The Study Of Copper Toxicity To Citrus (Citrus L.)

Using the method of nutrition culture, the effects of copper stress on the citrus growth, cell ultra-structure, activity of enzyme, photosynthesis were Studied. The results showed as follows: 1 The effects of copper stress on growth of Citrus1.1 Treatment with the concentration of 0.1 μ mol/L cupric sulfate promoted the growth of Citrus, While 5, 20, 40 μ mol/L cupric sulfate restrained it. Copper toxicity had been caused only when the concentration of cupric sulfate was above 5 u mol/L, and the more the concentration increased, the more toxicity was. In the treatment of 5, 20, 40μ mol/L cupric sulfate, The biomass of root decreased 17.31%, 26.23%, 34.20% respectively compared with control; While that of stem decreased 11.75%, 20.87%, 29.18%; that of leaves decreased 18.35%, 38.86%, 60.67%. And water content in root decreased 4.65%, 5.31%, 6.74%; While that in stem decreased 3.48%, 8.35%, 12.98% and that in leaves 3.89%, 12.98%, 19.45 % respectively.1.2 Copper stress caused injury on cell ultra-structure of citrus leaves, Under copper stress, the damage on chloroplast suffering from copper stress was most distinguished, grana lamellace twisted and disordered, membrane system of chloroplast damaged greatly; It was also found the clearance between cells became smaller, the cytoplasm segregated from cell wall and the cell wall began to decompose; vacuole was broken and disappeared under serious copper stress; at the same time, membrane system of mitochondrion damaged too, the number of cristae reduced, and further more the disappeared, The cell was dissolvedunder serious copper stress.1.3 Under copper stress, the root of citrus became black gradually, the tip of root became shorter and thicker. The cell wall of cortex and trachea became thin, clearance between cells of root tip became smaller, and the cell wall lost elasticity and became harder. The number of cristae reduced, membrane system damaged, membrane of cristae and karyon was broken; granulose reduced and even disappeared, The cell was dissolved under deep copper stress.2 The effects of copper stress on activity of enzyme and permeability of plasma membrane.2.1 Copper stress damaged the membrane of cell. The study showed that the high concentration copper stress (5 % 20 ?> 40 u mol/L) caused membrane lipid peroxidation and increment of permeability of plasma membrane. The permeability of K+ and the content of MDA increased with the concentration of copper. The activity of SOD, CAT, PPO increased as the concentration of copper enhanced, With the increase of cupric sulfate concentration, their activities decreased; While the POD activity always increased. The activity of SOD, CAT reached maximum in the concentration of 0.11? mol/L cupric sulfate, while the PPO activity reached maximum in the concentration of 5 u mol/L cupric sulfate.2.2 Treatment with 0.K 5n 10 u mol/L cupric sulfate, the protein of citrus leaves have no obvious change; Some protein were restrained and some new proteins were induced at the same time in the treatemt with high concentration of cupric sulfate (20 > 40 u mol/L).3 The effects of copper stress on photosynthesis3.1 The content of Chi in the treatment of 0.1 u mol/L cupric sulfate increased...