Judul: Seed-Borne Fusarium sp.Causing Damping-off of Pinus tecunumanii Seedlings in Tanzania
Abstrak: Seed-borne fungi are among the most serious groups of pathogens, causing significant losses in both quantity and quality of Pinus seeds. Conifer nurseries serve as reservoirs for a diverse suite of native and exotic pathogens, e.g., Fusarium and Phytophthora spp. These pathogens can move undetected through asymptomatic seedlings and infected nursery stock which can cause mortality in field-planted seedlings and risk of pathogen introductions into plantations. Occurrence of Fusarium spp. is one of the problems, most limiting to growth of seedlings in nurseries. The pathogen can be transmitted via seeds and causes damages to the seedlings during pre- and post-emergence stages. The present study aimed to perform seed health testing of P. tecunumanii through blotter test method and to identify seed-borne pathogens which affect the species and cause damping-off disease. Seed and symptomatic seedlings samples were collected from four different seed lots namely; Private Forestry Programme (PFP), Makungu, Mafinga, and Kilolo. The results came out with four major fungi species which are; Aspergillus niger, Penicillium sp, Rhizopus sp and Fusarium sp. Fusarium sp was suspected to be the major seed-borne fungi which causes damping-off disease in young seedlings. Identification of Fusarium started at the species level based on morphological and molecular characteristics. Morphological characterization was performed based on a key specific to Fusarium spp. Whereas, molecular identification was carried out by amplification and sequencing of the regions from internal transcribed spacer (ITS) and the elongation factor using specific primers for F. circinatum. The results tasted negative implying that the suspected Fusarium is not circinatum species but, based on the results of molecular identification using universal primer pairs ITS1 (forward) and ITS4 (reverse), isolate (TZA01_DM) is identical to the fungal pathogen Fusarium sp. Sequence alignment fungal nucleotides amplified with the database at Genebank showed that, pathogenic isolate (TZA01_DM) had the closest homology of 100% with Fusarium oxysporum from France, Iran, India, Ghana and Switzerland, also has the 100% similarity index with Fusarium mundagurra (China), Fusarium concentricum (China), and Fusarium annulatum (India and Spain). The pathogenicity test was conducted through the contact of the seeds with fungal culture for 12 hrs., followed both the isolates were pathogenic to the seeds of Pinus spp., causing a reduction in the percentage of emergence and seedling damping-off. Different three fungicides were used namely Multipower Plus (78% WP), Ridomil Gold (68 WG), and Farmerzeb (80 WP), to control the mycelial growth rate of Fusarium sp in vitro and in vivo and significant results were obtained through the analysis of data using one-way ANOVA (analysis of variance) and Statistical Package for the Social Sciences (SPSS). In vitro results indicated Farmerzeb to be the best compare to the rest of the fungicides. Under in vivo germination percentage for treated and untreated controls had significant difference. Results also showed no phytotoxicity observed throughout the experiment. This is a first report in Tanzania to identify different fungi species that affect forest seeds and went further to control Fusarium obtained from such seeds through available fungicides. Moreover, the study laid the foundation for some more research to be conducted on forest seeds. The
Keyword: Fungicides, Fusarium sp, in vitro, in vivo, Pinus tecunumanii

Judul: Keragaman fusarium spp. pada semai pinus merkusii Jungh. Et De Vriese
Abstrak: Penelitian dengan tujuan untuk mengetahui keragaman spesies Fusarium spp. serta peranannya pada semai pinus dengan mempelajari patogenisitasnya dan penggolongan F. oxysporum berdasarkan kompatibilitas vegetatifnya (Vegetative Compatibility Group)serta mempelajari hubungan antara penggolongan F. oxysporum berdasarkan VCG dengan tingkat patogenisitasnya telah dilakuakn pada bulan Agustus 2002 sampai April 2003. Penelitian dilaksanakan di Laboratorium Bioteknologi Kehutanan (Ektomikoriza) Pusat Penelitian Bioteknologi IPB danLaboratorium Mikologi Tumbuhan, Jurusan Hama dan Penyakit Tumbuhan Fakultas Pertanian IPB dan di Kebun Percobaan Taman Pagelaran Bogor.
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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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