KARAKTERISTIK FISIOLOGIS Ralstonia solanacearum PENYEBAB PENYAKIT LAYU BAKTERI NILAM

ABSTRAK Penelitian karakteristik Ralstonia solanacearum penyebab penyakit layu bakteri nilam telah dilakukan di pertanaman nilam petani di Pasaman Barat Sumatera Barat dan laboratorium serta rumah kaca Fakultas Pertanian Universitas Gadjah Mada, Yogyakarta. Kegiatan lapangan meliputi identifikasi gejala penyakit dan pengambilan sampel tanaman sakit pada empat kebun nilam terinfeksi penyakit layu bakteri berdasarkan tingkat serangan tertinggi (di atas 75%) yang dilakukan pada bulan Januari 2003. Kegiatan laboratorium dan rumah kaca meliputi isolasi dan pengamatan morfologi bakteri patogen, pengujian hipersensitif, patogenisitas, sifat-sifat bakteriologi, pigmen fluoresen, antibiotik, biovar dan ras patologi yang dilaksanakan pada bulan Januari sampai Agustus 2003. Hasil penelitian menunjukkan bahwa didapatkan 31 isolat bakteri patogen yang menunjukkan reaksi hipersensitif pada daun tembakau, dan 20 isolat dari isolat tersebut mampu menginfeksi bibit nilam dengan gejala layu seperti gejala di lapangan dengan masa inkubasi menunjukkan gejala 14,6 – 39,0 hari setelah inokulasi (HSI). Isolat Ns 31 adalah isolat paling virulen. Hasil analisis sifat-sifat bakteriologi menyimpulkan isolat bakteri asal nilam dari Pasaman Barat Sumatera Barat adalah Ralstonia solanacearum. Berdasarkan hasil pengujian biovar dan kisaran inang maka isolat tersebut dikelompokkan ke dalam biovar III dan ras satu. Kata kunci : Nilam, Pogostemon spp., penyakit, bakteri, Ralstonia solanacearum, Sumatera Barat, D.I. Yogyakarta ABSTRACT Physiological characteristics of Ralstonia solanacearum causing bacterial wilt disease on patchouli plant The study of characteristics of Ralstonia solanacearum causing bacterial wilt disease on patchouli plant was conducted in the patchouli plant field in Pasaman Barat West Sumatera and bacteriological laboratory and green house of Agricultural Faculty of Gadjah Mada University, Yogyakarta. The field activity were identification of disease symptom and collection of infected plant by bacterial disease from the patchouli plant field that have the height disease intensity (more than 75%) that was conducted on January 2003. Activity of laboratory and green house were isolation and assay of bacterial morphology, hypersensitive and pathogenicity test, bacteriological characteristic, fluorescens pigment, antibiotic, biotype and ras pathology were conducted from January to August 2003. Results showed that 31 isolates showed hypersensitive reaction on tobacco leaf. Twenty isolates infected patchouly plant with wilt symptoms with incubation period 14.6 – 39.3 days after inoculation. Ns 31 was the most virulent isolate. Analytic results of bacteriological characteristic showed that the bacterial isolates of Patchouli plant from West Pasaman-West Sumatera is Ralstonia solanacearum. Based on biotype and host range test, this isolates was grouped into biotype III and ras one. Key words : Patchouli, Pogostemon spp., disease, bacteria, Ralstonia solanacearum, West Sumatera, D.I. Yogyakarta