Wines & Vines Home
   
 
Welcome Guest
LOGIN |  CREATE ACCOUNT
 
ADVERTISEMENT
 
 
 
05.22.2013  
 

Grapevine Water Use From a Distance

Technology to remotely measure thermal energy in vineyards may help with irrigation management

 
by Paul Franson
 
 
napa valley tech group
 
This thermal image of vines shows a wide temperature difference among leaves. Source: Martin Mendez
Napa, Calif.—At a recent meeting of the Napa Valley Vineyard Technical Group devoted to irrigation, Martin Mendez, a senior research scientist at E. & J. Gallo Winery, said, “Management of water depends on what type of wine you want to make.”

An example: Mendez noted that Napa Valley generally starts with saturated soil in the spring and then drops to a threshold where growers start irrigating. The actual irrigation start date and in-season management should reflect the targets set for yield and grape and wine quality.

Too much water, of course, encourages vegetative growth. Therefore, the correct amount of water depends on the yield and quality desired based on the cultivar and style of wine.

“Deficit irrigation is widely used in later stages of ripening, but cutting water off before harvest isn’t the best solution,” Mendez said. It can stress the plants unnecessarily and reduces yield but doesn’t always improve flavors.

On the other hand, water may be wasted if applied where or when it’s not needed.

Unfortunately, growers may not have complete flexibility to irrigate. Availability of water for vine roots and protecting vines from frost by overhead spraying is increasingly looming as the largest issue facing grapegrowers in California. Grapevines will grow and produce grapes in many areas with the natural rainfall, but much falls at the wrong time (winter), varies by year and doesn’t necessarily provide optimum yield and quality.

Measuring water use  traditionally
Mendez, who has a Ph.D. focusing on irrigation management and how it influences grape yield and grape and wine quality, discussed new techniques for remotely measuring vineyard water use, and ways to correlate that to actual plant needs.

He started with a reminder of all the standard tools available to growers. Traditionally, these included visual clues like cessation of tip growth, soil moisture sensors and plant-based measurements like leaf water potentials (measured using a pressure chamber), sap-flow sensors or leaf porometers that measure leaf stomatal conductance.

These tools often have been used to estimate plant evapotranspiration (ET) using reference coefficients, a process that invokes controversy as it’s not related to the specific site and therefore does not always reflect the intrinsic characteristics of each vineyard.

Moreover, it’s difficult to find representative leaves or vines, as vineyards are largely variable in terms of soil texture, rooting depth and other characteristics that affect vine growth, yield and grape and wine quality.

Remote sensing becomes practical
More recently, remote sensing using thermography and energy balances have become practical for assessing large areas instead of individual leaves or vines.

They operate on a simple principle: Transpiring plants have lower leaf temperature than those that aren’t giving off water. In fact, Mendez said that there is a linear correlation between stomatal conductance and temperature; you can calibrate measurements with a leaf covered with water vs. one covered with Vaseline, which inhibits transpiration, although a more practical approach is to look at the difference between air and leaf temperature on a larger scale.

An expensive thermo graphic camera flown over the vineyard, or even tied to a balloon or installed in a satellite, can measure temperature and locate warm and cool areas (i.e, those with less or more water being transpired).

Another approach to remote sensing are vegetation indexes, perhaps the most commonly used being NDVI (Normalized Difference Vegetation Index), which can be used to estimate plant leaf area based on the different reflectance of light from plants at different wavelengths.

One limitation of remote sensing is the impact of bare ground or cover crops that can skew readings of the measured indices, though a solar array on the ground can provide an indication of solar activity for compensation.

It’s also important to differentiate between actual vine evapotranspiration (ETa) from potential (ETp), which is more commonly referenced. One approach is SEBAL (Surface Energy Balance Algorithm for Land), which combines spectral radiance readings from satellite-based sensors with actual meteorological data to calculate the energy balance at the earth’s surface. It produces water consumption, or actual evapotranspiration and biomass production of agricultural crops and native vegetation. Another energy balance model is METRIC (Mapping Evapo-Transpiration at high Resolution with Internalized Calibration), developed by Dr. Rick Allen of the University of Idaho.

In sum, Mendez noted that methods of evaluating proper irrigation levels are evolving from visual clues and vine and soil-based measurements to large-scale monitoring via remoter sensing. This can give a better indication of vineyard health and account for differences between and within vineyards, while avoiding the uncertainty caused by extrapolating a vineyard’s health from perhaps unrepresentative samples.

