Phytotoxicity of mercury in Indian mustard ( Brassica juncea L.)

This study investigated the phytotoxicity of mercury to Indian mustard ( Brassica juncea L.). Two common cultivars (Florida Broad Leaf and Long-standing) were grown hydroponically in a mercury-spiked solution. Mercury exhibited a significant phytotoxicity in these two cultivars of Indian mustard at elevated concentrations (⩾2 mg L −1). Mercury uptake induced a significant reduction in both biomass and leaf relative water content. Microscopy studies indicated that elevated mercury concentrations in plants significantly changed leaf cellular structure: thickly stained areas surrounding the vascular bundles; decreases in the number of palisade and spongy parenchyma cells; and reduced cell size and clotted depositions. The palisade chloroplasts exhibited decreases in their amounts and starch grains as well as a loss of spindle shape. However, due to high accumulation of mercury in plants, especially in the roots, Indian mustard might be a potential candidate plant for phytofiltration of contaminated water and phytostabilization of mercury-contaminated soils.