View
220
Download
6
Category
Preview:
Citation preview
Irrigation scheduling of fruit trees
Amos Naor
• Water stress assessment
• The interaction of crop-load with irrigation
Soil water stress indicators
Soil water potential - Tensiometer
Soil water potential - Tensiometer
The tensiometer exchanges water
with the soil-water until their water
potentials are equal. Ceramic cup Ceramic cup
The tensiometer is a pipe filled with
water that has ceramic (porous)
cup in the bottom.
Soil water content
All the modern measurement techniques
of water content are based on electrical
properties
Capacitance.
Dialectric constant.
Resistance.
Plant water stress indicators
Plant-based water stress indicators
Water potential (pressure chamber, psychrometry).
Relative water content.
Tissue size changes (dendrometers).
Stomatal conductance
Porometry
IR thermometry / Thermal imaging
Acoustic emission
Sap flow
Plant-based water stress indicators
Water potential (pressure chamber, psychrometry).
Relative water content.
Tissue size changes (dendrometers).
Stomatal conductance
Porometry
IR thermometry / Thermal imaging
Acoustic emission
Sap flow
Direct measurement of the water
potential
Pressurized
nitrogen Pressure
chamber (Scolander et al., 1965)
Leaf water potential Stem water potential
Trunk diameter changes
100.0
100.1
100.2
100.3
100.4
0:00 6:00 12:00 18:00
Trunk
diameter
changes
hour
Various commercial water stress probes
Thermal imaging
The energy from the sun is directed mainly to:
Heating the canopy.
Vaporizing water (transpiration)
Stressed plants close their stomata and reduce
transpiration thus more energy from the sun is
shifted to heat the canopy.
Stress plants are warmer than non-stressed plants
Thermal imaging: (Moeller et al., 2007)
Low irrigation rate
High irrigation rate
High irrigation rate
Relationships between CWSI and
stomatal conductance (Moeller et al., 2007)
CWSI
.2 .4 .6 .8
Sto
ma
tal co
nd
uctu
nce
(m
mo
le/m
2/s
)
0
100
200
300
400
500
r2=0.85
CWSI = (TCanopy – Twet) / (Tdry – Twet)
Relationships between CWSI and
stomatal conductance (Moeller et al., 2007)
CWSI
.2 .4 .6 .8
Sto
ma
tal co
nd
uctu
nce
(m
mo
le/m
2/s
)
0
100
200
300
400
500
r2=0.85
CWSI = (TCanopy – Twet) / (Tdry – Twet)
•Optimal meteorological
conditions.
•Good reference temperatures.
•High spatial resolution
Reducing spatial resolution
Crane
Airplane
Satellite
Pixel size and average
temperature
Current accuracy of CWSI assessment is limited
Summary of water stress indicators for
irrigation scheduling
• Point Vs. spatial measurements
• Setting thresholds (calibration)
Detection of irrigation malfunctions:
grapevines
not irrigated
currently
Thermal imagery allowed the
recognition of subsurface water
flow from the nectarines
currently
irrigated
not irrigated
currently
Vineyard, Upper Galilee, summer 2005
Alchanatis and Cohen
Leakage detection
23
Alchanatis et al
Almonds
Cotton, Northern Israel, Megido, July, 2008
Clogging in drippers
Cohen and Alchanatis
Irrigation malfunction detection in olives (Alchanatis et al)
Date suspected
points (area) Visible leaks
No visible leaks
Olives – Gshur
24/6 5.4% 8% 92%
26/8 8.2% 11% 89%
Crop load and irrigation
Crop load and water consumption (Lenz, 1986)
Apple trees were grown in
containers.
Trees with and without fruits
were compared.
Transpiration and leaf area
were measured.
Stomatal aperture is higher in
the presence of fruit.
0
100
200
300
400
500
600
No fruit Fruit
Tra
ns
pir
ati
on
(l/p
lan
t)
Leaf area per tree
Transpiration
0
1
2
3
4
5
No fruit Fruit
Le
af
are
a (
m2)
Crop load and stem water potential
Pan evaporation coeff.
