Judul: Karakterisasi beberapa genotipe cabai (Capsicum spp.) dan mekanisme ketahanannya terhadap begomovirus penyebab penyakit daun keriting kuning
Abstrak: The plant breeding program to develop resistant plants of Begomovirus is needed to characterize of pepper germplasm. The activities followed by study on resistance mechanism based on information of structural and biochemical resistance against Begomovirus and their vector Bemisia tabaci. Pepper yellow leaf curl virus (PYLCV) belongs to the genus of Begomovirus, the family members of Geminiviridae. The virus has been reported as the causal agent of yellow leaf curl disease in pepper and transmitted by an insect vector, B. tabaci Genn. Evaluation of genotypes characters showed that the morphological characters of leaves, stems, flowers, and fruits can be distinguished among the genotypes of pepper. There are significant differences among pepper genotypes for the following variables: height of dicotomous, plant height, canopy width, stem diameter, leaves length and width, and flowering times. Dendrogram analysis based on qualitative characters involving 29 genotypes classifies the genotypes into 4 different groups. Most of the genotypes belong to group I, genotypes IPB C15 and IPB C63 are in group II, IPB C12 genotype in group III, whereas IPB C20 and IPB C21 are in group IV. All genotypes are included in C. annuum, except IPB C63 genotype which belongs to C. frutescens. Capsicum species differs in the form of leaves, number of flowers at per node, the position of flowers, fruit color intermediate, and plants canopy. Resistance response of the genotypes was identified based on the measurement of disease intensity. IPB C12 genotype is resistant; IPB C10 and IPB C14 genotypes are moderately resistant; IPB C15, IPB C26, and 35C2 genotypes are susceptible. PYLCV detection using PCR technique has successfully amplified 780 bp-sized Begomovirus-specific DNA fragments. Dot blot hybridization is capable to detect PYLCV in resistant and moderately resistant genotypes to a dilution level of 1: 10, whereas susceptible genotypes can reach up to 1: 100 dilution level. Susceptible genotype tended to have a Begomovirus concentrations higher than genotypes resistant or moderate resistant. Genotypes resistance to Begomovirus is associated with structure of plants i.e. density of trichome and arrangement of palisade cells. An increased accumulation of salicylic acid and peroxidase enzyme activity are detected in Begomovirus-inoculated plants, 120 hours after inoculation. Based on the correlation among characters in pepper genotypes, it can be concluded that there is a correlation between the mechanisms of structural and biochemical resistance of plants following Begomovirus infection. Longer palisade cells will lead to thicker leaf and more accumulation of salicylic acid. Trichome density and palisade cells position are the structural barrier in the mechanism of pepper resistance to B. tabaci. Resistance mechanism to Begomovirus is the result of the width of palisade cells, increased accumulation of salicylic acid, and increased activity of peroxidase enzymes. There is a correlation between the structural and biochemical mechanisms to Begomovirus, with a positive correlation between the lengths of palisade cells and salicylic acid accumulation.
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Judul: Genetik ketahanan cabai terhadap begomovirus penyebab penyakit daun keriting kuning dan arah pemuliaannya, Genetics of resistance on chili pepper to yellow leaf curl begomovirus and strategy breeding
Abstrak: Begomovirus has been reported as the major pathogen for various important crops, including chilli pepper. Disease severity and yield loss caused by Begomovirus infection are affected by several factors, among others are plant varieties, viral strains and time of infection. The use of resistance varieties is considered as the most effective way to control the disease. Research activities were conducted to study the genetics of resistance of chilli pepper varieties to Pepper yellow leaf curl Begomovirus, in order to develop resistance chilli pepper varieties. Preliminary experiment was conducted to determine the transmission method using insect vector, Bemisia tabaci followed by determination of plant stage for inoculation of Begomovirus. Individual inoculation using 10 insects per plant with 24 h acquisition period and 48 h inoculation period on cotyledon stage was considered as the most effective and efficient way for Begomovirus transmission. Type of symptoms develop from Begomovirus infection can be differentiated into 5 groups, i.e (1) yellowing (2) yellowing and leaf curling (3) yellowing, leaf cupping with leaf curling, upward or downward, (4) yellowing, leaf cupping with leaf curling, upward and downward (5) yellowing, leaf curling, stunting. Twenty seven genotypes of chilli pepper were evaluated for their resistance based on score/type at symptoms and disease intensity. Disease intensity was ranged from 2.40% to 100% and they were group grouped into resistance (1 genotipe), moderate resistance (4 genotipes), moderate susceptible (4 genotipes), susceptible (8 genotipes) and highly susceptible (10 genotipes). Further analysis showed that resistance genotype (IPBC12) has more trichome than susceptible genotype (35C2) does salicylic acid contain was not significantly different between two genotypes, although Begomovirus infection could increase salicylic acid contain in resistance genotype. Genetic studies for resistance of chilli pepper to Yellow leaf curl Begomovirus was conducted using two methods, i.e. (1) analysis ofbasic population using six-population analysis and (2) analysis of random mating using diallel analysis. The result indicated that pepper resistance to Begomovirus was controlled by polygenes and there was extrachromosomal effect. The degree of dominance were over dominant. Gene action for resistance were additive, dominant and additive x additive interaction. However one population (IPBClO x IPBC14) showed additive gene action, dominant, additive x additive and dominant x dominant interaction. Estimation of broad-sense heritability were high but narrow-sense heritability were low to high. IPBC12 dan IPBC10 have the best combining ability for resistance to Begomovirus whereas IPBC14 have the highest yield. There are four crossing, i.e. IPBC10xIPBC12, IPBC12xIPBC14, IPBC14xIPBC18, dan IPBC18xIPBC26, that good combining ability and heterosis for resistance to Begomovirus and yield. Resistance verieties to Begomovirus could be established through hybrid cultivars to benefit the effect of dominance gene action. However, it could also be developed through open pollination using bulk or pedigree method.
Keyword: resistance, susceptible, combining ability, chilli pepper, Begomovirus

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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