Judul: Peranan Aspergillus niger dan bahan organik dalam transformasi P-Anorganik tanah
Abstrak: Tujuan percobaan adalah mengetahui kemampuan Aspergillus niger dan bahan organik dalam mempengaruhi transformasi P-anorganik tanah. Percobaan dilakukan di Laboratorium Biologi Tanah dan Laboratorium Kimia Tanah Fakultas Pertanian, Institut Pertanian Bogor, mulai September 1993 sampai Februari 1994. Tahap percobaan meliputi pengujian Aspergillus niger dalam melarutkan AIPO, dalam media Pikovskaya, persiapan inokulan serta pengujian Aspergillus niger terpilih dalam melarutkan fraksi P-anorganik tanah, dimana analisis P-anorganik dilakukan menurut metode fraksionasi Chang dan Jackson (Hesse, 1972). Percobaan disusun dalam rancangan acak kelompok 3 ulangan dengan pengelompokkan didasarkan waktu inkubasi (15, 30 dan 45 hari). Perlakuan yang dicobakan adalah: (a) Inokulasi Aspergillus niger 4 strain (tanpa inokulasi, strain 2C8J2, strain 2CJ, dan strain 2C₁8K₁) dan (b) Bahan organik kompos sampah kota 2 taraf (0 dan 10 ton ha¹). Media dasar untuk inokulasi digunakan tanah Ultisol Lampung bekas pertanaman tebu selama 2 musim tanam, yang dibuat dalam 2 kondisi (tanpa dan dengan sterilisasi). Hasil pengujian A. niger dalam melarutkan AIPO, media Pikovskaya menunjukkan strain A. niger-2CJ, A. niger-2CJ, dan A. niger-2C, K, mampu meningkatkan P-larut media masing-masing sebesar 125.0; 65.0 dan 135.0 persen…dst
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Judul: Produksi Inokulum Pupuk Hayati Cendawan Aspergillus niger Skala Lapang Menggunakan Limbah Organik Pertanian sebagai Karier
Abstrak: Exploiting microorganism become one of alternatives in using biofertilizer. Aspergillus niger represent one of examples of fungi which can be used as an agent of biofertilizer. The aim of this research was to produce a good quality of A. niger biofertilizer inoculum for field application using agricultural organic waste as a carrier. The research activities were carried out in two stages. First stage was screened the 5 agricultural organic wastes, namely corn cob, rice straw, banana stem, organic market waste, and sorghum stem as fungal growth medium. Split corn was used as a control treatment. Spore and propagule numbers were used as parameter measured for screening activities. Observation was conducted in 20, 40 and 60 days after inoculation. Second stage of the research was to analyze the quality of dried inoculum produced from the first stage of experiment that was kept in 0, 1, 2 and 3 months at room temperature. The parameter measured were spore and propagule numbers, root colonization, and growth respon. Rice and maize were used as tested crops. The A. niger grew very well in the all organic wastes tested. Amoung the 5 wastes tested, organic market waste was the best medium followed by sorghum stem, banana stem, corn cob and rice straw. The propagule obtained was higher than the spore number. The heating and the grinding treatments reduced the quality of inoculum. Reduction of spore number was 4,3%/g media and the propagule was 15,0%/g media compared with the control treatment. This indicated that viability of spore was better than miselia. Based on the numbers of spore and propagule productions indicated that inoculum quality obtained from organic market waste was better than the control treatment (split corn). The 3 months storage treatment had no effect on survival of the fungi obtained from organic market waste. Similarly, physical characteristic of carrier media. However, the 3 months storage treatment reduced the capability of the fungi in colonizing and improving plant growth. Similar results were also observed in the inoculum produced from split corn as a control treatment. The effect of organic matter derived from organic market waste was different from that split corn. Organic market waste increased the growth of rice and maize crops, whereas split corn reduce the growth of both crops.
Keyword: A. niger, Spore, Propagule, Inoculum, Colonization

Judul: Truncated Stop Loss as a Optimal Solution of Reinsurance Agreement in One-Period Model
Abstrak: Reinsurance is one of risk management efforts of an insurance company, which is called the cedent. Similar with insurance, reinsurance constitutes the cedent to pay the premium. We consider one-period reinsurance model and derive a rule which minimizes the ruin probability of the cedent for a fixed reinsurance premium. Therefore, it is needed to construct an optimal reinsurance agreement for the cedent. The premium is calculated according to four different principles, i.e. economic, generalized zero-utility, Esscher, and mean-variance principles. Stop loss is a reinsurance contract which protect the insurance company for losses that exceed a certain amount. The result of this research shows that a truncated stop loss is an optimal agreement in the class of all reinsurance contracts with various premiums calculated using above mentioned principles.
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