Germination and early physiological responses of Mung Bean (Vigna radiata L.) to gibberellic acid seed priming under PEG-induced osmotic stress

Drought is a major abiotic stress factor that affects germination, seedling establishment, and early growth in legume crops such as mung bean (Vigna radiata L.). This study evaluated the effects of seed priming with gibberellic acid (GA3) at 200 ppm for 24 h on germination and early physiological traits of five mung bean cultivars (MB1–MB5) subjected to polyethylene glycol (PEG 6000)-induced osmotic stress at 0, 5, 10, and 20%. Seed surface sterilization and priming with either H2O (control) or GA3 were performed before the experiment. On the seventh day, the germination percentage (GP), tissue water content (TWC), seedling vigor indices (SVI-I and SVI-II), and early growth parameters such as root length (RL), shoot length (SL), root fresh weight (RFW), shoot fresh weight (SFW), root dry weight (RDW), and shoot dry weight (SDW) were evaluated. Increasing PEG concentration adversely affected germination and seedling growth across all cultivars. GA3 priming was associated with partial improvement in overcoming the detrimental effects of stress, as indicated by increased germination stability percentage, tissue water content, vigor indices, and growth parameters, particularly at 5–10% PEG concentration; however, these responses varied among cultivars. MB4 and MB5 generally maintained higher GP, TWC, and vigor indices, whereas MB3 exhibited greater sensitivity to osmotic stress. Overall, the findings indicate that the response to GA3 priming is strongly genotype-dependent and suggest that GA₃ seed priming may represent a practical, low-cost approach to support early seedling performance under moderate osmotic stress conditions in mung bean.