Effect of cadmium, mercury and lead on seed germination and early seedling growth of Vigna ambacensis L.

The response of seed germination and early seedling growth of Vigna ambacensis L. to different concentrations (0.05–50 mM) of three heavy metals, cadmium, mercury and lead were studied. A progressive and significant decrease in percentage of seed germination, seedling growth and an increase in radicle and shoot metal content (5 days after incubation) was found with the increase in concentration of heavy metals. The degree of inhibition varied depending on the presence of heavy metals and their concentration. Percentage of seed germination, at 0.5 mM was 16, 66 and 69% for Hg, Cd and Pb respectively. Seed germination was most tolerant to lead and cadmium concentration compared to mercury. Hg and Cd at 10.0 mM and Pb at 50.0 mM stopped seed germination. Radicles were more adversely affected by heavy metals than shoot growth. Seedling growth was more sensitive to Cd than Hg and/or Pb at (0.5 mM) concentration. The heavy metal content of analyzed seedling parts increased with the increase of heavy metals concentration and to a higher extent in the radicle than in the shoot.