Journal of Applied Horticulture. 2005: 7(1): 43-45

Impact of explants and gamma irradiation dosage on in vitro mutagenesis in carnation (Dianthus caryophyllus L.)

Paramesh, T H; Sona Chowdhury

Division of Ornamental Crops, Indian Institute of Horticultural Research, Hessaraghata, Bangalore - 560 089, India.

In vitro shootlets of carnation (cv. IIHRS-1) were subjected to irradiation with gamma dosage of 20, 40, 60 and 80 Gy. In vitro shootlets required for the irradiation were generated on MS media supplemented with 0.25 mg BAP [benzyladenine], 0.1 mg NAA and 0.25 gibberellic acid/l. From irradiated shootlets, leaves were excised and used as explants for further culturing. Leaves were horizontally cut into half. The region adhering to stem was considered as the leaf base and the region that is away from the stem was considered as the leaf tip. The leaf tip and leaf base were incubated on MS media supplemented with (1) 1.0 mg thidiazuron (TDZ) and 0.1 mg NAA/l (M5) and (2) 0.3 mg TDZ, 1.0 mg BAP and 0.1 mg NAA/l (M6). Weekly observations were recorded for survival percentage, callus formation, regenerated shootlets and expansion of leaf area. The results indicated gamma-radiation at 40 Gy to be the ideal dosage for mutagenesis when mutagenesis was used in combination with regeneration. Survival percentage decreased with increased dosage of gamma radiation. However, regeneration was found to be ideal at approximately LD50 dosage. The maximum regeneration could be realized on M6 media.