Judul: Pemanfaatan Bakteri Rhizoplane dan Fungi Mikoriza Arbuskula (FMA) Untuk Meningkatkan Pertumbuhan Semai Jelutung (Dyera polyphylla Miq. Steenis.)
Abstrak: Nontimber forest products (NTFPs) represent sources of income from tropical forest, but some NTFP species have decreased in population and become endangered due to overexploitation. There is increasing concern that the planting stock of Dyera polyphylla is not sufficient to sustain the yield of NFTPs. The beneficial root colonizing rhizosphere bacteria, the so-called plant growthpromoting rhizobacteria have been known to carry out many important ecosystem processes, such as those involved in the nutrient cycling and/or seedling establishment. The roots of most plant species associate with certain soil fungi and establish what are known as mycorrhiza. The objective of this study was to determine the effect of two arbuscular miycorrhizal (AMF) fungi, Glomus sp., Gigaspora sp. and thirteen strains of rhizoplane bacteria (CK32, FL.13.2.1, JW1, JW6, JW9, JW13, JW14, CK26, CK4, JW3a, SB, NT, CR.R1), on the early growth of D. polyphylla, under greenhouse condition. Percentage of AMF colonization, plant growth, and nitrogen (N) and phosphorus (P) concentration were measured after 150 days of planting. The results showed that the percentage of AM colonization of D. polyphylla was 100%. Colonization by Glomus sp. significanly increased plant height by 18,95% and diameter by 16,16% compared to those non AMF. Combination of bacterial and AMF inoculant between JW13 dan Glomus sp. increased shoot weight by as much as 36,28% from control and increased N concentration by 69,59% compared to those of non inoculate a seedlings. Combination of JW1 and Gigaspora sp. increased P concentration by as much as 42,05% compared to those of non inoculate seedlings. Despite the difficulty of selecting a multifunctional microbial consortia, appropriate microbial combinations can be recommended for a biotechnological input related to improvement of plant performance.
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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: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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