Agriculture Reference
In-Depth Information
Table
.
Colouring of 'Jonathan' and 'Delicious' fruits in the top zones on different
rootstocks,
-
Average colour grade on a scale of to .
Rootstock
Variety
Top zone 'M.' 'M.' Own-rooted Seedling Average
'Jonathan'
outer
.
.
.
.
.
middle
.
.
.
.
.
inner
.
.
.
.
.
average
.
.
.
.
.
LSD
.
.
.
.
.
'Starking Delicious'
outer
.
.
.
.
.
middle
.
.
.
.
.
inner
.
.
.
.
.
average
.
.
.
.
.
LSD
.
.
.
.
.
% of surface red-coloured: Grade
,
-
; Grade
,
-
; Grade
,
-
; Grade
,
-
; Grade
,
-
.
From Gyuro
et al
.(
). Reproduced with permission.
proportion of red-coloured surface. Since
% of the canopy volume of the
'Jonathan' trees on 'M.
' was in this outer zone, compared with only
%,
', 'own roots' and
seedling respectively, the better average colour of fruits from the trees on 'M.
% and
% of the canopy volume of the trees on 'M.
'
was inevitable. Similar results, showing a decrease in average fruit colour in the
sequence 'M.
'
>
'M.
'
>
own root
>
seedling was shown for 'Starking'. For
both cultivars the trees on 'M.
' gave better-coloured fruits within each tree
zone. This probably also reflected differences in shade: whereas the outer zone
of dwarfed trees is largely 'top', that of larger trees includes lower peripheral
areas shaded from direct sunlight for part of the day.
Skin-finish
In general shaded fruits are less prone to russet and cracking than exposed
fruits, and it might be expected that fruits from trees on the most dwarfing
rootstocks would suffer more from these problems, but results are inconsistent
(van Oosten,
a).
Sugar and acid content
Sansavini
et al.
(
) found the percentage of soluble solids in expressed juice
of scion cvs. 'Golden Delicious' and 'Clear Red' to decline with increasing
rootstock vigour over the range 'M.
', 'M.
', 'M.
' and 'MM.
'. This is
in keeping with effects of increasing canopy shade. Ogata
et al.
(
) found
