Judul: Akumulasi aluminium pada melastoma affine dan melastoma malabathricum
Abstrak: Indonesia mempunyai lahan asam podsolik merah kuning seluas sekitar 47.6 juta ha. Lahan ini belum dimanfaatkan secara optimal untuk karena kelarutan aluminium sangat tinggi. Al menyebabkan perkembangan akar terhambat dan akar akan menjadi tebal, pendek dan kaku serta memperlihatkan bagian-bagian yang mati. Aluminium yang terikat di akar akan menghalangi proses pembelahan sel pada meristem apikal sehingga menghentikan perpanjangan akar. Hal ini menyebabkan akar tidak dapat melakukan penetrasi ke dalam tanah dengan baik. Al yang ditranslokasikan dari akar ke pucuk dalam bentuk kompleks Al-sitrat dan diakumulasikan dalam bentuk Aloksalat.
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Judul: Kadar aluminium tanaman melastoma Melastoma candidum dalam keterkaitannya dengan kandungan aluminium dapat dipertukarkan Aldd dalam tanah pada ultisols sajira, Banten
Abstrak: Kendala utama pengembangan pertanian pada Ultisols adalah tingkat kemasaman dan kandungan Aluminium dapat dipertukarkan (Alja) yang tinggi. Hal ini menyebabkan tanaman akan keracunan Al dan fiksasi P yang tinggi. Telah diketahui tanaman melastoma dapat mengakumulasi Al pada bagian daun, batang (kayu) dan perakarannya dalam jumlah yang tinggi. Karena itu melastoma dapat dijadikan sebagai suatu alternatif penanganan masalah tingginya kandungan Alaa pada Ultisols. Tujuan penelitian adalah untuk mengetahui seberapa besar tanaman melastoma dapat mengakumulasi Al pada bagian daun dan batang dan mempelajari hubungan antara kadar Al dalam tanaman melastoma dengan kandungan Alda dalam tanah. Penelitian Lapang dilakukan di kebun karet PT. Candipura, Desa Sajira, Kecamatan Sajira, Kabupaten Lebak, Provinsi Banten. Hasil yang didapat bahwa tanah lapisan atas (0-20 cm) mempunyai tekstur liat berlempung; struktur remah, berbutir, gumpal; konsistensi gembur. Tanah lapisan bawah (20-40 cm) bertekstur liat dan liat berdebu; struktur gumpal bersudut; dan konsistensi teguh. Reaksi tanah lapisan atas berkisar antara 4.4-4.5 dan di lapisan bawah antara 4.1-4.2. ...
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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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