Emergence and Seedling Establishment of Rice Varieties at Different Sowing Depths

Direct seeding of rice is an efficient and labor-saving planting method. Deep sowing during direct seeding may benefit rice, although it will influence seed germination and seedling establishment. In a pot experiment, thirty rice varieties were grown under two different sowing depths (0 cm and 2.5 cm) under dry-seeded conditions, and the germination rate and seedling establishment parameters were measured. The results showed that the seed germination rate and seedling emergence rate were higher than 90% at the 0 cm sowing depth, while under deep sowing, the seed germination rate, and seedling emergence rate were 77.70% and 50.97%, respectively. Rice varieties with seedling establishment rates > 80% and better growth under deep-sowing conditions were identified. In addition, variety, sowing depth, and their interaction significantly affected seedling establishment parameters. Parameters, such as the seed germination rate, seedling emergence rate, prophyll leaf length, first leaf sheath length, and first leaf length, which are highly related to sowing depth, were analyzed. The seedling rate was significantly positively associated with the seed germination rate, mesocotyl length, root length, root fresh weight, shoot fresh weight, and total fresh weight under deep sowing. An approach for screening rice varieties with tolerance to deep sowing is proposed.