storage and eating quality of apples have been demonstrated (Smith and
Stow, 1985), storage conditions have generally not been optimized for
specific clones.
VARIABILITY IN QUALITY PARAMETERS AT HARVEST
At the time of commercial harvest, apples of the same cultivar from
different orchards vary in visual quality such as size and red color. Also,
they vary in terms of eating quality such as concentrations of sugars and
acids, and fruit texture. Quality and degree of ripeness of apples on a
single tree is also variable and is influenced particularly by shade and
position within the canopy (Jackson et al., 1971). Ripening of individ-
ual Cox apples occurs typically over a period of three weeks (Johnson,
1995). Variation in the quality and physiological stage of individual fruits
within a tree is compounded by overall quality differences between or-
chards. The average, range, and standard deviation for measurements of
firmness, acidity and sugars in Red Pippin, Gala and Jonagold apples
from several orchards are presented in Table 4.1. Data presented in Fig-
ure 4.1 as box plots indicate the extent of orchard variability in the con-
centration of soluble solids and titratable acid, and in the firmness of
Cox apples before (pick 1), during (picks 2 and 3) and after (pick 4)
commercial harvest for long-term CA storage in 1995. Data are for Cox
apples from 32 commercial orchards throughout the major production
areas of the U.K. In these box plots, the box indicates the upper and
lower quartiles of the distribution of the values, and the line within the
box indicates the median. The vertical lines extending above and below
the box indicate the 90% and 10% points of the distribution. Clearly,
some account needs to be taken of the variability in these quality crite-
ria and of the marked change in the levels of firmness, soluble solids
and acidity as harvest is delayed. Loss of firmness and acidity occurs
during storage and the extent of this loss relates to the duration of stor-
age and the storage conditions that are imposed. An important approach
to the achievement of the desired quality in fruit ex-store is to relate har-
vest quality parameters to those of stored fruit. In several countries, no-
tably the U.S., South Africa and the U.K., programs are operated to
identify optimum harvesting dates for different orchards/growing regions
to achieve the required quality ex-store. Identification of suitable har-
vesting periods remains an important area of research in Europe (De
Jager et al., 1996), the U.S. (Silsby, 1993) and elsewhere. Relationships
between fruit parameters at harvest and ex-store quality will be consid-