Effects of seed priming using cold argon plasma on enhancement of guar (Cyamopsis tetragonoloba) seed germination and growth under salt stress conditions

Salinity stress is a significant abiotic factor that severely hinders seed germination and early seedling establishment in numerous crop species. This study investigated the effectiveness of cold atmospheric argon plasma as an eco-friendly seed priming strategy to enhance salinity tolerance in guar ( Cyamopsis tetragonoloba L.). An atmospheric-pressure dielectric barrier discharge (DBD) system was used for the treatment. Seeds were exposed to argon plasma at four different discharge power levels: 1.2 W (0.40 A, 3 V), 2.04 W (0.51 A, 4 V), 3.05 W (0.61 A, 5 V), and 4.26 W (0.71 A, 6 V) for one minute, while untreated seeds served as the control. Both plasma-treated and control seeds were placed in Petri dishes under three different salinity levels (0, 50, and 100 mM NaCl), with each treatment replicated three times. The effects of plasma treatment were evaluated by assessing germination performance, seedling growth traits (including fresh and dry biomass, and shoot and root length), oxidative stress markers (such as malondialdehyde and other aldehydes), photosynthetic pigments (chlorophyll a, chlorophyll b, total chlorophyll, and carotenoids), and ion homeostasis (the contents of Na⁺ and K⁺). The results showed that argon plasma treatment significantly improved seed germination and seedling growth in a power-dependent manner under saline conditions. Moderate discharge power levels (2.04 W and 3.05 W) produced the highest germination percentages and the greatest root and shoot elongation. Additionally, plasma-treated seedlings exhibited reduced lipid peroxidation, a lower Na⁺/K⁺ ratio, and enhanced accumulation of photosynthetic pigments, indicating better regulation of oxidative stress and improved ionic balance under salinity stress. Cold atmospheric argon plasma priming at optimal discharge power levels effectively enhances early-stage salinity tolerance in guar. This method represents a promising, sustainable, and non-chemical approach for improving crop establishment in saline environments.