Judul: Identifikasi dan isolasi cendawan ektomikoriza Scleroderma Pers.
Abstrak: Telah berhasil diidentifikasi tiga spesies Scleroderma dari hutan Haur Bentes, Jasinga; Kebun Percobaan Cikarawang, Fakultas Kehutanan, Institut Pertanian Bogor; dan halaman rumah di Bogor. Scleroderma yang ditemukan dari tegakan Hopea odorata, H. mengarawan, Shorea leprosula, S. stenoptera ialah Scleroderma columnare, sedangkan dari tegakan Pinus merkusii ialah S. dictyosporum dan dari tegakan Gnetum gnemon ialah S. sinnamariense. Sebuah basidioma S. columnare juga ditemukan tumbuh pada kayu yang melapuk. Dari lima macam medium yang digunakan untuk mengiso- lasi basidioma Scleroderma, pertumbuhan hanya terjadi pada medium Hagem saja. Setelah dua minggu, pertumbuhan terhenti pada saat koloni mencapai diameter 6 mm…dst
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Judul: Colonization dynamics of three ectomycorrhizal fungi scleroderma spp. and their role on host plant growth
Abstrak: Ectomycorrhizal symbiosis represented one of the most important mutualistic association in forest ecosystem. Scleroderma spp. have already been known as ectomycorrhizal fungi which could form symbioses with Dipterocarpaceae, Pinaceae, and Gnetaceae. This study was conducted in three steps, (1) Compatibility test of three ectomycorrhizal fungi Scleroderma spp. under in vitro condition. The aim of this study was to determine the mycelial antagonism and interaction patterns among the fungus under in vitro condition. Three species Scleroderma spp. were cultured on solid Modified Melin Norkrans (MMN) medium. Each fungus was cultured as single, pairs and triple combinations. A completely randomized design were used with 7 treatments and 8 replicates Petri dishes. We found that the radial growth of S. sinnamariense mycelia was two times faster than S. columnare and S. dictyosporum. There was no antagonism pattern between fungal mycelia when they grown together. (2) Colonization dynamics of three ectomycorrhizal fungi Scleroderma spp. and their relation to host plant growth. The aim of this study was to determine the compatibility and specificity of each ectomycorrhizal fungi with the host plants, and the effect on host plants growth. S. columnare, S. dictyosporum and S. sinnamariense were inoculated in single-, two-, and three- species treatments to Shorea pinanga, Pinus merkusii and Gnetum gnemon seedlings using spores suspension. After 6, 8, and 10 months of inoculation, seedlings were harvested to determine colonization percentage, height and diameter growth, and plant biomass. The results revealed that S. sinnamariense did not form association with S. pinanga and P. merkusii but form association with G. gnemon. On the other hand, S. columnare and S. dictyosporum both in single- and multi- species treatments could form association with all the host plants. Generally, Scleroderma spp. increased the growth of host plants. The last was (3) Root characteristics of ectomycorrhizal fungi on S. pinanga, P. merkusii, and G. gnemon. The aim of this study was to determine the morphology (hyphae colour, branching pattern, clamp-connection) and anatomy (mantel and Hartig net) of ectomycorrhizal roots in each host plants which associated with the ectomycorrhizal fungus. This result revealed that morphology were affected by fungi, while branching pattern and Hartig net were affected by plants. S. pinanga dan G. gnemon were have monopodial branching pattern which P. merkusii was dichotomously branching pattern. The depth of mantels and Hartig net were increase by time. The Hartig net was only at epidermis S. pinanga and G. gnemon, while its penetrated in cortex on P. merkusii., Fungi ektomikoriza memainkan peranan penting dalam berbagai ekosistem, melalui keterlibatannya dalam siklus karbon dan nutrisi, jejaring makanan di bawah tanah, serta dinamika komunitas tanaman. Fungi ektomikoriza merupakan salah satu komponen penting dalam ekosistem hutan, dan diketahui membentuk simbiosis dengan sebagian besar tanaman kehutanan. Scleroderma merupakan genus fungi ektomikoriza yang diketahui dapat membentuk simbiosis dengan Dipterocarpaceae, Pinaceae, dan Gnetaceae. Simbiosis dengan fungi ektomikoriza akan membantu pertumbuhan dan ketahanan hidup tanaman inang karena fungi ektomikoriza akan membantu dalam penyerapan unsur hara dan air, meningkatkan ketahanan terhadap patogen dan meningkatkan ketahanan terhadap kekeringan. Beberapa fungi ektomikoriza juga menghasilkan tubuh buah yang dapat dikonsumsi (edible mushroom). Penelitian ini dilaksanakan
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Judul: The Effects of Variance of Interest rate to Variance of Annuity Future Values
Abstrak: Time value of money is a concept that refers to the difference of the value of money due to time difference. The value of money for present time would not be the same as the value of money in the future. The value of money for present time is called as Present Value (PV) of the money and the value of money for future time is called Future Value (FV) of the money. Determination the value of money, for present and future time, depends on the time and rate of return. The value of money is determined by several factors such as inflation, fluctuation of interest rates, and government policy in securities and taxation. Due to fluctuation of the value of money we need a FV formulation, it is useful for knowing whether an investment can be profitable or not, and this information is useful also in budget analysis. Annuity is defined as a series of payments made for a specific period. The payment, fixed or varied, can be made at the beginning or at the end of the period. Annuity paid at the beginning of the period is called annuity-due and annuity paid at the end of the period is called immediate annuity-certain. The accumulated value of the annuity after few years later is called as a final value or a future value. Burnecki et al. (2003) have discussed about the FV of a fixed-rate annuity in which payments are made according to the arithmetic or geometric series. They have also examined FV for annuities in which payments are made according to arithmetic or geometric series with random rates of interest. This paper examines FV for annuity-due in which payments are made according to arithmetic or geometric series with interest rates as a random variable, which is normal distribution ,  . Future value formula is expressed in recursive form. FV for annuity-due which payments are made according to the arithmetic or geometric series with random rates of interest is calculated by theoretical way and simulation way. The random rates of interest is denoted as k k i  i  , where k i an independent random variable; i is a constant and k  is a random variable which has normal distribution ,  . By using the determined parameters, a sequence of random rates of interest are generated for theoretical calculation. Meanwhile for the simulation, the random rates of interest is generated 1000 times for the simulation. The generated data give mean value, variance, and standard deviation. Moreover, error of mean value, variance, and standard deviation from the theoretical and simulation results are calculated. Error calculation uses Symmetric Mean Absolute Percentage Error (SMAPE). The smaller the value of SMAPE is the more accurate the simulation. The interest rate variances are varied from 0.000036 to 0.0001 to study the relationship between variance of rates of interest and variance of future value. The theoretical and simulation results show that when the variance of random rates of interest increases, then the variance of FV increases linearly. FV of the annuity-due in
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