Abstract:

The delayed cultivation has been used to realize the long-term supply of fresh table grapes around the world. In order to make clear the changes of grape quality and the relationship between volatile compounds and developmental stages during on-vine storage under delayed cultivation facilities，this study chose Vitis vinifera‘Italia’as test material and measured the changes of berries respiration intensity，single berry weight，brightness L^*，brightness style a^* and b^*，tint strength C^*，and content of MDA，titratable acid，vitamin C，soluble sugar and volatile compounds. The results indicated that on-vine storage period could be divided into three stages by physiological indexes and the principal component analysis. The initial stage started from 0 to 20 days after maturation. During this period the berries respiration intensity，single berry weight，L^*，b^*，C^* and content of MDA，glucose，fructose and sucrose increased，while the absolute value of a^*，content of titratable acid and vitamin C decreased. As for volatile compounds，the content of linalool was stable，and C6 compounds were decreasing，but aldehydes were increasing. When grape berries developed to the middle stage（30–60 days after maturation），the respiration intensity and content of MDA increased while other indexes like tint strength，content of soluble sugar，soluble acid and vitamin C decreased undulately. As for volatile compounds，the content of linalool decreased while geraniol increased. Esters accumulated in this stage but the content of aldehydes decreased. In the final stage（70 to 80 days after maturation），berries respiration intensity and MDA content were high and other physiological indexes were low. As for volatile compounds，the contribution of C6 compounds to the fruit aroma increased. In conclusion，this study revealed that the grape quality was enhanced during the initial on-vine storage stage，then gradually declined in the middle stage with the contribution of major terpenes to aroma changing and lost the market value as C6 aldehydes metabolic pathway activated in the final stage. So the middle stage（30–60 days after maturation）was the key period for grape quality regulation during on-vine storage under delayed cultivation.

Key words: grape, delayed cultivation, on-vine storage, quality, volatile compound