Judul: Mutasi Induksi dengan Iradiasi Sinar Gamma secara Berulang pada Tunas In Vitro Celosia cristata L.
Abstrak: Celosia cristata L. atau lebih dikenal dengan nama bunga jengger ayam adalah tanaman hias dari famili Amaranthaceae. Peningkatan nilai guna dan ekonomi tanaman jengger ayam dapat dilakukan dengan menciptakan keragaman salah satunya melalui mutasi induksi. Penelitian ini bertujuan untuk mengetahui pengaruh iradiasi sinar gamma secara berulang terhadap keragaan tanaman jengger ayam pada generasi MV1 (mutan vegetatif pertama) dan MV2 (mutan vegetatif kedua). Penelitian ini dilaksanakan pada November 2016 hingga April 2017 di Laboratorium Kultur Jaringan 1, Departemen Agronomi dan Hortikultura, Fakultas Pertanian IPB dan iradiasi sinar gamma dilakukan di Pusat Aplikasi Isotop dan Radiasi Badan Tenaga Nuklir Nasional (PAIR BATAN), Pasar Jumat, Jakarta. Hasil penelitian menunjukkan bahwa teknik iradiasi sinar gamma secara berulang berpengaruh terhadap keragaan planlet Celosia cristata L. pada karakter kuantitatif serta kualitatif. Perlakuan dosis terbagi (fractionated irradiation) lebih banyak berpeluang menghasilkan tanaman mutan dibandingkan dengan perlakuan setengah dosis (split dose), terutama pada taraf dosis (35+15) Gy.
Keyword: iradiasi dosis terbagi, iradiasi setengah dosis, mutan, tanaman hias

Judul: Mutasi In Vitro pada Celosia argentea var. cristata (L.) Kuntze dengan Iradiasi Sinar Gamma secara Berulang
Abstrak: Celosia argentea var. cristata (L.) Kuntze atau biasa disebut dengan jengger ayam merupakan tanaman hias dari famili Amaranthaceae yang dibudidayakan baik sebagai tanaman hias pot, tanaman lanskap, maupun bunga potong. Peningkatan nilai ekonomi tanaman jengger ayam khususnya sebagai tanaman hias bunga potong yaitu dengan meningkatkan keragaman. Salah satu metode alternatif untuk meningkatkan keragaman adalah melalui induksi mutasi in vitro pada tanaman hasil kultur jaringan. Penelitian ini bertujuan untuk mengetahui pengaruh teknik iradiasi secara berulang dengan dosis terbagi (fractionated irradiation) terhadap keragaan planlet jengger ayam secara in vitro pada generasi MV1 dan MV2. Penelitian ini dilaksanakan pada November 2017 hingga September 2018 di Laboratorium Kultur Jaringan 1, Departemen Agronomi dan Hortikultura, Fakultas Pertanian IPB. Iradiasi eksplan jengger ayam dilaksanakan di Pusat Aplikasi Isotop dan Radiasi Badan Tenaga Nuklir Nasional (PAIR BATAN), Pasar Jumat, Jakarta Selatan. Hasil penelitian menunjukkan bahwa teknik iradiasi secara berulang dengan dosis terbagi (fractionated irradiation) berpengaruh terhadap keragaan planlet jengger ayam secara kuantitatif maupun kualitatif. Dosis iradiasi 45+15 Gy lebih banyak menghasilkan keragaman planlet jengger ayam dibandingkan dengan dosis iradiasi lain pada generasi MV2. Keragaman tersebut yaitu munculnya warna merah pada daun dan batang planlet, keragaan daun keriting, daun bercabang, dan perbedaan morfologi bunga in vitro dibandingkan dengan planlet kontrol.
Keyword: mutan putatif, pembungaan in vitro, 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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