The effect of hydro and osmopriming on alfalfa seed germination and antioxidant defenses under salt stress

Seeds of two alfalfa (Medicago sativa L) varieties, cv. Hamedani and Yazdi, were used to investigate the effects of osmo- and hydro-priming on seed germination, growth parameters, biochemical changes and antioxidant enzymes activities under high-level salt concentration (150 mM NaCl) stress. Seeds were primed with water and mannitol (4%) for 12 h at 25 +/- 1 degrees C. Ten-day-old seedlings obtained from seeds primed with mannitol (4%) and water showed more growth with respect to root and shoot length in comparison with seedlings obtained from non-primed seeds. The results showed that germination percentage was significantly higher than that of the unprimed seeds after priming. The priming treatment significantly enhanced the activities of catalase (CAT), peroxidase (POD), superoxide dismutase (SOD) and proline content and reduced the malondialdehyde (MDA) accumulation and electrolyte leakage under the salt stress condition. The results suggested that osmo- and hydro-priming were effective methods to enhance the ability of salt tolerance and to improve seed germination and seedling growth of alfalfa under high salt concentration stress condition. It seems that, these priming methods could be applied in alfalfa production in high saline soils in the future.