Abstract: Using the two soft strains‘Mianrou 1’and‘Mianrou 2’and two crisp strains‘Cuirou 1’ and‘Cuirou 2’selected from the F₁ cross progenies of‘Fuji’and Malus sieversii as the experimental materials，we measured the fruit firmness，fracturability，ethylene release and cell wall degrading enzymes and analyzed their correlation. The results indicated that：1）The firmness and fracturability of two crisp strains were extremely significantly higher than that of two soft strains during various period；2）The ethylene production rate was low and there is no obvious difference between the soft and crisp strains in the young fruit and fruit enlargement period，but the ethylene release rate in the fruit of two soft strains is ten times of that of two crisp ones in 130 days after blossom，which the fruit reached the mature period；3）Activity of pectinase and β-galactosidase in two soft strains were higher than that of two crisp strains in the most fruit growing period. But for the activity of α-L-arabinofuranosidase，β-xylosidase，amylase and lipoxygenase，the difference between that in the two crisp and soft strains was little in the early fruit development period，while the activity of them in the two soft stains were significantly higher than that of two crisp strains in the later fruit growing period；4）The correlation analysis showed that the soft/crisp flesh character was closely related to the enzyme activities of polygalacturonase，α-L-arabinofuranosidase and amylase.

Key words: Malus sieversii, F1 progenies, soft/crisp flesh, enzyme activity