Judul: Beberapa pendekatan dalam mengatasi penyakit bengkak akar pada kubis
Abstrak: Penelitian dilakukan di laboratorium Fitopatologi IPB Bogor dan rumah plastik di IPB Begor serta di Kebun Percobaan Pasir Sarongge. Penelitian dilakukan untuk menguji beberapa pendekatan dalam mengatasi penyakit bengkak akar yang mencakup: pengujian resistensi, pemanfaatan residu tanaman yang berasal dari pertanaman sebelumnya, dan modifikasi pH tanah yang berasal dari Pacet dan Lembang dengan penambahan kapur. Bahan inokulum diambil dari tanaman kubis yang terserang penyakit bengkak akar sebanyak 10 gram, ditumbuk dengan mortar, lalu diblender selama satu menit dengan di­ tambah air suling steril 10 ml, kemudian disaring, dan di­ peroleh suspensi inokulum. Konsentrasi inokulum ditentukan dengan menghitung jumlah spora/ml cairan dengan haemasito-meter. Residu tanaman yang dipakai berupa daun-daun dari sisa tanaman sehabis panen. Daun-daun tersebut dijemur dalam panas matahari selama dua hari, setelah itu dimasukkan ke dalam oven dengan suhu 6o⁰c selama 24 jam. Bahan yang sudah kering digiling dengan gilingan daging, lalu disaring dengan ayakan berukuran 2x2 mm. Untuk perlakuan residu tanaman digunakan residu tanaman: tanah ialah 1 : 100 atau 1% (b/b kering}.
Keyword: Resintenci;, Patogen;, Inokulum;, Bogor Agricultural University;

Judul: Uji kemampuan Pseudomonas spp. kelompok fluoresen dalam menekan Plasmodiophora brassicae Wor. penyebab penyakit akar bengkak pada kubis di lapang
Abstrak: Tujuan penelitian ini adalah untuk menguji kemampuan Pseudomonas spp. kelompok fluoresen dalam menekan Plasmodiophora brassicae Wor. penyebab penyakit akar bengkak pada kubis di lapang. Penelitian dimulai pada akhir Bulan Maret sampai Bulan Agustus 1994 di Laboratorium Cendawan Jurusan Hama dan Penyakit Tumbuhan dan di Kebun Percobaan IPB Pasir Sarongge. Penelitian ini menggunakan Rancangan Acak Kelompok. Terdapat tiga kelompok dan dalam tiap kelompok ada lima perlakuan. Perlakuan tersebut adalah : bakteri isolat I (KtgPS3), bakteri isolat II (JggSGN2), bakteri isolat III (CaiPS2), kontrol I (tanah persemaian tidak steril) dan kontrol II (tanah persemaian steril). Pengamatan dilaksanakan pada saat panen, yaitu 80 hari setelah tanam dengan menimbang bobot basah krop per petak, penghitungan luas serangan dan indeks penyakit. Bobot basah krop per petak pada perlakuan Isolat CaiPS2 memberikan hasil yang terbesar bila dibandingkan dengan hasil perlakuan lainnya namun tidak berbeda nyata secara statistik. Pemberian Isolat Pseudomonas spp. kelompok fluoresen dapat menurunkan luas serangan dan indeks penyakit akar bengkak walaupun secara statistik tidak menunjukkan perbedaan yang nyata.
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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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