Root and Shoot Response to Nickel in Hyperaccumulator and Non-Hyperaccumulator Species.

The soil-root interface is the micro-ecosystem where roots uptake metals. However, less than 10% of hyperaccumulators' rhizosphere has been examined. The present study evaluated the root and shoot response to nickel in hyperaccumulator and non-hyperaccumulator species, through the analysis of root surface and biomass and the ecophysiological response of the related aboveground biomass. Ni-hyperaccumulators (L.) Medik. and (J. Presl and C. Presl) F.K. Mey. and non-hyperaccumulators L. and L. were grown in pot on Ni-spiked soil (0-1000 mg Ni kg, total). Development of root surfaces was analysed with ImageJ; fresh and dry root biomass was determined. Photosynthetic efficiency was performed by analysing the fluorescence of chlorophyll a to estimate the plants' physiological conditions at the end of the treatment. Hyperaccumulators did not show a Ni-dependent decrease in root surfaces and biomass (except Ni 1000 mg kg for ). The non-hyperaccumulator suffers metal stress which threatens plant development, while the excluder exhibits a positive ecophysiological response to Ni. The analysis of the root system, as a component of the rhizosphere, help to clarify the response to soil nickel and plant development under metal stress for bioremediation purposes.