Improvement of Seedling Establishment of Rice Directly Sown in Early Winter by Chemical Treatment of Seeds and Use of Seeds in the Year of Harvest

Abstract

In cool climates, direct-sowing in early winter is an effective technique to improve rice productivity. We evaluated the effect of chemical treatment of rice seeds and harvest year on the seedling establishments. The most effective chemical was Thiuram (“Kihigen-R2-Furoable”; KG) among 26 combinations of chemical and material applications, which improved the seedling establishment approximately 17 points compared to the percent seedling establishment of non-treated control seeds (3～9%). In addition, harvest year strongly affected the seedling establishment; that is, the seeds sown in the year they were harvested gave better establishment than the seeds harvested in the previous year. The seeds sown in the year they were harvested showed greater dormancy than the seeds harvested in the previous year. An artificial dormancy-break treatment severely reduced the seedling establishment. These results showed that “KG” improved rice-seedling establishment, and that seed dormancy was important to attain high seedling establishment in direct sowing in early winter.