Objective To study physiological response mechanisms of Triadica rotundifolia when subjected to drought stress, thus providing a fundamental evidence for further exploring its drought resistance and a theoretical support for afforestation tree species selection and vegetation restoration in limestone areas.

Method Pot experiment using 2-year-old T. rotundifolia seedlings was set up for observing the dynamic changes of the leaf physiological indexes of T. rotundifolia seedlings under drought stress.

Result With the development of drought stress, electrolyte leakage rate and proline content increased significantly, and peaked at the end of stress (32 days), with the values of 37.42% and 197.18 μg·g^-1 respectively. SOD activity, MDA and soluble protein contents first increased and then decreased, and peaked at the 18th, 21th and 21th days with the values of 159.19 U, 31.89 nmol·g^-1 and 2.31 mg·g^-1 respectively.

Conclusion The physiological response mechanisms of T. rotundifolia are different at different drought stress periods. Specifically in the light and moderate stress periods, drought resistance is enhanced by increasing the activities of protective enzymes combined with osmotic adjustment, but mainly by osmotic adjustment under severe stress. In general, T. rotundifolia has certain ability of drought tolerance, thus it is one of the suitable species for ecological restoration in limestone areas.