More leaves, more fruits, is it so simple?
Insights into a scale-dependent relationship
Frédéric Normand 1 , Mathilde Capelli 1 , Pierre-Éric Lauri 2
1
CIRAD, UPR HortSys, 97455 Saint-Pierre, Réunion Island, France
2
INRA, UMR System, 34060 Montpellier, France
XII International Mango Symposium
Baise, Guangxi, China, July 10 th – 16 th 2017
2
3
Introduction
Context :
- low productivity of mango orchards - irregular bearing
- understand the role of endogenous factors in
flowering and fruiting
Introduction Concepts and vocabulary
The growth unit
(Hallé and Martin, 1978)
6 8 10 12 2 4 6 8 10 12 2 4 6 8 10 12 2 4
Yr n-1 Yr n Yr n+1 Yr n+2
GC 1 V R Fl Fr
GC 2 V R Fl Fr
Introduction
Concepts and vocabulary
6
Introduction
Structural and temporal continuity between vegetative growth and reproduction
-> vegetative growth may affect flowering, fruiting and yield
Characteristics of terminal growth units affect the probability of flowering and fruiting (Issarakraisila et al., 1991; Normand et al., 2009;
Dambreville et al., 2013; Capelli et al., 2016)
Context :
- low productivity of mango orchards - irregular bearing
- understand the role of endogenous factors in
flowering and fruiting
7
Introduction
Objective:
Investigate the relationship between vegetative growth and reproduction at different scales: the terminal growth unit, the scaffold branch, the whole tree
What is the effect of the vegetative growth established during a cycle on reproduction ?
A positive effect is expected (e.g. Oosthuyse and Jacobs, 1995)
- physiology : CHO assimilation and storage;
florigen synthesis
- demography : terminal growth units = possible
flowering and fruiting points
8
Materials and Methods
• Experiment in Réunion island (21°31’S; 280 m a.s.l.)
• 4 cultivars
Cogshall, Florida, weakly irregular bearer, vigour medium Irwin, Florida, regular bearer, low vigour
José, Réunion island, alternate bearer, vigour medium
Kensington Pride, Australia, rather regular bearer, vigourous
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Materials and Methods
• Experiment in Réunion island (21°31’S; 280 m a.s.l.)
• 4 cultivars
Cogshall, Florida, weakly irregular bearer, vigour medium Irwin, Florida, regular bearer, low vigour
José, Réunion island, alternate bearer, vigour medium
Kensington Pride, Australia, rather regular bearer, vigourous
• n = 3 trees, not pruned before and during the experiment
• 2 successive growing cycles (2 nd and 3 rd harvests)
• Quantification of vegetative growth : leaf area, nb terminal growth units
• Quantification reproduction : nb fruits produced
10
Materials and Methods
• At the terminal growth unit scale:
Leaf area : assessed from shoot basal diameter
(Normand and Lauri, 2012)
Nb terminal growth units and nb of fruits: counting
• Data aggregated at the scaffold branch and at the whole tree scales
Ø Ø
GU A-12
11
Results and discussion
Positive, linear relationship between leaf area and the number of fruits produced for the 4 cultivars
Terminal growth unit scale
0 50 100 150 200 250 300 0
5 10 15 20
Leaf area (dm²)
N u m ber of fr ui ts
cycle 1 cycle 2
Kensington Pride
0 50 100 150 200 250 300
0 5 10 15 20
Leaf area (dm²)
N u m ber of fr ui ts
cycle 1 cycle 2
José
0 50 100 150 200 250 300
0 5 10 15 20
Leaf area (dm²)
N u m ber of fr ui ts
cycle 1 cycle 2
Irwin
0 50 100 150 200 250 300
0 5 10 15 20
Leaf area (dm²)
N u m ber of fr ui ts
cycle 1 cycle 2
Cogshall
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Slopes : cycle 1: 0.05 cycle 2: 0.05
Slopes : cycle 1: 0.07 cycle 2: 0.04 Slopes : cycle 1: 0.06
cycle 2: 0.05
Slopes : cycle 1: 0.10
cycle 2: 0.08
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Results and discussion
Positive, linear relationship between leaf area and the number of fruits produced for the 4 cultivars
• Different range of vegetative growth produced
• Slopes vary with cultivar and cycle (except Cogshall)
• Linear relationship :
-> the increase in fruit number per increase in leaf area is independent of leaf area
• Slope : efficiency of vegetative growth to produce fruits Irwin has the highest slopes (0.10 and 0.08)
Terminal growth unit scale
0 200 400 600 800 1000 1200 0
20 40 60 80
Leaf area (dm²)
N u mber of f rui ts
Cogshall Irwin José
Kensington Pride
0 200 400 600 800 1000 1200 0
20 40 60 80
Leaf area (dm²)
N u mber of f rui ts
Cogshall Irwin José
Kensington Pride
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Results and discussion
Positive, linear relationship between leaf area and the number of fruits produced for the 4 cultivars
Scaffold branch scale
cycle 1 cycle 2
• Different range of vegetative growth produced
• Same meaning for the slope than at the growth unit scale
• Relationships mainly shaped by scaffold branch size
0 10 20 30 40 50 0.0
0.5 1.0 1.5 2.0 2.5
Normalized leaf area (dm²/cm²)
N o rm al iz ed number of fr ui ts ( nb/ c m ²)
CogshallIrwin José
Kensington Pride
0 10 20 30 40 50
0.0 0.5 1.0 1.5 2.0 2.5
Normalized leaf area (dm²/cm²)
N o rm al iz ed number of fr ui ts ( nb/ c m ²) Cogshall
Irwin José
Kensington Pride
15
Results and discussion
With data normalized by the scaffold size: linear, positive relationships for KP, Cogshall (cycle 1) and José (cycle 2) Scaffold branch scale
cycle 1 cycle 2
• Different range of vegetative growth produced
• Positive relationship -> scaffold branch autonomy (KP)
• No relationship -> partial scaffold branch autonomy (Irwin)
16
Results and discussion
Sample number not enough to draw conclusion at the cultivar level
Whole tree scale
0 500 1000 1500 2000 2500
0 50 100 150
Leaf area (dm²)
Num b e r of fr ui ts
Cogshall Irwin José
Kensington Pride
0 500 1000 1500 2000 2500
0 50 100 150
Leaf area (dm²)
Num b e r of fr ui ts
Cogshall Irwin José
Kensington Pride
• vigourous cultivars vs non vigourous cultivars
• general trend: positive and linear relationship between vegetative growth and number of fruits produced
cycle 1 cycle 2
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Results and discussion Whole tree scale
0 10 20 30 40 50
0.0 0.5 1.0 1.5 2.0 2.5
Normalized leaf area (dm²/cm²)
Normalized number of fruits (nb/cm²)
Cogshall Irwin José
Kensington Pride
0 10 20 30 40 50
0.0 0.5 1.0 1.5 2.0 2.5
Normalized leaf area (dm²/cm²)
Normalized number of fruits (nb/cm²)
Cogshall Irwin José
Kensington Pride
