Judul: Populasi Fungi Mikoriza Arbuskula dan Bakteri pada Mikorhizosfer Semai Trembesi (Samanea saman (Jacq.) Merrill) dalam Pot Organik
Abstrak: Mikorhizosfer merupakan modifikasi khusus di lingkungan sekitar miselium fungi mikoriza arbuskula (FMA). Penelitian ini bertujuan untuk : (1) menghitung jumlah spora FMA dan populasi bakteri, serta karakter morfologi bakteri yang terdapat pada mikorhizosfer semai trembesi; (2) menghitung kolonisasi akar pada semai trembesi. Bahan yang digunakan adalah benih trembesi, kertas koran, tanah pascatambang, kompos, cocopeat. Metode yang digunakan adalah penghitungan jumlah spora FMA, kolonisasi FMA, koloni bakteri, serta karakteristik morfologi bakteri. Rancangan percobaan yang digunakan adalah rancangan acak lengkap (RAL) dua faktor yaitu ukuran bahan dan komposisi bahan. Komposisi pot organik B menunjukkan hasil terbaik pada jumlah spora FMA serta populasi koloni bakteri media tanam. Komposisi pot organik C menunjukkan hasil terbaik pada jumlah spora FMA serta populasi koloni bakteri pot. Persentase kolonisasi akar terbaik ditunjukkan pada komposisi pot organik A. Terdapat delapan karakter morfologi bakteri yang ditemukan., The mycorrhizosphere is a specific modification in the environment surrounding the mycelium of arbuscular mycorrhizal fungi (AMF). This study aims to : (1) count the number of spores and populations of AMF bacteria, and morphological characteristics of bacteria found in the mycorrhizosphere of trembesi; (2) count root colonization in trembesi seedlings. The materials used are trembesi seeds, used newspapers, post-mining soil, compost, cocopeat. The method used is counting the number of AMF spores, AMF colonization, bacterial colonies, and the morphological characteristics of the bacteria. The experimental design used was a completely randomized design (CRD) of two factorial patterns, namely the sizes of the material and the composition of the materials. The organic potting composition B showed the best results on the number of AMF spores and the population of bacterial colonies in the media. The organic pot composition C showed the best results on the number of AMF spores and the population of pot bacterial colonies. The best percentage of root colonization was shown in the organik pot composition A. There are eight bacterial morphological characters found.
Keyword: bakteri, fungi mikoriza arbuskula (FMA), komposisi, korelasi, rhizosfer, AMF, bacteria, composition, correlation, rhizosphere

Judul: Populasi Fungi Mikoriza Arbuskula (FMA) dan Bakteri pada Rhizosfer Bibit Johar (Cassia siamea Lamk.) dan Trembesi (Samanea saman (Jacq.) Merrill).
Abstrak: Rhizosfer adalah daerah yang berada di sekitar perakaran tanaman yang banyak terjadi aktivitas mikroorganisme tanah. Daerah rhizosfer terkadang mengalami gangguan sehingga tidak dapat berfungsi sebagaimana mestinya. Gangguan di rhizosfer tersebut dapat diperbaiki dengan pemberian FMA dan amelioran tanah sehingga mendukung pertumbuhan tanaman. Tujuan penelitian ini adalah menganalisis jumlah spora FMA serta mengidentifikasinya sampai tingkat genus; menganalisis jumlah koloni bakteri dan karakter morfologi bakteri; dan menganalisis pertumbuhan bibit Johar (C. siamea) dan Trembesi (S. saman) pada tanah pascatambang pasir silika yang telah diberi perlakuan spora FMA dan amelioran. Spora FMA dihitung dengan metode ekstraksi spora dan penyaringan kemudian diidentifikasi hingga tingkat genus serta perhitungan jumlah koloni bakteri dengan metode Total Plate Counts (TPC) kemudia dilakukan pengamatan morfologi koloni bakteri dan pewarnaan Gram. Hasil penelitian menunjukkan pemberian FMA, kapur 3.6 g dan kompos 32.5 g mampu meningkatkan kepadatan spora FMA pada bibit C. siamea dan pemberian FMA dan kompos 32.5 g mampu meningkatkan kepadatan spora FMA pada bibit S. saman. Terdapat sembilan spora FMA yang berkarakteristik berbeda dengan genus Acaulospora dan Glomus. Pemberian FMA, kapur 3.6 g dan kompos 32.5 g mampu meningkatkan populasi bakteri pada bibit C. siamea dan pemberian FMA dan kompos 32.5 g mampu meningkatkan populasi bakteri pada bibit S. saman. Ditemukan delapan karakter morfologi bakteri yang berbeda berdasarkan bentuk, tepi, elevasi dan warna koloni dan dari kedelapan koloni tersebut didominasi oleh bakteri Gram positif berbentuk bulat. Pemberian FMA, kapur 3.6 g dan kompos 32.5 g menghasilkan pertumbuhan tinggi dan diameter bibit terbaik pada bibit C. siamea, pemberian FMA, kapur 3.6 g dan kompos 32.5 g menghasilkan pertumbuhan tinggi bibit terbaik dan pemberian kompos 32.5 g menghasilkan pertumbuhan diameter bibit terbaik pada bibit S. saman.
Keyword: amelioran tanah, bakteri, FMA, rhizosfer

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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