.4 .6 .8 1.0 1.2 1.4
-2.6
-2.4
-2.2
-2.0
-1.8
-1.6
-1.4
-1.2
-1.0
a ab
b
c
a a
b
b
a
a
b
b
654 664
1217
Frut/tree
Nectarine
Number of fruits and stem water potential
Fruit per tree
0 500 1000 1500 2000 2500
-3.0
-2.5
-2.0
-1.5
-1.0
-.5
0.0
Crop load and stem water potential
1L 1M 1H 3L 3M 3H 7L 7M 7HA
vera
ge m
idday s
tem
wate
r pote
ntial
up t
o h
arv
es (
MP
a)
-3.0
-2.5
-2.0
-1.5
-1.0
-0.5
0.0
Ortal
Matityahu
Apple
Crop load and stem
water potential
-4.0
-3.5
-3.0
-2.5
-2.0
-1.5
-1.0
-0.5
0.0
Low irr Med irr High irr
Ste
m w
ate
r p
ote
nti
al
(MP
a)
Low load High load
0
50
100
150
200
250
300
Low irr Med irr High irrS
tom
ata
l co
nd
ucta
nce (
mm
ole
/m2/s
)
Low load High load
Crop load and Stomatal
conductance
Olive Olive
Crop load and water relations in olive
R2 = 0.96
R2 = 0.92
R2 = 0.32
0
50
100
150
200
250
300
350
-5 -4 -3 -2 -1 0
Stem water potential (MPa)
Sto
ma
tal c
ind
uc
tan
ce
(mm
ole
/m2
/s)
Med. load 14:00
Low load 10:00
High load 10:00
S
tom
ata
l co
nd
ucta
nce
(mm
ole
/m2
/s)
Crop load and water relations in apple
0
5
10
15
20
25
30
-3 -2.5 -2 -1.5 -1 -0.5 0
Midday stem water potential (MPa)
High crop load
Low crop load
Poly. (Low crop
load)Poly. (High crop
load)
Naschitz et al, unpublished
Assim
ilation r
ate
(μ
mole
/m2/s
)
Stem water potential and apple fruit weight
R2 = 0.92
R2 = 0.94
0
50
100
150
200
250
-3.0 -2.5 -2.0 -1.5 -1.0 -0.5 0.0
)MPa( פוטנציאל מים בגזע
ם(ר)ג
ע צמו
מי
רפ
ל ק
שמ
אורטל Matityahuמתיתיהו
F
ruit w
eig
ht
(g)
Ortal
Midday SWP (MPa)
Low and Med.
crop load
High crop load
R2=0.97
0
20
40
60
80
100
-3.0 -2.5 -2.0 -1.5 -1.0 -0.5 0.0
)MPa( פוטנציאל מים בגזע
מ"מ
70מ-
ל דו
גרי
פז
חוא
אורטל מתיתיהו
Stem water potential and the yield of large fruit
Matityahu
F
ruit >
70 m
m (
%)
Ortal
Midday SWP (MPa)
Low and Med.
crop load
High crop load
Crop load and thresholds for irrigation (Naschitz et al, unpub.)
0
50
100
150
200
250
300
-3 -2.5 -2 -1.5 -1 -0.5
Fru
it w
eig
ht
(g)
Midday stem water potential (Mpa)
100 Fruit/tree
300 fruit/tree
600 fruit/tree
>1000 fruit/tree
25 t/ha
58 t/ha
93 t/ha
Irrigation levels:
1 mm/day
3 mm/day
7 mm/day
Optimal irrigation:
25 t/ha - ~2.5 mm/day
58 t/ha - ~4.5 mm/day
93 t/ha - ~7 mm/day
Optimal threshold:
25 t/ha - ~-1.4MPa
58 t/ha - ~-1.2MPa
93 t/ha - ~-0.8MPa
Summary of crop load and irrigation
0
100
200
300
400
500
600
No fruit Fruit
Tra
ns
pir
ati
on
(l/p
lan
t)
Summary of water stress indicators for
irrigation scheduling
• Point Vs. spatial measurements
• Setting thresholds (calibration)
Summary of irrigation malfunction
detection
Thanks
Recommended