Source: Wageninen University, Newsletter Plant Sciences Group June 2009

A research group comprising a large number of scientists from the Plant Sciences Group and the Jülich research centre in Germany has recently found three groups of volatile signal emissions for different types of damage. Roel Jansen of Wageningen UR Greenhouse Horticulture, part of the research team that started studying the detection of plant signal emissions in greenhouses, says the research is unique. The results could lead to the development of a detection system able to ascertain diseases at an early stage. The first phase of the research is almost finished and the results were published in the renowned scientific magazines Plant Biology and Annals of Applied Biology. The scientists plan to write a proposal for follow-up research.

The Wageningen scientist made grateful use of a gas chromatograph linked to a mass spectrometer. The gas chromatograph ensures that the various components are separated before the mass spectrometer analyses and identifies each component individually. It is a valuable installation that was purchased with donations for measuring plant transpiration. Gases emitted by plants when the temperature rises are the most common aromatic substances in the atmosphere. The research team found three groups of volatile signal emissions: Alcohols that are released when there is damage to a plant’s cell membrane, terpenes, oily substances released when the leaf hair is damaged, and a third group of hormones that are only released when plants experience stress, for instance in response to pathogens or insects. The concentration of these emissions in the air increases when a plant is under major attack.   

“We discovered which emissions are released under stress, caused for instance by pathogens, and in what concentration,” explains Roel Jansen. “This does not however reveal which disease we are dealing with. The method can currently be used by cultivators as an additional alarm system.” The research was performed in a small greenhouse of 40 m² in conditions that were far from ideal. A follow-up study would involve upscaling and eventually the development of a sensor that registers plant damage in greenhouses. “First we have to make some upscaling calculations,” Jansen continues. "What happens in practice can be studied, for instance, at Wageningen UR Greenhouse Horticulture in Bleiswijk." Jansen sees many more possibilities for sensor measurements in greenhouse horticulture in the future. “You could, for example, measure the plant’s growth stage."

Health monitoring of plants by their emitted volatiles: trichome damage and cell membrane damage are detectable at greenhouse scale
Annals of Applied biology, Volume 154 Issue 3, Feb 2009