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SOURCE- SINK RELATIONSHIPS
IN THE CUCUMBER PLANT (Cucumis sativus L.)
A thesis presented in partial fulfilment of the requirements for the degree or
Master of Science in
P J an t Sci c n c e at
Massey University
Garry Kenneth Burge 1980
Chapter
1 • 1 1 • I • 1
1. 1. 2
1 • 2 1. 2 . 1
1. 2. 2 1. 2 . J
1. 2 . 4
1 •
J
1 •
J .
11.
J .
2 1 • 4 22. 1 2. 1 • 1
Abstract.
Acknowledg~ents .
List of Tables. List of Figures. Introduction.
Review of Literature - The cucumber plant.
The young cucumber plant.
Contribution of cotyledons and leaves to gro1>1th.
Factors influencing Lhe growth of the young cucumber plant.
Sex expression.
Types of sex expression.
Sex differentiation of flowers . Factors influencing sex expression. Summary.
Fruit set.
Fertilised fruit . Parthenocarpic fruit
,,
. Mat ure plant.Review of Literature - Source- sink r elationships.
Termi·nology.
Sink strength.
Page vii
x xi xv xvi
2
8 8 9
10
1 6
1 6
1
6
18
23 27
27 27
Chapter
2. 1. 2 2.2
2. 2. 1 2.2.2
2.3 2.
3.
12. 3.2
2 . 4 3
3. 1
3.2
3 . J J . J .
13.J . 2
3 . 3 . 3 3 . J . 4 3.3 . 5 J . J . 6
J .J . 7 J .4 J . 4 .
1J . 4 . 2
Sink or source limitation.
Sink strength and the photosyntheLic rate .
E.f.fect on the photosynL11cLic raLc. Control mechanism.
Source or sink limitation.
Change with selection. Identifying limitation. Summary.
The c.f.fect of two auxin transport inh.ibl tors on growtl1 and
development. Introduction.
Materials and methods.
Hesults.
InLroduction.
Total planL dry weight and dry wci~1L
of component organs.
Partitioning of' dry weight. Fruit set.
Fruit size.
Distribution of fruit dry weight on various nodes.
Misshapen fruit.
Discussion.
Dry weight of component organs and partitioning between them.
Fruit data.
i i i
Page
JO
J1
J l J4 J8 J8 39
L~2
45
45 46
48 48L~8
50
SJ 56 56
58 59 59
62
Chapter
J . 4 . J J . 4 . 4
J . 5 4
4. 1
4 . 2 4 . J 4 . J .
14 . J . 2
4 . J . J 4 . J . 4
4 . J . 5
4 . J . 6 4 . 4
4. 4. 14 . 4 . 2 4 .4. J
4.5 5
5 .
1Effect of growth substance.
Relationship between stage of flower development and fruit set.
Summary.
The effect of leaf removal on growth and development.
Introduction.
Materials and methods.
Results.
Introduction,
Number of nodes per plant, total plant dry weight and dry weight of compo- nent organs.
Number and mean dry weigl1 t of fruit . Partitioning of the dry weight between
the component organs. Fruit data.
Sex expression. Discussion.
Dry weight and partitioning of the dry weight between the component organs.
Fruit data.
Influence of leaf removal treatments on the sex expression.
Conclusion.
Effect of shading on growth and develop- ment.
Introduction.
Page
63
64
65 67
67 67 69 69 70
71 71
72 75 76 76
78
8081
8J
8J
Chapter
5 . 2 5 . J 5 . 3 .
15 . 3 . 2 5 . 3 . J
5 . 3 . 4 5 . 4
5. 4. 15 . 4 . 2
5 . 5
66. 1
6 . 2
6 . J
6. 3. 15 . J . 2 6 . 3 .
J6 . 3 . 4 6 . 3 . 5 6 . J . 6 6 . J . 7 6 .4
6. 4. 1
Materials and methods. Results.
Introduction.
Dry weight and partitioning.
Absolute growth and partitioning of this growth over period two .
Fruit data. Discussion.
Dry weight and partitioning of the dry weight,
Distribution of fruit dry weighL on various nodes.
Conclusion.
The effect of carbon dioxide enrichment on growth and development.
Introduction.
Materials and methods. Results.
Introduction.
Absolute growth rate.
