Focus Orchard Trial: Ruby Pink fruit quality when grown in singles vs.
two or three fruit per cluster
Orchard:
H & LM Sanders
Orchardist:
Peter Sanders
Prepared by:
Virginie Grégoire, Fruit Growers Victoria Ldt.
Why we decided on this trial?
We wanted to determine if fruit quality
could be improved, (mainly fruit colour,
fruit size and pressure), when most clusters
are reduced to one fruit each compared to
leaving two or three fruits per cluster.
As a standard practice, Sanders winter prune
Pink Lady trees reasonably heavily to
achieve a ratio of buds to fruit number
relatively low, ie 1.0 to 1.5 buds per fruit.
Theoretically this practice should allow
Trial block before blossom 2013
growing apples in singles. That is, if every
bud flower’s and if at least one flower per cluster sets. Environmental conditions being unpredictable
as they are, we know this theory never actually happens and this means Sanders end up having to
grow fruit in 2s and 3s to achieve commercial yields. Is it worth leaving more buds on when winter
pruning and having to spend more time hand thinning after fruit set to make sure most fruits can be
grown in singles? Does the fruit quality improve significantly enough to justify a practice change and
is the change economical?
Some details on the trial
Treatment 1: Apples grown in singles (one fruit per cluster) as much as possible. Some fruits may
have been left on occasion in 2s to achieve the set crop load per tree.
Treatment 2: Apples grown in 2s and 3s (2 or 3 fruits per cluster) as much as possible. As for
treatment 1, some fruit naturally singled may have been left on occasion to achieve the set crop load
per tree.
All 20 trees (10 per treatment) were from the same row and selected randomly. Treatment distribution
was based on the number of flower clusters, trees with most clusters to bear fruits in singles and trees
with least clusters to bear fruits in 2s and 3s. All trees were hand thinned to 120 fruits per tree.
Results and discussion?
82
Fruit size (mm)
Fruit size (mm)
80
78
Single
76
Pair
As predicted fruits are consistently
larger when thinned down to one per
cluster with an average difference of
2 mm.
74
72
70
68
1
2
3
4
5
6
7
8
9
10
Av.
Trees & Average - Ordered smallest to largest
The difference in fruit colour between the
two treatments was not significantly
different, fruits in twos and threes showing
on average 3% more red skin surface.
Fruits grown in single were expected to be
redder (higher proportion of red skin
surface) and finding an explanation for this
result is difficult. Amongst the most
plausible:
-
-
85
75
Fruit colour
Single
% Red skin
65
Pair
55
45
35
25
In that particular canopy fruits
15
MIN
may not be the main shading factor
when grown in twos and threes.
One must keep in mind that fruit colour evaluation is very subjective.
MAX
On the other hand, treatments that had multiple fruits per cluster seemed to have a larger range of
redness overall. They were therefore more varaiable.
10.50
Fruit pressure (Kg)
Fruit pressure (Kg)
10.00
Fruits grown in twos and
threes were slightly firmer,
only 0.20 kg difference.
This
small
probably
insignificant
difference
most likely due to their
smaller size rather than the
number of fruits per cluster.
Single
Pair
9.50
9.00
8.50
8.00
7.50
1
2
3
4
5
6
7
8
9
10
Trees & Average - Ordered smallest to largest
Av.
14.00%
13.50%
Fruit sugar and starch level
don’t show any significant
difference between the two
treatments other than a wider
variation of sugar level when
grown in pairs, as shown in
graph below.
Brix index (%)
Single
13.00%
Pair
12.50%
12.00%
11.50%
11.00%
1
2
3
4
5
6
7
8
9
10
Av.
Conclusion
The trees that carried fruit predominately in singles produced larger average fruit size with a similar
level of colour, pressure and brix. Our expectation that fruit quality would also improve did not
eventuate however it was certainly not negative.
Fruit colour is often disadvantage by inter-fruit shading which in theory reduces when a crop is
carried in singles.
On the contrary the more wood and leaf in the tree the more shading is caused by foliage hence our
goal is to try and find the correct banana that maximise Class 1 yield per tree or per ha.
Assuming that fruits are always bigger when grown in a single, next it will be interesting to see if
trees cropped in singles can support higher total fruit numbers per tree and hence higher total yield so
the same fruit size. And will the higher fruit numbers per tree result in similar fruit quality. of better
quality when grown in single compared to fruits grown on bunch.
While this trial hasn’t solved the issue categorically, were convinced that in a perfect season, a canopy
that carries its crop load predominantly in singles will produce a better financial outcome. However
total crop load is critical as pink lady value drops with oversize fruit, therefore if crop loads are short,
it is sensible to carry the crop in 2’s and 3’s.
Our aim must be to try and use management techniques that minimise the need to hand fruit in
multiple clasters.