Agriculture Reference
In-Depth Information
Effects of imposed shade on fruit bud
production of apple cv. 'Cox's Orange Pippin'/'M.
Table
.
'
Number of fruit
Percentage full daylight in
bud clusters per tree
in spring
%
%
%
%
Spur clusters
Axillary clusters
Terminal clusters
The number of each type of bud cluster at each level
of shade was significantly less than the number on un-
shaded trees.
Data from Jackson and Palmer (b). Reproduced
with permission.
defoliated within
weeks after full bloom but the number of flower buds
formed on spurs defoliated after this period gradually increased. Defoliation
after harvest does not reduce flowering of apple in the following year (Tustin
et al.
,
-
) showed a very strong correlation between the
total leaf area of the spur rosette and floral initiation in the terminal bud of
the spurs (Table
). Huet (
,
.
).
c) concluded that the pattern of development of buds on non-
fruiting trees following defoliation was very similar to that in which flower
initiation was inhibited by fruiting. The effect of the leaves has been attributed
to their effects on carbohydrate supply and on the flow of cytokinins ( Jonkers,
Fulford (
). Introduction of zeatin and benzyladenine into cut petioles
of de-bladed apple leaves enhances flower formation (Hoad,
; Ryugo,
; Ramirez
and Hoad,
).
Effects of shade and light on flowering
The shaded inner parts of apple and pear trees tend to have very few flowers.
This may be due in part to cumulative effects leading to weak growth and poor
bud formation, but artificial shading of previously exposed trees reduces fruit
bud formation and flowering in the following year (Table
),
using controlled environments with artificial lighting found that reduced light
intensity for the
.
). Tromp (
weeks following bloom halved flowering in the following
year, while reducing light levels from weeks
had only a smaller and
non-significant effect. This early-season response again suggests the effect is
mediatedbychangesintheplastochronandattainmentofanadequatenumber
of nodes for flower formation.
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