A team of researchers in Greifswald has demonstrated in a study that plasma-treated water enables cereal plants to respond better to drought stress and thus to extreme weather conditions such as droughts. To this end, individual parameters that are considered indicators of oxidative stress in a plant were compared with each other and evidence of a link between plasma treatment and plant strengthening was formulated.
The research team is part of the alliance 'PHYSICS FOR FOOD – A REGION THINKS AHEAD!', which was initiated by the Neubrandenburg University of Applied Sciences, the Leibniz Institute for Plasma Science and Technology (INP) in Greifswald and other business partners in the region. The alliance is researching environmentally friendly physical methods for the agricultural and food industries in order to find an alternative answer to the challenges of the future.
Cold atmospheric pressure plasma is a physical method for reducing the use of chemical agents. It consists of electrons, ions, neutral atoms and molecules, as well as reactive species. The plasma-treated water is produced at the INP in Greifswald.
The results of the study by researchers from the INP and the Institute of Botany and Landscape Ecology at the University of Greifswald in the PHYSICS FOR CROPPING SYSTEMS flagship project have now been published in the Journal of Plant Growth Regulation:
Barley plants in a greenhouse were sprayed with both demineralised, plasma-treated water and demineralised water alone and then exposed to oxidative stress such as drought. The researchers analysed the effects of these treatments in the leaves and roots.
They found evidence of links between the previously identified benefits of direct plasma treatment – e.g. the inactivation of fungi, viruses or bacteria that cause plant diseases and the promotion of germination and growth – and the influence on the antioxidant system. When water is treated with plasma, low concentrations of hydrogen peroxide and nitrogen monoxide are produced, among other things. Both molecules stimulate the plant's signalling network to produce enzymatic and non-enzymatic antioxidants, i.e. to combat oxidative stress. The parameters for oxidative stress were compared in both the leaves and the roots – in both cases with and without plasma treatment – and evidence of correlations was documented.
Prof. Dr. rer. nat. Christine Stöhr, Professor of Plant Physiology at the Institute of Botany for Landscape Ecology at the University of Greifswald and head of the research group, sums up: "The plant obtained the components it needs to respond appropriately to oxidative stress from the plasma-treated water. The question remains whether further processes are taking place. The metabolism in a plant is extremely complex. We are now looking at the gene expression of the plant using the " " method to analyse which genes are activated that cause these reactions."
Another remarkable finding was that the effect of the plasma-treated water was detectable from the leaves to the roots. However, it also emerged that the antioxidants in the plant, which are enhanced by the plasma water, were only detectable when the plant was actually exposed to drought stress. This is referred to as a priming effect. Priming means inducing a physiological state in the plant so that it can respond better and more strongly to abiotic stress, such as drought, and biotic stress, such as pathogens. This type of training could well be useful for barley in the future, and plasma-treated water could be used as a priming agent.
Dr Henrike Brust, biologist at the Leibniz Institute for Plasma Science and Technology (INP) and member of the research group, adds: "This study shows that plasma-treated water definitely has an effect on plant physiology. Now we need to find out exactly how the processes in the plant work to make them more responsive to oxidative stress."
The results of the study are encouraging. The researchers in the PHYSICS FOR FOOD alliance are therefore continuing to pursue this approach in order to help strengthen plant resilience to climate change.
About PHYSICS FOR FOOD
The Neubrandenburg University of Applied Sciences, the Leibniz Institute for Plasma Science and Technology (INP) and commercial enterprises launched the project 'PHYSICS FOR FOOD – A REGION THINKS AHEAD! Since then, the alliance has been working with numerous other partners to develop new physical technologies for agriculture and food processing. These technologies utilise atmospheric pressure plasma, pulsed electric fields and UV light.
The aim is to optimise agricultural raw materials and reduce pollutants in food production, reduce chemical agents in seed protection and strengthen plants against the effects of climate change. It is funded by the Federal Ministry of Education and Research as part of the 'WIR! – Change through Innovation in the Region' initiative (funding code 03WIR2810).
