Judul: Penggunaan Mycorrhizal helper bacteria (MHBs) dan fungi mikoriza arbuskula (FMA) untuk meningkatkan pertumbuhan semai mindi [Melia azedarach Linn]
Abstrak: Laju degradasi kawasan hutan di Indonesia masih tinggi, yang menyebabkan semakin berkurangnya luas hutan dan meningkatnya luas lahan kritis. Dalam upaya untuk mengurangi dampak yang ditimbulkan dari kerusakan hutan tersebut, dilakukan kegiatan rehabilitasi hutan dan lahan. Namun yang menjadi kendala utama bagi keberhasilan kegiatan rehabilitasi adalah terhambatnya pertumbuhan semai dan semai memiliki daya hidup yang rendah. Untuk mengatasi masalah tersebut diperlukan bibit yang berkualitas baik dan dapat bertahan hidup pada tanah-tanah marginal. Namun untuk mendapatkan bibit yang berkualitas baik dan memiliki daya hidup yang tinggi dilapangan diperlukan input hara yang cukup, yaitu dengan pemberian pupuk. Pupuk yang diberikan haruslah aman bagi lingkungan dan sesuai dengan ekosistem. Penggunaan teknologi mikroba tanah yaitu dengan penggunaan mikoriza merupakan solusi yang tepat dan telah terbukti mampu meningkatkan pertumbuhan tanaman. Salah satu fungi mikoriza yang telah dikenal dapat dijadikan pupuk hayati (biofertilizer) adalah FMA (Fungi Mikoriza Arbuskular). Simbiosis antara fungi dengan perakaran tanaman, dalam perkembangannya dilapangan seringkali mengalami kendala. Untuk itu diperlukan mikroorganisme yang dapat memberikan pengaruh positif terhadap peningkatan kerjasama tersebut, yaitu jenis bakteri yang dikenal dengan nama Mycorrhizal Helper Bacteria (MHBs). MHBs merupakan bakteri spesifik yang dapat bersimbiosis dengan FMA dan mempunyai kemampuan untuk menstimulir perkembangan FMA. Dengan aplikasi MHBs dan FMA pada mindi diharapkan dapat meningkatkan pertumbuhan dan kualitas hidup semai mindi. Penelitian ini dilaksanakan di laboratorium dan Rumah Kaca Departemen Silvikultur, Fakultas Kehutanan Institut Pertanian Bogor. Pelaksanaan penelitian diawali dengan isolasi spora mikoriza, dimana isolasi spora tersebut dilakukan melalui teknik penyaringan basah bertingkat dan dilanjutkan dengan metode sukrosa sentrifugasi menurut Jenkins (1964). Selanjutnya spora Glomus sp dan Gigaspora sp yang sudah dipilih kemudian disimpan dalam refrigerator sampai digunakan. Tahapan penelitian selanjutnya adalah persiapan tanaman inang (tanaman mindi) serta perbanyakan dan pembuatan larutan isolat bakteri. Persiapan tanaman mindi yang dimaksud adalah perkecambahan benih mindi yang diawali dengan perlakuan pendahuluan dengan menjemur benih mindi dibawah sinar matahari selama 1 minggu sampai kulit bijinya menjadi retak. Inokulasi FMA dan bakteri dilakukan pada saat penyapihan sesuai dengan perlakuan yang diberikan. ...
Keyword: AMF, MHBs, Mindi

Judul: Penggunaan Mycorrhizal Helper Bacteria (MHBs) dan Fungi Mikoriza Arbuskula (FMA) Untuk Meningkatkan Perturnbuhan Semai Mindi (Melia azedarach Linn.)
Abstrak: Introduction. High rate of forest degradation in Indonesia causes reduction of forest area and increase of critical land area. In the efforts to reduce the impacts from such forest damage. land and forest rehabilitation is conducted. However, the main constraint for the success of rehabilitation is the retarded growth of planting stocks (seedlings) and low survival rate of the seedlings. For overcoming such problem, good quality seedlings, which could survive in marginal lands are required. For obtaining good quality seedlings which have high survival rate in the field, there is a need for sufficient input of nutrients through fertilizer application. The applied fertilizer should be environmentally friendly. The use of soil microbe technology, namely the use of mycorrhiza is an appropriate solution and has been proven to be able to increase plant growth. One of the mycorrhizal fungi which can be used as biofertilizer is AMF (Arbuscular Mycorrhizal Fungi). Symbioses between fungi and plant roots often suffer some constraints in the field. Therefore, there is a need for microorganism which could give positive effects for improving such cooperation. Such organism is bacteria species which is known as Mycorrhizal Helper Bacteria (MHBs). MHBs is a specific bacteria which is able to have symbioses with AMF and is able to stimulate the development of AMF. The application of MHBs and AMF on mindi is expected to be able to increase the growth and quality of mindi seedlings. Methodology. A completely randomized design two factors (Micorrhizal and Bacteria) was employed to examine the effect of mycorrhizal and bacteria on the plant growth. The parameter observed were: mycorrhiza infection percentage, height, diameter, shoot biomass, root biomass, shoot - root ratio and Index of Seedling Quality (1MB). Results and conclusion. Isolate of bacteria BGG02 which was combined with AMF Gigaspora sp (M2) gave the highest increase in mycorrhiza infection percentage, namely 58.3% as compared to mycorrhiza treatment without bacteria. Isolate BGG03 was more effective in increasing the mycorrhiza infection percentage if combined with Glomus sp (M1), namely 18.8%, whereas application of isolates BGG01 and BGG04 increased the percentage of mycorrhiza infection 1.8% when combined with mixture of AMF Glomus sp and Gigaspora sp (M1 M2). Application of bacteria, AMF or combination of them, gave positive effects toward mindi growth. Combination of isolate BGG01 and AMF Gigaspora sp (M2B1) gave the best respond toward parameters of height, diameter, root biomass, shoot biomass and Index of Seedling Quality (1MB), with increase value of respectively 352.7%, 4.8%, 2809.7%, 4545.7% and 488.3% as compared to control. In general, during the application of AMF, application of Gigaspora sp (M2) gave the greatest positive effect toward mindi growth as compared with application of other AMF, namely Glomus sp (M1) and mixture of Glomus sp and Gigaspora sp (M1 M2).
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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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