Germination as an Unreliable Indicator of the Effectiveness of Cryopreservative Procedures for Imbibed Seeds

Tomato seeds of 49 per cent moisture content have been thawedfrom liquid nitrogen (—196 °C) with no loss of germinationfollowing both slow (12 °C min^–1) and rapid (850 °Cmin^–1) cooling, using 35 per cent dimethyl sulphoxide(DMSO) as a cryoprotectant. Lower concentrations of DMSO resultedin reduced germination. High proportions of seedlings from frozen/thawedseed failed to survive transplanting into soil, especially ifthey had been cooled rapidly. Seedlings grown to maturity afterthe slow cooling treatment showed a greater proportion of morphologicalabnormalities than a control population or those that had beenrapidly cooled. It is suggested that if cryopreservative techniques are to beevaluated for the storage of recalcitrant seeds, false impressionsof efficacy might be gained by reliance solely on germinationtesting. Cryopreservation, germination, recalcitrant seed