Growth of Vigna radiata, V. mungo and V. unguiculata under abiotic stress of mercury

Mercury (Hg) poisoning in soil has become a global issue due to increase demand of safe food. In present study, toxic influence of Hg(II) was checked on seed and seedling growth of three pulses namely Vigna radiata (L.) Wilczek, V. mungo L. Hepper and V. unguiculata (L.) Walp both in vitro and in vivo conditions. In laboratory bioassays, pulse seeds were exposed to 3 mL of six different concentrations (50-500 mg L^-1) of Hg(II) in 9 cm diameter Petri plates. Germination percentage, shoot and root significantly declined by 2-30% in all Vigna spp. after 96 hours of growth over control in Petri plates. In pots, Hg(II) was applied in similar six concentrations in 360 g of soil. The germination rate, shoot and root growth were significantly reduced by 5-30%, 8-28% and 10-35% due to increasing concentration of Hg(II) in soil in 15-days old seedling over control. Morphological symptoms like wilting and necrosis of leaf margins, disorientation of roots and shoots growth were observed at higher dose of Hg(II). V. unguiculata and V. radiata were sensitive to detrimental influence of Hg(II) than V. mungo. In conclusion, Hg(II) had significant drastic effects on early growth of pulses, therefore more research is needed to explore the toxicity of different mercury based pesticides and fungicides that are generally utilized on agricultural land to increase yield and profit of crop.