Judul: Studi irradiasi sinar gamma pada tanaman iles-iles (Amorphophallus muelleri Blume)
Abstrak: Konjac (Amorphophallus muelleri Blume) is a triploid tuberous crop plant which produces apomictic seeds. It makes the genetic diversity of the plant is considered low. The objective of this research was to increase the diversity of konjac and to get a potential mutan in order to develop breeding materials. Gamma irradion was used in this experiment. The gamma irradiation was applicated in konjac’s seeds, using eleven treatments including control, from 0 Gy to 100 Gy with 10 Gy in every interval of the treatment. Result showed that control (0 Gy) and 10 Gy treatments that had succesfully produced potential mutans . Treatments level higher than 20 Gy to100 Gy caused mortal plant or kept seeds dormant until the end of the experiment. The 10 Gy treatment significantly delay seed sprouting more than five weeks after planting. All of the vegetative parameters of 10 Gy’s treated plants significantly exhibited lower productivity than those of control plants. Some mutans were observed on the leaf morphology. This experiment revealed that A. muelleri seed was sensitive to gamma irradiation.
Keyword: 

Judul: Karakterisasi Morfologi dan Pertumbuhan Ubi Kayu ‘Gajah’ Asal Kalimantan Timur Hasil Iradiasi Sinar Gamma
Abstrak: Cassava (Manihot esculenta Crantz.) is one of important food source, therefore it is very important to increase cassava yield and starch content, and decrease HCN content in the tuber through efficient breeding program. High genetic diversity is one requirement in successful breeding program. The objective of this experiment was to increase genetic variability of ‘Gajah’ genotype cassava from East Kalimantan through gamma irradiation. Stem cuttings of cassava were irradiated in PATIR-BATAN and planted in Cikabayan Experimental Field, IPB from December 2012 to June 2013. This research was arranged in randomized completely block design with one factor that was gamma ray irradiation rate. The gamma irradiation rate consisted of five levels i.e. 0, l5, 30, 45, and 60 gray (Gy). The research results showed that the LD20 was 16.04 Gy and the LD50 was 21.49 Gy. Gamma irradiation did not significantly affect the vegetative growth of cassava, but it caused changes in several morphological characters, i.e. pubescence on apical leaves, color of apical leaves, leaves retention, shape of central leaflet, petiole color, number of leaves lobes, and orientation of petiole. One of mutant candidate from 15 Gy-irradiated plants produced 17 tuber per plant, thus it is potentially developed further.
Keyword: 

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.
Keyword: