Effect of Drought and UV-B Stress on Anatomical and Physiological Characters in Acer negundo and Acer pseudoplatanus Species

Climate change is a situation that causes an increase in global temperature due to the increase in greenhouse gases in the atmosphere and the effect of natural processes. This temperature increase causes many environmental effects around the world. Two of these effects are ultraviolet-B (UV-B) radiation, a harmful type of electromagnetic light from the sun, and severe water shortages called droughts. In this study, we tried to determine how the wood structure (properties of libriform fibers and various mechanical properties) and plant photosynthesis parameters of Acer negundo and Acer pseudoplatanus species changes under two droughts (moderate and severe) and UV-B (low [8 kJ m⁻² h⁻¹] and high [12 kJ m⁻² h⁻¹]) stresses. Also, leaf gas exchange parameters (net photosynthesis, stomatal conductance, transpiration rate, and water use efficiency) were evaluated under these stressors. As a result, it was observed that fiber wall thickness decreased in seedlings exposed to both drought and UV-B radiation in both species. It was determined that plant gas exchange parameters decreased with drought stress but did not vary much with UV-B stress; the amount of plant transpiration decreased with the effect of drought and increased with the amount of UV-B radiation. The plant may have reduced transpiration to reduce the effect of drought stress and increased transpiration to use UV-B radiation for plant growth.