Leaves opposite to cluster

Fotosintesi
2 NADPH2
PIGMENTI
CO2
2 NADP
3 ATP
Energia solare
(8 FOTONI )
PIGMENTI
ECCITATI
FASE FOTOCHIMICA
3 ADP + 3 Pi
2 H2 O
O2
TRASFERIMENTO DI
ELETTRONI E FORMAZIONE
DI ATP
CH2O + H2O
FASE BIOCHIMICA
Grapevine photosynthesis vs. environmental,
physiological and cultural factors
• Phenological stage measurements are made
• Environmental conditions during readings
• Equipment available
• Units
(1 µmol CO2 m-2 s-1 = 0.63 CO2 mg dm-2 h-1)
Radiation
• Light response curve
• Light environment during leaf development
• Light environment after leaf development
100 %
Incident
6% reflected
Leaf
85% absorbed
9% transmitted
12
Pn
(µmol m-2 s-1)
Pn max
10
8
6
Quantum
yield
Light saturation point
4
2
Light compensation point
0
0
400
800
1200
PAR (µmol m-2 s-1)
1600
2000
12
Pn
(µmol m-2 s-1)
10
External canopy layer
(it gets 1600 µmol m-2 s-1)
8
6
4
2
2° layer (160 µmol m-2 s-1, 10% of 1600)
0
3° layer (16 µmol m-2 s-1, 10% of 160)
0
400
800
1200
PAR (µmol m-2 s-1)
1600
2000
Comparison of single leaf and whole-canopy assimilation
(A) rates.
Al
(µmol m-2 s-1)
Ac
(µmol m-2 s-1)
LA (m2) Morn.
Aft.
Morn.
Aft.
Vine 1 1.26 9.3  1.3 8.7  0.8 4.5  0.1 4.0  0.1
Vine 2 1.34
8.3  0.7 8.0  0.7 4.1  0.1 3.8  0.1
-2 -1
16 Pn (µmol m s )
Single leaf
14
12
10
8
6
4
2
0
- 48%
Free growing
canopy
- 26%
Constrained canopy
0
250 500 750 1000 1250 1500 1750 2000
Taken from Intrieri et al.
PFD (µmol m-2 s-1 )
Vitis (1997) 36: 167-173
Another good example…..
Total
(µmol s-1)
Leaf area per vine (m2)
Specific
(µmol m-2 s-1)
Leaf area per vine (m2)
12 Pn (µmol m-2 s-1)
10
8
6
4
«sun» leaves
2
«shade» leaves
0
0
300
600
900
1200
PAR (µmol m-2 s-1)
1500
1800
Sun leaves
PFD = 90% max
(1600 µmol m-2 s-1)
PFD = 90% max
PFD = 8% max
(150-200 µmol m-2 s-1)
R:FR = 0.40
Sun leaves then shaded
cv. Sangiovese
Pn
(µmol m-2 s-1)
1
2
10
8
6
Leaf age
4
2
58 gg
82 gg
(17 d of shade)
(41 d of shade)
0
113 gg
(72 d of shade)
0
400
1200
800
PFD (µmol m-2 s-1)
1600
2000
Sun leaves always in the sun
12
Pn
(µmol m-2 s-1)
10
cv. Sangiovese
8
6
4
2
Leaf age
0
58 d
0
Da Silvestroni et al., 1993
400
82 d
800
1200
PFD (µmol m-2 s-1)
113 d
1600
200
0
Temperature
• Long term effects
• Short term effects
Pn and other factors
• Diurnal variation
• Seasonal variation
• Leaf age
• Compensation mechanisms
• Source and sink balance
Gobelet
PAR (µmol m-2 s-1)
WCE (mmol s-1) VPD (kPa)
PAR
VPD
WCE
4
6
8
10 12 14
Solar time (h)
16
18
20
WCA (µmol s-1)
WCA
WCE
WUE
4
6
8
10 12 14
Solar time (h)
16
18
20
WCE (µmol s-1); WUE (WCA/WCE)
Gobelet
35
30
25
20
15
Fully
expanded
leaf
0
20
40
10
5
0
60 80 100 120 140 160 180
Leaf age (days)
Pn (mg dm h )
-1
Pn (µmol m-2s )
Sultana, lab, Kriedemann,
1970
Sangiovese, pots- outdoor,
Intrieri et al. 1992)
Sangiovese, field, Poni
et al. 1994
-2 -1
12
11
10
9
8
7
6
5
4
3
2
1
0
(31 days)
14
Pn (µmol m-2 s-1)
12
10
8
6
4
2
16 May
19 June
23 July
0
0
4
8
12 16 20 24 28 32 36 40 44
Leaf position on shoot stem
14
Pn (µmol m-2 s-1)
12
21 September
26 October
10
8
6
4
2
Shoot apex
0
0 4 8 12 16 20 24 28 30 36 40 44 48 52 56 60
Leaf position on shoot stem
basal
median
apical
bloom
c
Pn (µmol m-2 s-1)
c
b
b
b
aa
a
a
b
b
b
b
harvest
veraison
c
b
b
b
a
a
a
ns
a
a
a
a
a
a
c
c
b
b
a
a
May
June
July
Aug
Sept
Oct
12
Pn (µmol m-2 s-1)
Chlorophill (mg/dm2)
3.5
3
10
2.5
8
2
6
1.5
4
2 SE
2
0
1
0.5
0
20
40
0
60 80 100 120 140 160 180
Leaf age (days)
12
Pn (µmol m-2 s-1)
N (mg/cm2)
0.2
10
0.15
8
6
0.1
4
2 SE
2
0
0
20
40
0.05
0
60 80 100 120 140 160 180
Leaf age (days)

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