Judul: Pengaruh Dosis Pemupukan Kalium Terhadap Produktivitas Dua Varietas Ubi Jalar (Lpomea batatas (L.) Lam.)
Abstrak: Percobaan ini dilakukan untuk mengetahui pengamh dosis pemupukan kalium terhadap produktivitas dua varietas ubi jalar (Ipontoea bafatas (L.) Lam.) pada tanah andosol, Kebun Percobaan PD. HIKMAK Pangalengan dari bulan Maret sampai Agustus 2002.
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Judul: Pengaruh pemupukan nitrogen dosis tinggi terhadap produksi dua varietas ubi jalar (Ipomoea batatas L. Lamk)
Abstrak: Percobaan dilakukan untuk mengetahui pengaruh pemberian pupuk nitrogen dosis tinggi terhadap beberapa variabel vegetatif dan generatif yang diujikan. Percobaan dilaksanakan di Kebun Percobaan IPB Darmaga pada tanggal 31 Januari - 29 Mei 2000. Percobaan menggunakan rancangan petak terpisah dua faktor. Faktor utama (petak utama) adalah varietas Georgia Red dan Helalekue Baru. Faktor kedua (anak petak) adalah dosis pemupukan urea, yaitu dosis 0, 100, 200, 300 dan 400 kg urea/ha. Percobaan terdiri dari empat ulangan. Panjang stek ubi jalar yang digunakan yaitu ± 40 cm. Setiap ulangan terdiri dari 10 guludan (sepanjang 10 m), yang masing-masing berjarak 1 m. Stek ditanam dengan jarak 25 cm, sehingga setiap guludan terdiri dari 40 stek. Analisis ragam pada percobaan ini menunjukkan bahwa pemupukan urea dosis tinggi tidak berpengaruh nyata pada sebagian besar variabel pengamatan. Pemupukan hanya berpengaruh nyata pada variabel persentase tumbuh dan penutupan tanaman. Perbedaan varietas mempengaruhi penutupan tanaman, bobot basah ubi, berat kering ubi, serangan penyakit kudis dan kadar protein. Secara umum hasil percobaan menunjukkan bahwa variabel produksi (bobot ubi, bobot kering ubi, indeks panen, kadar protein dan produksi protein) dari Georgia Red lebih baik daripada Helalekue Baru. Tidak ada organisme pengganggu tanaman yang memperlihatkan dominansi pada lahan pertanaman, sehingga pengamatan hanya dilakukan pada serangan penyakit kudis (scab). Dengan kadar bobot kering ubi yang tinggi, maka varietas Helalekue Baru cocok untuk industri tepung dan pati, namun produksi bobot keringnya rendah...dst
Keyword: varietas ubi jalar, botani tumbuh, peranan pupuk, hama dan penyakit

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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