The photosynthetic pigments measured in the seedling needles showed a reduction with the increase of external salt concentration, for the seven P. abies populations under study. Total carotenoids (Fig 4a), chlorophyll a (Fig 4b), and chlorophyll b (Fig 4c) decreased with a similar pattern and, in most cases, the differences with the corresponding non-treated controls were found to be significant even in the presence of 75 mM NaCl, the lowest salt concentration applied in our experiments. Here again, quantitative differences in the response to salt stress, regarding the concentration-dependent reduction in photosynthetic pigments, were observed among populations.