Judul: Peningkatan Keragaan Coleus (Coleus sp.) melalui Induksi Mutasi Fisik dengan Iradiasi Sinar Gamma
Abstrak: The objectivse of this study were to see the effect in applicating several doses of gamma-ray irradiation (15, 30, 45, and 60 gray (Gy)), to obtain Lethal Dose 50 (LD50) values, and to gain new coleus performances in relatively short time. The study was conducted inside green house located at cikabayan experimental field, Bogor Agricultural University, Darmaga, Bogor on May to June 2013. The results showed that application of several doses of gamma irradiation on coleus were significantly different in character of height, number of leaves, and number of stem segment. Increasing the dose level of gamma irradiation given tend to inhibit the growth of the plants. Based on the result of the study, LD50 for yellow/green, green/brown, variegated green/brown of Coleus blumei, and Coleus amboinicus Lour were 48.66, 65.2, 52.81, and 37.62 Gy respectively. Coleus amboinicus Lour irridiated at a dose level of 45 Gy produced different leaf shapes compared to control.
Keyword: torbangun, ornamental plant, LD50 values, gamma-ray irradiation, coleus

Judul: Mutasi Induksi Fisik Pada Coleus Spp. Dengan Iradiasi Sinar Gamma
Abstrak: Tanaman Coleus spp. merupakan tanaman yang dikembangbiakkan secara vegetatif. Mutasi induksi dengan iradiasi sinar gamma merupakan salah satu cara dalam meningkatkan keragaman genetik. Mutasi dapat meningkatkan keragaman genetik karena sifatnya yang spontan dan acak. Pemuliaan mutasi pada tanaman yang diperbanyak secara vegetatif telah menghasilkan tanaman-tanaman yang menarik terlebih pada tanaman hias. Tujuan dari penelitian ini untuk (1) mengidentifikasi respon keragaan vegetatif dan perubahan kualitatif tanaman Coleus spp. hasil iradiasi sinar gamma, (2) mengidentifikasi keragaman genetik tanaman Coleus spp. hasil iradiasi sinar gamma pada generasi MV2 dan MV3, (3) mendapatkan tanaman mutan Coleus spp. hasil iradiasi sinar gamma serta (4) mengetahui pengaruh iradiasi sinar gamma terhadap aroma, rasa dan kadar total flavonoid tanaman Coleus amboinicus Lour. Penelitian ini menggunakan Rancangan Acak Kelompok Lengkap (RAKL) faktor tunggal dengan tiga ulangan. Iradiasi sinar gamma diberikan terhadap 360 stek pucuk tanaman masing-masing dengan perlakuan iradiasi tunggal dan iradiasi terbagi. Iradiasi dilakukan di BATAN (Badan Tenaga Nuklir) Jakarta, Indonesia. Semua tanaman yang diradiasi di tanam di lapang. Perbanyakan tanaman Coleus spp. di generasi MV1 digunakan untuk generasi MV2 dan perbanyakan tanaman di MV2 digunakan untuk generasi MV3. Hasil penelitian menunjukkan bahwa pemberian iradiasi sinar gamma terhadap Coleus spp. menghasilkan variasi keragaan karakter vegetatif dan perubahan sifat kualitatif tanaman. Iradiasi sinar gamma dengan dosis tertinggi memperlihatkan rataan terendah pada karakter tinggi tanaman, jumlah daun, jumlah ruas, jumlah cabang, lebar daun dan panjang daun. Pemberian iradiasi sinar gamma pada Coleus spp. menghasilkan keragaman genetik yang tinggi pada karakter jumlah daun dan jumlah cabang. Induksi mutasi fisik dengan iradiasi sinar gamma pada Coleus spp. menghasilkan 16 variasi tanaman mutan berdasarkan perubahan warna dan corak daun. Coleus amboinicus Lour. menghasilkan 2 mutan yaitu pada tanaman A40.6 dan A35.12. Coleus blumei ungu/hijau menghasilkan mutan terbanyak mencapai 11 mutan yaitu pada tanaman A40.1, A40.8, A40.4, A40.12, A45.3, A50.5, T20+20.5, T20+20.7, T25+25.5, T22.5+22.5.8 dan T25+25.8. Coleus blumei merah menghasilkan 3 mutan yaitu pada tanaman A50.6, A50.12 dan T25+25.12. Pemberian iradiasi sinar gamma mempengaruhi perubahan aroma, rasa dan kadar total flavonoid pada tanaman Coleus amboinicus Lour. Kadar total flavonoid yang dihasilkan berkisar antara 0.09-0.29%, kadar total flavonoid tertinggi diperlihatkan pada tanaman A40.6 yaitu sebesar 0.29%.
Keyword: Coleus amboinicus Lour, Coleus blumei, flavonoid, keragaman, mutan

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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