A comparative study of the pericarp of litchi cultivars susceptible and resistant to fruit cracking

Time-course changes of fruit cracking percentage, mechanical properties of pericarp and contents of cell wall components in litchi pericarp were studi ed by comparing two litchi cultivars differing in cracking susceptibility. Mechanical strength of the pericarp of crack-resistant cv. Huaizhi was grea ter than that of cracking-susceptible cv. Nuomici. The resistance of 'Huaiz hi' was also reflected in higher threshold cracking turgor as well as in hi gher pericarp tensile strength and extensibility. Correspondingly higher co ntents of calcium and structural components viz. cellulose, hemicellulose a nd insoluble pectin were found in the pericarp cell walls of 'Huaizhi', whi ch might have materially contributed to its higher pericarp strength and th us cracking resistance as compared with 'Nuomici'.