Abstract
The Norway spruce (Picea abies), the most important tree species in European forests, is
relatively sensitive to salt and does not grow in natural saline environments. Yet many trees
are actually exposed to salt stress due to the common practice of de-icing of mountain
roads in winter, using large amounts of NaCl. To help develop strategies for an appropriate
use of reproductive seed material on reforestation sites, ensuring better chances of seedling
survival in salt-affected areas, we have studied the responses of young spruce seedlings to
salt treatments. The specific aim of the work was to identify the optimal salt stress biomarkers
in Picea abies, using as experimental material seedlings obtained by germination of
seeds with origin in seven populations from the Romanian Carpathian Mountains. These
responses included general, conserved reactions such as the accumulation of ions and different
osmolytes in the seedlings needles, reduction in photosynthetic pigments levels, or
activation of antioxidant systems. Although changes in the contents of different compounds
involved in these reactions can be associated to the degree of stress affecting the plants,
we propose that the (decreasing) levels of total phenolics or total carotenoids and the
(increasing) levels of Na+ or K+ ions in Picea abies needles, should be considered as the
most reliable and useful biomarkers for salt stress in this species. They all show very high
correlation with the intensity of salt stress, independently of the genetic background of the
seeds parental population, and relatively easy, quantitative assays are available to determine
their concentrations, requiring simple equipment and little amount of plant material.
