Nickel Uptake by Rajmash (Phaseolus vulgaris L.) Grown on Sewage-Irrigated Soils

A pot experiment indicated that the root, shoot, total dry matter yields, Ni concentrations and uptake by rajmash increased with increasing levels of Ni-FA (fulvic acid). The mean root, shoot and total dry matter increased from 0.18 to 0.23, 1.61 to 1.94 and 1.79 to 2.17 g pot⁻¹ with increasing levels of Ni. The total dry matter yield showed positive and significant correlation with root density (r = 0.926**) and root length (r = 0.958**) and negative and significant correlation with root radius (r = -0.745**) and half distance between roots (r = -0.929**). Nickel concentration in root, shoot and total dry matter of rajmash ranged from 37.5 to 88.3, 11.2 to 29.3 and 24.4 to 58.8 mg kg⁻¹, respectively and the Ni uptake varied from 3.9 to 27.9, 6.3 to 85.8 and 11.0 to 113.6 μg pot⁻¹, respectively in different soils. The Ni content and uptake by root, shoot and total dry matter exhibited positive and significant correlation with pH (r = 0.870**, r = 0.826**), EC (r = 765**, r = 0.813**), organic carbon (r = 0.870**, r= 0.950**), CEC (r = 0.855**, r = 0.890**). Diffusion coefficient had positive and significant correlation with Ni uptake (r = 0.640*). Root density and length were positively and significantly correlated with soil parameters, uptake and yield and negatively correlated with clay. Similarly root radius and half distance between roots showed negative and significant correlation with soil parameters and positive association with clay. The DTPA-Ni showed positive and significant correlation with pH (r = 0.810), EC (r = 0.711*), organic carbon (r = 0.931**), CEC (r = 0.841**), Nicontent (r = 0.954**) and uptake (r = 0.973**).