Improving Table Grape Skin Strength/Firmness

One of the most important quality factors for table grape, which determines the eating quality, is skin firmness.

The consumer prefers firm table grapes; and it is commonly acknowledged that they have better eating quality and improved storage capacity. The correct crop nutrition will also improve table grape skin firmness.

Crop Nutrition and Table Grape Skin Strength/Firmness

Calcium is a key component of cell walls maintaining the membrane structure. Post-harvest berry quality is specifically influenced by calcium nutrition. It is very important to maintain sufficient level of calcium in berry skin via calcium applications to the vine throughout the season and/or calcium sprays targeted during fruit development. Calcium sprays directly on the fruit, especially late in the season during fruit maturity, are important to improve strength of skin. 

Calcium applied as calcium nitrate increases table grape berry firmness. Use of calcium also improves skin strength.