Objective The study was carried out to evaluate the seedling emergence capacity and seedling quality of different rice varieties with submergence tolerance under submerged direct seeding mode.
Method In this study, 11 rice germplasm resources with submergence tolerance obtained from preliminary screening were used as materials for field submergence direct seeding(submergence depth: 5 cm) and wet direct seeding was set as control. Main seedling qualities including emergence rate, tiller number per plant, plant height, stem height, leaf age and root-shoot ratio were studied under submerged direct seeding. The differences in responses of different rice varieties to the emergence rates and agronomic traits of submerged direct seeding were compared and analyzed. Based on the agronomic traits of submerged direct seeding and wet direct seeding, the seedling quality at seedling stage was compared.
Result Submerged direct seeding had great influence on emergence rate and root-shoot ratio at seedling stage, and emergence rate could be used as an important index to evaluate the submergence tolerance under submerged direct seeding. The emergence rate was used as cluster analysis to evaluate the submergence tolerance of various varieties, and two materials with stronger submergence tolerance were selected, namely, Diaoliwang and Chaoanlongyan. After 25 days of submerged direct seeding, the tiller number per plant and leaf age of each variety at seedling stage decreased, while the root-shoot ratio increased. The plant height and stem height showed a decreased trend for the varieties with strong submergence tolerance, whereas the varieties with weak submergence tolerance showed a reversed trend.
Conclusion Under submerged direct seeding, the emergence rates and the agronomic traits were influenced significantly at seedling stage, especially the root-shoot ratio was influenced most at seedling stage.
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