Evaluation of Cold Tolerance at Different Growing Period for Mini Core Collection of Rice(Oryza stiva L.)in China

The evaluation of cold tolerance at the germination period,the budbersting period,the seedling stage and the booting stage and its correlation analysis were conducted,using 204 accessions of core collection of rice(Oryza sativa L.)in China.The results showed that there were obvious different cold tolerance between Japonica rice and Indica rice of sub species,and among rice germplasms.The cold tolerance of Japonica rices was stronger than those of Indica rices,but there were some stronger cold tolerant germplasms of Indica rices.The Japonica rices such as Gaoyangdiandaodahongmang,Feidongtangdao,Muxiqiu,Weiguo,Xingguo,Shanjiugu,Zhonghua 8 ect.and Indica rices such as Baoxuan 21,Hongmisandanbai,Cungunuo,Honggu ect.were showed stronger cold tolerance in several growing stages,which should be used in rice breeding for cold tolerance and identification of gene associating with cold tolerance.The seed setting rate under natural low temperature and cold water irrigation were significantly positively correlated with the vigor of germination under low temperature,while which were significantly negatively correlated with dead seedling rate,that was the rice germplasms with stronger cold tolerance at the germination period and the bud busting period under low temperature,had stronger cold tolerance at the booting stage.So the vigor of germination and dead seedling rate under low temperature could be used as cold tolerant index of cold tolerance at the booting stage in early growing stage.