Measuring plant health in the field can be done with a field portable spectroradiometer from Spectral Evolution. The PSR+ is a full range 350-2500nm NIR spectrometer that is ideally suited for taking vegetation measurements using our unique leaf clip and ILM-105 illumination source.
Many factors can affect plant health:
Lack of water
Lack of nutrients
Using a PSR+ agricultural spectroradiometer and leaf clip, you can scan individual plant leaves and measure health and stress by looking at the red edge in the 680-760nm range of the leaf spectra. The red edge is usually centered around 720nm. In healthy plants the red edge shifts to the longer wavelengths - to the right on the spectra. There is also a deeper absorption feature at 680nm indicating there is more photosynthesis going on (more light being absorbed). In a stressed plant, the red edge is further to the left - toward the shorter wavelengths and there is less absorption and more reflectance in a feature at 630nm.
The PSR+ combines high resolution with high sensitivity as well as rugged construction for field use. All solid state arrays mean no moving optical parts for greater reliability. Lightweight and with 2 slide-in lithium-ion batteries for a full day in the field, the PSR plus is designed for single-user operation. The leaf clip has an external trigger for ease-of-use and an external illumination source to keep heat away from your samples.