Judul: The significance of mycorrhiza in regeneration of merbau [Intsia bijuga (Colebr.) O. Kuntze] originating from Papua
Abstrak: Merbau [Intsia bijuga (Colebr.) Kuntze] is considered as one of valuable timber tree in South-East Asia which has long been exploited but its silviculture for supporting plantation development is neglected. How to produce good quality of merbau seedlings by using generative and vegetative regeneration methods collaborated with the application of ectomycorrhizal association on merbau for improving the performance of the seedlings is an important issue to be answer. The research was carried out in a series of laboratory experiments and field work (exploration). Exploration was done in merbau natural stands, plantation and nurseries for collecting merbau seeds, wildlings, soils suspiciously containing ectomycorrhizal propagules, sporocarps and ectomycorrhizal root tips of merbau. While experiments to find out the efficient method of merbau regeneration through vegetative and generative propagation were conducted in the laboratory. Merbau was easily regenerated through seeds and shoot cuttings. Merbau seeds revealed variation in morphology and seed weight. Seed nicking followed with seed soaking in low concentration of sodium hypochlorite (0.525 %) for 15 minutes and then in hot water for 24 hours gave the highest percentage of seed germination of merbau (78.67%). Seed weight of > 2.25 g gave better in mean germination time and height performance of the seedlings. The application of auxin IBA/NAA (1000 ppm/500 ppm) gave highest percentage of rooted cuttings (77.1%) and of rooted and sprouted cuttings (50.0%). Merbau regeneration by micro cuttings in vitro was successful to produce explants although the regeneration was in low frequency. The constraints are mainly related to early defoliation of leaves and shoots, and the cessation of the growth after 2 months in the culture medium. Maintaining relatively high concentration of nitrogen and phosphate content close to those of MS medium likely gave beneficial effects for shoot initiation of micro-cuttings of merbau in vitro. Only one species of ectomycorrhizal fungus was found associated with merbau [Intsia bijuga (Colebr.) Kuntze]. The fungus formed mycorrhizae with monopodial pinnate branching type. The fungus was identified belonging to the genus of Scleroderma. The fungus could be cultured in both agar and semi-solid media of MMN. Other ectomycorrhizal fungi i.e. Scleroderma sinnamariense, Scleroderma columnare, Scleroderma. dictyosporum and Pisolithus sp were not able to form ectomycorrhizae with merbau seedlings. Inoculation using both suspension of spore masses and mycelia aggregates of Scleroderma sp did not gave any influences to the cuttings success. On the other hand the inoculation effectively improved the seedling and the transplanted-rooted cutting performance.
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Judul: Pemanfaatan Mycorrhizal Helper Bacteria (MHBs) dan Fungi Mikoriza Arbuskula (FMA) untuk Meningkatkan Pertumbuhan Semai Gmelina (Gmelina arborea Roxb.)
Abstrak: INTRODUCTION. Increase in the size of human population causes an ever increasing demand on paper produtcs. Therefore, there is a need to supply wood as raw materials in rapid manner. In relation with this, the Indonesian government has a policy to develop Industrial Plantation Forest (HTI). Gmelina is one of the forest tree species which has good prospect to be developed in Industrial Plantation Forest (HTI). This species is a fast growing species which could grow in various types of soil, and its wood is considerably useful. Development ofHTI in Indonesia is emphasized on critical land. The use of Arbuscular Mycorrhizal Fungi (AM F) is an appropriate solution for promoting plant growth in such condition. In the field, AMF had some constraints in creating symbiosis with host plants, Therefore, in this case, there is a need for bacteria which stimulates the AMF. One such bacteria, is known with the name Mycorrhizal Helper Bacteria (MHBs). MATERIALS AND METHOD. This research used Factorial Completely Randomized Design comprising 16 treatments, 5 replications and 3 units. Inoculation of mycorrhizal fungi and bacteria was conducted when the seedlings were 3 weeks old. Afterwards, observation was conducted for 3 months. For observing the plant's respond toward treatments, the observed parameters were among other things: height, diameter, root biomass, shoot biomass, shoot - root ratio, Index of Seedling Quality, and percentage of mycorrhizal infection. RESULTS AND CONCLUSION. Results of Analysis of Variance showed that mycorrhizal treatment had significant effect on parameters of root biomass and percentage of mycorrhizal infection. On the other hand, combined treatments of mycorrhiza and bacteria had significant effect toward parameter of root biomass. Combination of mycorrhiza with isolate BGLo3 gave the highest percentage of mycorrhizal infection, namely 25.49 %. Inoculation of isolate BGLo1 gave the best respond for parameters of height and diameter. Consecutively, the exhibited increases were 32.33 % and 31.25 % as compared with those of control. Combination of mycorrhiza with BGLo3 also exhibited the highest increase as compared with control, in terms of parameters of root biomass and Index of Seedling Quality, namely 2.28 % and 87.89 %. Inoculation ofmycorrhiza without bacteria exhibited the best respond for parameters of shoot - root ratio, namely with increase by 9.23 % as compared to control.
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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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