Optimization of the explant disinfection method and in vitro multiplication of saffron (Crocus sativus L.).

Saffron (Crocus sativus L.), renowned as the world’s most expensive spice extracted from its stigmas, is an autumn-flowering, sterile triploid geophyte species (2n=3x=24) belonging to the Iridaceae family. It is propagated vegetatively through the development of daughter corms from the mother corm. Low multiplication rates of daughter corms under natural conditions and many biotic and abiotic stresses reduce productivity, thereby restraining the availability of planting material. Thus, the main objective of this work is to improve the vegetative propagation of saffron through tissue culture. The results show that soaking of explants in 0.1% (w/v) mercury chloride (HgCl2) for 10 min is more effective for explant disinfection (95%), with a survival rate of over 85%. Whereas, for the initiation phase, the in vitro culture of whole corms on Murashige and Skoog (MS) medium supplemented with 0.5 mg /L of 1-naphthalene acetic acid (NAA) in combination with 3 mg/L of 6-benzylaminopurine (BAP) was more effective, resulting in a sprouting rate of 90% with a maximum of 5 sprouted buds per explant. As for the multiplication phase, the highest number of shoots (4 shoots/single shoot explant) was observed on MS medium supplemented with 8 mg/L of BAP in combination with 0.5 mg/L of NAA. The results of this study can serve as a starting point for establishing an efficient and reproducible in vitro regeneration system in order to increase the number of shoots per explant for proliferation and micro-corms formation phases by exploring other culture media with different PGR combinations.