Seed priming is a technique, which could improve the germination and establishment on the seeds, which were stored for 1.5 years under normal conditions. Therefore, this study was designed to evaluate the effect of different seed priming techniques, through un-soaked seed (control), Hydro-priming (soaked with distill water), 25 ppm of salicylic acid, 1.5% of Calcium chloride (CaCl2) and 3% of Potassium dihydrogen phosphate (KH2PO4) for 10 hours on seed germination%, seedling vigor and forage yield of two sudangrass genotypes (Piper black and Giza1). Two experiments (laboratory and field) were conducted at Sakha Agric. Res. Station, ARC, Egypt, during the two successive summer seasons 2019 and 2020.The results obtained indicated that 25 ppm of salicylic acid followed by 1.5% of CaCl2 and 3% of KH2PO4 treatments significantly affected on seed germination percentage, shoot and root length, fresh and dry seedling weight, seed vigor index, seedling vigor index, electrical conductivity and forage yield. Piper black genotypes were the highest in seed germination percentage, seed vigor index and seedling dry weight, but it was the lowest of electrical conductivity. It could be concluded that seed priming may serve as an appropriate treatment for accelerating the emergence so improve cutting and forage yield of sudangrass genotypes under study. Significant differences for fresh yield ton /hectare and piper black had higher fresh, dry and total yield ton /hectare than Giza1. Seed priming had highly significant differences at all cuts in the two seasons and SA25 ppm Salsilc acid treatment had superior and the highest dry yield in the two seasons, while control treatment was the lowest dry yield. Technique of seed priming led to improving germination, seedling characters, and forage yield under experiment conditions in comparison to non-primed seed (dry seed) in sudangrass seed stored for 1.5 years. Salicylic acid with 25 ppm had the highest values followed by1.5% of CaCl2 and 3% of KH2PO4 in the field conditions. Piper black genotype was the best as compared with Giza1 genotype, which gave the highest seed germination %, seedling vigor and viability. May be recommended for hydropriming seeds for 10 hours in water, which led to an increase in the total fresh yield by 30%, the highest seed germination percentage (94.00 and 92.50%), seed vigor index (20.79 and 19.84) and seedling vigor index (2194.11 and 2236.47) as practical seeds about 10 hours treatment.