Physiological Characteristics of 20 Tobacco Cultivars under Drought Stress and Assessment of Their Drought Tolerance at Germination and Seedling Stages

The drought tolerance of 20 tobacco cultivars were investigated by determining traits of germination characteristics,seedling quality and some physiological and biochemical characteristics under normal conditions and simulated drought stress.The ratios(relative values) of trait values under drought stress to those under normal conditions were used to assess drought tolerance.The correlation analyses showed that the relative values of germination index,vigor index,seedling fresh and dry weight were significantly correlated to each other,these parameters were suitable for evaluating drought tolerance.After the cluster analysis,20 tobacco cultivars were grouped into three classes: drought tolerance,intermediate drought tolerance and drought sensitivity,the results were consistent with that of the correlation analysis.The results would provide theory basis for research of drought tolerance mechanism,cultivation and breeding in tobacco.