Agriculture Reference
In-Depth Information
Table 4.5 Methods of Assessing Vine Water Status
Method
Advantages
Disadvantages
Weatherbased
Indirectly related to vine water
status; not variety specific
Evaporation pan
Simpleanddirectdaily
measurement; applies over a
whole vineyard
Birds may interfere; readings
corrected for rainfall; a
crop factor needed for local
conditions
Potential
evapotranspiration
Measurement of weather variables
can be automated; applies over a
whole vineyard
Requiresapowersource;crop
coefficient needed for local
conditions
Soilbased
Can be variety specific
Indirectly related to vine
water status; a site-specific
measurement
Tensiometers
Direct measure of soil suction;
most sensitive in the RAW range;
can register positive pressures;
those with pressure transducers
are loggable
Lesssuitableinthe DAW range;
water inside tensiometer may
freeze;requireasoilwater
retention curve to calculate
howmuchwaterisrequired
for irrigation
Gypsum blocks
Suitableforfullrangeofsuctions
for RDI; cheap and loggable
Installation disturbs the
soil;requireaninternal
calibration to obtain soil
matric suctions; life span of
three to five years
Capacitance probe
(FDR)
Can measure the full range of θ
atalldepths;loggable(ixed
type)orportable;minimalsoil
disturbance on installation
Air gaps around access tube
affect the reading; fixed
type is expensive; readings
with a portable probe are
time-consuming
“heta”probe(TDR)
Can measure the full range of θ at
all depths; loggable; portable for
a surface probe
Installation at depths below
the surface disturbs the soil;
readings affected by high
salinity
Plant based
LW P
Direct measurement of vine water
status
Variable from leaf to leaf and
vine to vine; time-of-day
dependent; cannot be
automated; a site-specific
measurement
Stemwaterpotential
Direct measurement of vine water
status; more sensitive to water
deficit than LW P
Cannot be automated;
time-of-day dependent;
labor-intensive
Infrared
thermography
Directly correlated with leaf
temperature; nondestructive
and can be automated
Correlation with leaf
temperature is specific to soil,
weather,andvariety;requires
complex calibration
Note. RAW = readily available water; DAW = deficit available water; RDI = regulated deficit irrigation;
FDR=frequencydomainrelectometry;TDR=Timedomainrelectometry; LW P = leaf water potential.
CompiledfromAgNote0294(2009),Shackel(2006),andCharlesworth(2000).
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