Non-Thermal Dielectric Barrier Discharge (DBD) plasma affects germination of coffee and grape seeds

Seeds of many plant species often fail to germinate even when moisture and temperature are adequate because they are dormant. Commonly, these seeds need to be exposed to cold temperature or some other forms of stress to release their dormancy. In the nursery, they use strong acids or hot water for the same purpose. Low-temperature plasma has been shown to be effective in improving germination of seeds. In the present study, we have used an atmospheric pressure dielectric barrier discharge (DBD) operated in Helium gas to treat dormant grape and coffee seeds. The seeds were treated at fixed power of 50 W for different durations (control, 30s, 60s, 120s and 240s). Exposure to plasma has affected germination rate and germination vigor of the seeds differently depending on the species. The germination rate of coffee seeds decreased after short exposure to plasma as compared to non-treated seeds. When the seeds were exposed to plasma for 120s germination was advanced but germination rate was the same as that of the control. However, for grape seeds, all plasma treatments increased germination rate as compared to the control treatment. Treating the seeds for 240s advanced germination by 10 days and more than doubled the rate of germination. The effect of plasma seems to be partly due to accelerated water uptake. Non-thermal plasma can enhance the vigor of coffee and grape seeds; this should improve seedling establishment and growth.