Judul: Perbaikan Karakter Agronomis Buru Hotong (Setaria italica (L.) Beauv) melalui Irradiasi Sinar Gamma
Abstrak: Buru Hotong (Setaria Italica (L.) Beauv) is potential source of food that has not been developed in Indonesia. The plants is in the family Gramineae and a self-pollinated crops. Buru hotong is a type of grasses, have a small seed, and green seed color at early stage and light brown when mature. Althought the nutrient content of buru hotong is very good, but the productivity is low. The plant also has a very high height. Lowering the plant staments a held and can be improve by mutation. The objectives of the research were to study the radiosensitivity of buru hotong to gamma ray irradiation, to obtain information on genetic variation of M2 and M3 populations. Seeds were exposed to gamma ray irradiation at the Center for Biological Resources and Biotechnology, Bogor Agricultural University and the field experiments were conducted at the field station of Bogor Agricultural University. To determine the radiosensitivity, the seeds of buru hotong was treated with gamma ray irradiation at 50 gray, 100 gray, 150 gray, 200 gray, 400 gray, 600 gray, and 800 gray. The M1 population were grown and observe for mortality to determine the radiosensitivity. The results of the observation on M1 showed that gamma ray irradiation gave different responses in germination percentage at each dosage of irradiation. The LD50 for buru hotong was found to be at 342,39 Gy. M2 populations were grown and observed for variability. The results showed that low dose of gamma rays irradiation produced genetic variability of agronomic characters in the M2 generation.
Keyword: 

Judul: Agronomic improvement characters and adaptation to drought stress on soybean [Glycine max (l) merr] through low doses of gamma rays irradiation
Abstrak: The increase in genetic variability of soybean plants improve the probability to select for desired characters, for example, adaptation to drought stress. Mutation breeding is a breeding methods that can be applied to improve genetic variability of soybean in a relatively short time. Similarly, mutation induction can also increase genetic variability of soybean by using low doses of gamma rays irradiation. The objectives of the research were : (1) to obtain information on the changes in morphological and agronomic characters due to the treatment of low doses of gamma rays irradiation on plant population; (2) to obtain information on genetic variability among irradiation doses in plant population; (3) to obtain mutant putative genotype with good morphological and agronomic characters on optimum as well as stress condition; (4) to obtain information on the character of physiological adaptation to drought and plants; and (5) to obtain to a mutant putative line which can tolerate drought and high yielding. The study result showed that in Lethal Dose 50 (LD50) value there were 457,13 Gy. Gamma ray irradiation produced four populations that showed different growth and development from the non-irradiated control (Argomulyo). Genetic variability of each trait was different in each population at M2 generation. The selection based on number of productive pods and weight of seed per plant resulted in a mean improvement of selected genotype compared to the mean of base populations in M3 generation, respectively. Putative mutant lines on M4 that was from M3 selection had a mean improvement of plant height, number of productive nodes and number of productive pods better than that of Argomulyo variety. There were different responses of drought tolerant varieties (Ceneng and Tanggamus) and drought sensitive varieties (Anjasmoro and Argomulyo) to soil water content. The escape mechanism was found as earlier maturity in Argomulyo variety. Avoidance mechanism due to the increase in root volume was found in Anjasmoro, Ceneng and Tanggamus varieties at 40 % field capacity. Tolerance mechanism was marked by the reduction of evapotranspiration in Tanggamus variety at 40 % field capacity. The research results showed that the performance of agronomic characters on drought condition were lower than that of in optimum condition in M5 population. The selection result on M5 generation indicated that the selected mutant strains had good agronomic characters and high yielding. They had good adaptability to drought and were high yielding in optimum conditions and drought conditions.
Keyword: 

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.
Keyword: