Abstract: Japonica rice (Xingshi) and indica rice (Guizao 2) seeds were used to investigate the vigor and some physiological indexes after stored at -20℃ and ambient temperature（25℃）for five years. The results showed that moderate drying could prolong the storage life of rice seeds. The indica rice (Guizao 2) seeds had strong ultra-dring tolerance. When moisture content fell to 2.4%, the vigor index of Guizao 2 seeds, compared with that of 5.8%, had no obvious change. On the contrary, the vigor index of Xingshi seeds decreased rapidly. The study also indicated that there were positive correlations between the antioxidation system, soluble proteins, heat shock proteins and vigor index. The content of abscisic acid (ABA) and phospholipase activity increased continuously during dehydration. The content of soluble proteins of Xingshi was more than that of Guizao 2, which might be a key reason for that Xingshi seeds are not tolerant to ultra-drying.

Key words: Oryza sativa, Seeds, Moisture content, Storage life, Physiology and biochemistry