Low Temperature Treatment during the Imbibition Period for the Induction of Secondary Dormancy in Rice Seeds(Oryza sativa L.).

Abstract

The conditions of low temperature treatuent for the induction of secondary dormancy in Kasalath seeds were investi-gated. Secondary dormancy was induced if the seeds kept imbibed at 10°C: and 15°C for more than 10 days, but not at 5°C for even 20 davs in Kasalath seeds. The effective temperatures for the induction of secondary dormancy ranged from 8°C to 19°C. As a result of screening of varieties for secondary dormancy in 81 varieties originating from Japan, China, Philippines, India, Korea, Italy, Romania, 8 varieties originating from India were found to have the ability to go through secondary dormancy. Secondary dormancy of dehusked seeds was induced by low temperature treatment (15°C, 16 days). The secondary dormancy of the dehusked seeds was broken by peeling of pericarp and testa and treatuent with a sodium hypochlorite solution (2.5%, 10 min). These results suggested that the pericarp and the testa played an important role in the induction of secondary dormancy at low temperature.