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Smart-Phone Based Image Analysis to Assess Vine Water Stress


Summary

Objective

To evaluate a range of potential sensor/analysis options to assess vine moisture stress and develop an app to allow the most promising system to be easily used by growers.

This system will provide vineyard managers with better information on the water status of their vineyards; which in turn will allow better irrigation decisions to be made to improve the use of irrigation water and produce higher quality fruit.

Background

A range of methods are available for the assessment of vine water status. However, none currently meet the portability and ease-of-use requirements for wide scale adoption. An easy, portable and cost effective system for the direct and real time assessment of vine water status remains a challenge for all agricultural industries. 

Stem water potential is generally considered the benchmark for assessment of plant water status, including vines. However, a number of limitations, including the extensive labour requirements, have limited its use in Australian viticulture.

Smart phones are a ubiquitous business tool and are the ideal mount for a plant based water sensor, given their portability and ease of access to software updates. They are generally equipped with high resolution cameras, or can have specialist sensors such as microscopes, stereo cameras, thermal cameras or spectrometers attached. 

The development of a smart phone based system to assess water stress in vines would promote the broader uptake of water stress monitoring across the viticulture industry, potentially improving water use efficiency and fruit quality.

Research approach

The field performance of four smart phone based methods of estimating vine water status will be compared against measurements of midday stem water potential, stomatal conductance and canopy temperature:

  • Thermal camera images will be used to calculate a Crop Water Stress Index. A portable and rapidly deployable system to provide wet and dry reference temperatures will also be developed.
  • A SCiO spectrometer will be used to capture reflectance at specific wavelengths, to calculate the Water Band Index.
  • Image analysis techniques will be developed to automatically locate the stomata in the magnified image and measure how open they are. 
  • A camera-based leaf assessment using stereo vision to build a depth map which represents the scene in three dimensions. 

Sector benefits

This project has the potential to provide inexpensive, easily accessible tools to assist grape growers to manage water stress for positive outcomes, increasing both on farm returns and winery returns as the result of improved and more consistent grape and wine quality.