RESPONSES OF ROOT GROWTH AND PROTECTIVE ENZYMES TO COPPER STRESS IN TURFGRASS

Root growth and protective enzymes of Festuca arundinacea L. and Lolium perenne L. under Cu stress were investigated in a hydroponic experiment. Cu stress significantly inhibited root growth (root elongation and dry biomass) of both turfgrasses. Malondialdehyde (MDA) content in roots of both turfgrasses markedly increased under copper stress. In F. arundinacea root, superoxide dismutase (SOD) activity increased greatly with increasing Cu concentration; peroxidase (POD) activity increased at low Cu level and decreased at high Cu level. Increased MDA content indicated the formation of free radicals tinder Cu stress, while increased SOD activity pointed to the operation of a scavenging mechanism. In roots of L. perenne. however, SOD and POD were not activated by copper. These results demonstrate that turfgrass cultivars clearly differ in tolerance to Cu stress, and that the tolerance depends largely on the enhanced activity of its antioxidant system.