Growth and physiological responses of Zea mays L. to Cu and Ni stress

Copper and Nickel are an essential micronutrient for plants، playing an important role in maintaining plants'' natural metabolism and growth، but in excess both heavy metal are also a proven inhibitor of various physiological functions. In this study maize (Zea mays L.) plants grown in hydroponic culture were treated with 0، 50 and 100 μm CuSO4 and 0، 100 and 200 μm NiSO4. Growth parameters and some biochemical changes were studied in roots and shoots of plants. The results showed that with increasing Cu and Ni concentration، root and shoot weight (27 to 52% in root and 24 to 62% in shoot)، root and shoot length (14 to 59% in root and 9 to 46% in shoot)، pigment contents (chlorophyll a 14 to 67%، chlorophyll b 32 to 79% and total carotenoids 25 to 74%)، reduction of dichlorophenol indophenol (48 to 67%) were decreased in contrast to controls، while soluble sugars leakage (0/5 to 2 fold)، K+ leakage (0/25 to 30 fold) and malondealdyde as indicator lipid of peroxidation (48 to 152% in root and 54 to 190% in shoot)، cell death (5 fold) and prolin content (12 to 29% in root and 9 to 107% in shoot) were increased in contrast to controls. The result showed that the maximum effects in growth parameters and some biochemical changes were observed in 200 μm Ni + 100 μm Cu. However، interaction of Cu and Ni were cooperation effects on together and was more effective compared to the others treatments.