ABSTRACT
Introduction ........................................................................................................ 557
Materials.............................................................................................................. 558
Water Content Analysis .................................................................................... 558
Freezing Treatments .......................................................................................... 558
Calorimetric Analysis........................................................................................ 559
Germination Test................................................................................................ 560
Light and Transmission Electron Microscopy (LM and TEM) .................. 560
Results and Discussion ..................................................................................... 560
Acknowledgments ............................................................................................. 562
References ........................................................................................................... 563
Orthodox seeds undergo a programmed desiccation at the termination of
their development. In these seeds, desiccation tolerance is acquired during
development and is lost after germination. In contrast, recalcitrant seeds do
not tolerate a reduction in water below a relatively high level without loss of
viability (Roberts, 1973). Conventional storage techniques are thus not
applicable to these seeds and cryopreservation is the only feasible alternative
for their long-term storage. However, their high freezable water content
promotes injuries, and their low-temperature conservation represent
a challenge (Kermode, 1997). In order to improve cryopreservation
techniques, recalcitrant seeds are good models to analyze the impact of
freezing rate, storage time, and temperature on the degree of injury. Previous
studies have demonstrated that only minor damage occurs if plant tissues
are submitted to rapid cooling (21968C) (Wolfe and Bryant, 2001). Those
seeds with lower freezable water would be more easily cryopreserved.
