Saffron is an important medicinal plant widely cultivated for nutrition and economic properties. The mutation can be used to increase the variation in this plant. The aim of this study was to evaluate of the effect of gamma radiation on the in vitro cormogenesis and the corm size and then acclimatization of the corms. Three ecotypes of the saffron corms were collected from Mashhad, Torbat-e Heidarieh and Sarayan provinces in Iran. Gamma radiation with the intensities of 2.5, 5, 7.5 and 10 Gray were used for corm treatment. Then, for In vitro propagation, the SH medium containing 3 mg/L BAP and 1 mg/L NAA was applied. The highest survival rate was observed in the 2.5 Gray treatment of apical buds, in Torbat-e Heydarieh ecotype with 90% survival. After two months, the bud number on each explant was determined. The highest bud number was observed in 2.5 Gray dose in the Sarayan ecotype with 11.03 buds per explant. The buds were transferred to a room with the temperature of 15°C and a photoperiod of 10/14 hrs (light/dark). The Rooting was done on a SH medium containing 2 mg/L BAP with 9% sucrose. The best treatment for cormogenesis induction was 1 mg/L IBA in ½ SH medium. Then, the MS medium with 6% sucrose was used to increase the size of corms in the dark condition at 25°C which led to a mean diameter increase of 1.22 cm. Finally, the corms were transferred to cocopit-perlite pots to check the survival rate. The acclimatization percentage was 91.66%. This study showed that the lower dose of Gamma ray can increase the number of sprouts and thereby the number of corm production.

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