The synergistic effects of hydro and hormone priming on seed germination, antioxidant activity and cadmium tolerance in borage

This research investigated the effects of priming with water for 24 hours and hormone-priming with different concentrations of gibberellic acid (GA3) (50, 100, 150 mg L–1) for 24 hours and hydro and hormone priming techniques either alone or in combination on the germination, growth and biochemical properties of borage seedlings under cadmium stress conditions. The results showed that cadmium stress reduces seed germination and seedling growth indices. Seed priming led to a significant increase in the germination percentage and rate, seedling dry weight and length, seedling vigor indices, as well as the catalase and peroxidase activity of borage seedlings under both cadmium stress and non-stress conditions. Among the priming treatments, the combination of hydro and hormone priming showed the greatest effects on the improvement of germination and seedling growth under cadmium conditions, significantly greater than those achieved with the individual uses of hydro or hormone priming. At all levels of cadmium stress, utilization of combined hydro and hormone priming led to a 0.9 to 11.53-fold, and 0.95 to 2.63-fold increase in seedling dry weight as compared with the control treatment and individual use of hydro or hormone priming, respectively. The highest activity of catalase and peroxidase enzymes in borage seedlings was obtained from seeds primed with the combination of hydro priming with 150 mg L–1 GA3, which was significantly higher than those of the other treatments. Generally, at all levels of cadmium stress, combined hydro and hormone (specially 150 mg L–1 GA3) priming had the most positive effects on seed germination, growth and biochemical properties of borage seedlings