the ultra-dried seeds were hydrated for 48 h in a desiccator containing saturated calcium chloride (CaCl2) solution (relative humidity was 35%), and then they were hydrated for 48 h in the other desiccator containing saturated sodium chloride (NaCl) solution (relative humidity was 75%) at ambient temperature of 20-30℃ before the experiment of seed germination process and physiological indices.