more leaves, more fruits, is it so simple? insights into a...

More leaves, more fruits, is it so simple? Insights into a scale-dependent relationship

Frédéric Normand1, Mathilde Capelli1, Pierre-Éric Lauri2

1 CIRAD, UPR HortSys, 97455 Saint-Pierre, Réunion Island, France 2 INRA, UMR System, 34060 Montpellier, France

XII International Mango SymposiumBaise, Guangxi, China, July 10th – 16th 2017

3

Introduction

Context :

- low productivity of mango orchards- irregular bearing- understand the role of endogenous factors in flowering and fruiting

IntroductionConcepts 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+2Yr n+1Yr n

GC 1V R Fl Fr

GC 2V R Fl Fr

IntroductionConcepts 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 cultivarsCogshall, Florida, weakly irregular bearer, vigour mediumIrwin, Florida, regular bearer, low vigourJosé, Réunion island, alternate bearer, vigour mediumKensington Pride, Australia, rather regular bearer, vigourous

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• Experiment in Réunion island (21°31’S; 280 m a.s.l.)

• 4 cultivarsCogshall, Florida, weakly irregular bearer, vigour mediumIrwin, Florida, regular bearer, low vigourJosé, Réunion island, alternate bearer, vigour mediumKensington Pride, Australia, rather regular bearer, vigourous

• n = 3 trees, not pruned before and during the experiment

• 2 successive growing cycles (2nd and 3rd harvests)• Quantification of vegetative growth : leaf area, nb terminal

growth units

• Quantification reproduction : nb fruits produced

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• 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 3000

5

10

15

20

Leaf area (dm²)

Num

ber o

f fru

its

cycle 1cycle 2

Kensington Pride

0 50 100 150 200 250 3000

5

10

15

20

Leaf area (dm²)

Num

ber o

f fru

its

cycle 1cycle 2

José

0 50 100 150 200 250 3000

5

10

15

20

Leaf area (dm²)

Num

ber o

f fru

its

cycle 1cycle 2

Irwin

0 50 100 150 200 250 3000

5

10

15

20

Leaf area (dm²)

Num

ber o

f fru

its

cycle 1cycle 2

Cogshall

12

Slopes : cycle 1: 0.05cycle 2: 0.05




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• 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 fruitsIrwin has the highest slopes (0.10 and 0.08)

Terminal growth unit scale

0 200 400 600 800 1000 12000

20

40

60

80

Leaf area (dm²)N

umbe

r of f

ruits

CogshallIrwinJoséKensington Pride

0 200 400 600 800 1000 12000

20

40

60

80

Leaf area (dm²)

Num

ber o

f fru

its


14



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 40 500.0

0.5

1.0

1.5

2.0

2.5

Normalized leaf area (dm²/cm²)

Nor

mal

ized

num

ber o

f fru

its (n

b/cm

²) CogshallIrwinJoséKensington Pride

0 10 20 30 40 500.0

0.5

1.0

1.5

2.0

2.5

Normalized leaf area (dm²/cm²)N

orm

aliz

ed n

umbe

r of f

ruits

(nb/

cm²) Cogshall

IrwinJoséKensington Pride

15


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)

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Sample number not enough to draw conclusion at the cultivar level

Whole tree scale

0 500 1000 1500 2000 25000

50

100

150

Leaf area (dm²)

Num

ber o

f fru

its


0 500 1000 1500 2000 25000

50

100

150

Leaf area (dm²)

Num

ber o

f fru

its


• 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 discussionWhole tree scale

0 10 20 30 40 500.0

0.5

1.0

1.5

2.0

2.5


Nor

mal

ized

num

ber o

f fru

its (n

b/cm

²)


0 10 20 30 40 500.0

0.5

1.0

1.5

2.0

2.5


Nor

mal

ized

num

ber o

f fru

its (n

b/cm

²)


With data normalized by the tree size: sample number not enough to draw conclusion at the cultivar level

• Differences among cultivars in the efficiency of vegetative growth to produce fruit, independently of the tree size

cycle 1 cycle 2

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Conclusion

• More leaves -> more fruits, but effects of- cultivar- growing cycle- scale considered (growth unit, scaffold, tree)

• Interest of the relationship- slope = efficiency of vegetative growth to produce fruit - vigour vs productivity- indicator of interest (irregular bearing, cultivar/rootstock evaluation) - results at the terminal growth unit scale consistent with results

at larger scale- suggest underlying mechanisms

• Practical consequence - stimulate early and important vegetative growth by appropriate

cultivation practices

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Thank you for your attention

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