Partitioning of the absolute growth . Fruit data.
Leaf data. Stem data.
Redistribution of assimilates.
Discussion.
Absolute growth rate and partitioning.
v
Page 83 85
85 85 88
89
92 92
93
95 96
96 96 99 99 99
100 102 105 107 108 109 109
Chapter
6 .4. 2 6 . 4 . J
6 . s
7
7. 1
7. 2 7 . J 7 . 4
7 . 5
Fruit data. Leaf data. Summary.
Source- sink relationships in the Cucumber plant.
Partitioning of dry weight.
Source or sink limitation. Fruit set.
Distribution of fruit growth on various nodes.
Conclusion. Appendices. Bibliography.
Page
1 1 1 1 1 J
1 1 J
1 1 5
1 1
5
1 1 9
123 125
126
ABSTRACT
In an attempt to increase the sink strength of the fruit , two auxin transport inhibitors were sprayed on to the whole plant or applied to the fruit , four days after first anthesis. Application to the plant
i ncreased fruit set , reduced the dry weight of all the component organs, but had l i t t l e effect on the
partitioning of the dry weight. With application to the fruit chlorflurenol had l i t t l e effect, but TIBA at 200 ppm reduced fruit set on the lower nodes where _i_ t was applied. This reduction in fruit set r educed fruit dry weight and partitioning to the fruit.
As neither o1 these grO\vLlL ~ulJsLan es increa~ccl
sink strength i t was decided to investigate source sink relationships by altering the source strength. With increasing degree of leaf removal total plant dry weight was reduced but the parLitioning was l i t t l e affected. However with the severest leaf removal treatment a greater proportion was partitioned into the stem and less into the fruit , but the proportion partitioned into the l eaves was not altered.
Deleafing as a method of reducing source strength has been criticised due to i t s effect on the distribu-
tion of hormones. For this reason the effect of shading was investigated. The partitioning of the absolute growth on plants that had developed medium
sized fruit was not affected by up to 58% shading. However with an increase in shading from 58% to 70%
the partitioning to the :fruit was reduced. Below a critical level of assimilate supply the competitive ability o:f the vegetative organs seemed to be higher than tlle :fruit.
As delea:fing and shading reduced source strength the e:f:fect of increasing source strength by carbon dioxide enrichment was investigated. Enrichment was applied from :first anthesis and increased the growth rate of the plant in the following five weeks. The partitioning was not differenL to the control plants in the first week folloHing anthesit:>. However in week bvo the partition i_ng to -Lhe fruit was less wi tlt enr_i.ch- ment. There appeared to be an accwnulaLion of assirni- lates jn the leaves due Lo -Lile mo hi LisinG ahi 1 i ty of the growing regions being i11sufficienL .for Lhc hie;lter raLe of assimilation. In week three and four the mobilising ability of the growing regions increased and there
appeared to be a redistribution of stored assimilates as there was a loss o.f l eaf and petiole dry weight. The accumulation of assimilates inhibited the NAR but
:following the redistribution o:f stored assimilates the NAR recovered. In the :fifth week the partitioning was very similar with or without enrichment, and these
partitioning :figures were very similar to that obtained with the various shading treatments in the previous
ix
experiment. I t appears that once the plant develops several medium sized fruit i t partitions about 70% of the absolute growth into the fruit,
2J%
into Lhr leaves ,6%
into the stem, and1%
into Lhc rooLs, over a widerange of assimilation rates.
With higher raLes of assimilation l'ruit set and fruit size increased. This cuJ l i var has many po Len ti al fruit si tes as i t produces few rna·1 c flowers and o.ften several flowers per node. With greater raLes of' assimilation fruit set will increase and should be capable of utilising L.hc greater supply.
the plant appears to 1.Jc s ourc t~ l i..mj_ t t!cl.
Therefore
Grateful acknowledgements are made to Dr K.J . Fisher and Dr D.J . Woolley for their encouragement and guidance in this project. I would also like to acknowledge the assistance given by Dr D.R.K. llarcllng, L. Gould and
F. Anderson in harves ting the plants, and H.M. Gordon who typed this thesis . Finally I would like to thank my wife , El 1 ie , and 111y t wo daugh tc re;, Fri tlta and Morwenna, for their encouragement and patience whilst I completed this project.
