Research On The Mechanismof Of Heavy Metal Tolerance In Cucumber Under Shed Protection

RESEARCH ON THE MECHANISM OF HEAVY METALTOLERANCE IN CUCUMBER UN])ER SHED PROTECTIONWith the development of life level and change of consumption intention, reen vegetable?was accepted by more and more people. However, the development of chemical industry in cities and the hree waste?of industry given off seriously polluted the soil, air and water, which the plant lived on. The vegetable planted under polluted environment, content heavy metal and other pollutants, these affected people health and lives. Consequently, the study of heavy metal pollution on vegetables is urgently important.The experiment was carried out to study arsenic, cadmium, lead, manganese, mercury, zinc the effect of cucumber seeds germination, crop growth, yield, qualities, the change regular of SOD,POD,CAT,PPO,NR and the regular of heavy metal accumulation in soil and cucumber fruits. The results showed that:High concentration of heavy metal delayed the seeds germination and growth. After treated with heavy metal, the cucumber plant height, stem diameter, leaf-number, square of leaf and the plant spread are lower than the contracts and the first female flower nodes are higher than of the contracts. The higher of the concentration of heavy metal, the fruits yield lower.After polluted by mercury and zinc in soil, the contents of total chlorophyll is not only reduction but also negative correlation with the heavy metal concentration, and the coefficient of correlation is -0.87 and 0.79.The roots activities was decreased.After treated with heavy metal, the activities of POD,SOD,CAT in cucumber seeds are increased in low concentration treatment ,and decreased in high concentration treatment. The critical band pattern of POD iso-enzyme is changed by heavy metal pollution.The activity of nitric acid deoxidize enzyme is negative correlation with mercury concentration, the coefficient of correlation is -0.96 . Zinc polluted critical value on NR and POD is 400mg/kg. Mercury polluted tolerant critical value on SOD and POD is 30mg/kg. Mercury and zinc are hardly effect on PPO activity.Mercury reduced the contents of vitamin C and total sugar in cucumber fruits, but zinc increase the content of vitamin C, hardly influenced the total sugar. So, we regard that zinc can improve the quality of cucumber fruits.Mercury and zinc accumulation is increasing with the appended quantity of heavy metal, the coefficient of correlation is 0.92 and 0.94.Mercury in fruits increasing with its quantity in soil, however, when zinc concentration is 400mg/kg, zinc content in fruits reach the highest numerical value: 89.30mg/kg, which far surpassed the standard of FAO/ WHO.