Seed treatment with a DBD isolation barrier vacuum reactor. Using the drainage of the insulating barrier in the air at atmospheric pressure and room temperature, the effect of non-thermal plasma treatment of seeds on the development rate of seven broccoli cultivars cultivated in Mosul (Al Rashidiya) was investigated. The use of DBD at atmospheric pressure had a significant influence on germination and plant growth of the seven cultivars of broccoli from the seeds used for a period of 0.5, 1, 3, 5, 10, 15 minutes as compared to the control group. In comparison to the control sample, the favorable effect of plasma therapy on seedling growth for the timing (0.5 and 1 minute) had the optimum timing of exposing (broccoli) seeds to plasma from 3, 5, 10, 15 minutes. On the other hand, a negative effect was found after the seeds were exposed to plasma discharge for an extended period of time. The explanation for this might be due to the mechanical effect of the process of exposing seeds to plasma therapy, which resulted in a decrease in plant development and vitality when compared to the time of 0.5 minutes. These findings revealed that the newly constructed cold plasma reactors may considerably increase seed germination and plant development; however, the plasma processing duration for each seed must be tuned.