Judul: Pengaruh varietas kedelai, mulsa jerami dan aplikasi PGPR terhadap penyakit pustul bakteri dan kelimpahan bakteri rizosfer
Abstrak: Bacterial pustule caused by Xanthomonas axonopodis pv. glycines is one of important bacterial diseases of soybean in Indonesia. The development of alternative control of the disease is required to support Integrated Pests and Diseases Management for sustainable agriculture. This research was conducted to observe the effect of straw mulch, Plant Growth Promoting Rhizobacteria (PGPR) on the incidence of bacterial pustule disease and the abundance of chitinolytic bacteria, heat tolerant bacteria, and fluorescence bacteria on two soybean varieties. All of the factors as combinations were not significant to affect the value of total area under disease progress curve (AUDPC) of bacterial pustule. Factor that significantly affected the values of AUDPC was varieties. Gepak Kuning variety has lowest AUDPC value compare to Anjasmoro variety. In addition, combination of Gepak Kuning variety and straw mulch showed AUDPC value. Abundance of fluorescence bacteria on soybean rhizosphere treated with PGPR is significantly higher compared with those on plants without PGPR. The other treatments and their combination did not significantly affect the abundance of rhizosphere bacteria.
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Judul: Ketahanan terhadap hawar daun bakteri dan keragaan produktivitas padi sawah yang ditanam tunggal dan campuran
Abstrak: The core of Indonesian agricultural development policy is to meet the demand of rice as staple food. The improved varieties which have been used still faced constraints such as abiotic and biotic stress. One of the important biotic stress is Bacterial Leaf Blight disease caused by Xanthomonas oryzae pv. oryzae. According to the previous research, mixture varieties planting could reduce disease intensity and increase the yield. The aim of this research was to find out the genotype that resistance to BLB, yield stability, genetic variability and other characters stability on single and mixture planting. The experiment used 17 genotypes as treatments which consisted of 7 cultivars and 10 cultivar mixtures with different resistance to BLB background. The trial was designed in Randomized Complete Block Design and replicated three times. The trial was conducted during two seasons in Majalengka and Pacitan. The characters observed were Bacterial Leaf Blight spreading, plant height, number of panicle per hill, number of well-filled grain per panicle, number of unfilled grain per panicle, number of total grain per panicle, 1000 grains weight, well-filled grain percentage, yield per ha and sink size. The disease spreading data was used to analyze the first appearance of disease, disease incidence, disease severity and Area Under Disease Progress Curve (AUDPC). The yield data was used to analyze yield stability and genetic parameters, while agronomic characters data was used to analyze the difference between two seasons and between single and mixture genotype using t test. According to the result of analysis, there was no difference between single and mixture genotype on the first appearance of disease, disease incidence, disease severity and AUDPC. The result of combine and stability analysis showed that genotype, season and their interactions influenced the yield; and the stable, unstable and specific single and mixture genotype could be determined. According to t test to other characters, there was no difference between single and mixture genotype. Based on the result of the analysis, the effect of mixture to reduce the Bacterial Leaf Blight disease and to increase the yield has not been known yet.
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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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