Abstract: An experiment was undertaken to study the effects of ascorbic acid (AsA) priming on oat seed germination and seedling growth under salt stress conditions. Oat seeds were primed with different AsA concentrations (0, 0.5, 1.0, 1.5 and 2.0 mmol·L^-1) and then germinated in different concentrations of NaCl stress (0, 50, 100 and 200 mmol·L^-1). Changes in germination percentage (G_p), germination index (G_i) and mean germination time (MGT) were analyzed. Results showed that the G_p, G_i and MGT of oat seeds declined significantly under NaCl stress. With increasing AsA concentrations, G_p at first increased and then decreased under NaCl stress at 100 and 200 mmol·L^-1. However, the seeds’ G_i declined with increasing AsA concentrations, while their MGT increased. The effects of different concentrations of AsA and NaCl and their interaction on G_p, G_i and MGT were highly significant (P<0.01). The level of oat seed vigor was decreased by NaCl stress. However, priming with exogenous AsA promoted the vigor of salt-stressed seeds and this effect was closely related to the concentrations of AsA and NaCl. Optimal effects were reached at AsA concentrations of 1.0 mmol·L^-1 under NaCl stress at 100 and 200 mmol·L^-1. However, the germination time of oat seeds was prolonged by AsA priming under NaCl stress.

Key words: ascorbic acid, oat, priming, seed vigor, NaCl stress