Se(IV), Se(VI), Cu and Zn phytotoxicity in correlation to their accumulation in Sinapis alba L. seedlings

Phytotoxicity of Se(IV), Se(VI), Cu and Zn to Sinapis alba L. seedlings was expressed by inhibition of selected physiological processes (root and shoot growth, fresh and dry biomass production, water content) and correlated with their bioaccumulation. Roots growth was inhibited more than that of shoots and only Se(IV) reduced also shoots growth (IC50= 25.8 mg L). Se(VI) decreased more roots (IC50= 23.6 mg L) than shoots growth (IC50= 461.4 mg L). Phytotoxicity to roots growth increased as follows: Zn < Se(VI)≅Cu < Se(IV). All metals, except Cu, decreased more roots and shoots fresh mass than that of dry mass. Water content was for all (semi)metals more depressed in shoots, however, for Zn any significant changes in roots WC were confirmed. In any case transportation index Ti overreached value 1 and that indicate metals storage in the roots; however, for control the opposite results were obtained. While the highest bioaccumulation factor (BAF) was determined for Cu in both roots (1.016) and shoots (0.271) the lowest values for this parameter were confirmed for Se(VI) in the roots (0.061) and for Se(IV) in the shoots (0.010). While in the control Cu, Se and Zn content was higher in the shoots, treatment with these metals increased their accumulation mainly in the roots. Statistically negative correlation was confirmed among Se(IV), Se(VI) and Cu accumulation in the roots and water content in the roots, and among Se(IV) and Cu accumulation in the roots and water content in the shoots.