Effects of light availability and training systems on apple fruit quality

The correlation of light availability and fruit quality traits for apple fruits (Malus × domestica Borkh.) within the canopy in two training systems, Slender Spindle and Bi-axis, were tested on nine-year-old trees of ‘Gala’ grafted on M9 rootstock. Three trees were chosen for each training system and twelve fruits from each tree were selected in different canopy positions and labeled after fruit set. The light availability for each fruit was measured using a digital camera equipped with a fisheye lens. At harvest, fruit size, over color and quality traits were assessed for each monitored fruit. The results indicated a large variability of fruit light availability within the canopy depending on fruit position. The upper and outer fruit positions for both training systems resulted in significantly higher light compared to the lower and inner positions. The percentage of fruit skin color and the soluble solids content (SSC) were influenced by the canopy layers. Fruits in the upper tree positions had a higher percentage of over color and higher SSC, while no differences were found in the inner and outer positions. Fruit position didn’t affect fruit size, ripening stage, and flesh firmness. The two training systems resulted in no differences for light availability or fruit quality traits.