Rice Breeding Lines with High Seedling Emergence from Direct Sowing into Submerged Soil

Abstract

We investigated the seedling emergence of rice seeds direct-sown in submerged soil. Germinated seeds with 0.4 to 1.4mm coleoptiles were placed at 1, 2, or 3 cm beneath the submerged soil surface in a growth chamber kept at 15 or 25°C. In the field, seeds held on seeder-tape were placed at 2 cm beneath the soil surface with a tape seeder. Cultivar Ta Hung Ku, from China, proved to be a new genetic resource, with the highest percentage of seedling emergence. We screened rice lines with a high seedling emergence rate by testing in the growth chamber and in the field. To breed a practical cultivar with good agronomic characters and a high seedling emergence rate, we crossed cv. Dontokoi with Ta Hung Ku. From the hybrid progeny, we selected the lines with a high seedling emergence rate by repeated backcross selection. However, these lines had inferior grain yield and quality, so further attempts at selecting lines with high yield and good grain appearance are necessary.