Nickel Toxicity Effects on Growth and Metabolism of Eggplant

Abstract

Contamination of agricultural products with heavy metals including Ni has become an important concern throughout the world due to potential adverse effects on human health. The industrial use of nickel has led to environmental pollution by the metal and its byproducts during production, recycling, and disposal. Eggplant (Solanum melongena L.) is a vegetable crop consumed by many ethnic groups and grown in many parts of the world. A study was conducted to investigate effects of Ni concentration on metabolic activities affecting developmental responses in eggplant. Seeds of eggplant, cv. Hybrid P.K.123, were sown in refined sand at levels of from 0.1 to 400 μM. Exposure of plants to Ni > 50 μM decreased biomass, concentration of photosynthetic pigments in leaves, concentration of Fe in leaves and stem, and activities of catalase and peroxidase. Decreased concentration of chlorophyll and the activities of heme enzymes, catalase, and peroxidase with increased Ni may indicate interference by Ni in iron metabolism of plants. The concentration of Ni in plants and proline and activities of superoxide dismutase and ribonuclease increased with increasing levels of nickel. Oxidative damage measured as level of lipid peroxidation was observed in leaves of plants. At 400 μM Ni, visible symptoms of Ni toxicity, chlorosis and necrosis, were observed on young leaves along veins and margins at 10 days after treatment. Appearance of metal-specific toxicity effects is likely the result of membrane damage as a consequence of production of reactive oxygen species (ROS) especially at higher (300–400 μM) levels of Ni.

Keywords:

• Solanum melongena
• Eggplant
• Enzymes
• Oxidative stress