Study On Soil Quality Level And Product Quality Characteristics Of Apocynum Venetum Cultivated Land In The Upper Yellow River Valley

This study takes the Robinia L.produced in Qinghai as the research object,and systematically analyzes and evaluates the seven heavy metal elements contents（As,Cd,Cr,Cu,Zn,Pb,Ni）,pollution level and pollution situation in the root soil,leaves and stems of the Robinia L.The relationship between the plant and the heavy metal elements in the rhizosphere soil of the plant was analyzed.The physical and chemical components in the root soil and whether the nutrients in the plants had an effect on the heavy metal elements.In view of the problems in the evaluation,the correlation between the content of heavy metal elements,physical and chemical properties and nutrient components in the root soil and plants of the plant were discussed.It can provide the basis for the safety evaluation of the Lop leaf in Qinghai Province,and also provide reference for the quality evaluation of the Lop leaf and the establishment of the limit standard of metal elements of the Lop leaf.The research results are as follows:（1）The single pollution level of heavy metals As,Cd,Cr,Cu,Ni,Pb and Zn in the root soil of Apocynum venetum was in the non pollution level,and the P level was in the safety level,indicating that the root soil of Apocynum venetum was not polluted by these heavy metals.（2）Heavy metal elements in rhizosphere soil interact with each other,and p H value,moisture,urease,organic matter,phosphatase,NH4⁺,NO₃^-in rhizosphere soil have certain influence on heavy metal elements in soil,which indicates that physical and chemical components in soil have certain influence on heavy metal elements in soil.（3）The single pollution level of As,Cd,Cr,Cu and Pb in the leaves of Apocynum venetum in the growing and mature stages was in the non pollution level,and the P level was in the safety level,which indicated that Apocynum venetum was not polluted by these heavy metals in the middle growth stage.The contents of Cd and Pb in the leaves of Apocynum venetum were higher than those in the leaves of mature stage,and the contents of As,Cr,Cu,Ni and Zn in the leaves of mature stage were higher than those in the leaves of growing stage.The contents of these heavy metals in the leaves of Apocynum venetum increased with the growth of Apocynum venetum.During the growth of Apocynum venetum,there is a certain relationship between the heavy metal elements in the leaves,and the content of nutrients in the leaves also has a certain impact on the content of heavy metal elements.The components in leaves of Apocynum venetum will interact with each other in the growing period,but not in the mature period.（4）The single pollution level of heavy metal elements As,Cd,Cr and Cu in the long-term stem of Apocynum venetum was in the non pollution level,the single pollution level of Pb was in the light pollution level,and the total P was in the warning line,indicating that the long-term stem of Apocynum venetum was polluted by heavy Metal Element Pb.The single pollution level of As,Cd,Cu and Pb in the mature stem of Apocynum venetum was in the non pollution level,the single pollution level of Cr was in the light pollution level,and the total pollution level of P was in the safety level,indicating that the mature stem of Apocynum venetum was not polluted by these heavy metals.During the growth of Apocynum venetum,there is interaction between heavy metal elements in the stem,and the nutrients in the stem have a certain effect on the content of heavy metal elements in the stem.（5）The contents of As,Cd,Cr,Cu,Ni,Pb and Zn in leaves and stems of Apocynum venetum show certain changes（increase or decrease）with the increase of these heavy metal elements in root soil.According to Pearson correlation analysis,it w As found that As,Cr,Ni,Zn in rhizosphere soil during the growth period of apocynum venetum had obvious correlation with heavy metals corresponding to As,Cr,Ni and Zn in apocynum venetum stems,and Cu in rhizosphere soil had obvious correlation with Zn in apocynum venetum leaves during the mature period of apocynum venetum plants,but there was no correlation between other heavy metals.