Effect of Temperature Stress on Growth and Physiological Indexes of Different Varieties of Flue-cured Tobacco Seedlings

Pot-culture tobacco with 5 true leaves was used as material. The experiment was carried out with three flue-cured tobacco varieties seedlings under the temperature stress to study the changes of chlorophyll contents, MDA contents, nitrate reductase contents, root vigor, stem length, maximum leaf length and the maximum leaf width. The results showed that: (1) The contents of chlorophyll and NRase reduced under temperature stress. (2) The MDA content in Yunyan 87 increased significantly under low temperature stress; The MDA content in Honghuadajinyuan under low temperature was not significantly different, but that under high temperature increased significantly; The MDA content in K326 variety under temperature stress was significantly higher than that in the control group. (3) The seedlings root vigor of Honghuadajinyuan and K326 under temperature stress was significantly higher than that of the control group. (4) The morphological index of K326 decreased significantly. (5) The cold resistance of Honghuadajinyuan was the strongest, Yunyan87 was the second and K326 was the weakest. (6) The high temperature resistance of Yunyan87 was the strongest, Honghuadajinyuan was the second, and K326 was the weakest.