Mark Greenspan, Ph.D., CPAg, CCA Advanced Viticulture, … - Irrigation... · Sap flow, dendrometry, surface renewal. t , c. m Rapid Growth Slowing Growth Almost Stopped Stopped Dead

Mark Greenspan, Ph.D., CPAg, CCAAdvanced Viticulture, Inc.

www.AdvancedVit.com

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To discuss a simple irrigation

management scheme

• based on continuous soil moisture

measurements

• focusing on soil moisture dynamics

• in conjunction with plant moisture status

Water conservation

• high vine WUE

• precise, efficient irrigation

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Allow vines to deplete rain-fed soil moisture to encourage deep and extensive rooting

Impose mild stress on vines to put them in a state of high water use efficiency

Monitor vine stress to create sufficient stress, but not excessive stress

Use soil moisture monitoring to precisely apply irrigation.

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om Soil moisture

• Identify effective root

zone

• Track rainfed moisture

depletion

• Determine actual

depth of irrigations

• Indicate onset of vine

stress

• Determine exactly

how long irrigations

take to become

depleted

• Precisely irrigate

Plant moisture

• How does vine

respond to soil

moisture content?

• Identify water-use

efficient state/range

• Avoid excessive vine

stress

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Monitoring is “feedback” used to adjust

irrigation schedule

Methods include:• Visual Indicators – shoot elongation rates, shoot

tips, droopy tendrils, leaf sun-avoidance, basal

leaf senscence

• Plant water status instruments:

Pressure Chamber

Porometer

Sap flow, dendrometry, surface renewal

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Rapid Growth Slowing Growth Almost Stopped Stopped Dead Tip

5 4 3 2 1

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Pressure Chamber

Porometer

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Pressure chamber• Measures “suction” in the xylem vessels• Advantages: Portability; repeatability; ruggedness• Disadvantages: No indication of vine physiological response; reading depends

on time since last irrigation, grape variety, daytime conditions, etc.

Measurement can be misleading on its own

• IMPORTANT: Place leaves in plastic bags immediately before removal and during measurement

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omPorometer

• Measures stomatal conductance (facility of pores to transpire water)

• Advantages: Portability; vine response to water status; indirect indication of photosynthesis

• Disadvantages: More delicate instrument; sensitive to environmental conditions; more variability than leaf water potential measurements

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What are stomata?

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Suzy Y. Rogiers*, Dennis H. Greer, Ron J. Hutton and Joe J. Landsberg

Journal of Experimental Botany, Vol. 60, No. 13, pp. 3751–3763, 2009

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Porometer/Stomatal Conductance - Units are in mmol/m2/s

450 400 350 300 250 200 150 100 50 0500

“Luxury” Mid-Range Mod.

Stress

Stress Extreme

Stress

Slight

Stress

9 10 11 12 13 14 15 16 17 188

“Luxury” Mid-Range

Mod.

Stress Stress

Extreme

Stress

Slight

StressShoot stopping

Pressure Chamber/Leaf Water Potential (-bars)

High WUE

Range

Red target White target

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Measure at multiple levels to determine

depth of irrigation

Measure continuously

Use to determine nominal irrigation volume

per application

Use to determine nominal irrigation

interval between applications

Use in conjunction with plant moisture

status measurements to precisely adjust

intervals per changing weather conditions

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Soil matric

potential sensors

Soil water content sensors &

probes

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20

Relative permittivity

of water is

About 80x that of air

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Stair-steps

indicate

day/night water

pattern

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Upper

limit of

RAW

Lower

limit of

RAW

Set a reference

volume for

refill point

Progressive

stress reflected

in slope

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ETo = 4.42”

Kc = 0.5

ETc = 2.21”= 66 gal/vine

Actual Irrigation: 12 gallons/vine

18% of Etc

Possible IF vines are in high WUE range

Cab. Sauv, 8’ x 6’ spacing, south Napa

County, 3rd leaf

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Vin

e W

ate

r S

tress

Budbreak Bloom & Fruit Set

Veraison Maturity

“Magic Window”

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About 2 weeks prior to veraison and

through complete veraison

Achieving moderate stress:• Reduces and stops vegetative growth

• Puts vines in high water use efficiency range

(important for low irrigation volumes)

• Stimulates production of ripening enzymes in fruit

• Most effective in red varieties

• Allows for flavor ripeness at lower brix

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Soil Moisture

• Measure continuously, and at several depths

• Use multi-level to determine proper volume, THEN

• Use to sum/average graph to determine intervals as

season progresses

• Irrigation scheduling adjusted to soil characteristics

using these tools

Plant moisture status

• Measure to track stress and adjust refill point and

irrigation intervals as needed

Mark Greenspan, Ph.D.Advanced Viticulture, Inc.

Windsor, California707-838-3805

Web: www.AdvancedVit.comEmail: [email protected]