Improving consistency of soluble solids concentrations in summerfruit (SF11000)

What was it all about?

Consistent fruit size and high soluble solids concentration in peaches and nectarines are important components of fruit quality and consumer acceptability. A high degree of variability within trees can be a major impediment to meeting consumer and export market requirements for consistent quality.

This project investigated factors influencing variation in fruit quality within trees and how it can be improved through tree management and fruit thinning.

Key findings included…

• Variation in soluble solids concentration within trees resulted from differences in fruit size, fruit height within trees, fruit exposure to sunlight, and fruit shading
• The main factors associated with different concentrations were sun exposure, competition between fruit and the availability of carbohydrate to individual fruit during growth
• Lower crop loads generally increased the proportion of high quality fruit at harvest
• Fruit skin blush (the amount of uniform red colour) was found to be a reasonable predictor of soluble solids concentration in fruit within the top and bottom of trees.
• Fruit shading and low light penetration restricted fruit growth and accumulation of sugars in fruit at the bottom of trees.

Some variation in soluble solids concentration is yet to be explained, requiring more research.

Findings suggest that growers can improve the consistency of fruit quality by managing trees to achieve a more uniform leaf-to-fruit ratio, conducting earlier fruit thinning, and using light enhancing tree training systems such as Spanish open vase.