berry = sugar sinkcesonoma.ucanr.edu/files/288475.pdf · 2018-08-07 · poor cane ripening reduced...

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Source: Sink Relationships in the Grapevine

S. Kaan Kurtural

Department of Viticulture and Enology

Source: Sink Relations

3/4/20182

Leaf = Photosynthesis = Source

Berry = Sugar Sink

UCCE Sonoma County Grape Day February 8, 2018

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Sink – growing apex

Source – Leaf photosynthesis

Sink ‐ berry

Sink – roots, trunk

Source-Sink

1

Amount of available light

From the Exposed Leaf to Fruit Sink

Depends on number of sinks

4

Fraction of DM exported to clusters

3

Amount of intercepted light –depends on leaf area and canopy

structure

2

3

Function of the grapevine canopy

• Carbon fixation

• Yield

• Controlling cluster microclimate

• Berry chemistry

• Incidence of fungal infection

Optimum light environment in the fruit zone during ripening

Maximize diffuse or indirect sunlight within the canopy interior

Minimize exposure of clusters to direct sunlight – particularly in warm climates


4

A

G

B

FC

DH

E

Radiation Effects on Whole Canopy

0

1

2

3

4

5

6

7

8

9

10

0 750 1000 1250 1500 1750 2000 2250 2500

PPFD (mol/m2/s)

Ne

t C

an

op

y P

n (

m

ol C

O2/

vin

e/s

)

LLN#2

LLN#3

10 % transmitted

100% incident

6% reflected

LLN#1

1% transmitted

0.1% transmittedKurtural et al. 2003; Dami et al. 2005; Kurtural et al. 2005; 2006

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Common canopy types

Canopy type Leaf area per vine Exposed leaf area Interior leaf area

22 m2 8 m2 (35%) 14 m2

22 m2 6 m2 (25%) 16 m2

22 m2 15 m2 (70%) 7 m2

Evolution of berry chemistry ‘Cabernet Sauvingon’


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Source:Sink Management

Balancing vegetative growth with reproductive growth

Not a direct measurement

Single most important practice

Vine balance thresholds

Ravaz index: 5 to 10 kg/kg

Pruning weight/ m of row:

0.8 to 1.0 kg/m

Unbalanced vines• Large canopies

• High water demand

• Fruit of inferior ‘quality’

Source-SinkYield and berry size, maturity, leaf area and wine sensory

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Source-Sink 2

Source-Sink Balance

Balance between being sink limited or source limited

Source-sink balance

When fruit number is increased, fruit size does not change, when sink-limited, and decreases under source-limited conditions

Yield increases with crop load (bud or cluster numbers) when sink-limited, and does not increase when source-limited


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For dry-farmed vines at Oakville in Napa Valley, sink limited

Nuzzo and Matthews 2006

Yield at Different Crop Loads by Thinning at Veraison (clusters/vine)

Berry Size at Different Crop Loads on dry farmed Cabernet Sauvignon

Nuzzo and Matthews 2006

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Response of Berry Size to Crop Load in Shiraz

Freeman et al. Shiraz - in Coombe and Dry.

Source/Sink 1


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Changes in Brix after Veraison

• Low crop level accelerates sugar accumulation

• Reduces amount of harvested ‘wine’

• Dry farmed Cabernet Sauvignon

Nuzzo and Matthews AJEV 2006

Sugar Accumulation at Various Crop Loads (0.5 – 2.0)


Cabernet Sauvignon

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Brix Delay with Crop LoadSlope = 1 day / ton Cluster thinning


Anthocyanin Concentration Dependency

L.E. Williams


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Sugar Yield at Various Crop Loads

Crop Level and Leaf Area

Experiments to reduce leaf area per unit of fruit until vines were clearly source limited

Responses of size, sugar, and color to increasing source (leaf area) saturated at about 10 – 12 sq. cm. / gm fruit

10-12 cm2 leaf area / g fruit should form a cornerstone of our sense of ‘balance’

Source-limited

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Ratio of Leaf Area to Fruit

S. Poni - Italy

Vine Balance

Data does not indicate leaf area or pruning weight to fruit ratios provide an absolute value of source/sink relationships in grapevines

What can one measure to estimate whether the crop load can be ripened well?

