Variability of nitrogen content in the needles of Douglas-fir (Pseudotsuga menziesii Mir/Franco) provenances

Nitrogen content in the needles of twenty Douglas-fir provenances, originating from different sites within the native range of the species in the USA, was studied in a Douglas-fir provenance test established at the montane beech site on acid brown soil. Based on the variability of nitrogen content in the needles, the intensity and dynamics of the physiological processes of Douglas-fir mineral nutrition were analyzed as the indicators of Douglas-fir adaptive potential to the sites in Serbia. All the trees of the study provenances were of the same age and grown under the same site and population conditions. The quantities of nitrogen absorbed in Douglas-fir needles were correlated with the geographical characteristics of the native sites of the observed provenances. The differences in nitrogen content in Douglas-fir needles point out the variability in the intensity of the physiological processes in the genotypes of the different provenances. Since the study Douglas-fir trees are cultivated on relatively small areas, in more or less equal general conditions, it can be concluded that the parameters of mineral nutrition depend on the genotypes constituting the gene pool of the study Douglas-fir provenances