SHARE »
Close
 
Currently no comments posted for this article.
 
CURRENT NEWS INDEX »


 
Wines & Vines Home
 
866.453.9701 | 415.453.9700 | Fax: 415.453.2517
65 Mitchell Blvd., Ste. A San Rafael, CA 94903
info@winesandvines.com
Wine Industry Metrics
 
Off-Premise Sales » Month   12 Months  
March 2013 $546 million
5%
$6,988 million
7%
March 2014 $572 million $7,451 million
     
Direct-to-Consumer Shipments » Month   12 Months  
March 2013 $177 million
20%
$1,483 million
10%
March 2014 $213 million $1,634 million
     
Winery Job Index » Month   12 Months  
March 2013 253
15%
166
27%
March 2014 292 210
     
 
MORE » Released on 04.14.2014
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Wines & Vines
Packaging Conference
 
Learn More »
 
 

Practical Winery & Vineyard Library
 
Search the PWV archive »
 
 

Direct To Consumer
Wine Shipping Report
2014
 
Download full report »
 
 

CALENDAR
  • April 23-26
     
    CABs of Distinction in Paso Robles
     
  • April 26
     
    Siera Pelona Valley wine festival
     
  • April 27
     
    TAPAS Grand Tasting
     
  • April 29
     
    Rendez-Vous Laffort
     
  • MORE »
 

READER COMMENTS
 
Article: Starbucks Expands Wine Sales to More Cities »
 
Pretty amazing that the 1st wines chosen are from Argentina, Italy, and New Zealand! I...
Reader: Jacques Brix
 
Article: Starbucks Expands Wine Sales to More Cities »
 
Given Starbucks commitment to sustainability and global responsibility, I expect this move could be a...
Reader: Guest
 
Article: What to Do About Red Blotch »
 
There is NO correlation with planting density. Also FPS is working on the problem. New...
Reader: Guest
 
Article: Premiere Wine Auction Nets $5.9 million »
 
Thanks for letting us know Janet, we've updated the story. Cheers
Reader: Andrew Adams
 
Article: Will Barrels Go the Way of Floppy Disks? »
 
Fun piece. Particularly enjoyed the three clearly superior attributes of standard barrels, including looking cool...
Reader: Tom Gable
 
 


Directory/Buyer's Guide — Your Wine Industry Marketplace
 
 
WINERY SEARCH
 
 
Advanced Search »
SUPPLIER SEARCH
   by Product
 by Company Name or Brand
 
Browse by Category »
2014 Directory/Buyer's Guide
The Wines & Vines Directory and Buyer's Guide
 
 
EXPANDED ONLINE SEARCH INCLUDED WITH PURCHASE
 
ORDER NOW »
 
LEARN MORE »
 
 
Wines & Vines Magazine
 
 
LEARN MORE »
 
SUBSCRIBE »
 
Digital Edition Now Available!
Wines & Vines Digital Edition Now Available
 
LEARN MORE »
 
ORDER NOW »
 
 
The Wines & Vines Online Marketing System
 
The Industry Standard winery marketing application
 
FREE LIVE DEMO »
 
VIEW VIDEO »
 
 
 
 
Latest Job Listings
 Estate Ambassador
 Napa, CA
DTC, Tasting Room and Retai
 Northern California Sa...
 Fresno, CA
Sales and Marketing
 Northern California Sa...
 Bakersfield, CA
Sales and Marketing
 Pt Tasting Room Help A...
 Napa, CA
DTC, Tasting Room and Retai
 Assistant Winemaker
 Lompoc, CA
Winemaking and Production
 Customer Service Repre...
 Fairfield, CA
General Administration and
 Tasting Room Sales Ass...
 Rutherford, CA
DTC, Tasting Room and Retai
 2014 Harvest Intern
 Sherwood, OR
Winemaking and Production
 Business Systems Analy...
 Lodi, CA
General Administration and
 On Premise Sales Repre...
 Chicago, IL
Sales and Marketing
 
More Job Listings >>
Follow Us On:
 
 





Home  |  About Us  |  Editors  |  Subscribe  |  Print Edition  |  Digital Edition

Advertise  |  Site Map  |  Contact Us  |  Privacy Policy
 
 
Copyright © 2001-2014 by Wine Communications Group, Inc. All Rights Reserved.
No material may be reproduced without written permission of the Publisher.
Wines&Vines does not assume any responsibility for any unsolicited manuscripts or materials.