Judul: Formulasi Aktinomiset Rizosfer Pemacu Tumbuh dengan Menggunakan Bahan Pembawa Gambut
Abstrak: Aktinomiset yang hidup di sekitar perakaran (rizosfer) merupakan salah satu kelompok bakteri Gram-positif yang dapat berperan penting sebagai agen pemacu pertumbuhan tanaman atau Plant Growth Promoting Rhizobacteria (PGPR). Penelitian ini bertujuan memformulasi aktinomiset rizosfer pemacu tumbuh menggunakan bahan pembawa berupa gambut, serta mengetahui kemampuannya dalam memproduksi IAA, melarutkan fosfat, dan tumbuh pada media bebas nitrogen. Pengamatan morfologi isolat ARJ 16, ARJ 28, ARJ 32, dan ARJ 34 memperlihatkan keragaman warna miselium aerial dan tipe miselium yang sama, yaitu spiral. Berdasarkan pengamatan tersebut keempat isolat termasuk ke dalam genus Streptomyces. Keempat isolat tersebut mampu tumbuh pada medium bebas nitrogen (N-free medium) yang ditandai dengan tumbuhnya koloni aktinomiset pada media tersebut. Isolat-isolat tersebut juga mampu melarutkan fosfat dengan indeks pelarutan fosfat tertinggi ditunjukkan oleh isolat ARJ 34. Berdasarkan uji secara kolorimetri, keempat isolat diketahui mampu menghasilkan IAA dengan konsentrasi tertinggi yaitu 30,43 ppm yang ditunjukkan oleh isolat ARJ 28, dan konsentrasi terendah yaitu 21,93 ppm yang ditunjukkan oleh isolat ARJ 16. Identifikasi isolat aktinomiset berdasarkan gen 16S rRNA menyatakan bahwa keempat isolat tersebut termasuk ke dalam genus Streptomyces. Keempat Streptomyces tersebut telah berhasil diformulasi menggunakan bahan pembawa utama yaitu gambut. Streptomyces di dalam bahan pembawa mampu mempertahankan viabilitas selnya sebesar 108 CFU g-1 setelah masa penyimpanan selama lima minggu pada suhu ruang., Actinomycetes that live in the area around roots (rhizosphere) are a group of Gram-positive bacteria that can play an important role as plant growth promoters or Plant Growth Promoting Rhizobacteria (PGPR). This study aims to formulate growth-promoting rhizosphere actinomycetes using peat as a carrier, and to determine their ability to produce IAA, solubilizing phosphate, and grow on nitrogen-free media. Morphology of isolates ARJ 16, ARJ 28, ARJ 32, and ARJ 34 varied in color diversity of aerial mycelia and the same type of mycelium, namely spiral. Based on the four isolates included in the genus Streptomyces. The four isolates were able to grow on nitrogen-free medium which was characterized by the growth of actinomycete colonies on the media. These isolates were also able to solubilize phosphate with the highest phosphate solvent index shown by isolate ARJ 34. Based on colorimetric tests, all four were known to be able to produce IAA with the highest concentration of 30.43 ppm indicated by isolate ARJ 28, and the lowest concentration of 21 93 ppm indicated by ARJ 16 isolate. The identification of actinomycete isolates based on the 16S rRNA gene stated that the four isolates belonged to the genus Streptomyces. The four Streptomyces were successfully formulated using the main carrier material, namely peat. Streptomyces in the carrier material was able to maintain cell viability of 108 CFU g-1 after five weeks of storage at room temperature.
Keyword: IAA, phosphate solubilization, PGPR, Streptomyces

Judul: Formulasi Aktinomiset Rizosfer dan Aplikasinya sebagai Pemacu Tumbuh Tanaman Jagung
Abstrak: One of the beneficial microorganisms in plant growth is actinomycetes. Actinomycetes are gram-positive bacteria that mostly inhabit the soil and can act as a source of antibiotics, pathogen controllers, and plant growth-promoting agents by being explored through bioformulation. This study aimed to formulate rhizosphere actinomycetes using peat as a carrier material and apply the formula to promote the growth of corn plants. The method used consisted of rejuvenation and observation of the morphology of actinomycetes isolates, formulation and testing of formula viability, and formula application. The rejuvenation results of four actinomycetes isolates with the codes ARJ 16, ARJ 28, ARJ 32, and ARJ 34 which were observed macroscopically showed that the isolates had white and gray colors while microscopic observations showed that the isolates had the same mycelia, namely spirals. The four rhizosphere actinomycetes formulas with peat carrier material were able to maintain viability at 16 weeks ranging from 107-108 CFU g-1. The rhizosphere actinomycete formula can significantly increase the growth parameters of maize plants including plant height, fresh weight, and dry weight. The F34 formula containing ARJ 34 isolate was the treatment with the best effect in increasing the growth of corn plants during the vegetative period.
Keyword: aktinomiset, formulasi, pemacu tumbuh, PGPR

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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