Salinity stress is one of the most serious factors limiting crop productivity. Recently, various compounds exploited to alleviate the plant stress. Polyamines are recognized as groups of phytohormones to regulate the plant tolerance to salt stress, depending on its concentration and plant species. For this reason, an experiment was carried out in a factorial design with two factors include salinity, which was applied to the root medium as NaCl (0, 40, 80 and 120 mM), and polyamines priming (Putrescine, Spermidine and Spermine) in 40 ppm concentration for 24 h. Results revealed that salinity significantly decreased final germination percentage, energy of germination and vigor index. Salinity stress also delayed seed germination processes, in which mean germination time and T50 increased. Seedling length, seedling fresh and dry weight were also negatively affected by salt stress. Seed priming with polyamines improved all of the mentioned traits. In this respect, spermidine and spermine were superior treatments. Biochemical analysis of borage plants showed that polyamines stimulated the catalase and Superoxide dismutase activity under salt stress, which led to amelioration of stress-induced Malondialdehyde accumulation. Total protein and soluble sugar contents also are negatively affected by salinity, however, polyamines alleviated the adverse effects of salinity on proteins only. In general, these results indicated that polyamines priming (especially Spm and Spd) could be as an effective method to improve salt stress tolerance of borage seeds.
