Abstract
Plasma-activated water (PAW) is a sustainable and innovative alternative for agriculture, especially in controlled environments like greenhouses. Tomato and pepper are key horticultural crops worldwide, with a considerable part of their production in greenhouses. This study examined the effects of PAW irrigation on seed germination, plant growth, and oxidative stress in tomato and bell pepper plants. PAW was activated for up to 15 min using a 1 L capacity plasma reactor based on a glow-type discharge in air with water-cathode. The concentration of nitrogen compounds and the energy efficiency of synthesis obtained with the reactor were moderately high (5.4 mM and 60 nmol/J, respectively). The most notable effects of PAW were observed in bell pepper. The germination percentage in bell pepper increased by up to 26%, while no significant effects were found in tomato seeds. PAW irrigation significantly promoted plant growth, with dry weight increasing by up to 61% in bell pepper and 42% in tomato. Lipid peroxidation results showed no oxidative damage in either crop. The biochemical analysis of antioxidant enzymes (catalase, superoxide dismutase, and guaiacol peroxidase) confirmed that plant defense systems responded adequately to PAW irrigation. These results highlight PAW's potential as an innovative and eco-friendly alternative in agriculture.