Fruit and Vegetable Quality

that influence the mechanical properties of fruit during development with
a view to improving firmness at harvest and ex-store. It is clear from re-
cent work that under U.K. conditions higher yields per tree can result in
adverse effects on fruit texture, and significant improvement in firmness
of fruits has been achieved through thinning of the crop at specific stages
of development (Johnson, 1994b). The increase in firmness coincided
with increased dry matter and alcohol-insoluble matter. This suggests
that crop load is a factor that determines the amount of photosynthate
that is available for incorporation into the cell walls of the developing
fruit. Cultural practices that are likely to encourage water uptake and de-
press the accumulation of dry matter in the developing fruit, such as ex-
cessive irrigation or extensive use of herbicides in orchards, should be
avoided (Richardson, 1986). This is a good example of how a posthar-
vest quality problem is being tackled from a consideration of all aspects
of apple development, maturation and ripening. In this case, consistent
textural quality in Cox apples is only likely to be achieved by an inte-

Research to Improve the Firmness of Cox Apples 81

FIGURE 4.3Relationship between the firmness of Cox’s Orange Pippin at harvest in
1994 and after storage in 1.2% O 2 , 1% CO 2 at 3.5°C until January 9th, 1995. Fruit
was harvested on 1 (pick 1), 12 (pick 2) and 22 (pick 3) September, and on 3 October
(pick 4)