The Seedlings of Different Japonica Rice Varieties Exhibit Differ Physiological Properties to Modulate Plant Survival Rates under Submergence Stress.

Oryza sativais a major food crop in Asia. In recent years, typhoons and sudden downpours have caused field flooding, which has resulted in serious harm to the production of rice. In this study, our data revealed that the plant heights of the fiveJaponicavarieties increased during submergence. The elongation rates of TN14, KH139, and TK9 increased significantly during submergence. Chlorophyll contents of the five varieties significantly decreased after submergence and increased after recovery. Moreover, the chlorophyll content of KH139 was significantly higher than those of the other four varieties after recovery. The plant survival rates of the five varieties were higher than 50% after four-day submergence. After eight-day submergence, the survival rate of KH139 remained at 90%, which was the highest among the different varieties. The KH139 presented lower accumulation of hydrogen peroxide and the catalase activity than those of the other four varieties under submergence. Thesucrose synthase 1andalcohol dehydrogenase 1were induced in KH139 under submergence. The results presented that different varieties ofjaponicarice have different flood tolerances, especially KH139 under submergence was superior to that of the other four varieties. These results can provide crucial information for future research onjaponicarice under flooding stress.