Comparison on seed dormancy between high dormancy maintainer line II112B and its parents in indica rice(Oryza sativa L.)

The forming and changing trend of seed dormancy and the influence of husk and embryo on seed dormancy were studied in Ⅱ112B and its parents,IR112-12 and Ⅱ-32B in indica rice(Oryza sativa L.).Ⅱ112B and IR112-12 were a maintainer line and a restorer line,respectively,with high seed dormancy index.Ⅱ-32B was a maintainer line with low seed dormancy index.Heritability of seed dormancy was studied by using P1,P2,F1,F2,B1,B2 generations of Ⅱ-32B/IR112-12 and Ⅱ-32B/Ⅱ112B.Results showed that in Ⅱ-32B,seed dormancy index at the 20th day after heading was 25.22%,which declined slowly with the seed maturity,and disappeared at the maturing phase.While in Ⅱ112B and IR112-12,seed dormancy index at the 20th day after heading were 88.89% and 100%,respectively,always keeping at a high level with the seed maturity gradually.Seed dormancy of Ⅱ112B and IR112-12 could be relieved through 2-3 months after the seeds being harvested and stored at in-door natural conditions.Husks of Ⅱ112B and IR112-12 had inhibitor on seed germination.There was more inhibitor in the husks of IR112-12 than that of Ⅱ112B,and there was no inhibitor in the husks of Ⅱ-32B or the inhibitor of that was tiny.Seed dormancy index of embryo of IR112-12 was higher than that of Ⅱ112B.Maybe it is the reason why IR112-12 has higher seed dormancy index and it is more difficult to relieve the dormancy.The broad-sense heritability of the dormancy index was 98% and 96%,while the narrow-sense heritability was 65% and 62%,in the two combinations,respectively.High seed dormancy index was partial dominant of inheritance.Selection for seed dormancy,therefore,could be at early generations.