Judul: Blast Resistance Test On 51 Rice Strains Against Blast Disease (Pyricularia oryzae) race 173.
Abstrak: Padi hasil persilangan program pemuliaan padi Departemen Agronomi dan Hortikultura IPB sebanyak 51 galur telah berhasil diuji dengan menggunakan metode injeksi. Pengujian tanaman dilakukan dengan dua kali penapisan, penapisan I sebanyak tiga ulangan dan penapisan II sebanyak dua ulangan. Penapisan I dimulai dengan memproduksi spora Pyricularia oryzae di media oatmeal agar kemudian dicuci dengan akuades steril setelah diinkubasi selama 10 hari. Penyinaran n-UV dilakukan untuk menginduksi spora sehingga spora dapat dipanen. Suspensi spora dengan konsentrasi 105 – 106 spora/ml diinjeksi pada daun tanaman padi yang berumur 20 hari (± 4-5 daun). Penapisan II dilakukan untuk menguji 18 galur padi hasil penapisan I dengan tingkat ketahanan >90%. Sebanyak 7 galur diperoleh dari hasil penapisan I dan penapisan II dengan tingkat ketahanan 100% yaitu IPB107-F-5-1, IPB107-F-7-3, IPB113-F-2-2, IPB117-F-7-2, IPB140-F-2-1, IPB149-F-4, dan IPB149-F-8. Identifikasi gen ketahanan Pi-ta dilakukan dengan Polymerase chain reaction (PCR) menggunakan 2 pasang primer yaitu primer ekson1 yang mengamplifikasi daerah ekson 1 dan primer ekson2 yang mengamplifikasi daerah ekson 2 pada gen ketahanan Pi-ta. Hasil identifikasi didapatkan bahwa semua galur yang tahan mempunyai gen Pi-ta, termasuk kontrol peka (Kencana Bali). Hasil yang diperoleh berbeda dengan penelitian sebelumnya yang menunjukkan bahwa Kencana Bali tidak memiliki gen ketahanan Pi-ta. Hal tersebut diduga bahwa varietas Kencana Bali mengalami delesi pada bagian belakang ekson2. Kata kunci : galur padi, penyakit blas (Pyricularia oryzae), gen Pi-ta
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Judul: Resistance Test toward of 48 Lines Rice to Blast Disease (Pyricularia oryzae) Race 001
Abstrak: Blast disease, caused by Pyricularia oryzae Cav., is one of the major fungal diseases infected rice (Oryza sativa L.) in Indonesia. The aim of this research was to examine the resistance of rice from the infection of P. Oryzae race 001 and to detect the existance of Pi-ta gene in resistant lines of rice. Resistance evaluation to blast disease (Pyricularia oryzae) on Cisadane (resistant), Kencana Bali (susceptible) as control, and 48 lines of rice was carried out in the green house by using injection inoculated method with P. oryzae race 001. Rice seedling were planted on sterilize soil, and sixteen days old of rice were soaked in the fungal spore suspension (105 spores/ ml) in the dark for 24 hours, and moved to the light. Rice disease was observered on 7-9th days after infection. There were 2 step screening of blast-resistant, which screening I performed a total of three replicates and screening II performed from selected plant in screening I a total of two replicates for each line of rice, with 10 plants in each replication. The result of second screening at green house showed that 13 lines resistant to P. oryzae 001 were IPB140-F-2-1, IPB115-F-4-2-2, IPB113-F-2-2, IPB107-F-7-3, IPB140-F-5, IPB149-F-2, IPB149-F-8, Martapura, IPB149-F-4, IPB149-F-5, IPB113-F-1, IPB102-F-92-1-1, IPB107-F-5-1 with the percentage of resistance ≥ 80 %. Two pairs of DNA primers specific to the dominant indica Pi-ta gene were designed from DNA sequence in gene bank with accession number AF207842 to amplify the Pi-ta DNA fragments by polymerase chain reaction (PCR) method. The results revealed that all of 13 resistant and 2 susceptible lines (IPB107-F-18-4-2 and IPB107-F-16E-6) of rice carrying Pi-ta genes, even in Kencana Bali. The previous experiment shown that Kencana Bali does not have Pi-ta resistance gene. It is expected that Kencana Bali has deletion of Pi-ta resistance gene in the end part of exon 2. Further more, those results also indicated that Pi-ta gene did not confer resistance to race 001 of Pyricularia oryzae. Resistance to P. oryzae race 001 might be controlled by different resistant gene.
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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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