Pengaruh Mutasi Fisik Iradiasi Sinar Gamma terhadap Keragaman Genetik dan Penampilan Coleus blumei

ABSTRACTMutation breeding such as gamma ray irradiation is one of strategy to increase genetic variability. The aim of this research was to indentify genetic variability, performance changes and to obtain putative mutant of Coleus blumei purple/green through gamma ray irradiation. The experiment design used was Randomized Complete Block with single factor and three replications. The gamma ray irradiation was given to shoot cuttings of C. blumei by fractionated irradiation dose: 0 Gy (control), 20+20 Gy, 22.5+22.5 Gy, 25+25 Gy and 27.5+27.5 Gy. The irradiated shoot cuttings were planted in field until MV3 generation. The result of this research showed that gamma ray irradiation on C.blumei purple/green produced the high genetic variability on number of leaves and number of branches i.e. 58.48% and 74.02% by 25+25 Gy dose and number of branches by 20+20 Gy and 22.5+22.5 Gy dose i.e. 53.47% and 68.97% respectively. Physically induced mutation by gamma ray irradiation produced 5 putative mutants respectively on colour and pattern of leaf changes in the following plants: 20+20.5, 20+20.7, 22.5+22.5.8, 25+25.5 and 25+25.8.Keywords: fractionated irradiation, mutagen, ornamental plant, putative mutan, shoot cuttingABSTRAKPemuliaan mutasi dengan iradiasi sinar gamma merupakan salah satu cara dalam meningkatkan keragaman genetik tanaman. Tujuan penelitian ini untuk mengidentifikasi keragaman genetik, perubahan penampilan dan mendapatkan mutan putatif pada tanaman Coleus blumei ungu/hijau melalui iradiasi sinar gamma. Penelitian menggunakan rancangan kelompok lengkap teracak (RKLT) faktor tunggal dengan 3 ulangan. Iradiasi sinar gamma diberikan terhadap stek pucuk C. blumei ungu/hijau dengan dosis terbagi yaitu: 0 Gy (kontrol), 20+20 Gy, 22.5+22.5 Gy, 25+25 Gy dan 27.5+27.5 Gy. Semua tanaman hasil iradiasi ditanam di lapangan sampai generasi MV3. Hasil penelitian menunjukkan bahwa pemberian iradiasi sinar gamma pada C. blumei ungu/hijau menghasilkan keragaman genetik yang cukup tinggi pada karakter jumlah daun dan jumlah cabang dengan nilai KKG masing-masing 58.48% dan 74.02% pada dosis 25+25 Gy serta karakter jumlah cabang dengan nilai KKG 53.47% dan 68.97% masing-masing pada dosis 20+20 gy dan 22.5+22.5 Gy. Mutasi induksi fisik dengan iradiasi sinar gamma pada C. blumei ungu/hijaumenghasilkan 5 mutan putatif berdasarkan perubahan warna dan corak daun yaitu pada tanaman: 20+20.5, 20+20.7, 22.5+22.5.8, 25+25.5 dan 25+25.8.Kata kunci: iradiasi terbagi, mutagen, mutan putatif, stek pucuk, tanaman hias