Effect of salinity stress on growth and macroelements uptake of four tree species

Woody plants grown near the roads are force-fed by salt and this has negative effect on their growth and decorative value. The aim of the presented study was to investigate the effects of salinity on growth and nutrient composition of four trees species often planted along the roads and streets in Poland. Two years old seedlings (bare root) of four tree species: Acer negundo, A. platanoides, Quercus robur and Tilia cordata were potted and grown outside under four soil salinity levels maintained by drenching plants with tap water containing 0.25, 0.5, 1.5, and 3.3g NaCl/L H2O. Plant height, soil samples for electrical conductivity (EC) and pH determination as well as leaf samples for macroelements (N, P, K, Ca, Mg) content evaluation were collected after each growing season of two years of experiment. Electrical conductivity of the growing medium varied insignificantly between species, but salt concentration in the growing medium was distinctly higher in the upper than in the bottom part. Soil salinity had strong but variable effect on plant growth during the experiment. Only Acer negundo growth was not affected even by the highest concentration of NaCl solution. With increasing salinity of growing medium more Na+ was taken by all species but the biggest amount of sodium ions was accumulated in the leaves of Tilia cordata, while the lowest in Acer negundo. Than potassium ions content decreased with increasing medium salinity only in the leaves of Quercus robur and Tilia cordata. In the leaves of Acer platanoides and Tilia cordata calcium concentration was decreased at increased salinity, in two other tested species amount of Ca2+ in the leaves was elevated. The main conclusion that can be drown is that Acer negundo is highly tolerant to salinity stress while Acer platanoides was the most sensitive among tested species.