Electrohydraulic Discharge Induced Gas-Liquid Interface Plasma for Seed Priming in Hydroponics

Abstract

Seed priming is a vital process in agriculture, improving germination and uniformity. This study presents an innovative seed priming approach using electrohydraulic discharge plasma (EHDP) techniques, inducing gas-liquid interface plasma on wet seeds—EHDP-wet seed surface priming—and on seeds submerged in water—EHDP-immersed seed priming. These techniques were applied to green oak leaf lettuce (Lactuca sativa L.) seeds. The results show that EHDP-immersed seed priming significantly enhances germination rate (98.3%, compared to a control of ~80%), germination uniformity (~5 hrs compared to a control of ~15 hrs), and the Mean Germination Time (MGT) (~1.87 days compared to a control of ~2.5 days). The presented method exploits three primary plasma formation regions, each generating distinct reactive oxygen and nitrogen species (RONS) and ions that interact differently with the seeds. RONS, particularly hydrogen peroxide (H2O2), nitrate (NO $_{3}^{-}$ ), and nitrite (NO $_{2}^{-}$ ), play crucial roles in germination, vigor, nutrient uptake, and hormonal regulation, thereby effectively breaking seed dormancy. Potential plasma treatment damages were addressed, revealing no significant variations in plant height, root length, leaf diameter, leaf thickness, or leaf numbers between control and plasma-primed groups, affirming EHDP plasma priming’s safety. This study underscores the EHDP plasma priming’s potential to enhance seed germination and early plant growth, while also reducing contamination risks without negatively impacting plant health and development, indicating its transformative potential for the agricultural industry.

Keywords

• Atmospheric-pressure plasmas
• arc discharges
• electrohydraulic discharge plasma
• gas-liquid interfacial plasma
• seed priming