Impact of Heavy Metals (Cr, Pb and Sn) on In Vitro Seed Germination and Seedling Growth of Green Gram (Vigna radiata (L.) R. Wilczek)

Heavy metal toxicity has been known for more than a century and focus on the effects of heavy metals particularly on plant growth and development has only recently received more attention due to increasing pollution day by day. The effects of chromium (Cr), lead (Pb) and tin (Sn) on green gram [Vigna radiata (L.) Wilczek] were studied in the present investigation under in vitro growth conditions. The doses of 1, 10, 20, 50 and 100 ppm were used in the present experiments. The percentage of seed germination and early seedling growth were affected by Cr, Pb and Sn at higher concentrations. It has been observed that the effect of chromium is very significant and a drastic decrease in seed germination was noticed as well as early seedling growth with increasing concentrations especially at 50 and 100 ppm when compared to other heavy metals. Both lead and tin exhibited gradual/moderate reduction in seed germination and shoot length with increasing concentrations. In contrast, an abnormal root growth was noticed in tin treatments. The content of total chlorophyll decreased with increasing chromium concentrations. Similarly, abnormal total chlorophyll content was noticed in both lead and tin treatments. This investigation may be useful to study plant growth patterns particularly in areas polluted with heavy metals.