Responses to dehydration and conservation of the non-orthodox seeds of Warburgia salutaris

Seeds from naturally-ripened fruits of Warburgia salutaris, for which viability retention on slow air-drying has not been achieved, survived relatively rapid dehydration in silica gel to water contents at which they could be cryopreserved by immersion in liquid nitrogen. Subcellular events during natural seed maturation were attenuated when premature fruits were harvested and stored, perhaps explaining improved responses to desiccation and cryopreservation presently reported for mature seeds. However, the desiccated mature seeds did not survive for more than a few weeks when stored at 16°C or 25°C, and lost viability far more rapidly at 6 ± 2°C, revealing their chilling-sensitivity. Seedlings were readily established from seeds retrieved from cryostorage and germinated in bottom-heated sand-beds at 25°C.