Apple growers use starch patterns, firmness and mineral analysis to predict optimum picking date, firmness coming out of store and storage disorders, but not eating quality. New Zealand research has shown a link between dry matter content and both ex-store sugar levels and eating quality.
AHDB Horticulture funded a desk study by Tim Biddlecombe of the Farm Advisory Services Team (FAST) to investigate the factors that determine the dry matter content (DMC) of fruit.
DMC includes compounds that may contribute to the flavour of the fruit and will be incorporated into the structural elements of the cell, and influence the textural properties of the fruit. It is influenced by many factors in the orchard environment.
Overall light levels, the efficiency of light interception by the orchard and the distribution of light throughout the canopy will all affect the DMC. Crop load and time of thinning also have an influence, with DMC increasing as a result of early thinning and large fruit size, and DMC decreasing with large crop loads of small fruit.
In general, restricted irrigation regimes - especially closer to harvest - are thought to improve fruit DMC. It was also noted that increased fruit potassium had a positive effect on DMC.
In terms of tree management, practices that improved light interception and distribution also had a positive effect on DMC.
The report recommends that the relationship between harvest DMC and ex-store quality for fruit grown in the UK needs to be confirmed.
The full Grower Summary for Project TF 222 can be found on the AHDB Horticulture website - horticulture.ahdb.org.uk.
For details on all AHDB Horticulture activity, see horticulture.ahdb.org.uk.