Pollution to the environment by heavy metals is mainly due to human activities. The presence of heavy metals even in traces is toxic to both plants and animals. The excess of cobalt can affect the plant’s physiological functions. In order to control cobalt heavy metal soil pollution by a low cost technique an attempt was made employing biosorption using Dictyota dichotoma. In this study, the seedlings of (cowpea) Vigna unguiculata (L) were treated with various concentrations of cobalt chloride and its impact on the morphometric, biochemical and enzymatic characteristics were studied. Eight days after treatment with different concentrations of cobalt chloride (2mM, 4mM, 6mM, 8mM, & 10 mM), the growth parameters such as leaf area, fresh weight, dry weight, shoot length, root length were found decreased than in the control. Biochemical parameters such as soluble sugar and protein content were decreased with the increase in the concentrations of cobalt chloride. On the contrary the contents of free amino acid, proline and leaf nitrate were increased with increase in the concentrations of cobalt chloride. The activities of enzymes such as catalase and peroxidase barring nitrate reductase were found increased with the increase in the concentration of cobalt chloride. Application of 6mM cobalt chloride solution treated with various concentrations of Dictyota dichotoma such as 2gm/L, 4gm/L & 6gm/L & 8gm/L on the experimental plants has brought about changes in the suppressed characteristics showing relief from stress due to cobalt chloride. Atomic Absorption Spectroscopy (AAS) technique was employed to confirm the presence of cobalt in the treated and control plants. Comparison of the values of treated plants with control reveals that cobalt chloride has seriously affected the (cowpea) Vigna unguiculata (L) plants and Dictyota dichotoma is effectively biosorbed the cobalt heavy metal.
