Early detection of leaf water stress is critical for precision
agriculture. Spectroscopy is well-suited for accurate measurement of
water stress in plant leaves and provides an effective technique for
nondestructive, rapid and accurate measurement. Water stress can
signify overall plant physiological health and is important for
agricultural assessment of nutritional health, diseases, crop quality
and other critical factors. Knowledge of plant health and water stress
can lead to precision irrigation strategies based on real data.

Water stress has an impact on a plant’s photosynthetic performance
and the severity decides whether or not a plant can recover from
damage inflicted with additional irrigation.

The PSR+ is a high resolution/high sensitivity field spectroradiometer
covering the full UV/VIS/NIR range from 350-2500nm. It is a rugged,
field portable instrument with all solid state photodiode arrays and
no moving parts for reliable operation. The PSR+ provides auto-
shutter, auto-exposure and auto-dark correction for one-touch
operation. It can be equipped with both direct attach lenses and fiber
mount FOV lenses. It is available with a range of accessories
including contact probe, Miniprobe, pistol grip, benchtop probe and
leaf clip. For measuring leaf water stress the unique leaf clip is an
invaluable resource. The leaf clip has a pushbutton trigger and a
separate tungsten halogen illuminator that rail mounts to the PSR+ -
keeping heat away from your sample during measurement to prevent
burnout. An integral swing-away reflectance panel provides for
convenient reference measurements.

A researcher can use the leaf clip to measure leaf water stress in
situ.  The resulting spectra can show the primary water absorption
feature wavelengths for  analysis of water stress: 760,970,1200,1450
and 1950 nanometers. Changes in the red edge that indicate water
stress (moving to shorter wavelengths) can also be noted as an
indication of less chlorophyll production. All spectra are saved as
ASCII files for use with third party software including ENVI, R2 and
chemometrics software. In addition, the DARWin SP Data Acquisition
software which controls the instrument includes pull-down menus for
19 vegetation indices including WBI (Water Band Index) and NDWI
(Normalized Difference Water Index).

An optional GETAC PDA has a digital camera and GPS and tags
photos, coordinates, voice notes and altimeter readings to your
 First in Full Range PDA Spectrometer, Spectroradiometer and Spectrophotometer Systems
Every Spectral Evolution instrument
includes DARWin SP Data Acquisition
software with 19 built-in vegetation
indices, including the Water Band Index
(WBI) and the Normalized Difference
Water Index (NDWI).
Measuring leaf water stress
 First in Full Range PDA Spectrometer, Spectroradiometer and Spectrophotometer Systems
1 Canal Street  ◊  Unit B1
Lawrence, MA 01840  USA
Tel: 978 687-1833  ◊  Fax: 978 945-0372

Copyright © 2012 Spectral Evolution, Inc
The leaf clip includes a built-in white reference and is designed to keep the heat from the illumination
away from your sample so that measurements can be accurate and non-destructive.
PSR+  works with our unique leaf clip for detecting plant stress in the field.
A spectra taken with the leaf clip and PSR+ showing the water absorption bands and the red edge.