Abstract
We previously reported a method of screening seed with a high seedling emergence rate in which seeds were sown 20 mm deep from the soil surface at 25°C in a growth chamber. In this paper, we propose a new method of evaluating seedling emergence under field conditions. In the field test, seeds held on seeder-tape were placed at a 20 mm depth from the soil surface with a tape seeder. As a preliminary test, 23 representative rice cultivars from various origins were tested for the rate of seedling emergence. The results showed a positive correlation between the percentage of seedling emergence in the growth chamber test that in the field test. To confirm this correlation, we repeated the test using 103 rice cultivars in total among them, 47 cultivars were from Russia, and 50 from Nepal. The results showed a significant correlation between the values obtained in the growth chamber and the field test. We found a new gene source with the highest percentage of seedling emergence “Ta Hung Ku” from China. Next, the seedling emergence of 347 F3 lines of Dontokoi/Ta Hung Ku were tested. It was difficult to select the lines with a high emergence rate in a growth chamber. However, it was confirmed that several lines had a higher percentage of seedling emergence than Ta Hung Ku in the field test.
