Abstract: Changes in the micro-distribution of calcium in litchi (Litchi chinensis Sonn. ) pericarp ( fruit skin) were compared using electron probe ( X-ray despersive spectrometer ) between ‘Huaizhi’ and‘Nuomici’, which differ significantly in cracking susceptibility. The results showed that cracking-resistant ‘Huaizhi’has a stronger ability to accumulate calcium than the susceptible ‘Nuomici’. Before spongy tissue was visible 〔10 days after anthesis (DAA) 〕, calcium had accumulated at the site of spongy tissue formation, which formed calcium-rich zones in the inner mesocarp. These calcium-rich zones largely disappeared as the spongy tissue was formed (52 - 66 DAA) , with endocarp becoming“calcium rich”, indicating intercellular re-localization of calcium occurred within the pericarp. At later stages of fruit development (66 and 80 DAA) , calcium accumulated abundantly in the ep idermis cells, which formed a calcium-rich layer in both cultivars.However, the lowest calcium region was localized in the sclerenchyma tissue immediately beneath the ep idermis. The paper also discussed the interrelation between difference in calcium accumulation ability within the two cultivars and their seed development aswell as the roles of calcium in various parts in mechanical properties of the pericarp.

Key words: Litchi chinensis Sonn., Pericarp, Calcium, Cracking suscep tibility, Electron probe