Application to volatile compounds on-line detection of plant stress

Application to volatile compounds on-line detection of plant stress 

Many components of the natural defence response in plants are VOCs, which are emitted as a response to pathogen attack. Their detection raises several difficulties due to their great variety, low concentration (generally in the parts per billion (10 ) or parts per trillion (10 ) range) and the rapidity of the emission processes, which can occur in a matter of a few minutes. 

One of the most sensitive methods to detect volatile compounds released by the plants is that of laser photoacoustic spectroscopy (LPAS), which permits the identification of many molecules signalling plant defence mechanisms (e.g. see Harren and Reuss (1997)). The technique is based on the photoacoustic effect, i.e. the generation of acoustic waves as a consequence of light absorption the general principles of photoacoustic spectroscopy were briefly outlined in Section 5.3. 

Looking at these values one can appreciate the versatility of applications of LPAS not only in plant 

The ability of the technique to follow the process in real time (data are registered every 2 min), together with its high sensitivity (variations of few picolitres per minute can be detected), are remarkable. 

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