Total Chlorophyll Content Variations in Some Oriental Beech (Fagus orientalis L.) Origins Exposed to Drought Stress

Aim of study: Oriental beech ( Fagus orientalis Lipsky.) seedlings of 4 different origins were divided into different irrigation regimes as "irrigation once a day (control)", "irrigation once every 2 days" and "no irrigation at all" in the 2nd growth period. The main aim of this study was to determine which origin was more tolerant to drought. Area of study: Beech seedlings were produced from seeds originating from Bolu, Istanbul, Zonguldak and Giresun in the Greenhouse of Artvin Coruh University, Faculty of Forestry. Material and methods: The beech seeds used in the study were collected by the Regional Directorates in 2021. The seeds were planted in polyethylene tubes Greenhouse. As of July 2023, Oriental beech seedlings in their second growth period were subjected to three different irrigation, total chlorophyll contents were measured by using the hand-held SPAD-502 Plus device and the data were analyzed statistically. Main results: In the variance analysis made according to different irrigation regimes in terms of total chlorophyll contents, statistically significant ( p<0.05 ) differences were detected between the origins, and in the Duncan Test used to determine which groups the differences originated from, it was found that all the origins were in 12 separate groups. It was also understood that the chlorophyll content of the origins was less in the regimes of irrigation once every 2 days and no irrigation at all, compared to the regime of irrigation once a day (control). Research highlights: It was determined that total chlorophyll contents decreased in all origins in regimes exposed to drought stress compared to the control regime, but this change was less in the Istanbul (180 m) origin than in the other origins.