Effects of irrigation and fruit position on size, colour, firmness and sugar contents of fruits in a mid-late maturing peach cultivar

• Irrigation exerted a great influence on the majority of the traits studied.
• Sorbitol content affected by height (or location) of fruit in the crown.
• Sucrose and fructose contents were affected by orientation.
• Exposure to sunlight influenced soluble solid content.
• Significant correlations were detected among fruit attributes.

Experiments were conducted on a mid-late maturing peach (Prunus persica) cv. ‘Catherine’ in 2008 in order to study the influences of irrigation and fruit location within the canopy, on fruit growth and several fruit-quality attributes, including sugar and acid contents. Trees were subjected to full irrigation (FI) and regulated deficit irrigation (RDI). Fruit height in the crown, exposure to sunlight and orientation were recorded. Fruit diameter, fresh weight, firmness, flesh and skin colour attributes, soluble solids content, pH and sugar and acid contents were determined for each fruit at harvest. Water stress had a high impact on most of the fruit-quality variables studied. Fruits from trees under RDI were firmer than those from FI trees but did not differ in weight and diameter, perhaps due to the low crop load supported by the studied trees. In contrast, fruits from RDI trees had more soluble solids, glucose, sorbitol, and malic, citric and tartaric acids. Height in the crown partially affected positively soluble solids content. Exposure to sunlight strongly influenced stone dry weight and soluble solid content. Finally, orientation did not have a significant influence on most of the fruit-quality attributes considered in this study. Our results suggested that leaving a low crop load on the tree maintaining fruits only in the most ideal parts of the canopy may improve fruit quality under water restriction conditions. In this way, the negative effects of water stress may be counteracted and fruit quality for this mid-late maturing peach cultivar would be improved.