Zinc Tolerance of Sisymbrium lipskyi Plants and Their Phytoremediation Potential

The study was focused on effects of increased zinc concentrations on growth, mineral composition, chlorophyll and carotenoid content in Sisymbrium lipskyi N. Busch from North Caucasus. Plants were cultivated in sand in presence of 80, 160 and 320 mg Zn per kg of substrate. S. lipskyi demonstrated relatively high resistance to zinc toxicity at doses of 80 and 160 mg/kg – plants showed no significant decrease in dry biomass accumulation, no significant changes in chlorophyll a/b ratio, and water status was consistent. A significant inhibitory effect of zinc was observed only at its concentration of 320 mg/kg and resulted in significant decrease in biomass and chlorophyll b content. The balance of mineral elements was disturbed, mainly due to decrease in mineral elements translocation from roots to above-ground organs of plants. The predominant accumulation of zinc in roots (except for the 320 mg/kg treatment) defines S. lipskyi as a species capable of restricting zinc supply to above-ground organs, as evidenced by low values of translocation factor. This feature of mineral metabolism, along with relatively high tolerance to zinc, suggests to consider S. lipskyi as a promising species for phytostabilization of relatively polluted soils.