Abstract
Rice lines with a high seedling emergence rate were screened by sowing the seed 20 or 30 mm deep from the soil surface at 20°C or 25°C in a growth chamber, or placing the seeder-tape 20 mm deep from the soil surface in the field. As the gene sources of a high seedling emergence rate, we used Akamai from Japan, Arroz da Terra from Portugal, Dunghan Shali from Hungary, and Ta Hung Ku from China. However, these varieties had many inferior characters. To breed a practical cultivar with good agronomic characters in addition to a high seedling emergence rate, the Dontokoi or Kinuhikari were crossed with these varieties. From the hybrid progenies of Akamai and those of Ta Hung Ku, the lines with a high seedling emergence rate were selected by repeating the selection from early generations. From the hybrid progenies of Arroz da Terra and the those of Dunghan Shali, any lines with a high seedling emergence rate were not selected due to much trouble such as the frequent occurrence of leaf blast. For selecting the lines with a high seedling emergence rate, selection should be repeated from early generations. However, the lines selected for a high seedling emergence rate had inferior grain yield and quality, and further attempts of selecting the lines with high brown rice yield and good grain appearance are necessary.
