Comparative Study of Pb and Ni Phytoextraction Potential: in Two Raya Varieties of Brassica juncea (L.) Czern for Tolerance and Accumulation

Abstract

Heavy metal contamination poses a major threat to crop productivity and food security. The present study evaluated the comparative effects of nickel (Ni) and lead (Pb) on growth, physiology, and anatomy of two Brassica varieties, Khanpur Raya (V1) and Raya RL-18 (V2), under controlled pot experiments. Plants were exposed to 80 mg Ni kg⁻¹ soil (T1) and 80 mg Pb kg⁻¹ soil (T2) for 14 days. Results revealed that Ni exerted greater phytotoxic effects than Pb, significantly reducing plant height, shoot fresh and dry weight, and photosynthetic traits (net CO₂ assimilation, stomatal conductance, transpiration rate, and intercellular CO₂ concentration). Raya RL-18 exhibited greater sensitivity, showing higher reductions in chlorophyll a, chlorophyll b, and total chlorophyll content compared to Khanpur Raya. Anatomical observations highlighted pronounced root modifications (epidermal and cortical alterations) and decreased leaf lamina thickness in V2, whereas V1 maintained comparatively stable structures. Both metals increased water use efficiency and altered stomatal density and aperture. Collectively, the study demonstrates that Ni toxicity is more severe than Pb, with varietal differences shaping stress responses. Khanpur Raya exhibited greater tolerance, suggesting its potential for cultivation in moderately contaminated soils and for use in phytoremediation strategies.

Keywords: Heavy Metals, Brassica Varities, Toxicity, Morphology, Chlorophyll, Anatomy

https://doi.org/10.5281/zenodo.16912670