Judul: Phenotypic and molecular characterizations of bacterial pathogen and epidemy of bacterial leaf blight on Acacia crassicarpa seedlings
Abstrak: Bacterial leaf blight (BLB) disease is a new and deadly disease on Acacia crassicarpa nursery in Pelelewan Riau and never been reported either in Indonesia or in other countries. This research was designed to study etiology of BLB disease on A. crassicarpa seedlings and other factors that triggered epidemy of BLB disease. The result showed that the first symptom of BLB appeared on 5-6 weeks-old seedlings and blight was formed within 1-2 weeks., Bacterial leaf blight (BLB) disease is a new and deadly disease on Acacia crassicarpa nursery in Pelelewan Riau and never been reported either in Indonesia or in other countries. This research was designed to study etiology of BLB disease on A. crassicarpa seedlings and other factors that triggered epidemy of BLB disease. The result showed that the first symptom of BLB appeared on 5-6 weeks-old seedlings and blight was formed within 1-2 weeks.
Keyword: molecular identification, epidemy of BLB, Xanthomonas campestris, disease symptom, Riau

Judul: Perlakuan Benih dan Perendaman Akar Bibit dengan Agens Hayati untuk Mengendalikan Serangan Xanthomonas oryzae pv. oryzae serta Meningkatkan Pertumbuhan Tanaman Padi di Rumah Kaca
Abstrak: Xanthomonas oryzae pv. oryzae (Xoo) causing bacterial leaf blight (BLB) in rice is a seed-borne pathogen, could reduce yield by 60%. This experiment was conducted to evaluate the effect of seed treatment and root dipping on BLB incidence and vegetative growth of rice plant in the greenhouse. The experiment was arranged in a split plot-randomized complete block with four replications. The main plots were seed treatments (6 levels) and the subplots were root dipping (8 levels). Matriconditioning was conducted using burned rice hull 30 mesh as carrier or media with ratio of seed:carrier:solution of bactericide or biological agents = 1:0.8:1.2 (g:g:ml) at 25 0C for 30 h. Root dipping was conducted for 1 h. The results showed that seed treatment with matriconditioning + Pseudomonas diminuta A6 + Bacillus subtilis 5/B improved seed germination, vigor index, germination rate, and reduced the BLB incidence. Matriconditioning + P. diminuta + B. subtilis was able to increase plant height without root dipping treatment. However, the seed treatment should be followed by root dipping on 3 week-old seedling in order to increase plant dry weight. Seed treatment using matriconditioning + P. diminuta + B. subtilis and followed by root dipping with P. diminuta + B. subtilis (106 cfu/ml) effectively and efficiently increased plant dry weight. Seed treatment with matriconditioning + P. diminuta + B. subtilis or root dipping with P. diminuta + B. subtilis (106 cfu/ml) produced the highest number of tillers up to 4 weeks after transplanting. Severities of BLB up to 4 weeks after transplanting was low (1.7%-2.5%). Seed treatment using matriconditioning + 0.2% bactericide or roots dipping with P. diminuta + B. subtilis (108 cfu/ml) reduced the BLB incidence effectively at vegetative phase.
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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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