Judul: Bacterial diversity from the spores of arbuscular mycorrhizal fungi gigaspora sp. and Glomus sp. and their potential as mycorrhiza helper bacteria
Abstrak: Mycorrhiza Helper Bacteria are bacteria that potentially assist the development of mycorrhiza. This study was aimed to explore the Mycorrhizal Helper Bacteria (MHB) from the spore of Arbuscular Mycorrhizal Fungi (AMF) Gigasprora sp. and Glomus sp. The enzymatic activity (cellulase, protease and pectinase), antagonists with pathogen Sclerotium sp., Rhizoctonia sp., Ganoderma sp. and mycorrhizal stimulation were conducted. The results showed that there were 7 species of bacteria isolated from the spores of Gigaspora sp. and 5 species from the spores of Glomus sp. Of the 12 bacteria, 7 bacteria had the potential to produce the enzymes of hydrolytic cellulase and proteases. Based on in vitro test, there were 4 species of bacteria found to have the ability to inhibit the growth of 3 species of pathogens tested. Eight types of bacteria were found to be capable of stimulating the development of mycorrhizal hyphae. There were 3 isolates of bacteria showed the antagonistic toward pathogenic fungi as well as stimulation of AMF. The bacteria obtained were very potential to be developed as biological agents in improving the quality of soil and plants growth.
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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: Pricing of Lookback Options with Floating Strike Price Using The Monte Carlo Method
Abstrak: Opsi lookback adalah opsi yang payoff-nya bergantung pada harga saham terbesar atau harga saham terkecil yang dicapai selama masa berlaku opsi. Opsi lookback dikatakan dengan floating strike price jika nilai dari strike price sebesar harga saham pada saat jatuh tempo. Nilai hampiran opsi lookback ditentukan dengan metode Monte Carlo, sedangkan nilai eksak didapat dari nilai simulasi terbesar yang mampu dihitung oleh komputer. Berdasarkan hasil penghitungan, nilai galat relatif yang dihasilkan semakin kecil dengan semakin bertambah banyaknya simulasi yang dilakukan, sehingga metode Monte Carlo untuk menghitung harga opsi lookback dengan floating strike price konvergen ke nilai eksaknya., Lookback option is an option whose payoff depends on the maximum or minimum of the asset price reached during the option period. The lookback option is said to be a floating strike price if the value of the strike price is equal to the stock price at maturity. The value of the lookback option is determined by the Monte Carlo method, while the exact value is obtained from the largest simulation value that the computer can compute. Based on the calculation results, the resulting relative error value get smaller with the increasing number of simulations performed. Therefore, the Monte Carlo method to calculate the price of the lookback option with the floating strike price converges to the exact value.
Keyword: lookback option, floating strike price, Monte Carlo method, convergent