Abstract: The cold tolerance of 20 tobacco cultivars at germination and seedling stages were investigated by determining germination characteristics, seedling physiological and biochemical characteristics at normal temperature (20-30℃) and low temperature (11℃) stress. The ratios (relative values) of traits at low temperature to those at normal temperature were used to assess cold tolerance. The correlation analysis showed that the relative values of germination percentage, germination index, vigor index and malonaldehyde content were significantly correlated to each other, which were suitable for evaluating cold tolerance. By cluster analysis, 20 tobacco cultivars were grouped into three classes: cold tolerance, intermediate cold tolerance and cold sensitivity, and the results were consistent with that of correlation analysis.

Key words: low temperature stress, tobacco, seedling stage, cold tolerance, cluster analysis