DESICCATION AND CRYOPRESERVATION OF EMBRYONIC AXES OF TRICHILIA-DREGEANA SOND

When excised zygotic axes of the recalcitrant seeds of T. dregeana wer e flash-dried, they maintained viability to a water content of 0.16 g H2O per g dry matter (g g(-1)), in contrast to slowly-dried whole seed s which lost viability at an axis water content of 0.55 g g(-1). Ultra structural examination showed extensive damage and total lack of subce llular organisation in meristematic axis cells of seeds dehydrated slo wly, while the cells of flash-dried axes retained general cytoplasmic and organellar integrity. The flash-dried axes, however, did not survi ve exposure to liquid nitrogen without cryoprotection, and a cryoprote ctant mixture of DMSO and glycerol resulted in the highest survival fo llowing cryopreservation. Ultrastructure of cells from surviving axes indicated an apparently normal metabolic state, compared to the total ultrastructural derangement in the non-surviving axes.