Variability of potassium concentration in the needles of Douglas-fir provenances

Douglas-fir is one of the most common conifer species in the forest plantations of Europe. The provenance test model is based on the analysis of the properties (growth, anatomical, physiological, chemical, mechanical and other properties) of Douglas-fir in order to justify the transfer of seeds from North America to the ecosystems of Serbia. This type of program has been implemented in Serbia on several locations using different Douglas-fir provenances. Given that the analysis of different physiological properties of trees is important for the introduction of specified provenances into habitats in Serbia, in this paper the variability of potassium concentration in young Douglas-fir needles of different provenances was examined in an experimental field in Serbia. Potassium is very important in the physiological processes of plants. It is an essential element involved in a number of biochemical and physiological processes and plays a significant role in the adaptation of plants on biotic and abiotic stress factors. The highest potassium concentration was found in the ?Oregon 205-14? provenance - the only provenance in which the potassium concentration was significantly higher than the average value, so it can be characterized as a superior provenance for the uptake and accumulation of this element. It was found that, at this stage of development, the differences in the potassium concentration in trees in the provenance test have no significant effect on growth parameters. Further studies should show whether the concentration of this biogenic element in any way affects other properties important for the selection of provenances during the introduction process, such as resistance to stress factors.