Abstract:To understand the physiological response mechanisms and post-drought recovery capabilities of different tree species to drought stress, a pot experiment was conducted on the seedlings of Michelia maudiae and Elaeocarpus decipiens, which have both ornamental and ecological values. Gas exchange parameters, leaf water status, superoxide dismutase (SOD) activity, and osmotic adjustment substances were measured during the drought and rewatering processes. The results showed that under drought stress, the leaf water potential and photosynthetic parameters of E. decipiens seedlings decreased more rapidly than those of M. maudiae, with a 99.1% decrease compared to the control after only 6 days. Before rewatering, the SOD activity in the leaves of M. maudiae and E. decipiens seedlings was 36.1% and 33.4% of the control, respectively; the proline content in the leaves of the two tree species was 2.1 and 5.5 times that of the control, respectively; however, the soluble sugar content of E. decipiens seedlings was not significantly different from that of the control. Seven days after rewatering, the net photosynthetic rate, stomatal conductance, and transpiration rate of M. maudiae seedlings did not yet recover to the control level, while those of E. decipiens seedlings fully recovered. The SOD activity and osmotic adjustment substances of the two tree species gradually returned to the control level after rewatering. Therefore, there are differences in the response to drought stress and post-drought recovery capabilities between M. maudiae and E. decipiens seedlings. Elaeocarpus decipiens is more sensitive to drought but has a stronger recovery ability after rewatering than M. maudiae. This study clarifies the physiological response mechanisms of M. maudiae and E. decipiens to drought and rewatering from the perspective of plant physiology, providing a reference basis for practical applications such as seedling cultivation management, landscaping, and tree species selection.
