Judul: Keefektifan Beberapa Isolat Plant Growth Promoting Rhizobacteria untuk Menekan Penyakit Bulai (Peronosclerospora maydis (Rac.) Shaw) pada Tanaman Jagung Manis
Abstrak: Bulai adalah penyakit penting yang menyerang tanaman jagung di Indonesia. Pada penelitian ini digunakan tanaman jagung manis sebagai model tanaman penelitian. Penelitian ini bertujuan menguji keefektifan aplikasi plant growth promoting rhizobacteria (PGPR) untuk menekan penyakit bulai pada tanaman jagung manis. Isolat bakteri PGPR yang diuji yaitu P14, J8, G4, dan campuran bakteri P14 dan J8. Isolat diencerkan pada media air steril kemudian diaplikasikan pada benih dengan cara perendaman benih. Terdapat dua percobaan, yaitu percobaan untuk mengamati pengaruh PGPR terhadap sifat agronomis tanaman jagung manis dan percobaan untuk mengamati pengaruh PGPR terhadap keparahan dan kejadian penyakit bulai pada tanaman jagung manis. Perlakuan yang diberikan terdiri atas 7 perlakuan yaitu aplikasi PGPR, formulasi komersial Benprima, fungisida berbahan aktif metalaksil, dan kontrol. Seluruh bakteri PGPR yang diujikan memiliki potensi untuk meningkatkan perkecambahan dan bobot basah tajuk, tapi tidak dapat menekan kejadian penyakit bulai. Bakteri G4 yang berasal dari guano dapat meningkatkan tinggi tanaman, bobot basah tajuk, dan bobot basah akar tanaman.
Keyword: bulai, plant growth promoting rhizobacteria, jagung manis

Judul: Keefektifan Beberapa Isolat Plant Growth Promoting Rhizobacteria untuk Pengendalian Penyakit Embun Bulu pada Tanaman Mentimun di Lapangan.
Abstrak: Penyakit embun bulu merupakan penyakit penting pada tanaman mentimun. Embun bulu disebabkan oleh Pseudoperonospora cubensis. Salah satu teknik pengendalian yang menjanjikan adalah pengendalian hayati dengan plant growth promoting rhizobacteria (PGPR). PGPR adalah bakteri pengoloni akar yang dapat memicu pertumbuhan dan menginduksi tanaman resisten. Penelitian bertujuan mengetahui keefektifan beberapa isolat PGPR dalam mengendalikan penyakit embun bulu pada tanaman mentimun di lapangan serta melihat pengaruhnya terhadap pertumbuhan tanaman. Isolat bakteri yang diuji ialah P14, J8, dan kombinasi J8+P14 dengan pembanding PGPR komersial dan fungisida berbahan aktif polioxin. Perlakuan dilakukan dengan perendaman benih dan penyiraman tanaman. Hasil penelitian menunjukkan bahwa kombinasi J8+P14 memiliki pengaruh nyata dan hasil terbaik terhadap panjang akar, daya berkecambah benih, diameter batang, tinggi tanaman, bobot buah, panjang buah, insidensi dan keparahan penyakit. PGPR tunggal J8, P14, PGPR pembanding juga dapat memicu daya kecambah benih yang lebih baik dibanding dengan kontrol. PGPR kombinasi mampu menekan keparahan penyakit hingga 29.41%. Selain itu, PGPR komersial dan fungisida polioxin juga mampu menekan keparahan penyakit berturut-turut 26.47% dan 23.53%.
Keyword: induksi tanaman resisten, pengendalian hayati, penyakit penting mentimun, Pseudoperonospora cubensis

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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