Aachen, Germany
June 28, 2016

Our eyes perceive a leaf as green because wavelengths in the green region of the spectrum are reflected by pigments in the leaf, while the other visible wavelengths are absorbed. This same principle applies to wavelengths beyond the visible range and LemnaTec uses near infrared (NIR) cameras to measure the spectrum of absorption and reflection. This provides information about the water content of the plant’s tissue which is related to its developmental status, health and productivity.

In healthy vegetation, chlorophyll absorbs energy from blue and red light to fuel photosynthesis and thereby convert light energy into chemical energy. This chemical energy is stored, primarily in sugars, and forms the basis of production for all other constituents of the plant. Plant tissue with high water content reflects less near infrared radiation than tissue containing less water. In fact, NIR reflectance is inversely proportional to water content.

The following image shows how wheat dries down over time, changing the NIR-absorption of the leaves in the band between 1,450 and 1,600 nm. Blue/green colours represent high water content while yellow/red colours represent low levels.

By calibrating the NIR signals against actual water content readings from the samples, image characteristics can be translated into quantitative data. Since this process is non-destructive, plants can be monitored throughout an entire lifecycle resulting in detailed and accurate biological information.   

Website: http://www.lemnatec.de

Published: June 28, 2016