Judul: Peningkatan Keragaman Kembang Sepatu (Hibiscus Roso-Sinensis Linn.) Melalui Mutasi Iuduksi Dengan Iradiasi Sinar Gama
Abstrak: T ujuan penelitian ini adaIah untuk mengetahui dosis iradiasi sinar gamma yang dapat menyebabkan kematian 50"/0 dari populasi kembang sepatu VI dan V2 dan meningkatkan keragaman kembang sepatu pada daun dan/atau bunga. Penelitian dilaksanakan di Kebun Perrobaan Kayu Manis, Bogor pada bulan Februari bingga Juni 2006. Penelitian menggllnakan metode percobaan fuktorial, yang terdiri dari dua faktor yang disusun dalam Rancangan Kelompok Lengkap Teracak (Randomized Complete Block Design). Faktor pertama adaIah varietas Hibiscus rosa-sinensis dengan bunga warna mernb (VI) dan pink (V2). Faktor kedua adalah dosis iradiasi yang terdiri dari lima dosis, yaitu 0 (RO), 35 (RI), 45 (R2). 55 (R3) dan 65 (R4) Gy. Pemberian dosis iradiasi meggunakan teknik iradiasi acute. Tiap kombinasi perlakuan digunakan tiga tanaman dengan tiga ulangan. …
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Judul: Induksi Mutasi Fisik pada Paku Bintik (Microsorum punctatum) melalui Iradiasi Sinar Gamma
Abstrak: Pemuliaan mutasi dengan iradiasi sinar gamma merupakan salah satu cara dalam meningkatkan keragaman genetik tanaman. Tujuan penelitian ini adalah mengetahui radiosensitivitas dan nilai LD50 (Lethal dose 50) sinar gamma pada M. punctatum serta mengamati keragaan tanaman M. punctatum hasil iradiasi sinar gamma pada MV1. Nilai LD50 merupakan salah satu parameter untuk mengukur tingkat sensitivitas suatu jaringan terhadap iradiasi. Semakin rendah nilai LD50 suatu jaringan tanaman, semakin tinggi tingkat radiosensitivitasnya, sehingga semakin besar peluang terjadinya mutasi. Penelitian ini menggunakan rancangan acak lengkap (RAL) faktor tunggal (dosis iradiasi sinar gamma) dengan 3 ulangan. Iradiasi sinar gamma diberikan terhadap stek rimpang dengan satu daun dari tanaman M. punctatum secara tunggal (acute irradiation) menggunakan Gamma Cell 220 dengan dosis 0, 10, 20, 30, 40, dan 50 gray. Semua rimpang dengan satu daun hasil iradiasi ditanam di lapangan hingga 16 minggu setelah iradiasi (MSI). Hasil penelitian menunjukkan bahwa pemberian iradiasi sinar gamma pada M. punctatum menghasilkan LD50 sebesar 86,25 gray dan perlakuan iradiasi sinar gamma antar perlakuan berbeda nyata terhadap tinggi dan lebar daun, sedangkan karakter jumlah daun tidak berbeda nyata. Perlakuan iradiasi juga menyebabkan defisiensi warna hijau pada daun M. punctatum. Secara morfologi, perlakuan iradiasi sinar gamma terhadap M. punctatum belum menghasilkan mutan-mutan yang diinginkan, namun secara genetik, terdapat penggandaan jumlah kromosom dan aberasi kromosom pada perlakuan dosis iradiasi tertinggi (50 gray).
Keyword: LD50, radiosensitivitas, tanaman hias

Judul: Thermal Characteristics and Dynamics of Tropical Cyclone over Western North Pacific Ocean: A Case Study of Typhoon Songda (Chedeng) 2011
Abstrak: The frequent occasion of Tropical Cyclone (TC) over Western North Pacific (WNP) Ocean lies from 10˚N to 26˚N and 121˚E to 170˚E. Sources of TC development come from warm ocean temperature where latent heat is released during condensation processes and subsequently concentrated in the boundary layer. Relative humidity at 850-700 hPa is responsible to produce the most intense storm. Meanwhile, weak vertical wind shear between 850-200 hPa is one of the dynamical factors that lead to the development of TC. Pressure level of 850-200 hPa is chosen to minimize the thermodynamic effect in the lower troposphere. Typhoon Songda (Chedeng in the Philippines) or TSC lasted from May 18th to 30th, 2011 and strengthened into powerful Super Typhoon stage between May 24th and 27th. Long curving track and the exhibition of all sequences of TC life cycle, TSC is then considered as an ideal case of TC. The objective of the study with case of TSC is to investigate the role of thermal characteristics and dynamics on TC intensity. The research is carried out by using Advanced Research of Weather Research and Forecasting model (WRF ARW model) version 3.3. Two domains are employed in the model. The first domain situate from 02˚N to 40˚N and 118˚E to 149˚E and cover spatial resolution () of 33.1 km. The second domain situate from 09˚N to 27˚N and 119˚E to 132˚E with of 11 km. Timestep of the model () is 120 seconds. The model is supported by the following physical parameterization, i.e., Yonsei University Scheme (YSU) in the boundary layer, Kain-Fritsch scheme (KF) in the cumulus, and WRF Single-Moment 3-class scheme in the microphysics. Initial meteorological condition prior to the formation of the cyclone is generated using WRF ARW standard-release model. Sensitivity of the model output is obtained from a selected single-parameter change scenarios, namely, 10 % to 20 % decrease and increase of wind shear initial data at 850-200 hPa, and by 10 % to 20 % decrease of relative humidity initial data at 850-700 hPa. The result showed that the negative correlations between wind shear and intensity are found in wind shear scenarios. Wind shears of 10 ms-1 which lead to strengthening of the wind intensity in the early period of Typhoon development are found in wind shear scenarios. The effect of wind shear changes on wind intensity is statistically significant in the 20 % wind shear scenarios. During mature stage, weak wind intensity occurred when wind shear increase as given in the WRF standard-release and the 20 % decreasing scenario. Different situation is found in the 20 % increasing scenario where wind shear tend to weak and lead to strong wind intensity at this stage. Meanwhile, the reduction of moisture supply at 850-700 hPa resulting from 20 % decreasing relative humidity play a major role in the weakening of wind intensity and reduces mechanical energy of the cycle process as much as 300 J kg-1.
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