Remediation of Nickel-Contaminated Soil by Brassica juncea L. cv. T-59 and Effect of the Metal on Some Metabolic Aspects of the Plant

ABSTRACT

Among four cultivars of Brassica juncea L., viz., TM-4, TM-2, RH-30, and T-59, cv. T-59 was relatively more tolerant to nickel (Ni) toxicity based on the growth parameters, seedling vigor index, and metal tolerance index. Nickel application inhibited the activity of the nitrate-assimilating enzyme nitrate reductase in the roots, stem, and leaves, whereas the total organic nitrogen, proline, and activity of a polyamine-metabolizing enzyme, diamine oxidase, increased in this tolerant cultivar (T-59). It accumulated a good amount of Ni from the soil in its root and shoot (i.e., 6.0–6.51 μg Ni g⁻¹ dry weight) during 2 months of cultivation with an 8.0 mM Ni supply in the soil. The data presented in this paper indicate that Ni tolerance and its removal by Indian mustard from subtropical Indian soil is cultivar dependent, possibly due to different genetic and physiological adaptations of the cultivars.

KEYWORDS:

• Brassica juncea
• diamine oxidase activity
• nickel tolerance
• nitrate reductase activity
• phytoremediation
• total organic nitrogen