Changes in Salix viminalis L. cv. 'Cannabina' morphology and physiology in response to nickel ions--hydroponic investigations.

The aim of the study was to assess the ability of 'basket willow' to bioaccumulate nickel with simultaneous analysis of biomass parameters and biomarkers of plants physiological reaction to the metal. Cuttings of Salix viminalis L. cv. 'Cannabina' were cultivated in Knop's medium containing nickel at 0-3mM stabilized with quartz sand. Higher nickel contents were observed in Salix rods and roots (~15), and lower for leaves and shoots (~3 mg kg(-1)DW) after 14 days at 3 mM Ni. The strongest inhibition was observed for root biomass, weaker for shoot, root and leaf elongation, and the weakest for the photosynthetic area (4, 24, 36, 55 and 70% of control, respectively). Soluble carbohydrates in leaves reached 340% of control at 3.0mM Ni. Phenolics content increased four-fold at 3mM Ni versus control, while salicylic acid content at 2.5 mM Ni was nearly 68 times higher than for Ni-untreated plants. The exudation of low molecular weight organic acids increased from ~40 to 130 μM kg(-1)DW at 3 mM. The investigated cultivar exhibits sufficient resistance to nickel and can be cultivated at heavily contaminated sites. Nevertheless, strong inhibition of plant growth was observed resulting probably from Ni-induced disturbances in nutrient uptake accompanied by oxidative stress.