Download - Plant Water Status
-
7/30/2019 Plant Water Status
1/36
Deficit Irrigation forMediterraneanAgricultural Systems
DIMAS
METHODOLOGY WORKSHOP
IAS-UCO, Crdoba-Spain, 9-11 February 2005
Plant water status
-
7/30/2019 Plant Water Status
2/36
Plant water status (PWS)
Indicatorsndicators off PWSWS:
tissue water content
relative water content(RWC)
energy status of the water in the cell
water potential()
basic parameters:
crop canopy temperature
stem diameter
stomatal conductance
sap flow
visible symptoms of water stress
indirect methods:
-
7/30/2019 Plant Water Status
3/36
Plant water status (PWS)
IncaosncaosooPWPWfoorgorgohnhn
tissue water content
relative water content(RWC)
energy status of the water in the cell
water potential()
basic parameters:
stem diameter
crop canopy temperature
stomatal conductance
sap flow
visible symptoms of water stress
indirect methods:
-
7/30/2019 Plant Water Status
4/36
Measurement of Plant WaterMeasurement of Plant Water StatusStatus
FW DW
TW DW
WATER CONTENT
=WC(DW basis)FW DW
DW=RWC(DW basis)
WATER POTENTIAL
Water potential is defined as the potential energy per unit mass of water withreference to pure water atzero potential (atmospheric pressure and 20 C),(Campbell, 1977)
Measurement of water potential is probably the most satisfactory singlemeasurement of plant and soil water status (Kramer and Koslowski, 1979)
-
7/30/2019 Plant Water Status
5/36
Measurement of Plant WaterMeasurement of Plant Water StatusStatus
PLANT WATER POTENTIAL
= = T (
l
s)
rs-l
Water flow through the soil-plant-system:
l = s (T rs-l)
l = o+ p (vacuole)Water stress
WATER POTENTIAL MEASUREMENTS
- Pressure chamber method (Scholander et al., 1965)
Principles (x)
-
7/30/2019 Plant Water Status
6/36
xylem= leaf =, xylem
-
7/30/2019 Plant Water Status
7/36
Method of measurement
How to measureHow to measure ??
- leaf water potential
- stem water potential
-
7/30/2019 Plant Water Status
8/36
Method of measurement
When to measureWhen to measure ??
-predawn water potential
- mid-day water potential
Plant water potential varies
throughout the day
Predawn, usually reflectaverage soil moisture tension
predawn, preferred baseline measurement
Mid-day, reflectsthe tension bythe plant to satisfy the water
demandmid-day, indicate the maximum water potential for the day
-
7/30/2019 Plant Water Status
9/36
Problems ?
Critical values ofmid-day
AlfalfaAlfalfaCottonCotton
CornCorn
PotatoesPotatoesSoybeanSoybean
SorghumSorghum
SugarbeetSugarbeet
SunflowerSunflower
WheatWheat
1.01.0 1.31.31.21.2 1.51.5
1.21.2 1.31.3
0.80.8 1.01.01.11.1 1.51.5
1.31.3 1.51.5
1.21.2 1.41.4
1.01.0 1.41.4
1.41.4 1.91.9
l (MPa)Crop
http://weather.nmsu.Teaching_Material/soil698/pressure_bomb/
-
7/30/2019 Plant Water Status
10/36
What to measureWhat to measure ??
(Fereres et al., 1999)
Shackel et al., 1997
stem water potential:
Measure of stress in tree crops
LWP muchmore variable and less hepful
-
7/30/2019 Plant Water Status
11/36
Leaf - stem water potential
convergence
-
7/30/2019 Plant Water Status
12/36
shaded leaf water potential vs. stem water potential
-
7/30/2019 Plant Water Status
13/36
-
7/30/2019 Plant Water Status
14/36
Stem water potentialStem water potential
((ShackelShackel et al., 1997)et al., 1997)
-
7/30/2019 Plant Water Status
15/36
C ti it i fContinuous monitoring of t k di ttrunk diameter
-
7/30/2019 Plant Water Status
16/36
Continuous monitoring ofContinuous monitoring oftrunk diametertrunk diameter
for precise scheduling of irrigationsfor precise scheduling of irrigations
trunk diameter fluctuationstrunk diameter fluctuations
-
7/30/2019 Plant Water Status
17/36
trunk diameter fluctuationstrunk diameter fluctuations
-
7/30/2019 Plant Water Status
18/36
Trunk Diameter Fluctuations
1.5
1.6
1.7
1.8
1.9
2.0
2.1
2.2
2.3
2.4
jun 3
12:00a.6./p.6.
jun 4 0:00
a.6./p.6.
jun 4
12:00a.6./p.6.
jun 5 0:00
a.6./p.6.
jun 5
12:00a.6./p.6.
jun 6 0:00
a.6./p.6.
jun 6
12:00a.6./p.6.
jun 7 0:00
a.6./p.6.
jun 7
12:00a.6./p.6.
jun 8 0:00
a.6./p.6.
