Measuring Chlorophyll Fluorescence

NIR spectroscopy can be used to measure chlorophyll fluorescence for determining the nutritional status of plants, as well as the presence of nutrients in water bodies. SPECTRAL EVOLUTION’S SR-3500 full range UV/VIS/NIR field portable agricultural spectrometer be used to perform chlorophyll measurements.

A green laser in the 530nm range can be used to excite the chlorophyll a and b molecules to fluoresce. The spectrometer can capture the scan showing the peaks. As samples are scanned, the difference between healthy samples and distressed samples can be seen in the difference in amplitude between the a and b chlorophyll peaks.

Measuring chlorophyll fluorescence can indicate plants that are stressed by lack of water, disease, or insect infestation. These measurements can be performed on forest canopies, crops, or single leaf samples.

For water samples, chlorophyll fluorescence can be used to determine water quality. Chlorophyll is essential to the existence of phytoplankton and algae. Monitoring chlorophyll levels can help researchers track algal growth, including blooms, and its influence on algal growth. Too much growth or bloom and subsequent crash depletes the dissolved oxygen level and leads to most fish kills. These blooms are most often the result of high chlorophyll conditions and high nutrients that can be caused by leaking septic systems, poorly functioning wastewater treatment plants, or fertilizer runoff. Measuring chlorophyll fluorescence using NIR spectroscopy is faster and more cost effective that using grab samples sent to a lab. The following images show examples of spectra collected by our spectrometers from healthy and distressed foliage.

The SR-3500 is a field portable, full range with a spectral range of 350-2500nm, ideal for vegetation, forest canopy, water body, climate, and agricultural research.