Effect Of Two Kinds Of Heavy Metal Stress On Growth And Metabolism Of Two Lawn Grasses

The degree of Master treatise analysed effects on the accumulation of biomass, plant growth and metabolism of two plants, using of simulated potted plant experiment. While perennial ryegrass (Lolium perenne L) and creeping bent {Agrostis stolonifera) were exposed to cadmium(Cd) and lead(Pb), the biomass, plant growth and chlorophyllous content of the two plants, and the antioxidant enzymes in the roots would been changed. Bases of the study results, this treatise demonstrated the effects on development and metabolism of the plant by heavy metal.The results showed that Cd was one of the most toxic pollutants and was non-essential for plant. Cd would interact with phytosynthetic, respiratory metabolism in plants, resulted in poor growth and low biomass accumulation. When the plants exposed to Cd, and the cadmium concentration in the Hoagload was 1.5 × 10~-3mol L~-1, the metabolism and development of plant would be affected. The effect of the roots biomasses was litter than that of leaves biomasses by Cd. The toxic symptom of roots by Cd damaging, was roots perish and death and leaves chlorophyll dropping. When Cd was entered into leaf, it would over-produced free radicals and reactive oxygen species (ROS). These species of radicals reacted with bio-moleculars and caused lipids peroxidation, membrane damage, inactivation of enzymes, thus affecting cell viability. Theantioxidative system of plants were comprised of superoxide dismutase (SODs), catase (CAT), peroxidase (POD), ascorbate peroxidase (APX) and glutathione peroxidase (GPOX). The maximum affection of Cd occurred in roots was to CAT, followed to SOD and POD.Lead would take biomass decrease, especially, roots biomass and calyptrogen cell drop. When Pb went into the leaves and induced over-production of ROS, the ROS would attack the chlorophyll in the chloroplast and conduced the leaves losing green. The results showed the activity of roots cell antioxidative enzymes was enhanced at low Pb concentration in the Hoagload, and the activity of enzymes would being climbed with exposed time extend. It was demonstrated the ROS in cell was being moved up and the activity of antioxidative was raised too. At high Pb concentration, the enzyme activity would fast raised, but it was dropped then. It illuminated that most ROS had made the enzyme's activity losed. The enzyme activity of SOD, CAT were more sensitive to Pb poisonous affection than POD.Heavy metal ions entered into plant and enhanced increase of ROS, fortunately, understanding the biochemical detoxification strategies that plants adopt against oxidative strees induced by accumulated metal ions was a key to manipulate heavy metal tolerance in plant. When the accumulated metal ions were bigger and more longtime, the balance would broken off, overproduced ROS induced metabolize and cell construction damaged. The results supported the heavy metal ions induced enhancement of ROS and the ROS attracted to the chlorophyll in the choloroplast and damaged the mitochondrial sub-construction infected the plant metabolism. Cd-induced poisonous affection was stronger than Pb's. The resistance to heavy metal poisonous affection of perennial ryegrass was stronger than creeping bent.