Plasma agriculture for pesticide reduction

We propose to investigate the optimum plasma conditions for boosting plant growth and protecting crop yield in the field, as a simple but effective method of enhancing food production (and therefore food security) whilst reducing the requirement for pesticides.

The effectiveness of plasmas in extending the shelf-life of packaged food has already been demonstrated by the commercial partner in this proposal (a spin-out of the University of Glasgow). There is compelling evidence that plasma treatments can have additional effectiveness in the crop growth cycle itself, not just in preserving the eventual harvest. Plasma treatment (direct and indirect) of seeds prior to planting can encourage early germination, inducing faster early leaf cover than non-treated seeds. This is because the plasma itself, together with the altered air chemistry produced by it, encourages the hard, protective seed coating to split, and simultaneously reduces competing organisms (bacteria and fungi) that may be located on or under that coating; additionally, the plasma has potential to generate micro-doses of nutrient for the developing plant by fixing the nitrogen locally. The end result is a seedling which produces leaf cover earlier than normal, depriving co-located competitor weed seeds of light, and so reducing the need for pesticides. As the plant develops and begins to fruit, the possibility of attack from adult insects is a continuous threat, sometimes devastating whole harvests: the Asian fruit fly (D suzukii) is a major threat to fruit crops across the US and southern Europe, and is beginning to gain a foothold in the UK. Unlike the traditional fruit-fly (D melanogaster), suzukii attacks whole, undamaged fruit, laying eggs which then destroy the the harvest. Cold plasmas generating ozone can kill adult fruit-flies of both types in a controlled laboratory setting, and has also been shown to be successful in killing larvae in the same context; even insects have to breath oxygen, and ozone damages the respiratory system. We proposed to explore the range of plasma conditions that can be effective in eradicating such pests in a more realistic environment, and because the ozone is generated from the ambient air, and is only transiently stable, there are no external pesticide chemicals required to be delivered to the site, nor is there any residue. This effective pesticidal treatment needs only the plasma electrode system and a source of electricity, which could be provided by solar or wind-power, and is therefore widely applicable - including potentially planetary space missions that need self-sustaining crop yields.