Optimized atmospheric air cold plasma seed treatments differentially enhance plant growth and herbivore resistance in soybean (Glycine max) and sorghum-sudangrass (Sorghum x drummondii)

Atmospheric air cold plasma treatments (cold plasma; CP) have emerged as a promising technology in various fields, including medicine, agriculture, and environmental sciences. While CP treatment has been optimized in many fields, we lack empirical data on the efficiency and effectiveness of CP treatments in deterring insect herbivory, a recent development in CP application. Needless to say, by fine-tuning parameters such as plasma discharge method, exposure time, source gas, and input voltage, researchers can enhance the desired effects while minimizing any potential side effects. Reactive oxygen and nitrogen species (ROS and RNS) generated during CP treatments can potentially play a crucial role in enhancing plant defense mechanisms and inhibiting herbivore growth, as they have been associated with plant signaling pathways against insect herbivores. To understand the differential effectiveness of various CP treatments on plant and insect herbivore traits, soybean seeds ( Glycine max ) and sorghum-sudangrass seeds ( Sorghum x drummondii ) (sorghum) were treated under three different voltages and time exposures using two different plasma generation reactors: pin-to-plate and plasma jet. We then evaluated the effects of CP seed treatment on herbivory using two different lepidopteran pests: fall armyworm (FAW) ( Spodoptera frugiperda ) on sorghum-sudangrass and soybean looper (SBL) ( Chrysodeixis includens ) on soybean. The results showed that CP had significant positive effects on plant growth and development, alongside negative effects on herbivore growth and development. More prominently, the results revealed that the effect of CP varies significantly based on the reactor and has differential effects on soybean and sorghum. Collectively, these findings show the need for continuous optimization of CP treatments to fully harness their potential while ensuring their safe and effective application across different domains. • Atmospheric air cold plasma (CP) treatment can differentially enhance plant traits. • Use of CP as a pest management strategy against herbivores is underexplored. • CP treatment negatively affected growth and development of Fall armyworm. • CP treatments positively influenced soybean growth and development. • Optimizing CP input voltage and time exposure is necessary to maximise its potential.