Judul: Karakterisasi interaksi antara tanaman aquilaria microcarpa baill dengan fusarium solani dalam pembentukan gaharu
Abstrak: Aquilaria microcarpa is native to Indonesia and has been identified and promoted as potential tree species to yield high quality agarwood (gaharu). Individual trees of this species, both in its natural habitat and plantation, do not always yield agarwood due to many influencing factors. It is estimated that only 10% trees would be able to yield the resin. A clear mechanism of agarwood formation is unknown and there is a lack of information on underlying causes and triggers of the formation due to natural complexity and uncertainty. However, natural defense mechanisms through a series of pathogenesis are presumed as naturally observed in other resin producing tree species. Research on the characterization of host-pathogen interaction in gaharu formation was carried out based on the above mentioned problems with the following specific objectives, namely: i). to identify morphological characters of A. microcarpa trees interacting with F. solani sp, ii). to determine wood anatomical characters of A. microcarpa interacting with F. solani, and iii) to verify the genotypes of A. microcarpa seedlings and trees interacting with F.solani based on microsatellites. Results on tree morphological analysis showed that two out of 17 morphological characters (descriptor), namely tree height (m) and branching angles (0), showed significant differences between inoculated and non-inoculated individuals. In addition, microscopic observations on wood anatomical characters of A. microcarpa revealed that inoculated plants clearly deposited golden-brown colored resin in pores and canticles with a distinct scent. Further verification using GC MS on the sediment deposits identified common compounds as reported in many previous research on agarwood, namely: baimuxinal, elemol, 3-phenyl-2-butanone and chromone-3-one. On the other hand, tests on the viulence degrees of F. solani showed that one out of 4 strains, i.e. F.solani FORDA 512, showed the highest level of virulence and was significantly different with other F.solani, especially if inoculated on seedlings A60, A68 and B30. Two microsatellite loci of A. crassna, i.e. 6Pa18 and 71Pa17, were successfully transferable to A. microcarpa and could be used to characterize the genotypes of Fusarium-treated seedlings (n=40), inoculated trees (n=20) and non-inoculated trees (n=20). There were differences in terms of genetic structures between tree population and seedling population. Further sequence analysis on the microsatellite fragments on the most virulent F.solani FORDA 512- inoculated seedlings indicated genotype dependant responses for both seedling and tree stages. In addition, Sequence based cladogram showed that inoculated seedlings were closely placed with inoculated trees indicating certain genetic roles in the agarwood formation. In conclusion, tree morphological (i.e. height growth and branch habit) as well as genetic and genomic characters were clearly observed and useful to provide early information on gaharu formation. It is also supported by the wood anatomy analysis showing the presence of gaharu resin.
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Judul: Peranan Zat Ekstraktif Dalam Pembentukan Gaharu Pada Aquilaria crassna Pierre ex Lecomte dan Aquilaria microcarpa Baill
Abstrak: This research is aimed at investigating the anti fungal activity (AFA), the correlation of gaharu tree’s phenolics in relation with the susceptibility of the trees to Fusarium bulbigenum attack in the formation of agarwood, and to observe total phenolics content and tree’s chemicals of Aquilaria crassna and Aquilaria microcarpa pre-inoculation, the reology of tree’s chemical and microorganism change along inoculation time. There were variations of anti fungal activity among trees, and the highest is at tree no. 10 that AFA was in the middle class (39,77%), but entirely agarwood trees exhibited a low anti fungal activity at lab scale. Further fractionation and bioassay showed that the most active component are likely in the ethyl acetate fraction that exhibited strong anti fungal activity at 4% concentration. Trees as many as 20 of A. microcarpa at Carita and 10 of A. crassna at Darmaga were inoculated with isolate of F.bulbigenum in spiral pattern around the stem. Prior to inoculation, strips were taken from the stem for total phenolics content and chemicals analyzing. The result revealed that total phenolics content and infection area exhibited a negative correlation, which means the higher the phenolics content, the smaller the infection area. The preinoculation chemicals analysis showed that tree with smaller infection area had larger type of compounds and higher concentration of phenolics than tree with wider one. Some chemicals that at certain plants acted as defense system, according to some references, were found at higher concentration in the gaharu trees with smaller infection or they were not even traced in other tree. The reology analysis revealed that the largest types of compounds were noticed at three day’s old inoculation. Agarwood constituents and other aromatic compounds were detected since three days after inoculation which is indicated the agarwood formation was taken place. Meanwhile, the microbiology analysis showed there was no microbes change in the inoculation sites along 6 month inoculation time, but some small insects, such as ants and bugs, were found at the area.
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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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