For many plant species, little is known about the long-term viability of their seeds when subjected to dry, cold conditions for longer than a few seasons. We do know, however, that seeds of some species recovered from archaeological excavations have germinated after several hundred years of dormancy and agricultural crop seeds can be stored dry in banks for long periods of time with little effect on their germination potential. For most temperate plant species, removing moisture from their seeds and freezing them will extend their life for decades. These seeds are considered to have orthodox seed storage behavior. However, there are a few species such as oaks and hazel nuts that are intolerant of extreme desiccation and cannot be stored long-term in the conventional manner. These seeds are considered to have recalcitrant storage behavior. Scientists have set optimal temperatures for orthodox seeds at -20°C and optimal water content between 15% and 24% RH. Under these conditions, free and bonded water in cellular cytoplasm is reduced to the point that ice crystals will not damage the cytoplasm and cell reactions are slowed to retard the aging process.
