Comparison of the Gas Exchange Parameters of Two Maple Species (Acer negundo and Acer pseudoplatanus) Seedlings under Drought Stress

In this study, two-year-old bare-root Acer negundo and Acer pseudoplatanus seedlings were grown indoors (control vs. drought-stressed) and outside the hoop house to examine leaf gas exchange parameters in the late growing period. Besides morphological features, several gas exchange parameters, such as net photosynthetic rate (Anet), transpiration rate (E), stomatal conductance (gs), intercellular CO2 to ambient CO2 (Ci/Ca), water use efficiency (WUE=Anet/E), intrinsic water use efficiency (iWUE=Anet/gs) were measured. As a result, A. pseudoplatanus seedlings had a higher stem height growth. A. negundo had a higher Anet, and a lower iWUE and Ci/Ca than A. pseudoplatanus. Seedlings grown under control treatment had a higher Anet, gs, E, and a lower iWUE, WUE, and Ci/Ca values than other treatments. In conclusion, there was no significant difference between the two Acer species in terms of gas exchange parameters. However, it can be said that A. negundo and A. pseudoplatanus are drought resistant.