Low temperature storage of corms extends the flowering season of saffron (Crocus sativus L.)

Abstract

SummaryConditions for the cold-storage of saffron crocus (Crocus sativus L.) corms to delay flowering have been characterised. Storage of corms at 2ºC after flower initiation resulted in a time-dependent abortion of those flowers already initiated. The more advanced the stage of flower initiation at the beginning of cold-storage, the faster the rate of flower abortion. Overall, no benefit resulted from cold-storing corms after flower initiation. Corms stored in the cold before flower initiation, formed flowers when incubated after storage at 21º–25ºC. The number and size of flowers formed, and the yield of spice saffron per corm, depended both on the duration and conditions of cold-storage. Storage at freezing temperatures (0º or –1ºC) damaged the corms. Flowering could be induced in corms stored between 0.5º–2ºC. Within this range, temperature had little effect on the subsequent behaviour of corms. Flower number and flower size decreased gradually with increasing duration of cold-storage. This decrease was slower when storage was performed in 1% oxygen than in a normal atmosphere (21% oxygen). Corms lifted after leaf-withering, and stored at 2ºC in 1% oxygen for 70 d, could be forced to flower from early December until the end of January with the same yield of spice saffron as non cold-stored corms.These results complement previous findings on the control of saffron flowering. Taken together, they allow saffron flowering without loss of spice yield from early September to the end of January. Flowering could be further delayed until May by extending the duration of cold-storage, but this delayed flowering resulted in a significant reduction in spice saffron yield.