Accumulation of metals and its effects in Brassica juncea (L.) Czern. (cv. Rohini) grown on various amendments of tannery waste

The metal accumulation potential and its tolerance in the plants of Brassica juncea (L.) Czern. (cv. Rohini) grown on various amendments of tannery sludge (10%, 25%, 35%, 50%, 75%, 100%) were studied after 30, 60, and 90 days after sowing. These plants were found to be effective accumulators of metals (Cr, Fe, Zn, and Mn); however, the seeds accumulated the least quantities of all the metals tested. The oil content of the seeds was found to increase up to 35% tannery sludge followed by a decrease. An increase in the photosynthetic pigments, protein, and sugar contents was recorded at the lower amendments of tannery sludge at initial exposure periods followed by a decrease compared to their respective controls. However, the malondialdehyde, proline, and ascorbic acid contents of the roots and leaves of the plant increased at all the sludge amendments and exposure periods, compared to their respective controls. The levels of cysteine and nonprotein thiol contents in the roots and leaves of the treated plant were found higher at all the sludge amendments and exposure periods except at 90 days, where a decrease was observed in the leaves at 100% tannery sludge as compared to their respective controls. The tolerance exhibited by the sludge-grown plants of B. juncea in the present study may be attributed to the enhanced level of the antioxidants induced under stress conditions.