Judul: Relationship between the development of ectomycorrhizae and the population of microorganisms in the rhizosphere and the effect on the growth of Eucalyptus pellita and E. urophylla
Abstrak: Laboratory experiments were carried out to determine the relationship between the ectomycorrhizal development on the root of E. pellita and E.urophylla and the development of the microorganisms in the rhizosphere. The study was also made to determine the effect of the ectomycorrhizal development on the growth of the seedlings. Ten-day-old seed lings were inoculated with Scleroderma columnare, Laccaria laccata, Russula cyanoxantha or a combination of these three species of mycorrhizal fungi. After one month the inoculated seedlings were planted in Dipterocarp soil, alang-alang soil, burnt secondary forest soil or fumigated Dipterocarp soil.
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Judul: Colonization dynamics of three ectomycorrhizal fungi scleroderma spp. and their role on host plant growth
Abstrak: Ectomycorrhizal symbiosis represented one of the most important mutualistic association in forest ecosystem. Scleroderma spp. have already been known as ectomycorrhizal fungi which could form symbioses with Dipterocarpaceae, Pinaceae, and Gnetaceae. This study was conducted in three steps, (1) Compatibility test of three ectomycorrhizal fungi Scleroderma spp. under in vitro condition. The aim of this study was to determine the mycelial antagonism and interaction patterns among the fungus under in vitro condition. Three species Scleroderma spp. were cultured on solid Modified Melin Norkrans (MMN) medium. Each fungus was cultured as single, pairs and triple combinations. A completely randomized design were used with 7 treatments and 8 replicates Petri dishes. We found that the radial growth of S. sinnamariense mycelia was two times faster than S. columnare and S. dictyosporum. There was no antagonism pattern between fungal mycelia when they grown together. (2) Colonization dynamics of three ectomycorrhizal fungi Scleroderma spp. and their relation to host plant growth. The aim of this study was to determine the compatibility and specificity of each ectomycorrhizal fungi with the host plants, and the effect on host plants growth. S. columnare, S. dictyosporum and S. sinnamariense were inoculated in single-, two-, and three- species treatments to Shorea pinanga, Pinus merkusii and Gnetum gnemon seedlings using spores suspension. After 6, 8, and 10 months of inoculation, seedlings were harvested to determine colonization percentage, height and diameter growth, and plant biomass. The results revealed that S. sinnamariense did not form association with S. pinanga and P. merkusii but form association with G. gnemon. On the other hand, S. columnare and S. dictyosporum both in single- and multi- species treatments could form association with all the host plants. Generally, Scleroderma spp. increased the growth of host plants. The last was (3) Root characteristics of ectomycorrhizal fungi on S. pinanga, P. merkusii, and G. gnemon. The aim of this study was to determine the morphology (hyphae colour, branching pattern, clamp-connection) and anatomy (mantel and Hartig net) of ectomycorrhizal roots in each host plants which associated with the ectomycorrhizal fungus. This result revealed that morphology were affected by fungi, while branching pattern and Hartig net were affected by plants. S. pinanga dan G. gnemon were have monopodial branching pattern which P. merkusii was dichotomously branching pattern. The depth of mantels and Hartig net were increase by time. The Hartig net was only at epidermis S. pinanga and G. gnemon, while its penetrated in cortex on P. merkusii., Fungi ektomikoriza memainkan peranan penting dalam berbagai ekosistem, melalui keterlibatannya dalam siklus karbon dan nutrisi, jejaring makanan di bawah tanah, serta dinamika komunitas tanaman. Fungi ektomikoriza merupakan salah satu komponen penting dalam ekosistem hutan, dan diketahui membentuk simbiosis dengan sebagian besar tanaman kehutanan. Scleroderma merupakan genus fungi ektomikoriza yang diketahui dapat membentuk simbiosis dengan Dipterocarpaceae, Pinaceae, dan Gnetaceae. Simbiosis dengan fungi ektomikoriza akan membantu pertumbuhan dan ketahanan hidup tanaman inang karena fungi ektomikoriza akan membantu dalam penyerapan unsur hara dan air, meningkatkan ketahanan terhadap patogen dan meningkatkan ketahanan terhadap kekeringan. Beberapa fungi ektomikoriza juga menghasilkan tubuh buah yang dapat dikonsumsi (edible mushroom). Penelitian ini dilaksanakan
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Judul: Cycle Hamilton pada Graf Lengkap, Graf Regular, dan Graf 2-Connected 4-Regular Berorder Kurang dari Sepuluh
Abstrak: Suatu graf disebut graf Hamilton apabila graf tersebut memuat cycle Hamilton, yaitu cycle yang melewati setiap vertex tepat satu kali. Menentukan keberadaan cycle Hamilton pada suatu graf dapat menggunakan syarat cukup yang berupa teorema-teorema yang telah diperkenalkan sejak tahun 1950-an. Beberapa syarat cukup yang dibahas dalam karya ilmiah ini adalah syarat cukup yang berhubungan dengan graf lengkap dan graf regular. Suatu graf lengkap berorder 𝑛������ ≥ 3 dan graf r-regular berorder 𝑛������ ≤ 2𝑟������ + 1 merupakan graf Hamilton, Karena kedua graf tersebut memuat cycle Hamilton. Selanjutnya, syarat cukup tersebut digunakan untuk menentukan keberadaan cycle Hamilton pada graf 2-connected 4- regular berorder kurang dari 10.
Keyword: graf Hamilton, graf regular, graf lengkap, graf 2-connected 4-regular