HEAVY METAL TOXICITY AND IT'S PHYSIO-BIOCHEMICAL EFFECTS ON MAIZE (Zea mays L.)

Waste disposals from industries, commercial, agricultural, medical and automobile are major soil pollutants that contain heavy metals, inorganic and organic compounds etc. In agricultural lands heavy metals accumulated into the soil which effect crop growth, and ultimately food production. Maize genotype Pak-afghoi was used to investigate the effect of heavy metals.  Different concentrations of Mn and Cr were applied separately and in combined form to observe the growth and photosynthetic pigments in Pak-afghoi.  High toxic affect was found under treatment 0.5mMolar MnCl2 + 0.25Molar CrCl3 which affect chlorophyll ‘a’ and chlorophyll ‘b’ in stem and leaves, leaves per plant and plant height. But under heavy metal stress carotenoides were increased when treated with 0.5mMolar MnCl2 + 0.25mMolar CrCl3 that builds a defensive mechanism as well as make the tolerance under heavy metal stress. Less toxic effect was observed under treatment 0.25mMolar CrCl3, 0.5mMolar MnCl2 and 0.25mMolar MnCl2 which did not affect chlorophyll contents in stem and leaves, leaf area, plant height and leaves per plant. When manganese was applying separately it did not affect much more on plant growth but when it was applied in combined form, plant growth was badly affected. Similarly, small concentration of chromium did not affect plant growth but in combined form, it affected photosynthetic pigments and growth related traits. The results were concluded that the application or exposure of maize with heavy metal caused adverse effects on growth and development in Maize plant.