Chromium Phytotoxicity Alters Metabolism in Radish

ABSTRACT

Industrialization has posed an increasing threat to the environment. Effluents from different industries ultimately find their way into water used to irrigate crops. There is a risk that heavy metals accumulating in these agricultural soils may eventually contaminate the human food chain. Radish, an important vegetable consumed by humans, was selected as the test plant. The cv. Jaunpuri was grown in refined sand supplemented daily for 50 days with complete nutrient solution. On the 51st day pots with plants were separated into three lots, one lot served as the control and received only the nutrient solution, and in each of two other lots chromium (Cr) as dichromate was added at 0.1 and 0.5 mM to the basal nutrient solution. At 0.5 mM Cr, toxicity symptoms were observed 5–8 days after treatment expressed as reductions in leaf size accompanied by loss of turgor, and old leaves became chlorotic and wilted. Treatment with Cr reduced growth, biomass, concentration of chlorophyll (a and b), relative water content in leaves, iron, phosphorus, sulphur in shoots (leaves and stem plate) and activity of catalase in leaves, but increased the concentration of chromium, iron, phosphorus, and sulphur in roots, and increased the activity of peroxidase and acid phosphatase in leaves of radish.

KEYWORDS:

• Raphanus sativus
• chromium
• enzymes
• phytotoxicity
• radish