Effect of heavey metal on biomass and yield of different crop species

Abstract

Different crop species, viz cowpea (Vignn imgrrici,larri), okra (Abeb~zoschuse sc~ileilrrrs)r,a dish (Rnpl~oa~srast i~yrs). spinach (Spailicia olerocerr), chickpea (Cicer arieriiiurt~), pea ( P I ' s Is~n tiiw~ia nd wheat (Triticurn aesti~w?rw) ere grown in heavy metals contaminated soils to examine their effects on biomass, yield and metal distribution in different parts of crop plants. The appiication of copper, zinc, lead and cadmium in general reduced the economic yield and biomass of almost ail the vegetable crops by 9-67 and 9-32 5% while enhanced the yield and biomass of field crops by 10-30 and 0-14% respectively. However mercury invariably reduced the yield and biomass of both vegetable and field crops. Among the heavy metals, Zn showed highest tissue concentration followed by Cu, Pb and Cd. The concentration of metals was higher in edible parts of leafy vegetables such as spinach and radish than in the edible parts of fruit type of vegetables and field crops. Among the crops, wheat showed maximum uptake of Cu and Zn, while spinach and okra manifested maximum uptake of Pb and Cd respectively. Although maximum proportion of heavy metals absorbed by the crops accumulated in their vegetative shoots (leaves, stem and root), but substantial proportion of metals transported to seeds and fruits as well.