Cold tolerance analysis on filial generation of Indica, Japonica and common wild rice at seedling stage in field

[Objective]The present research was carried out to obtain rice germplasm resources on rice cold tolerance breeding, and preliminarily determine the strategy for rice cold tolerance breeding. [Method]Cold tolerance characters of four parents (Indica rice 9311, Japonica rice Bai R54, Nippon bare, and common wild rice DP10 ) and their filial generations were investigated at seedling stage under natural cultivation conditions in field. All materials grouped 6 to observe their cold damage performance on Mar. 22. [Result]Under natural low temperature condition, 39 accessions with strong cold tolerance and excellent comprehensive agronomic traits were screened out for rice breeding. Out of which, 33 accessions had 87.5% Japonica genetic constitution, 6 accessions had 75.0% Indica genetic constitution. Moreover, the 60 cold tolerant accessions had 50.0% wild rice genetic constitution with worse comprehensive agronomic traits. All the cold sensitive rice accessions had a high Indica rice genetic constitution of 87.5%. [Conclusion]Among all the filial generations of four parents, those with more genetic constitution of Japonica and common wide rice showed stronger cold tolerance. Japonica and common wild rice are important germplasm resources in cold tolerance breeding, the cold tolerance level of Indica rice could be enhanced by introducing genetic constitution of Japonica or common wide rice .