Dehydration of seeds is a key feature in the management of accessions in the bank. Dehydration may last several months and require considerable knowledge of the seed morphology and anatomy and also of those physiological parameters related to seed development and maturity.
Seed dehydration is normally carried out in rooms under controlled temperature (10-20ºC) and humidity (10-15%).

 

Photo (left): Juniperus oxycedrus L. subsp. macrocarpa – fruits and seeds (orthodox) (© 2005 Josep Bonet - JBS); Castanea sativa - fruits and seeds (recalcitrant) (© 2006 David Fenwick).

Dehydration is the most delicate procedure of all those normally conducted in a seed bank, and also one of the most difficult problems to solve regarding ex situ conservation. Moisture loss should be carried out steadily because the different stages of seed development are affected by mechanical, chemical, morphological and physiological factors that may well enhance germination but may induce dormancy as well. Each type of seed tolerates a different dehydration process that should be properly conducted, otherwise seeds may lose their viability.