| With the development of industrialization,urbanization and agricultural modernization,releasing heavy metals into the soil has increased year by year,the soil heavy metal pollution has become a threat to human health,environmental and social issues that affect the quality of human life.Poplar is the world's most widely distributed in plain areas,the most resilient,largest area of cultivation,timber production is one of the tallest tree speeies,are also fast growing plantation of shelterbelt in northern China and one of the main tree species.Due to poplar is general construction in the field by the roadside as highway roadside trees and landscape tree species,they are more susceptible to heavy metal pollution.Along with the poplar plangting area is increasing,the pest problems are becoming more serious.Trends in the occurrence of poplar pests under heaver metal stress ralely reported.In this paper,we studyed the biomass of poplar seedling and the defensive protein activities in poplar leaves under heavy metal stress and the effect on the growth and detoxifying metabolism for gypsy moth(Lymantria dispar)at three concentrations of cadmium(Cd,1.0,3 0,6.0mg/kg)and copper(Cu,400,700,1000mg/kg)with one-year poplar potted seedlings.To explore the changes in insert resistance of wood and the trends in the occurrence of forest pest under the stress of heavy metal pollution,and it can provide a theoretical basis for appropriate prevetion and control measures for poplar pest damage.The results were as follows:1.The effect on the enrichment and biomass of heavy metals in poplar leaves at different concentrations of copper and cadmium.With different concentrations of Cd,Cu treatment after 60d,Cd and Cu are found in the the enrichment of poplar leaves.Enriched content of heavy metal is positively correlated with concentrations,that is,with the increase of Cd and Cu concentrations,enrichment of Cd,Cu content in the poplar leaves of all treaments increased significantly(P<0.05)compared with the control.Different concentrations of Cd and Cu on the fresh weight and dry weight of stem,toot and the total showed a certain inhibitory effect.With the increase of concentrations of Cd,Cu,inhibitory effect on the poplar biomass enhanced,high concentration of Cd,Cu treatment showed significantly inhibitory effect compared with the control performance(P<0.05),but the difference is not obvious between the medium and low concentration of Cd,Cu treatment and the control performance.2.The effect on defensive protein of heavy metals in poplar leaves at different concentrations of copper and cadmium.With the concentrations of heavy metal Cd,Cu increasing and prolonging of time,defense protease activity in the leaves showed regular changes.On 30-40 days after the heavy metal stress,at the high concentrations of Cd or Cu,the defensive protein CAT,SOD,PPO,PAL,CI,TI activities were signifieantly higher than those of the control and peaked on 40th day with low concentrations of Cd or Cu,did not result in any changes in the defensive protein activity.However,on 50-60 days after the treatments at high concentrations of Cd and Cu,CAT,SOD,PPO,PAL,CI and TI activities were significantly lower than those of the control.While low concentrations of Cd and Cu treatments were still not different from the control treatment,though their activities were the lowest on 60th day.3.The effect on the growth and detoxifying metabolism for gypsy moth(Lymantria dispar)at different concentrations of copper and cadmium.The heavy metal Cd,Cu showed a significant impact on the third,fourth instar larvae growth and detoxification metabolic enzyme(P<0.05).High,medium,low concentrations of Cd and Cu showed significant inhibitory effect on the average weight of gypsy moth larvae and pupal weight(P<0.05).With the concentrations of heavy metal Cd,Cu increasing,the survival rate of gypsy moth larvae,pupa and adult eclosion rate decreased significantly.The SOD,ACP and AKP enzyme activity in vivo in the third instar larvae of gypsy moth at medium and high concentrations of Cd,Cu are lower than the control group(P<0.05),but the low concentrations of Cd,Cu treatment is not obvious(P>0.05).And the activity of POD and GSTs change is just the opposite,The POD and GSTs enzyme activity in the third instar larvae of gypsy moth at medium and high concentrations of Cd,Cu increased significantly compared with the control group(P<0.05),but he low concentrations of Cd,Cu treatment is not obvious(P>0.05).The SOD,POD,ACP,AKP and GSTs enzyme activity in the fourth instar larvae of gypsy moth at medium and high concentrations of Cd,Cu decreased significantly compared with the control group(P<0.05),but the low concentrations of Cd,Cu treatment is not obvious(P>0.05).Above all,High concentrations of Cd and Cu showed significant inhibitory effect on the growth of poplar and significantly interfered with protease acitivy in the poplar leaves.High,medium and low concentrations of Cd and Cu showed significant inhibitory effect on the growth of gypsy moth larvae,and medium,high concentrations of Cd and Cu significantly interfered with the detoxifying metabolism for gypsy moth larvae.the research shows that poplar and gypsy moth larvae on heavy metal pollution stress have obvious density in response,pest prevention and control in the production practice should be based on the degree of heavy metal pollution to take appropriate measures.The results for our forest ecosystem health,as well as heavy metal pollution in case forests provides scientific and theoretical basis for the integrated management of pests and diseases... |
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