TOXIC EFFECTS OF HEAVY METALS ON EARLY GROWTH AND TOLERANCE OF CEREAL CROPS

Abstract

Metals have strong influence on development and growth of crops. To simulate how cereal crops are affected and/or tolerated from heavy metal contamination by disposal of unregulated wastes as soil amendments, the nutrient culture experiment was conducted with barley (Hordeum vulgare L.), rice (Oryza sativa L.) and wheat (Triticum aestivum L.) at control (0), 1, 5, and 10 µM of copper (Cu), zinc (Zn), lead (Pb), magnesium (Mg) and sodium (Na). A 4 x 3 factorial experiment for each metal was set-up in a completely randomized design with four replications. Seed germination, total root numbers, root length, shoot height, and root: shoot ratio of seedlings were measured and integrated to calculate a metal tolerance index for each crop. Among the metals, Cu exerted the most adverse effects on seed germination, early growth and tolerance of crop seedlings followed by Zn and Pb. Wheat and rice seedlings were more susceptible to metal toxicity than barley. The effect of 10 µM Cu, Pb and Zn was more pronounced on crop seedlings especially on wheat and rice.