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: Uji ketahanan 25 genotipe semangka. Citrullus lanatus (Thunb) Matsum & Nakai terhadap Fusarium oxysporium f.sp.niveum
Abstrak: Penelitian bertujuan untuk mengevaluasi ketahanan 25 genotipe semangka terhadap penyakit layu fusarium. Penelitian ini dilaksanakan di Rumah Kaca dan Laboratorium Mikologi Tumbuhan, Departemen Proteksi Tanaman, Fakultas Pertanian, Institut Pertanian Bogor, Penelitian dilaksanakan mulai bulan April 2005 sampai bulan Desember 2005. Uji patogenisitas isolat Fusarium oxysporum f. sp. niveum (Fon) pada benih semangka menunjukkan bahwa isolat tersebut mampu menginfeksi benih semangka. Isolat dibiakkan dalam media jerami padi, kemudian dilakukan inokulasi pada 25 genotipe semangka dengan kepadatan inokulum 2,5 x 105 konidia/g jerami. Dari 25 genotipe semangka, 18 genotipe introduksi dan 7 genotipe lokal. Faktor-faktor yang diamati antara lain jumlah benih yang mengalami pre-emergence damping off dan post-emergence damping off, persentase kejadian penyakit dan masa inkubasi Fon. Jumlah benih yang mengalami pre-emergence damping off 22% dan Jumlah benih yang mengalami post-emergence damping off 21,3%. Persentase kejadian penyakit tertinggi pada genotipe Charleston-Gray, Sunflower, Long Dragon AG-13, New Long ET-03, Select Dragon 117-S dan Sugar Baby-2 sebesar 83,3%, sedangkan yang terendah terdapat pada genotipe Dragon Giant 145, Kaisar, TM-Lion dan Lokal Kupang sebesar 16,6%. Masa inkubasi paling cepat pada genotipe TM-Lion yaitu 21 Hari setelah tanam (HST). Genotipe yang tidak terinfeksi Fon post-emergence damping off antara lain: Lokal Kuansing Panjang, Super King, 144 (6372), Dragon Giant 145, Offen 230 Tawiwu, Sugar Baby-2, TM-Dragon dan Sea Dragon. Pada umumnya, gejala penyakit yang muncul pada genotipe semangka yang diuji sama. Gejala diawali dengan pertumbuhan tanaman yang kerdil, kotiledon bibit yang terserang tampak seperti kekurangan air, mengering, berwarna coklat dan kemudian tanaman mati. Bagian pangkal batang yang terserang mengalami pemucatan, menggenting, kering, berwarna coklat kemudian tanaman rebah dan mati. Berdasarkan kriteria ketahanan, genotipe Charleston-Gray, Sunflower, Long Dragon AG-13, New Long ET-03, Select Dragon 117-S dan Sugar Baby-2 termasuk rentan. Genotipe New Champion CC-702, Banyuwangi, Honky Star 288, Offen 230, Tawiwu, Kiara 362 dan TM-Dragon merupakan kriteria yang agak tahan. Genotipe Sea Dragon, Round Dragon (311), Super New Dragon, Super King, 144 (6372), Diana Bangkok Dragon, Lokal Bone, Lokal Jombang dan Lokal Kuansing Panjang memiliki kriteria tahan dan genotipe Dragon Giant 145, Kaisar, TM-Lion dan Lokal Kupang memiliki kriteria sangat tahan.
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Judul: Asymptotic Distribution of Estimator for the Intensity Function of a Doubly Periodic Poisson Process
Abstrak: In this manuscript, estimation of the intensity function of a doubly periodic Poisson process is discussed. It is assumed that only a single realization of the Poisson process is observed in a bounded window [0,n]. It is also assumed that the period of the intensity function is known. The rate of consistency and asymptotic normality of the estimator are formulated. Finally, a confidence interval for the local intensity function is also formulated.
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