Differential Response of Brassica Cultivars to Potentially Toxic Elements and Their Distribution in Different Plant Parts Irrigated with Metal-Contaminated Water

Abstract

The increasing concentration of potentially toxic elements (PTEs) in agricultural soils has greatly disturbed the quality and productivity of soils. In this study, we investigated the uptake and distribution of cadmium (Cd), lead (Pb), and nickel (Ni) by two Brassica cultivars (Khanpur raya and Sandal canola) grown on soil irrigated with metal-contaminated water. Distilled water was spiked with salts to prepare irrigation water with various levels of metals (Ni application at 90, Cd at 20, Pb at 500, Ni + Pb at 20 + 500, Ni + Cd at 90 + 20, Cd + Pb at 20 + 500, and Ni + Cd + Pb at 90 + 20 + 500 mg L−1). These treatments were compared with water without the addition of any salt. The results indicated that compared to the control treatment, increasing metal concentrations decreased the shoot weight (44.25%, 29.03%), root length (33.33%, 12.74%), and shoot length (19.73%, 11.06%) in Khanpur raya and Sandal canola, respectively. Compared to the control treatment, irrigation with contaminated water decreased the photosynthesis rate (98.42%, 99.34%), chlorophyll content (18.27%, 13.73%), respiration rate (7.97%, 6.47%), and transpiration rate (9.90%, 33.33%) in both varieties, respectively. Notably, the concentrations of Ni (0.01 and 0.003), Cd (0.01 and 0.012), and Pb (0.03 and 0.05%) in the seeds were increased, as well as in Khanpur raya and Sandal canola, respectively, compared to the controls. Furthermore, the PTE accumulation in different components was recorded, with the order of soil > root > shoot > seed. It was observed that brassica cultivars differed significantly in their response to the growth and accumulation of PTEs in edible parts. It was concluded that Khanpur raya did not exhibit a decline in growth due to PTEs in irrigation water and prevented the translocation of PTEs towards edible parts compared to Sandal canola and thus can be safely grown in soils receiving PTE-contaminated water.