Survival and recovery of asparagus shoot tips after cryopreservation usingthe "droplet" method

In vitro cultured shoot tips of asparagus (Asparagus officinalis L.) were s uccessfully cryopreserved using the "droplet" method. Excised shoot tips, p re-treated with liquid cryoprotective medium, were suspended in small dropl ets (c. 5 mul) of cryoprotectant on aluminium foil and then rapidly frozen by direct immersion in liquid nitrogen. Shoot tips of all eight asparagus g enotypes tested were successfully cryopreserved, and within 7 days had resu med growth into well developed shoots (5-8 mm long) without intermediate ca llus formation. High survival and regrowth was achieved without any cold ha rdening or pre-growth, and ranged from 58% for clone M120 to 96% for cultiv ar 'Rutgers Beacon', with a mean frequency of c. 80% across all eight genot ypes.