Koç, İsmail2023-07-262023-07-2620212618-6616https://search.trdizin.gov.tr/yayin/detay/1129429https://hdl.handle.net/20.500.12684/12248Two-year-old (plug+1) containerized Abies balsamea (L) Mill. and Abies concolor seedlings were grown under various irrigation in the greenhouse to examine gas exchange parameters end of the growing period when they were exposed to extreme drought stress. Relative height growth (RHG) and relative root collar diameter (RRCD) were measured next to gas exchange parameters, such as net photosynthetic rate (Anet), stomatal conductance (gs), transpiration rate (E), intrinsic water use efficiency (iWUE=Anet/gs), and water use efficiency (WUE=Anet/E). As a result, A. balsamea seedlings had a higher RHG and RRCD than A. concolor. Species had a significant effect on leaf gas exchange parameters that A. balsamea had a higher Anet, gs, and a lower iWUE than A. concolor. Increasing irrigation increased Anet and E. The interaction of species and time was statistically significant for gs and iWUE measurement. İncreasing prolonged drought decreased gs and did not change iWUE values for A. balsamea, while increased gs and reduced iWUE for A. concolor seedlings. Even though Anet, E, and WUE were not statistically significant under the interaction of species and time, there is a decreasing trend for A. balsamea on these parameters. In contrast, A. concolor had a decreasing trend on Anet, and WUE and an increasing trend for gs when the seedlings were exposed to extreme drought or extended the dehydration period were observed. A. balsamea had a better performance and drought tolerance than A. concolor when exposed to a prolonged drought.eninfo:eu-repo/semantics/openAccessArticle525926051129429