Sub-cellular localization and quantitative estimation of heavy metals in lemongrass plants grown in multi-metal contaminated tannery sludge

Abstract Major objective of the study was to assess the localization pattern of heavy metals in different parts of lemongrass plant when grown in multi-metal contaminated sites. Microscopic and quantitative investigations (by ICP-OES) were carried out in root and leaves of plant to examine the compartmentalization of heavy metals. Along with it, the morphological variations in the size of trichomes in test plants were also perceived. Differential distribution of Cr, Pb, Ni and Cd was observed in root and leaf sections. Localization of these heavy metals in different parts of the plant cultivated in sole tannery sludge was compared with the plants grown in garden soil; which served as control. Histochemical methods for Pb, Cd and Ni detection revealed their significant accumulation in the root and leaf sections. Cr accumulation in roots of test plants was confirmed by fluorescence staining. Translocation factor 1 was observed for Ni and Pb. SEM studies revealed that the size of trichomes enlarged in plants grown in tannery sludge. Hence, our study provides an insight into the localization pattern of heavy metals in lemongrass plants and suggests that lemongrass can serve as a Ni and Pb phytoextractor when grown in multi- metal contaminated sites. In addition, enhancement in the size of trichomes was detected due to heavy metal stress which may prompt increment in essential oil yield thus; cultivation of lemongrass in heavy metal contaminated sites can also prove profitable economically.