Post-Germination Growth Stimulation in Mustard Greens (Brassica juncea L.) by Gaseous Products from Air Plasma Discharge

Plasma agriculture is an emerging sector with potential to improve agricultural yield and promote sustainable development. While several studies have demonstrated positive impacts on seed germination and post-treatment plant growth indices, the response of vegetative stage plants to plasma-derived components remains underexplored. In this study, the effects of gaseous products generated by dielectric barrier discharge (DBD) plasma on the vegetative growth of mustard greens (Brassica juncea L.) were investigated. Fourteen-day-old plants were exposed to plasma gas (indirect plasma) at varying frequencies, and growth parameters were monitored after 7 and 14 days of treatment. The results revealed that exposure to plasma gas for 30–45 min per day positively impacted root length, plant height, leaf area as well new leaf formation rate, with increases ranging from 16 to 30%. Additionally, plasma-exposed plants exhibited significantly higher chlorophyll content (33%), total protein content (15–20%), and dry/fresh weight ratio (17%) compared to the control sample. Interestingly, cold plasma treatment demonstrated a greater influence on root growth, while a negative effect was observed on aboveground parts at high exposure frequencies. These findings demonstrate that plasma treatment not only benefits seed germination but also has the potential to enhance crop yield through its stimulatory effects on vegetative growth.