Agriculture Reference
In-Depth Information
Figure 9.1
Flower initiation and fruit bud differentiation in relation to
node production within the bud. From Abbott (1977). Reproduced
with permission.
node numbers of
for 'Golden Delicious' apple,
for 'Comice' pear and
for Japanese pear have been reported by Luckwill and Silva (
), Dheim
and Browning (
a, b) respectively. The critical node
number may be lower for buds on long shoots than for spur buds, as discussed
later (p.
) and Banno
et al.
(
).
The first doming of the bud apex(Figure
), indicating the change from
the vegetative to the floral condition, usually coincides with the cessation of
shoot growth of apple (Fulford,
.
b; Luckwill and Silva,
; Dencker and
Hansen,
) and of Japanese pear (Banno
et al.
,
a, b,
). This may
be a causal relationship (Luckwill,
). Where it appears to be the case, the
positive effect of checking shoot growth on flower development may be very
localized and is probably due to weakening of correlative inhibition. Some
treatments appear, however, to influence flower initiation and development
and shoot growth independently (Tromp,
). Development of flower
buds does not start uniformly throughout the tree. The terminal buds of short
shoots (spurs) begin their transformation to flower buds
,
-
weeks earlier than
do lateral buds (Buban, cited by Faust,
). Young spurs show earlier flower
initiation than old spurs. In general, where flower induction occurs relatively
late in the season the fruit buds are 'young' at the onset of winter, are relatively
narrow and pointed, and give rise to blossom clusters with large primary leaves
and long-stalked flowers which tend to set few fruits (Abbott,
,
,
;
Luckwill,
).
