Genetic diversity is the basis for adaptation and survival of tree species under changing environmental conditions, representing the key issue of stability and productivity of forest ecosystems. In this study, core and marginal populations of Taurus cedar (Cedrus libani A. Rich.) were investigated due to their importance in gene conservation. Assessment of genetic diversity in isolated populations is of great importance for the conservation and improvement programs. Under global climate change conditions, they may possess genotypes of future adaptive potential. The aim of this study is to determine the amount of proline to understand water deficiency stress of the population, total soluble proteins, MDA, H2O2 alpha-amylase, the variability of antioxidant as CAT, SOD, APX and GuPX of Taurus Cedar seeds fromfive core populations (KahramanmarwAndirm/Elmadagi (AND), Adana-Pozanti/Pozanti (POZ), Mersin-Anamur/Abanoz (ANA), Antalya-Finike/Ayktricay (FIN) and Antalya-Kas/Karacay (KAS)) and one marginal provenance (Amasya-Tokat-Niksar/catalan (NIK)) in Turkey. According to the results, a significant difference was detected between populations. Significantly higher amounts of proline were detected for ANA (7,46 mu mol/g) and POZ (7,22 mu mol/g) populations, whereas the lowest amounts of proline were detected in KAS (3,98 mu mol/g) population, which represent the optimal distribution of Taurus cedar. This finding indicates that POZ and ANA populations, in the transition zone from Mediterranean region to steppe territory, are more resistant to the frost, than the other populations. The highest a-amilase enzyme amount was detected in POZ population, growing in the optimum range for Taurus cedar. Significantly higher levels of H2O2 were detected in NIK (11,97 mu mol/g) and ANA (11,60 mu mol/g). This is an indication of higher levels of oxidative stress in the seed samples of these populations. With the present research it's verified that, enzymes such as SOD, CAT, GuPX and APX, controlling reactive oxygen species (ROS) levels in plant cells, are the elements of the antioxidant defence system functioning as protective mechanisms for plants against stress conditions. From the practical point of view, improvement in afforestation performance can be achieved on the steppe of Central Anatolia Region holding the potential afforestation areas of Turkey, through use of forest reproductive materials from POZ and ANA stands with their higher resistance against stress, and NIK as an isolated and marginal population.

As a non-project study, this research was carried out using the facilities of projects no KUBAP-01/2013-17, 01/2013-59, and 01/2014-21. The seed samples were supplied from General Directorate of Forestry (GDF). We acknowledge the support and contributions of Kastamonu University and GDF. We are also thankful for the supports of my M.Sc. students Asuman TAN and Halit CELIKBAS in laboratory studies.

Kastamonu University; GDF; [KUBAP-01/2013-17]; [01/2013-59]; [01/2014-21]