nutrient contents will cause low productivity of casava. One of the way to increase productivity and nutrient content is an intercropping casava and legume. In this study, three variety of cassava were used are Mangu, Gajah and Adira-1. The variety was planted in monoculture and intercropping. Variety affect in plant height, stem diameter, number of attached leaves, number of fallen leaves, fresh and dry weight of cassava leaves. The casava intercropped have the plant height and stem diameter more than in the monoculture, but intercropping between cassava and yam bean did not increase cassava productivity. The treatment of intercropping system increased number of cassava tuber per plant, fresh and dry biomass of cassava and Adira has fresh and dry biomass biggest. The highest tuber of cassava produced by Mangu variety with 4,27 kg per plant or 34,16 ton per hectare. The interaction of variety and cropping system not affect in the growth and production of cassava and yam bean. The intercropping system in casava increase amount of Nitrogen, Pottasium, Kalium and Al in the soil.
Keyword: cassava, growth, intercropping, production, yam bean

Judul: Pertumbuhan Tiga Varietas Lokal Ubi Kayu (Manihot esculenta Crantz) pada Kondisi Bulan Lembab
Abstrak: Ubi kayu merupakan makanan alternatif pengganti sumber karbohidrat. Kemudahan penanaman dan ketahanan terhadap kekeringan, ubi kayu sangat potensial untuk dikembangkan. Penelitian bertujuan mengetahui pengaruh penyiraman setara bulan lembab terhadap pertumbuhan ubi kayu lokal varietas Mangu, Genjah Bayam, dan IR Jonggol. Penelitian dilaksanakan di Rumah kaca Kebun Percobaan Cikabayan IPB Dramaga Bogor pada bulan Oktober 2021 sampai Februari 2022. Penelitian menggunakan Rancangan Acak Kelompok dengan dua faktor dan tiga ulangan. Faktor pertama adalah penyiraman yang terdiri dari 163,5 ml hari-1 polibag-1 (100 mm bulan-1 curah hujan) dan 196,3 ml hari-1 polibag-1 (120 mm bulan-1). Faktor kedua adalah varietas yang terdiri dari Mangu, Genjah Bayam, dan IR Jonggol. Penyiraman tidak berpengaruh nyata terhadap semua variabel pertumbuhan ubi kayu. Hasil penelitian menunjukkan varietas berpengaruh nyata terhadap semua variabel pertumbuhan ubi kayu, kecuali bobot batang, tangkai daun, dan daun. Tidak ada pengaruh interaksi antara penyiraman dan varietas pada semua variabel pertumbuhan. Pertumbuhan varietas IR Jonggol lebih tinggi dibandingkan dengan varietas Mangu dan Genjah Bayam., Cassava is an alternative food as a substitute for rice and corn. With the ease of planting and the resistance to drought, it is the potential to develop. The experiment aimed to identify the effects of watering on the growth of local cassava varieties of Mangu, Genjah Bayam, and IR Jonggol. The experiment was conducted in the Greenhouse at the Cikabayan Experimental station of IPB Dramaga, Bogor, from October 2021 to February 2022. The experiment used a randomized block design with two factors and three replications. The first factor was watering consisting of 163,5 ml day-1 polybag-1 (100 mm month-1 rainfall) and 196,3 ml day- 1 polybag-1 (120 mm month-1). The second factor was varieties consisting of Mangu, Genjah Bayam, and IR Jonggol. The watering had no significant effect on all cassava growth variables. The varieties were significantly effect to all cassava growth variables, except the weight of stem, petiole, and leaves. There was no interaction effect between watering and variety on all growth variables. The growth of varieties of IR Jonggol was higher than that of Mangu and Genjah Bayam.
Keyword: growth, oldeman, varieties, watering

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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