Assessment of Cr tolerance and accumulation in selected plant species

Comparisons of relative growth and survival rates of 10 plant species in test-tube nutrient-solution culture indicated that soybean and sunflower were Cr-tolerant. Comparison of relative growth and tissue Cr concentrations between soybean and sunflower showed that soybean was most tolerant to both Cr(VI) and Cr(III). Higher tissue Cr concentrations (20 000, 7400, 1300 μg g-1 in the roots, stems, and leaves, respectively) were observed in all soybean tissues when exposed to 1.0 mM Cr(III) as compared to sunflower (14 000, 900, 460 μg g-1 in the roots, stems, and leaves, respectively). With Cr(VI), sunflower had higher Cr concentrations in the root than did soybean (1800 vs. 700 μg g-1); however, there was a higher Cr level in soybean leaves and stems (27 and 21 μg g-1, respectively) compared to leaves and stems of sunflower (6 and 0 μg g-1, respectively), indicating significant translocation from the roots into the above-ground parts in soybean. Soybean can be considered to be a viable candidate as a rhizofiltration species for phytoremediation purposes.