Investigation of basic morphological and physiological changes in some oriental beech (fagus orientalis lipsky.) origins exposed to drought stress

In this study, it was aimed to determine the responses of some Oriental beech (Fagus orientalis Lipsky.) origins to drought stress. After the seedlings originating from Bolu, Istanbul, Zonguldak and Giresun were grown in the Greenhouse of the Forestry Faculty of Artvin Coruh University, they were maintained at regular intervals and drought stress applications were applied to the Oriental beech seedlings in the 2nd growth period starting from July 2023. Three different irrigation regimes (irrigation once a day (control), irrigation once every 2 days, no irrigation at all) were created to apply drought stress to the seedlings. After the treatment, firstly the root collar diameters, seedling heights, number of side branches, total chlorophyll contents and chlorophyll fluorescences of the seedlings were measured in the greenhouse. Root volumes, root areas and root lengths were determined with root samples taken from the seedlings; relative water contents, hydrogen peroxide (H2O2) and melondialdehyde (MDA), one of the end products of lipid peroxidation, were analyzed with leaf samples. It was observed that there were significant differences between the origins in terms of all parameters. It was determined that the amounts of relative water content, chlorophyll fluorescence and total chlorophyll content of the seedlings decreased in groups exposed to drought stress compared to the control group. An increase in hydrogen peroxide contents and malondialdehyde levels was observed in the groups exposed to drought stress compared to the control group. As a result; It was determined that the Istanbul origin, which was least affected by drought stress in terms of physiological characteristics and had showed the best root and stem development in terms of morphological characteristics, was the most tolerant origin to drought stress.