Judul: Seleksi Bakteri Diazotrof Endofitik Padi Penghasil Asam Indol-3-Asetat (AlA)
Abstrak: Penelitian ini bertujuan: (1) Mengisolasi dan menyeleksi bakteri diazotrof endofitik dari tanaman padi, (2) Mengukur aktivitas enzim nitrogenase dan produksi AIA bakteri diazotrof endofitik, (3) Menguji pengaruh bakteri diazotrof endofitik terhadap perkembangan akar tanaman padi secara in vitro, (4) Menguji pengaruh bakteri diazotrof endofitik terhadap pertumbuhan, penambahan N simbiotik padi di rumah kaca.
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Judul: Produksi hormon asam indol-3-asetat oleh bakteri diazotrof endofitik dan aplikasinya pada tanaman kentang
Abstrak: Bakteri diazotrof endofitik adalah bakteri yang hidup di jaringan tanaman dan menambat nitrogen. Inokulasi bakteri diazotrof endofitik dapat mempengaruhi pertumbuhan tanaman melalui hormon tumbuh yang dihasilkannya, seperti asam indol-3-asetat (AIA). Seleksi bakteri adalah dengan mengukur produksi AIA oleh 14 isolat bakteri diazotrof endofitik. Hasil seleksi didapat lima isolat dengan AIA tertinggi (BBd1, BCr1.2, BPr2.3, KACP13, dan RIFCB2) dan satu isolat unggul (APK2.4) yang kemudian diinokulasikan pada tanaman kentang (Solanum tuberosum L. cv. Granola). Inokulasi dibedakan menjadi empat perlakuan: kultur murni, supernatan, pelet, dan supernatan diotoklaf. Pembanding adalah AIA sintetis dan blanko. Hasil pengamatan menunjukkan AIA bakteri diazotrof endofitik dapat memproduksi AIA dan juga meningkatkan pertumbuhan tanaman kentang. Aplikasi supernatan BCr1.2 meningkatkan tinggi batang 23%; panjang akar 77%; dan jumlah akar 167%. Aplikasi supernatan BPr2.3 meningkatkan tinggi batang 109% dan jumlah akar 283%. Aplikasi supernatan BBd1 meningkatkan tinggi batang 5%; panjang akar 89% dan jumlah akar 150%. Aplikasi supernatan KACP13 tidak meningkatkan pertumbuhan tanaman. Supernatan yang diotoklaf tidak meningkatkan pertumbuhan tanaman karena AIA rusak jika dipanaskan. Aplikasi kultur murni RIFCB2 meningkatkan tinggi batang 136%; panjang akar 69%; dan jumlah akar 33%. Aplikasi pelet isolat APK2.4 meningkatkan panjang akar tanaman 130%. Isolat yang menunjukkan respon terbaik adalah BCr1.2 (supernatan) dan RIFCB2 (kultur murni) karena meningkatkan baik tinggi batang, panjang, serta jumlah akar tanaman.
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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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