Judul: Deteksi dan identifikasi bakteri yang terbawa benih padi IR 64 yang terkena penyakit garis merah bakteri (Bacterial Red Stripe)
Abstrak: Isolat bakteri yang dideteksi berasal dari benih padi IR 64 yang tanamannya memperlihatkan gejala BRS. Metode penelitian dimulai dari mendeteksi bakteri dengan mengada- kan isolasi.., kemudian bakteri diidentifikasi, diinokulasi- kan dan reisolasi. Sebelum diisolasi, benih sakit mendapat dua macam per- lakuan, yaitu dikupas kulitnya (beras) dan tidak dikupas (gabah). Masing-masing perlakuan didesinfestasi dengan empat cara, yaitu dicuci dengan alkohol, NaOCl, air menga- lir dan dengan air steril. Pada benih sakit yang didesinfestasi dengan NaOCl dan alkohol, tidak didapatkan bakteri yang virulen, sedangkan pada pencucian benih dengan air mengalir dan air steril, didapatkan bakteri yang bersifat virulen, dan termasuk ge- nus Pseudomonas...
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Judul: Identifikasi beberapa isolat bakteri yang berasal dari tanaman padi varietas IR 64
Abstrak: Tujuan dari penelitian ini adalah untuk mengidentifikasi beberapa isolat bakteri yang berasal dari tanaman padi varietas IR 64. Penelitian ini dilakukan di Laboratorium Bakteri Patogen Tumbuhan dan rumah kaca, Jurusan Hama dan Penyakit Tumbuhan, Fakultas Pertanian, Institut Pertanian Bogor, mulai bulan Januari 1994 sampai dengan September 1994. Inokulum bakteri yang digunakan diperoleh dari daun padi yang menunjukkan gejala penyakit di kebun petani desa Sindang Barang dan kebun percobaan Cikeumeuh, Bogor. Dari 11 isolat yang diperoleh dari kedua tempat terse- but ternyata hanya 5 isolat (D3C, D₁B, X12, WA, WB) yang diduga patogen. Metode yang dilakukan dalam penelitian ini adalah: isolasi, inokulasi, reisolasi dan identifikasi. Isolasi bakteri dari daun yang bergejala dilakukan dengan metode penggoresan suspensi bakteri. Inokulasi bakteri pada tanaman dilakukan dengan cara: pengguntingan, penempelan dan penyemprotan. Reisolasi bakteri patogen dilaksanakan dengan cara mengisolasi patogen tersebut dari daun yang menimbulkan gejala. Identifikasi isolat-isolat bakteri ini dilaksanakan dengan: uji Gram, hipersensitivitas, oksidatif-fermentatif, hidrolisis pati, fluoresens pada medium King's B, pewarnaan kapsul, bentuk sel, hidrolisis gelatin, aktivitas oksidase, warna koloni pada medium Nutrien Agar. Hasil dari identifikasi yang dilakukan adalah: isolat D3C diduga patogen Xanthomonas campestris pv. oryzicola, isolat D₁B Xanthomonas oryzae pv. oryzae, isolat X12 dan WA Pseudomonas fuscovaginae dan isolat WB Pseudomonas avenae.
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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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