Table
3 .
13.2
3 , 3
3 . 4
3 , 5
3,6
3,7
3,8
3 , 9
3 .
103. 1 1
3 .
12LIST OF TABLES
The treatments.
Effect of site of application on fruit dry weight (g/pl).
Interaction between site of application and rate on total plant dry weight and weight of component organs (g/pl).
Effect of growth substance on fruit and stem dry weight (g/pl) .
Effect of site of application on percent total dry weight in roots
( % ) •
Effect of growth substance on percent total dry weight in fruit, leaves and st em (
% ) •
Interaction between growth substance and site of application on percent
total dry weight in leaves (%).
Interaction between site
or
application and rate on percentweight in stem(%) .
total dry
Interactions between site and rate, and site and growth substance on fruit set on nodes 1- 8.
Effect of treatments on fruit set on nodes
3- 5 .
Effect of treatments on fruit set on nodes
6-8 .
Effect of treatments on the fruit set on nodes
9- 16 .
Page
47 49
49
50
50
51
52
52
53
54
55
56
Table
J. 1 J
J .
143. 1 5
3. 1 6
4 .
14. 2
4. 3
4. 4
4 . 5
4 . 6
4 . 7
4 . 8
5 .
1Effect of site of application on mean fruit dry weight (g).
Percent total fruit dry ,.,reigh t on nodes 1-8 and 9-16
( %) .
Effect of treatments on percent total fruit dry weight on nodes
3- 5
and nodes 6-8
(%) .
Percent fruit dry weight that was in misshapen fruit.
Leaf removal treatments.
Effects of treatments on number of nodes, total plant dry weight and dry we.ight of component organs (g/pl) .
Number and mean dry weight of fruit with various leaf removal treatments (per plant) .
Percent total dry wci~1t in the component organs
(% ) .
Association between a fruit and a node with a leaf.
Distribution of fruit dry weight on the various nodes
(%) .
Effect of treatments on fruit numbers on various nodes (per plant).
Number of nodes with male flowers, on various nodes numbered from the base of the plant.
Mean dry weight of the leaves with the different shading treatments (g/
plant).
Page
57
58
59
69 70
71
72
73
74
75
85
Table
5,2
5,3
5 . 4
5,5
5 . 6
5 . 7
5.8 5.9
5. 10
6. 1
6 . 2 6 . 3 6 . 4
6 , 5
Mean dry weight of the leaves at the two harvests (g/plant) .
Significant interactions on the dry weight of the component organs
(g/plant).
Percent dry weight in the roots with the various shading treatments .
Percent dry weight in the roots at the two harvests.
Significant interactions on percent dry weight in the component
organs.
The absolute growth between Ill and H2 and the partitioning of this between the component organs.
Effect of shading on fruit set. Percentage of fruit dry weight on
various nodes
(% ).
Distribution of the absolute fruit growth over period two on the various nodes
(% ).
Absolute growth rate of total plant and t r (g.pl -1 . day -1).
componen o gans
Partitioning of the absolute growth
(% ).
Relative growth rate of the fruit. Per cent absolute fruit growth in week
5
on nodes 1-10.Number and mean dry weight of fruit at harvest six.
xiii
Page 86
86
87
87
88
89
90
9192
100
102 103 103
104
Table
6.6
6.7
6 . 8
6.9 6. 10
Dry weight and per cent total fruit dry weight in aborted fruit at liarves t
six.
Leaf area and number of l eaves per plant.
Leaf area of individual l eaves at harvest six (cm2/plant) .
Net assimilation rate (g/m2/day).
Stem length and stem weight per length for each harvest .
Page
105
106
·106
107 108
Figure
J. 1
4. 1
5. 1
6. 1
6 . 2
6. J
6.4
LIST OF FIGURES
Stage of flower development at t ime of growth substance application.
Partitioning of dry weight with the leaf removal treatments.
Dry weight of component organs at two harvests and with different
shading treatments.
Per cent absolute growth partitioned into fruit and leaves in each week.
Per cent absolute growth partitioned into petioles, stem and roots in each
week.
Distribution of aborted fruit dry weight at harvest six.
Net assimilation rate in each week.
Between pages 45-1+6
71- 72
85- 86
100-101
101-102
10J-1 0 Li-
105- 106
