Comparison of Cold Tolerance at the Booting Stage for Cold Tolerant Japonica Rice Germplasm under Different Cold Stress

In order to provide the excellent genetic resources for selecting japonica rice standard variety of cold tolerance at the booting stage and genetic breeding of cold tolerance in rice,the cold tolerance intensity of 12 accessions of japonica rice germplasm from Heilongjiang,Jilin,Liaoning and Yunnan provinces at the booting stage were evaluated under the artificial climate rooms for low temperature where cultivars were exposed to 15℃,17℃ or 19℃.Exposures lasted for 4 days and 6 days.The results showed that the unfilled grain rate(UGR) of rice dramatically increased with increasing stress intensity.The variance and coefficient of UGR were maximum at 15℃ for 6 days,so this cold stress was applied to high cold tolerant japonica variety identification.Kuiku 131 and Longdao 3 showed theirs strong cold tolerance capacity at the booting stage by analysis of variance and multiple comparison of UGR at 15℃ for 6 days.When selecting the standard variety of cold tolerance at the booting stage in different province of China,we should consider the performance of PUG of testing varieties in this experiment,and combine with the light and temperature conditions in local rice-growing areas,respectively.