Exploring the Effects of Diluted Plasma-Activated Water (PAW) on Various Sprout Crops and Its Role in Autophagy Regulation

Abstract

Plasma-activated water (PAW) has gained attention across agricultural, medical, cosmetic, and sterilization fields due to its production of reactive oxygen and nitrogen species (ROS and RNS). Although PAW has been primarily explored for seed germination and sterilization in agriculture, its role as a nutrient source and physiological regulator remains less understood. In this study, PAW generated by a surface dielectric barrier discharge (SDBD) system contained approximately 1000 ppm nitrate (NO3−) and was designated as PAW1000. Diluted PAW solutions were applied to sprout crops—wheat (Triticum aestivum), barley (Hordeum vulgare), radish (Raphanus sativus), and broccoli (Brassica oleracea var. italica)—grown under hydroponic and soil-based conditions. PAW100 and PAW200 treatments enhanced growth, increasing fresh biomass by up to 26%, shoot length by 22%, and root length by 18%, depending on the species. In silico analysis identified nitrogen-responsive transcripts among several autophagy-related genes. Consistent with this, fluorescence microscopy of Arabidopsis thaliana GFP-StATG8 lines revealed increased autophagosome formation following PAW treatment. The growth-promoting effect of PAW was diminished in atg4 mutants, indicating that autophagy contributes to plant responses to PAW-derived ROS and RNS. Together, these findings demonstrate that diluted PAW generated by SDBD enhances biomass accumulation in sprout crops, and that autophagy plays a regulatory role in mediating PAW-induced physiological responses.