Studies on cold tolerance of rice,Oryza sativa L..IV.Preliminary genetic analysis of cold tolerance on Yunnan rice genetic resources

This is the forth paper of the series to describe cold tolerance of rice.The parents of Kunmingxiaobaigu,Yunnan local variety with cold tolerance and Nipponbare,Japanese variety with coldsusceptiveness as well as their F2 progenies were used as test materials for evaluation of cold tolerance in Phytoton in National Agricultural Research Center for Hokkaido Region.Fertility percentage was used as criterior for cold tolerance and the program designed by Ishige in 1979 to analyze the data.The results showed that there should be three effective factors conferring cold tolerance at booting stage in the combination of Kunmingxiaobaigu and Nipponbare.No relationship was detected between cold tolerance at flowering stage and any trait of plant height,growth days,anther length,anther width,anther length×width,spikelet number per panicle.