Non-thermal Plasma Activated Water for Increasing Germination and Plant Growth of Lactuca sativa L

Non-thermal plasma is widely considered as an effective technology for applications in agriculture. Particularly, numerous reports studies have highlighted the role of plasma-activated water (PAW) for seeds germination, plant growth, stress tolerance, and antibacterial ability. The present study investigated the effects of PAW on lettuce ( Lactuca Sativa L. ) seed germination and seedling growth. PAW was achieved by using an atmospheric pressure dielectric barrier discharge in Ar (50%) –N 2 (40%)–O 2 (10%) gas mixture for treatment time ranging from 5 to 30 mn. The physicochemical properties of PAW (temperature, pH, electrical conductivity, concentrations of nitrate, nitrite, and hydrogen peroxide) were evaluated. Results show that water-activated during moderate time, 10 to 20 mn, contains reactive oxygen and nitrogen species at relevant concentration levels to have active impacts on seed germination and seedling growth. Germination potential significantly increased by about 117%, 56%, and 77% after 15 mn of treatment, for the first 3 days, respectively, compared to control. For long time PAW (25–30 mn), the germination rate is either constant or decreases. Positive effects of PAW treatments were registered on the growth parameters of seedling including stem and root length, leaf weight, leaf area and chlorophyll content, and the vigor of seedlings. Chlorophyll content significantly increased by 220% for PAW-treated 15 mn and by about 165% for PAW-treated 20 mn, respectively, compared with control. Additionally, PAW induce morphological changes on lettuce seeds which are associated with oxidizing species leading to better water and nutrients uptake.