2016 Volume 85 Issue 3 Pages 253-259
A laboratory experiment was conducted to examine the effect of draining just after seeding compared with flooded condition on emergence and seedling establishment of rice with several treatments, such as temperature (21/13ºC and 18/10ºC of day/night) and soil reduction (reduced soil by adding rice straw and normal). Methylene blue was used to examine the soil reduction. The soil and the vicinity of the seeds in draining treatments maintained an oxidative condition during the experiment even in reduced soil, while soil reduction proceeded in flooded treatments. The emergence percentage was lowered in flooded treatment, especially under the combination of lower temperature and reduced soil. Establishment percentage was lowered in reduced soil, but it was significantly higher in draining than in flooded treatments. The period from emergence to first leaf elongation was 2-3 days in draining treatment, while over 7 days in flooded treatments. This quick elongation of first leaf was considered to be important for stable establishment. Also in the field experiment, draining treatment for 12-13 days just after seeding until confirmation of emergence and root elongation showed better establishment and seedling growth, and resulted in higher grain yield compared with the flooded treatment. The difference in daily mean soil temperature at one cm under the soil surface between draining and flooded treatments was negligible. These results indicate that draining management is effective for high and stable establishment of seedlings even in Hokkaido.
