Agriculture Reference
In-Depth Information
Figure 10.3
Relationship between fruit weight and calcium
concentration in fruits harvested at different dates from trees subject
to different levels of shading. Harvest dates J
=
27 July,A
=
24
August,S
=
21 September. Shade treatments 0
=
100% daylight,
1
=
37% daylight,2
=
25% daylight. Reproduced from Jackson
et al.
(1977),with permission.
) concluded that auxins produced by the seeds play a sig-
nificant role in Ca translocation into fruits. The seeds themselves have a
higher Ca concentration than other parts of the apple fruits and their Ca
content is less affected by reduction in the Ca content of the medium around
the roots than is that of the rest of the fruit (Huguet,
Bangerth (
-
triiodobenzoic acid (TIBA), which inhibits auxin transport, is sprayed on
apple trees as early as
). When
,
,
weeks after full bloom, Ca accumulation by the
fruit is reduced (Stahly and Benson,
,
; Stahly,
). Lang (
)
and Lang and Ryan (
) have shown that there is no increase in the
number of xylem vessels in apple fruit pedicels from just after flowering
onwards. There is a decline in xylem pedicel conductance as the season
progresses and this is more severe in the cv. 'Cox', which is very subject
to Ca deficiency disorders, than in the cv. 'Gala', which is less subject to
these.
Terminal fruits of 'Granny Smith' and 'Royal Gala' have higher Ca concen-
trations than similar-sized or smaller fruits growing laterally on one-year-old
shoots or
-year-old spurs (Volz
et al.
,
).
