Preliminary Study Of The Softening Mechanism On Early-ripening Apple Varieties

Fruit softening is the physiological and biochemical process during fruit development and mature. Except the changes in color, fragrance and taste, the hardness, pine real, crispy toughening and greasy thick also related with fruit softening. In addition, the softening fruits are susceptible to mechanical damage and germs infection. Harvesting time and storage life are also affected. Therefore, the problem of fruit softening has attracted the attention of horticultural and physiological experts. Thus it's urgent to identify the factors that affect fruit softening and put forward the control measures in fruit production. Fruit softening is regulated through related key enzymes, but they were different in the different cultivars. In order to study the mechanism of softening in early-ripening apple cultivars, the fruit hardness, activities of amylase, cell wall hydrolysis enzymes and ethylene production were compared among three early-ripening apple cultivars.1. Fruit hardness of the three cultivars decreased during fruit development, however, in 75 days after blooming (DAFB) the declining ranges were different in the three cultivars. The declining range of'Liaofu'was 35% while that of'Taishanzaoxia'and'Jizaohong'were 50% and 53%, respectively.2. Activity of PE and Amylase of the three cultivars showed little differences. The activities of PG and Cx in'Taishanzaoxia'and'Jizaohong'were significantly higher than that of'Liaofu', and the activities of PG and Cx in the three cultivars were negatively correlated with fruit hardness.3. Ethylene production was positively correlated with the activity of PG and Cx during fruit development.4. Using RT-PCR method to test the expression of PG gene in 'taishanzaoxia' and 'liaofu' in different sampling period. The results indicated that: the expression of PG gene gradually rise at 40 DAFB, and both cultivars are basically the same. Until the stage 75 DAFB, there appeared a clear difference: the expression of'taishanzaoxia'reached its peak and then declined; while that of 'liaofu ' rose throughout the whole fruit development.5. The decrease of 'taishanzaoxia' fruit hardness was significantly delayed in 1-MCP treated fruits. But the declining ranges were different between different treatments. The hardness of fruits treated by 1 - MCP fumigation declined quite moderate in the whole storage process, while control fruit and those treated by 1 - MCP gush greatly declined at the fourth day of the fruit storage.6. The production of ethylene was obviously reduced by 1 - MCP treatment in this experiment , but different processing releases a quantity change between vinyl significant difference; The activities of PG were obviously suppressed and increased slower. Activities of other three enzymes showed little differences in the whole storage process .7. The decline of total alcohols and total aldehydes and increase of total esters were obviously reduced both by 1 - MCP fumigation and 1 - MCP gush fruit treatment. But aroma components had some differences between them. Aldehydes, alcohols and ester material content can become the potential evaluation index in fruit storing properities.