GERMINATION OF LYCHEE SEEDS AFTER MATURATION AND THEIR ULTRASTRUCTUREOBSERVATION

Lychee is one of the famous fruits in the subtropical regions. However , lychee seeds do not undergo maturation desiccation during developmen t, and cannot tolerate drying and chilling in storage. Under natural c onditions, lychee seeds can only maintain viability for several days, and their germplasm conservation is rather difficult using conventiona l methods. So they are called recalcitrant seeds([1]). As to the physi ological mechanisms of seed recalcitrance, some people thought that th is kind of seed somewhat germinates before or after maturation, and th us is desiccation sensitive([2,3]). The responses are Similar to the c hanges that occur on the dehydration of orthodox seeds following imbib ition and loss of desiccation tolerance([4]). Using lychee seeds as ex perimental materials, the authors studied their imbibition dynamics, c hanges of free-water and bound-water contents and the ultrastructure o f cells in the embryonic axes ([5,6]), to investigate the characterist ics of their germination susceptibility and metabolic levels.