Effects Of Environmental Factors On Soil Heavy Mental Accumulation Of Lolium Perenne L.

Lolium perenne L.has a large biomass and high reproductive capacity,and it has good remediation effects on the heavy metal Cu-Pb complex contaminated soil in previous experiments.In order to make it more resource-efficient and more effective in remediation of heavy metal soils,it is necessary to understand the impact of various environmental factors on the growth of ryegrass and its enrichment of heavy metals.The main contents of this study are divided into three parts.The first is that the ryegrass was used as the test object and different levels of environmental factors were set under the Cu,Pb single and Cu-Pb combined stress to explore the effects of different environmental factors on the seed germination and seedling growth of ryegrass.The second is the same ryegrass as the test object,resetting the level of single environmental factor screening.Under the Cu,Pb single and Cu-Pb combined stress,its biomass,contents of various parts of plant,enrichment coefficient and translocation coefficient were analyzed to speculate on the potential of restoration of ryegrass to Cu and Pb contaminated soils at a single environmental level.Thirdly,using ryegrass as test plant,the experiment was conducted to explore the effects of moisture,temperature and fertilization on the growth of ryegrass and its enrichment of heavy metals,in order to obtain the ecological environment suitable for the restoration of heavy metal polluted soil by ryegrass.The main findings are as follows:(1)The seed germination and seedling growth of ryegrass at 70%field capacity(70%WHC),80%field capacity(80%WHC)and 90%field capacity(90%WHC)processing group were significantly higher than that of the other treatments.And they were also significantly higher than other treatment groups between 15?-30?.However,no significant trend was found in the fertilization levels.Compared with Pb,Cu obviously inhibited the germination and growth of ryegrass.(2)The seed germination and seedling growth of ryegrass were inhibited when the soil moisture was too little or too much,the temperature was too high or too low.The degree of inhibition was different.However,they were also different in the fertilization treatment group due to the different nature of fertilizer.(3)The effects of different water gradients on the growth of ryegrass and its enrichment of heavy metals were significant under the single environmental factors of soil moisture.Under the single Cu stress,the tolerance of ryegrass to Cu decreased when the soil moisture was above 70%WHC,which would inhibit the growth of ryegrass,as did the trend of Cu content in roots.Under the single Pb stress,the growth of ryegrass was inhibited when the soil moisture was more than 80%WHC.The concentration of heavy metals in root of ryegrass increased with the increase of water content.The increase of water could increase the enrichment of heavy metal Pb in the roots of ryegrass.Under Cu-Pb combined stress,the increase of water contributed to the growth of ryegrass,and the contents of Cu,Pb in ryegrass also changed obviously.(4)The increasement of temperature could inhibit the growth of ryegrass.Under the single Cu stress,the biomass of ryegrass differed significantly at different temperatures.The over-temperature was not conducive to the enrichment of heavy metal Cu in the upper part of ryegrass.Under the single Pb stress,there was no significant difference in root biomass of ryegrass at different temperatures,indicating that temperature had little effect on the growth of ryegrass roots.Under Cu-Pb combined stress,the biomass of ryegrass differed significantly under different temperatures.The increasement of temperature was beneficial to the enrichment of heavy metals Cu and Pb on ryegrass.(5)The biomass of the upper part of ryegrass was significantly different under different fertilization treatments,while the difference of the root biomass was not significant.Under the single Cu stress,fertilization was beneficial to the growth of ryegrass and also could promote the enrichment of heavy metal Cu on ryegrass.Under the single Pb stress,fertilization could promote the content of Pb in the roots of ryegrass.Under Cu-Pb combined stress,the content of Pb in the root of ryegrass was opposite to the single Pb stress.After the application of N,the content of Pb decreased,and the application of NP further inhibited the absorption of Pb at the root.And the inhibition of Pb in roots was stronger after the application of NPK.(6)Under the interaction of water,temperature and fertilization,the growth of ryegrass and its concentration of Cu and Pb were all significantly affected by the interaction of its factors.