Effects of mercury on germination, growth and ultrastructural deformation in Vigna radiata (L) Wilczek

Mercury is one of the heavy metals that can cause harm to crops, ecosystems, and human health. Vigna radiata (L) Wilczek plants were cultivated hydroponically in solutions containing varying doses of mercury (Hg), ranging from 1 to 5 ppm, as HgCl ₂ . The negative impact of mercury on seed germination was observed at concentrations of 2 ppm and 5 ppm, with 50% inhibition noted. Both catalase and peroxidase, two of the enzymes under study, were found to raise activity to 3 ppm in treated plants before declining. In the plants treated with mercury, the activity of other enzymes continuously decreased with an increase in mercury concentration. The transverse sections of the treated plant were subjected to energy dispersive X-ray analysis (EDX), which revealed that mercury was deposited throughout the plant's tissues of both root and stem. All treated plants showed a decrease in morphological characteristics such as root and shoot length as compared to the control. The biochemical characteristics of the treated plants showed a similar pattern. Mercury was deposited in the roots and stems of the treated plants, causing anatomical deformation, as seen in the scanning electron micrograph of the experimental plants. In plants exposed to mercury at concentrations of 1 ppm or higher, conducting tissues in both the roots and the stems shrank, and in plants exposed to mercury at concentrations of 3 ppm or higher, tissue damage was documented. The study demonstrated that mercury has a cytotoxic impact on the well-known legume V. radiata and that plants growing in areas contaminated by mercury can be correlated with the investigation.