TrunkDiameter
Fluctuations(mm)
T1.75
T2.75
1
3
4
2
-
7/30/2019 Plant Water Status
19/36
Citrus; San Joaquin Valley
-0.30
-0.20
-0.10
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
J un 24 J ul 4 J ul 14 J ul 24 Aug 3 Aug 13 Aug 23
Control
T8
Onset of 25% ETc
J uly 1
-
7/30/2019 Plant Water Status
20/36
Trunk diameter fluctuationsduring deficit irrigation andafter reirrigation
(Fereres et al., 1999)
l f S S
-
7/30/2019 Plant Water Status
21/36
(Fereres et al., 1999)
Values of MDTS, MSWP, MLWP, PLWP,for de deficit irrigation treatment, relative to the control
-
7/30/2019 Plant Water Status
22/36
-
7/30/2019 Plant Water Status
23/36
Linear Variable Differential Transducer
(LVDT; Model DF 2.5, Solartron Metrology; UK)
Problems?
t t
t t
-
7/30/2019 Plant Water Status
24/36
crop canopy temperaturecrop canopy temperature
Water flow through the soil-plant-system: l = s (T rs-l)
l = s+ p (vacuole)
Water stress Change the energybalance, andcanopy
temperature
Difference between leaf an air temperature:
Relatable to leaf water potential
(Infrared Thermometers)
-
7/30/2019 Plant Water Status
25/36
Method Canopy temperature based
Crop Water Stress Index (CWSI):
Tmax= a ( 1 b )-1
Tminx= a+ (b VPD)
Tmin= f (VPD)
=CWSIT T
min
Tmax Tmin
CWSI =1 (T /Tmax)
How to measureHow to measure ??
-
7/30/2019 Plant Water Status
26/36
stomatal conductancestomatal conductance
-
7/30/2019 Plant Water Status
27/36
stomatal conductancestomatal conductance
Water flow through the soil-plant-system: l = s (T rs-l)
l = s+ p (vacuole)
Water stress stomatal closureg=1/r)g=1/r)
(g=1/r)
Degree of stomatal opening:
indicative of plant water status
(Porometers)
-
7/30/2019 Plant Water Status
28/36
system Delta T AP4(DeltaT devices LTD, Cambrige, England)
CIRAS-1 (PP Systems Hitchin HertsU.K.)
Problems ?
-
7/30/2019 Plant Water Status
29/36
-
7/30/2019 Plant Water Status
30/36
PROBLEMS
-
7/30/2019 Plant Water Status
31/36
Diurnal evolution of leaf conductancein almond trees
0 6 8 10 12 14 16
Hour of day
Irrigatedunirrigated8
6
gl
(mm
s-1)
4
2
0
(Castel and Fereres, 1982)
Stomatal conductance and leaf water potential on spring in
-
7/30/2019 Plant Water Status
32/36
irrigated and rainfed peaches. Winters, California, 1980
(Fereres and Goldhamer, 1990)
STOM
ATALCOND
UCTANCE
(mms-1)
LEAFWATE
R
POTENTIAL
(MPa)
Daily course of Pn, LWP and SC
-
7/30/2019 Plant Water Status
33/36
Drip-irrigated olive orchard,
cv. Picual
(Gimnez et al., 1997)
Relationship in sunflower between leaf expansion rated l f i l
-
7/30/2019 Plant Water Status
34/36
and leaf water potential
-1.5 -1.0 -0.5
-0.0
-0.4
-0.8
-1.2
Leaf Water Potential (MPa)
LER(d
ry/we
t)
Exp. 1Exp. 2
y = 1.74 + 1.13 x
r2 = 0.80 ***
(V.O. Sadras, F.J . Villalobos, and E. Fereres, 1993)
-
7/30/2019 Plant Water Status
35/36
Leaf expansion rateLeaf expansion rate
-
7/30/2019 Plant Water Status
36/36