Judul: Analisis keterpautan marka RAPD (Random Amplified Polymorphic DNA) dengan ketahanan penyakit layu fusarium pada semangka
Abstrak: Penelitian ini dilakukan untuk memperoleh penanda DNA yang bisa membedakan tanaman semangka yang tahan dengan tanaman semangka yang rentan terhadap penyakit layu Fusarium. Penelitian ini dilakukan dengan menggunakan anilisis Random Amplified Polymorphic DNA (RAPD). Penelitian berlangsung di Laboratorium RGCI (Research Group for Crop Improvement) pada bulan Desember 2006 Mei 2007. Pengamatan dilakukan dengan melihat husi elektroforesis DNA yang divisualisasikan dengan UV illuminator dan didokumentasikan menggunakan kamera digital. Genotipe semangka yang diuji dalam penelitian adalah empat genotipe yang rentan terhadap panyakit layu fusarium yaitu Charleston Gray dengan persentase kejadian penyakit layu fusarium sebesar 83.3%, Long Dragon AG-13 66.6%, New Long ET-03 66.6%, dan Sugar Baby 66.6%; serta genotipe yang tahan terhadap penyakit layu fusarium yaitu Dragon Giant 145, Kaisar, Lokal Kupang yang ketiganya memiliki persentase kejadian penyakit yang rendah yaitu 16,6% Sebanyak 3 primer 10-mer acak yang mengandung 60% Guanin-Cytosine (GC) digunakan untuk reaksi amplifikasi sifat ketahanan populasi semangka yang terdiri dari 4 genotipe semangka rentan dan 3 genotipe semangka tahan penyakit layu fusarium. Primer tersebut yaitu P01 (GTA GCA CTCC), 109 (TGG AGA GCAG), dan G10 (AGG GCC GTCT) dengan temperature anneling yang berbeda-beda yaitu: P01-16,01°C; 105 21,57 °C; G10 26,92 °C. Hasil amplifikasi dari ketiga primer yang digunakan pada gel agarose 1.5% yang dilihat di UV illuminator memperlihatkan marker P01-700 terkait dengan sifat ketahanan terhadap penyakit layu fusarium pada populasi semangka yang digunakan dan secara spesifik dapat membedakan semangka tahan dan rentan. Marker P01700 dilaporkan terkait (1.6 CM) terhadap gen resisten ras 1 penyakit layu fusarium pada semangka. Pada 700bp muncul pita pada ketiga DNA semangka tahan penyakit layu fusarium sedangkan pada keempat DNA semangka rentan fusarium tidak muncul. Sedangkan 109500 dan G10sso kurang spesifik dalam membedakan kedua kelompok genotipe tersebut. Sehingga berdasarkan hasil analisis RAPD dengan menggunakan marka P01700. genotipe Charleston Gray, Long Dragon AG-13, New Long Et-03 dan Sugar Baby 2 tidak memiliki gen ketahanan terhadap penyakit layu fusarium. Sedangkan genotipe Select Dragon, Lokal Kupang dan Kaisar merupakan genotipe yang memiliki gen ketahanan layu fusarium.
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Judul: Keragaman genetik beberapa varietas semangka (Citrullus lanatus [Thunb.] Matsum & Nakai var. lanatus) berdasarkan karakter agronomi dan ketahanan terhadap penyakit layu fusarium (Fusarium oxysporum f.sp. niveum Snyder & Hansen)
Abstrak: Breeding for disease resistance and high yield as well as fruit quality e.g. attractive rind and flesh colors are of watermelon improvement strategies to better meet market demands. Thus, evaluation and analysis of genetic variation toward agronomical characters on commonly cultivated watermelon varieties would be one of Indonesia initial watermelon breeding programs. This work should be collaborated with evaluation in cultivar disease resistance e.g. fusarium wilt (Fusarium oxysporum f.sp. niveum), of which its control so far still depends on resistant cultivar. The study consisted of two experiments : (1) Evaluation toward agronomical characters on watermelon varieties (Citrullus lanatus [Thunb.] Matsum & Nakai var. lanatus) and (2) Evaluation toward resistance against three isolates of Fon (Fusarium oxysporum f.sp. niveum). The first experiment was aimed to analyse genetic variation among watermelon varieties and screen varieties with high yield and/or attractive performance. The second experiment was aimed to screen varieties with good resistance against all of Fon isolates. Thirty three of watermelon varieties were subjected in the first experiment designated on Randomized Complete Block Design with three replications. Meanwhile, three isolates of Fon i.e. ‘Karawang’, ‘Lampung’ and ‘Purwakarta’ were used against 35 watermelon varieties in the second experiment designated on Completely Randomized Design with two replications. Evaluation of agronomical characters showed that based on ANOVA there were significant differences among 33 varieties for all quantitative characters. Based on all agronomical characters, Principal Component Analysis explained 75.69% total variance, whereas cluster analysis distinguished 33 varieties into three groups with 68% genetic variation. Resistance evaluation against Fon isolates showed that of 35 varieties, six varieties were demonstrated having good resistance against all of three Fon isolates. Difference was also observed within incubation period through either among varieties against the same isolate or variety against various isolates. Shortest incubation period occured on variety ‘Hitam Manis’ against isolate Karawang (< 10 days after inoculation) and the longest one occured on ‘New Dragon’ against isolate Lampung (> 23 days after inoculation). Therefore, apparently there was gene-for-gene resistance mechanism underlying through differences of genotypic reaction against the three of Fon isolates reflected in disease index and incubation periods.
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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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