Effects of calcium cyanamide application on seedling emergence in the submerged direct-seeding of rice [Oryza sativa]

The application of calcium cyanamid is effective in the control of apple snail (Pomacea canaliculate (LAMARCK) ) that damage rice seedlings. An investigation of the effects of calcium cyanamide application on seedling emergence in the submerged direct seeding of rice was carried out in pot experiments. In the case of seeds not coated with calcium peroxide, seedling emergence was inhibited. On the other hand, seeds coated with calcium peroxide showed normal seedling emergence, and the emergence rate increased as the quantity of calcium cyanamid application increased. In pot experiments, the concentration of calcium cyanamid in the soil solution after puddling was measured during 4 days. Compared with the concentration of calcium cyanamid in the soil just after puddling, the concentration of calcium cyanamid in the soil 4 days later was decreased to 27% -17%. In the other experiment carried out, in which soil was incorporated with wheat straw, calcium cyanamid inhibited the seedling emergence of non coated seeds, but that of coated seeds was not.