Effects of drought and uv-b stresses on some anatomical, morphological and physiological characteristics of Acer negundo L. and Acer pseudoplatanus L. saplings

Climate change is a situation that causes an increase in global temperature with the elevated of greenhouse gases in the atmosphere and the effect of natural processes. This increase in temperature leads to many environmental impacts around the world. Two of these effects are UV-B radiation, a harmful type of electromagnetic radiation from the sun, and severe water shortages, called droughts. The increase in UV-B radiation can affect plants' reproduction and growth processes. Drought can alter ecosystems, reducing the chances of survival of plant and animal species. Plants, one of the living organisms that can be affected by environmental factors, are affected by both UV-B radiation and drought. In this study, the response of anatomical, morphological and physiological characters of Acer negundo (Ash Leaf Maple) and Acer pseudoplatanus (Mountain Maple) saplings to UV-B radiation and drought stress were investigated and the changes in maple saplings were determined by using two different sapling species. The results of the study showed that A. negundo seedlings were more tolerant to increased UV-B radiation, while A. pseudoplatanus seedlings were more tolerant to drought stress. When anotomic characters were analysed, it was determined that A. negundo and A. pseudoplatanus showed different reactions to drought and UV-B stress. In both species, fibre wall thickness decreased in seedlings exposed to both drought and UV-B radiation at the same time compared to the control groups. When morphological characters were examined, it was determined that stomatal length and width were generally not significantly affected by drought and UV-B stress. However, stomatal width increased in seedlings exposed to high doses of UV-B radiation and pore length decreased in seedlings exposed to both high doses of UV-B and drought at the same time. It was determined that plant gas exchange parameters decreased with drought stress but did not show much variability with UV-B stress compared to control group values. It was determined that the amount of plant transpiration decreased with the effect of drought and increased with the amount of UV-B radiation. It is thought that the plant may have decreased transpiration to reduce the effect of drought stress and increased transpiration to use UV-B radiation for plant growth. In conclusion, it was determined that the responses of A. negundo and A. pseudoplatanus seedlings to the treatments differed between treatments and species. The reasons for the different responses of plants to the same treatments and their responses to stresses are still unclear. Therefore, it is recommended that the responses of woody species to stresses should be investigated in more detail.