Judul: Pengaruh Populasi Tanaman dan Pemupukan Kalium Terhadap Pertumbuhan dan Produksi Jagung Manis (Zea mays L. var. saccharata Sturt)
Abstrak: Penelitian ini bertujuan untuk mengetahui pengaruh po- pulasi tanaman dan pemupukan kalium terhadap pertumbuhan dan hasil tanaman jagung manis varietas Seleksi Darmaga II dengan pengaturan populasi 37 500, 50 000, 62 500 dan 75 000 tanaman per hektar. Dari percobaan ini diharapkan dapat diketahui respon pemupukan kalium pada berbagai ting- kat populasi tanaman sehingga dapat menentukan tingkat do- sis yang tepat untuk masing-masing populasi....
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Judul: Pengaruh Cara Pengendalin Teki (Cyperus Rotundus L.) dan Pemupukan Nitrogen Terhadap Pertumbuhan dan Produksi Jagung Manis (Zea mays saccharata sturt)
Abstrak: Tujuan percobaan ini ialah untuk mengetahui sejauh mana pengaruh cara pengendalian teki dan pemupukan nitrogen terhadap pertumbuhan dan produksi jagung manis varietas Seleksi Darmaga 2 (SD-2). Percobaan dilakukan di Kebun Percobaan IPB Cikarawang, Bogor (240 m dpl) sejak tanggal 20 Desember 1986 hingga 4 Mei 1987. Rancangan yang digunakan adalah Rancangan Petak Terpisah dengan tiga ulangan. Petak utama adalah pengendalian teki yang terdiri dari empat cara yaitu Kontrol (tidak dikendalikan), Mekanis (dengan menggunakan cangkul/kored pada 14 HST), 2,4-D amine 12 kg b.a./ha (6 kg b.a./ha pada 33 hari sebelum tanam, 3 kg b.a./ha pada 23 hari sebelum tanam, dan 3 kg b.a./ha pada 14 HST), dan Glyphosate 2.88 kg b.a./ha (pada 33 hari sebelum tanam). Anak petaknya adalah pemberian nitrogen lima taraf yaitu 75, 150, 225, 300, dan 375 kg N/ha. Sepertiga dosis N diberikan pada waktu tanam dan sisanya pada 28 HST. Semua perlakuan disiang dan digulud pada pemupukan N yang kedua. Parameter yang diamati ialah bobot kering teki dan gulma selain teki; umur tanaman saat 50% bunga jantan menyerbuk (J50) dan saat 50% keluar rambut (B50); diameter batang; tinggi tongkol utama; tinggi tanaman maksimum; jumlah dan bobot tongkol yang dapat dipasarkan, yang tidak dapat dipasarkan, dan total; dan kandungan padatan terlarut pada biji. Kecuali terhadap bobot kering teki, tidak diperoleh interaksi antara pengendalian teki dan pemupukan nitrogen.
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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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