Seed Germination and Coleoptile Growth of New Rice Lines Adapted to Hypoxic Conditions

We investigated the morpho-physiological traits of rice (Oryza sativa L.) during the germination and post-germination phases to explore avoidance of hypoxic conditions. We compared four lines selected for anaerobic germination (AG lines) with the variety IR42. The germination capacity of AG lines was higher than that of IR42. The germination percentages and coleoptile elongation differed among the four AG lines; IR06F459 showed the fastest germination and rapid coleoptile elongation. The coleoptiles of IR06F459 were significantly longer than those of IR42. The α-amylase activity in germinating seeds was significantly higher in IR06F459 than in IR42. At 2 days after sowing, the sucrose and glucose concentrations in germinating seeds were higher in IR06F459 than in IR42. These results show that IR06F459, an AG line with a long coleoptile, has high α-amylase activity and high sucrose and glucose concentrations in germinating seeds. These attributes partly explain its vigorous germination and coleoptile growth under hypoxic conditions.