Effect of Storage Temperature on Green Spore Longevity for the Ferns Equisetum Ramosissimum and Osmunda Regalis

Green spores of ferns lose viability quickly, and need specialized treatment for long-term conservation in germplasm banks. Dry storage at different temperatures was studied in green spores of Osmunda regalis and Equisetum ramosissimum. Changes in germination percentage, time to 50% of maximum germination (T50) and tendency for normal growth of the gametophyte were assayed during 24 months of storage. Spores stored at 25ºC died within 1 month. Spores stored at 4ºC maintained high viability for about 3 months, and then aging was evident by a decrease of final germination percentage, an increase in T50, and abnormal development of the gametophyte. Germination of spores stored at -25ºC was highly variable during the storage period. Spores cryopreserved at -80ºC and -196ºC maintained high viability, rapid germination and normal growth throughout the study period. Cryopreservation of green spores is a feasible method to preserve viability and ensure normal gametophyte development for several years.