Soft Fruit - Crop Post-Harvest: Science and Technology - page 260

Table 11.3 Fresh Weight and Hue Angle of
Strawberry cv. Elsanta Fruit at Different
Developmental Stages.
Colour stage

Table 11.5 Mean Weight (g) for Secondary and
Primary Strawberry cv. Elsanta Fruit Grown
between Winter and Early Summer (February and
May) 2001 (Experiment 1) and Summer (July and
July) 2001 (Experiment 2) (n

Fresh weight (g) Hue Angle (H°)

64).
Mean fruit weight

=

Green I 3.03 111.54

White 6.55 109.30

Red 16.59 40.30

Fruit position Experiment 1 Experiment 2

Source: Terry et al . 2002 with permission.

Primary 33.71 14.53
Secondary 26.33 9.62
Source: Adapted from Terry and Joyce (2006).

Table 11.4 Mean Number of Days after Planting
(DAP) and Days after Anthesis (DAA) Until
Harvest for Secondary and Primary Strawberry
cv. Elsanta Fruit Grown between Winter and Early
Summer (February and May) 2001 (Experiment 1)
and Summer (July and July) 2001 (Experiment 2)
(n = 64).

1987) or a biphasic growth curve (Thompson 1969;
Coombe 1976; Miura et al . 1990). Large strawberry fruit
size is an inherent trait, however, variations in berry size
occur depending on the physiological interaction between
blossom position, number of developing achenes, fruit
competition, plant vigour and pre-harvest environmental
conditions (Table 11.5; Janick & Eggert 1968; Terry &
Joyce 2004b; Terry et al . 2007b). The strawberry inflores-
cence or infructescence possesses a terminal primary
inflorescence with secondary and tertiary inflorescences
attached below this primary bloom (Plate 11.3). Apical
dominance within the cyme mediates interfruit competi-
tion for assimilates (Terry et al . 2007b). Primary fruit
usually have a faster growth rate and achieve larger size on
maturity (Moore et al . 1970; Table 11.5). This phenome-
non is physiologically determined and independent of
environmental conditions. Removal of the primary bloom
at anthesis results in an increase in secondary fruit weight
at harvest (Stutte & Darnell 1987). Final fruit size and
shape are also closely correlated with the number and size
of fertile achenes on a fruit (Nitsch 1950; Moore et al .
1970; Manning 1993). The major cause of malformed
berries is inadequate pollination, whereby not all achenes
are fertilised. In this respect, control of fruit growth is
attributed to assimilate sink strength mediated by auxin
secreted from developing achenes.

Experiment 1 Experiment 2

Fruit position DAP DAA DAP DAA

Primary 94.1 41.5 40.4 21.3

Secondary 95.0 41.1 42.0 21.9

Source: Adapted from Terry and Joyce (2006).

green stage I, green stage II, white, and full red (Plate 11.2;
Table 11.3). As fruit overripen ( ca . 35 days after anthesis
(DAA) ) they become a darker red/purple. This colour
change is mediated by a shift in anthocyanin glycosylation
caused by cell decompartmentalisation (Manning 1993).
Depending on environmental conditions, the strawberry
plant is able to bear full red fruit within approximately
24-28 days after anthesis (Terry et al . 2004). Variation in
time to reach maturity is cultivar dependent, but is primarily
governed by temperature (Perkins-Veazie & Huber 1987;
Terry & Joyce 2004b) and hence enzyme mediated
metabolic rate (Manning 1993). Under extreme environ-
mental conditions, time to strawberry fruit maturity after
planting and after anthesis can vary considerably (Table 11.4).
Similarly, final fruit weight is dependent on rate of fruit
development (Table 11.5) and preharvest irrigation (Terry
et al . 2007b). Berry growth is usually measured by changes
in fresh and/or dry weight or dimensions. Upon maturity,
the full red stage and maximum weight and size of the fruit
is achieved (Plate 11.2).
Soft fruit growth is often characterised by either a single
sigmoidal-shaped (Woodward 1972; Stutte & Darnell

FRUIT RIPENING
Distinct cellular and compositional changes occur during the
ripening process. Auxin and its derivatives play the primary
role in controlling ripening. Nitsch (1950) first demonstrated
that achenes, believed to be the source of auxin, mediate the
growth and therefore all ontogenetic aspects of strawberry
fruit development. The removal of achenes in the early
stages of growth retards the ripening process (Nitsch 1950).
With the onset of ripening, changes in texture, colour,