A water-culture experiment was employed to study the effect of osmotic stress on contents of proline (PRO), soluble sugar (SS) and malondaldehyde (MDA) in flue-cured tobacco leaves under different potassium supplying. The results showed that the contents of PRO, SS and MDA in the leaves of different potassium supplying treatment increased significantly under osmotic stress, and the peak value appeared at 24h and then declined. The changes of these indices was almost the same between the two osmotic stress treatments, but the peak value was obviously higher at the osmotic potential of -0.2MPa than that of -0.4MPa. Under osmotic stress, significant accumulation of PRO and SS in tobacco leaves was observed and the notable decrease of MDA content was also found with the increasing of potassium supply, which suggested that the drought resistance of tobacco plant was improved.