• Impact on the cluster microclimate

• Important determinant of fruit composition

• Leaf area effects amount of radiation hitting the berry


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Sugar delay

Sugar maturity not reached

Low color

And with more severe overcropping:

Poor cane ripening

Reduced fruitfulness, Slow, inhibited budbreak

Increasingseverity

Over cropping ? Is this a thing?

Crop load management- the new reality

Hand pruned vs. Machine pruned Pinot gris

What is your ideal crop load if economic threshold is 12 T/A?

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So crop it as much as you want?

Yield vs. ‘Quality’ Is this a thing on which we can hang out hat?

We have been unable to provide evidence that high yield or high vigor would reduce berry anthocyanin content across our trials in CA


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What factors affect berry chemistry?

• Cluster microclimate

• Temperature

• Irradiation

• Row orientation

• Canopy height

• Amount of exposed leaf area/run of row

Row orientation?

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Row orientation?

Temperature of berries


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VSP vs Sprawl1 foot canes with sprawling vegetation

Fish eye lens pictures from cluster perspective

6 clusters (east, west and interior) from 4 vines and 2

trellis (VSP and Sprawl)

2 bud spur-pruned vertical shoot positioned (VSP)

VSP versus California Sprawl

0

4

8

12

16

20

24

28

32

36

40

44

48

VSP - SW Sprawl - SW VSP - NE Sprawl - NE VSP - int Sprawl - int

Training side

Po

rosi

ty

Porosity

0


Training side

Dam

age

Damage

0

4

8

12

16

20

24

28

32

36

40

44

48

52


Training side

TA

_SD

M

TA_SDM

VSPSprawl

SE NW Interior SE NW InteriorSE NW Interior

Canopy porosity Visual assessmentof damage

Anthocyanins

R2=0.54

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Canopy Porosity (%)0 10 20 30 40 50 60 70

Tot

al A

ntho

cyan

ins

(mg

per

Ber

ry)

1

2

3

NEGATIVE RELATION BETWEEN CANOPY POROSITY AND ANTHOCYANINS

OPTIMIZATION OF CANOPIES THROUGH METABOLIC MARKERS

3/4/201838

Develop a metabolic marker for exposure

Relate marker to changes in composition

Measure exposure

Design trellis and manage exposure to

achieve optimal quality

R2= 0.56


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METABOLIC DATA LOGGER (BIOMARKER) VS CANOPY POROSITY ASSESSMENT

3/4/201839

Canopy porosity (%)

0 10 20 30 40 50 60 70

Tot

al F

lavo

nols

(mg

per

Ber

ry)

0.00

0.05

0.10

0.15

0.20

0.25

Biomarker

0 20 40 60 80 100 120

To

tal F

lavo

nols

(mg

per

Ber

ry)

0.00

0.05

0.10

0.15

0.20

0.25

R2= 0.23 R2= 0.55

Exp - Deg - Exp + Deg - Exp + Deg + Exp + Deg ++

Co

nten

t pe

r be

rry

(nor

mal

ized

)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

ProanthocyanidinsAnthocyaninsFlavonols

Induction

Degradation

Optimal value

New Source:Sink trial at Oakville Station

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How does it look in the field?

33%: 10 clusters33%: 2/3 of leaf area removed

100%: 30 clusters100% All leaves retained

Yawn. Nothing new here? Or is there?


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Shifts in ripening

Shift in phenology

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Summary

Vine balance can be evaluated on basis of adequate sugar and color accumulation

Exposed leaf area per foot of row may be a better indicatorNot grower friendly

Berry flavors are derived from berry metabolismBerry flavors are not translocated – more on this throughout the day

3/4/201846

THANK YOU FOR LISTENING!


berry = sugar sinkcesonoma.ucanr.edu/files/288475.pdf · 2018-08-07 · poor cane ripening reduced...

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