Study on the Relationship between Sugar Concentration and Cell Number and Size Distribution in Nectarine

Variation in soluble solids concentration (SSC) in fruit within a tree can significantly reduce the proportion of harvested peach and nectarine that meets consumer requirements. Accumulation of SSC during fruit growth may be influenced by cell number and size in mesocarp tissue. The relationship between sucrose, the major component of SSC, and both cell size and number was investigated in Prunus persica 'Summer Flare 26' nectarine. Variation in sucrose concentration within, and between fruit, was partly explained by cell size as measured by cell area or cell number per fixed area of tissue. This correlation was consistent within fruit categorised as ripe and unripe. Sucrose concentration was moderately correlated to cell number per fixed area in small and medium-sized fruit but not in large fruit. Total sucrose content in fruit within three positions in a tree was strongly correlated to total cell number but the relationship was mediated by cell size, particularly in fruit from the middle and bottom of the tree. Sink size (i.e., total cell number) and sink activity (i.e., cell size), were able to explain 77% of variation in sucrose content between fruit within a single tree. Further anatomical studies on a larger fruit population are being conducted to confirm these findings.