Quantitative assessment of nickel phytoremediation potential of some Brassica species in nickel enriched soil as influenced by organic amendments

Abstract

Screen-house experiments were conducted to evaluate the nickel phytoremediation potential of Brassica juncea, Brassica napus and Eruca sativa in nickel enriched (i.e. 0, 150, 300, 450 and 600 mg/kg soil) soils using 3% farmyard manure-amended (w/w), 3% sewage sludge-amended (w/w) and un-amended soil. The results of the study revealed that the mean stem yields of Brassica species was higher by about 12% and 25% in the sewage sludge-amended and farmyard manure-amended soils, respectively as compared to un-amended soils. The corresponding differences in the mean leaf and seed yields were about 19 and 35%, and 13 and 28%, respectively in the sewage sludge-amended and farmyard manure-amended soils over un-amended soils. In the sewage sludge- amended soil, the mean Ni content was higher by about 10% in the stem and 4% each in both leaf and seed over un-amended soil. Addition of farmyard manure (farmyard manure-amended soil) resulted in decrease in mean Ni concentration by about 23.4, 33.1 and 32.3% in stem, leaf and seed, respectively over un-amended soil. Among the species, the order of mean nickel concentration was: Brassica napus>Brassica juncea>Eruca sativa. Whereas, the order of nickel concentration in different plant parts was: seed > leaf > stem. The mean Ni removal by stem, leaf and seed were 25.1, 27.9, and 26.8% less in the farmyard manure-amended soil in comparison to the sewage sludge-amended soil, respectively. The order of Ni removal rate was: stem>leaf > seed. Overall, the total removal of Ni by Brassica juncea (stem, leaf and seed) was higher by 1.2 times of Brassica napus and 2.4 times of Eruca sativa.