Germination of lychee seeds after maturation and their ultrastructure observation

Lychee is one of the famous fruits in the subtropical regions. However, lychee seedsdo not undergo maturation desiccation during development, and cannot tolerate drying andchilling in storage. Under natural conditions, lychee seeds can only maintain viability forseveral days, and their germplasm conservation is rather difficult using conventional meth-ods. So they are called recalcitrant seeds.

Lychee is one of the famous fruits in the subtropical regions. However, lychee seeds do not undergo maturation desiccation during development, and cannot tolerate drying and chilling in storage. Under natural conditions, lychee seeds can only maintain viability for several days, and their germplasm conservation is rather difficult using conventional methods. So they are called recalcitrant seeds([1]). As to the physiological mechanisms of seed recalcitrance, some people thought that this kind of seed somewhat germinates before or after maturation, and thus is desiccation sensitive([2,3]). The responses are Similar to the changes that occur on the dehydration of orthodox seeds following imbibition and loss of desiccation tolerance([4]). Using lychee seeds as experimental materials, the authors studied their imbibition dynamics, changes of free-water and bound-water contents and the ultrastructure of cells in the embryonic axes ([5,6]), to investigate the characteristics of their germination susceptibility and metabolic levels.