2018 Volume 87 Issue 2 Pages 140-146
To improve seedling establishment of non-coated rice seeds direct-seeded with a puddling seeder, the effects of germination level at the time of seeding on seedling establishment and early growth were investigated. Seeds with coleoptiles shorter than 1 mm (pre-germinated seeds), coleoptile-elongated seeds, root-elongated seeds, coleoptile-removed seeds, and root-removed seeds (all non-coated seeds) were seeded in a growth cabinet, and seedling emergence, establishment, and growth were assessed. Seeds with elongated coleoptiles and roots exhibited faster seedling emergence and better seedling establishment and better growth than the pre-germinated seeds. The root-removed seeds also showed similar seedling establishment, but the coleoptile-removed seeds showed poor seedling establishment. This suggests that root-elongated seeds are more useful than the coleoptile-elongated seeds, for direct seeding using a seeding machine. To elucidate the effect of the root-elongated seeds used for direct seeding on seedling establishment and early growth, field experiments were conducted in 2015 and 2016. The root-elongated seeds and pre-germinated seeds were seeded in early April and usual mid-May. The root-elongated seeds showed improved seedling establishment and early growth in both experiments with different seeding time, optimum- and low-temperature conditions. Therefore, using root-elongated non-coated seeds is considered to improve seedling establishment in direct seeding with a puddling seeder.
