Cold plasma seed treatment processes and the role of contact surfaces to improve germination.

What is it about?

Cold plasma technology is effective in improving seed germination properties, especially if dielectric barrier discharges are used. For example, a He-N2 plasma treatment of 20 min reduces the median germination time of lentil seeds from 1420 min to 1145 minutes, i.e. a gain in vigor of 275 min (i.e. +19.4%). . Basically, this result depends on the plasma-seed interaction and therefore on the contact surfaces between the seeds themselves as well as between the seeds and the plasma. According to a topography modelling carried out under Blender, it appears that each seed is exposed to 92% to the plasma, which means that 8% of the external surface remains unexposed during a treatment. On the other hand, the realization of two consecutive treatments separated by an agitation of the seeds, leads to a significant increase in this surface exposure as it increase from 92% to 99%. In other words, seeds outer surface exposed to plasma can increase from 92% (single plasma exposure time of 20 min) to 99% (two consecutive plasma exposure times of 10 min each). This results in improved germination rates and median germination times while "plasma" conditions remain unchanged. The article provides also more information with alternative configurations including shaking which offers additional benefits.

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Photo by Markus Spiske on Unsplash

Photo by Markus Spiske on Unsplash

Why is it important?

This article is important from an engineering point of view because it specifies some technical methods and tricks for obtaining the best germination rates and the shorter germination times without increasing energy expenditure. Moreover, certain elements can be transposed to other applications, in particular the catalysis or the upgrading of gaseous effluents.