Assessment of Heavy Metals (Cd, Co, Cr and Pb) Effects on In Vitro Seed Germination and Seedling Growth of Vigna mungo

Vigna mungo generally called as black gram is a nutrient food crop which is widely used in Indian cuisine and also used in traditional ayurvedic medicine. By natural and anthropogenic activities, black gram growth is highly affecting by heavy metal pollution. Hence, it is necessary to conduct the experiments to know the effects of various heavy metals on growth of black gram in turn yield levels. In the current study, we aimed to study the in vitro effects of heavy metals such as chromium (Cr), cadmium (Cd), cobalt (Co) and lead (Pb) on germination of seeds and seedling morphology of black gram. The concentrations include 1, 10, 20, 50 and 100 ppm of respective heavy metal (Cr, Cd, Co and Pb) along with the two positive controls i.e. tap water (T.W) and distilled water (D.W) were used without any heavy metal for the preparation of media. Upon treatment, percentage of germination and both root and shoot lengths of black gram were significantly affected by increasing concentrations of cadmium, cobalt and lead when compared to controls. Specifically, germination percentage was reduced from 1 ppm to 100 ppm i.e. 77% to 46% with Cd, 64% to 50 % with Co and 78% to 70 % with Pb treatments. This data indicates that each heavy metal has its own impact on black gram seed germination. Similarly, shoot and root lengths were also reduced upon these heavy metal treatments. Although the percentage of germination decreased drastically (36% at 100 ppm) along with the increasing concentration of chromium, the root and shoot lengths were suddenly increased (hugely root length) when compared to controls. In conclusion, each heavy metal has its own critical point for each seedling or plant growth.