Abstract: To investigate the effects of antitranspirant with different concentration on photosynthesis and antioxidant responses of Bougainvillea spectabilis under drought stress， the plants were treated for 21 days under natural drought condition after applying water and 400， 800， 1200 times dilution antitranspirant as a foliar spray， and the plants under normal culture condition were set as the control group. The results showed that antitranspirant reduced the stomatal conductance and transpiration rate， maintained a relatively higher net photosynthetic rate and a stable intercellular CO2 concentration in Bougainvillea spectabilis when compared with single drought stress. Moreover， antitranspirant could alleviate the loss of chlorophyll content and relative water content， reduce the increase of electrolyte leakage and malonaldehyde content， and further improve the activities of SOD， POD， CAT and APX as well as proline content in Bougainvillea spectabilis under drought stress. These results indicated that antitranspirant could enhance the resistance to drought stress of Bougainvillea spectabilis， and the best concentration was the antitranspirant with 800 times dilution.

Key words: Bougainvillea spectabilis, drought stress, antitranspirant, physiological characteristics, photosynthesis