Judul: Analisis Daya Gabung dan Heterosis Ketahanan terhadap Penyakit Bulai (Peronosclerospora maydis) dan Daya Hasil Jagung Manis
Abstrak: Zea mays var. saccharata Sturt. more popular called sweet corn was horticulture crop that have high economic value. This experiment consist of three experiments. First experiment aimed to evaluate 74 sweet corn lines of downy mildew resistance. The result showed that 74 sweet corn lines, had different resistance to downy mildew, 18 lines belonging to medium susceptible and 56 lines belonging to susceptible. Seven lines sweet corn selected with different response to downy mildew disease, the lines were DMST531 (B) 29.95%, DMSG781 (D) 37.00%, DMSC499 (A) 52.80%, DMSS491 (F) 59.15%, DMSE711 (E) 76.65%, DMSK5 (C) 84.35% dan DMSF11 (G) 88.50%. Clustering based on coefficient similiarity 81%, resulted in four cluster, one was lines DMST531, DMSF11, DMSG781 and DMSS491, second was line DMSC499, third was line DMSK5 and fourth was line DMSE711. Second experiment studied combining ability and heterosis for downy mildew (P. maydis) resistance in sweet corn. General combining ability (GCA) and specific combining ability (SCA) values were significant for disease resistant but the resiprocal effect was not significant. Diallel analysis based on disease incidence showed that more negative value was better than positive value. Genotype DMST531 showed more negative GCA value (-1.70) and the combination DMSK5xDMSS491 showed more negative SCA value (-2.11). The combination DMSK5xDMSS491 also showed more negative heterosis (-2.50%) and more negative heterobeltiosis (-2.50%) compared to the others. Additive variance was lower than dominant variance indicating downy mildew resistance is influenced by additive gene action. Third experiment studied combining ability and heterosis for yield and yield component in sweet corn. Resiprocal effect was not significant for all traits, indicating that gene location at nucleus more influential. Specific combining ability (SCA) x enviroment interaction was not significant for all traits, suggesting that screening at one location would be adequate. This experiment showed that non-additive gene action were more important for controlling inheritance of all traits. Genotype DMSG781 were good combiners for yield and yield per plot, genotype DMSE711 for ear diameter, ear rows, plant height and ear height. Genotype DMSF11 good combiners for ear lenght and rendement. Combination DMST531xDMSK5 were the best SCA for yield and yield per plot, DMSC499xDMSS491 for ear length, DMSS491xDMSF11 for ear diameter, DMSE711xDMSS491 for ear rows, DMSE711xDMSK5 for plant height and ear height. Combination DMSC499xDMSS491 have higher heterosis and heterobeltiosis for yield and yield per plot, DMSS491xDMSC499 and DMSK5xDMSE711 for ear lenght, plant height and ear height, DMSS491xDMSF11 for ear diameter, DMSK5xDMSS491 for rendement, DMSS491xDMSE711 for number of rows, DMSG781xDMSC499 for total soluble solid, DMSS491xDMST531 day of tasseling, day of silking and day of harvest.
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Judul: Evaluasi daya gabung dan heterosis jagung manis (Zea mays L. var. saccharata)
Abstrak: The aims of this research were to estimate the values of general combining ability, specific combining ability and heterosis in sweet corn using a half dialel mating design. There were 7 inbreds, 21 hybrids, and 2 checks varieties (Bonanza and SG 75) used in this research. This research was conducted in Leuwikopo experimental station Dramaga Bogor, from November 2014 to January 2015. The experimental design was a randomized complete block design with 3 replicates. General combining ability values were estimated by Griffing II method. Heterosis were calculated based on mid-parent and high-parent values. Inbred JM8-4-3-1- 15-14 has the highest general combining ability in sugar content and yield. Inbred JM14-4-10-10-13-15 has the high general combining ability in ear length and days to harvest. Inbred JM17-6-13-1-12 has highest general combining ability for ear height. Hybrid 17 X 14 has the highest specific combining ability for yield and ear length. High heterosis values for yield and ear length were found in hybrid 17X6 hybrid.
Keyword: Bogor Agricultural University, combining ability, Griffing method, half diale, hybrid

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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