Genotype-specific responses of sorghum (Sorghum bicolor (L.) Moench) to surface discharge cold plasma seed treatment

Cold plasma is an innovative non-thermal technology increasingly explored in agriculture as a sustainable alternative to chemical seed treatments. It has the potential to improve seed performance and promote uniform crop establishment. This study evaluated the effect of surface discharge cold plasma treatment on seed germination and early seedling growth of two sorghum (Sorghum bicolor (L.) Moench) genotypes, White Sorghum and Red Sorghum. Seeds were exposed to dielectric barrier discharge cold plasma under atmospheric air for 1, 2, 3, and 5 min, along with an untreated control. The experiment was conducted in a Factorial Completely Randomized Design (FCRD) with five treatments and four replications. Germination percentage, root length, shoot length, fresh weight, dry matter production, and Seedling Vigour Index I and II were recorded and analyzed. Results demonstrated that short-duration plasma exposure significantly improved germination and seedling growth compared with control seeds, although responses varied among genotypes. Red Sorghum recorded the highest germination percentage (88%) at 2 min plasma exposure, whereas White Sorghum recorded the highest germination percentage (94%) at 3 min exposure. Prolonged exposure (5 min) reduced germination in both genotypes, indicating a dose-dependent response. Root length, shoot length, dry matter production, and vigour indices were the most responsive quantitative traits and showed strong positive correlations with germination percentage. Principal component analysis further confirmed that biomass- and vigour-related traits contributed substantially to treatment variability among genotypes and exposure durations. Overall, 3 min plasma exposure in White Sorghum and 2 min exposure in Red Sorghum were the most effective treatments for enhancing germination and early seedling establishment under controlled conditions.