| The Qinghai-tibet plateau is known as the "roof of the world" and "the third pole of the earth".It is the "river source" and "ecological source" of China and Asia.It is the "sensor" and "sensitive zone" of climate change in Asia and the northern hemisphere;There are a variety of unique ecological system types and rare species of plants and animals,which is an important part of global biodiversity conservation.Mineral resources are abundant,which is one of the important distribution areas of nonferrous metals and precious metals in China.However,altitude cryosphere and alpine environment under the condition of ecosystem is very fragile,is sensitive to global change and human interference response,anti-interference ability is low,pollution and the destruction of land once,it will be hard to recover in a short time.In recent years,as the demand of the economic development of the Qinghai-tibet plateau,the large-scale development of mineral resources,the rapid development of railway and highway mining,processing and use,waste such as make a lot of lead and other heavy metal residues to soil,heavy metal pollution.At the same time,a large number of studies have shown that heavy metals can also be transferred to areas far away from the source of pollution through long-distance transport of fine particles.The Qinghai-tibet plateau as an unique geographical unit,its surrounding countries not only has a long history of human activities,and to accelerate their own industrialization is,therefore,the Qinghai-tibet plateau is in danger of heavy metal pollution,heavy metal contaminated soil repair management work is imminent.Because of the advantages of high efficiency and low consumption,simple method,soil and water conservation and beautification environment,plant repair technology has attracted the attention of soil scientists,botanists and environmentalists.However,the plant restoration technique has its own limitations,which is not suitable for the environmental climate and other natural conditions are not suitable for the contaminated site of super-rich plant growth and cannot use plant repair technology,which reduces the efficiency of plant restoration.At present,the bioremediation of soil cadmium pollution mainly focuses on the study of cadmium accumulation of super plants,but the accumulation of cadmium ultra small plant growth,biomass,the cadmium pollution of soil bioremediation efficiency is low,and not suitable for growing in the Qinghai-tibet plateau area.Based on this,this study choose root developed,there are many branches and high biomass,frequent tationally cutting resistance,is suitable for the growth of the Qinghai-tibet plateau gramineous highland barley and hanging ear batch alkali grass and legume alfalfa for phytoremediation of heavy metals such as material,using petri dish cultivation experiment carried out research work.To screening of heavy metal cadmium tolerance optimum grass/legume species/varieties of plants,the organic acids and pH of screening potential heavy metal lead repair plant germination,seedling growth and the impact on heavy metal cadmium tolerance ability,to explore the gramineae,leguminosae plants,cadmium metal elements and organic acids and pH characteristics and mechanism of interaction between,for the Qinghai-tibet plateau region of the heavy metal cadmium polluted soil provide theoretical basis for repair work.This research is divided into three parts: 1)To study the tolerance of 13 different species of gramineae and 12 leguminous plants;2)The effects of different pH on the potential heavy metal cadmium restoration plant gramineae K14 and alfalfa W3 under the condition of exogenous cadmium treatment;3)The effects of oxalic acid on the potential heavy metal cadmium restoration plant gramineous barley K14 and leguminous alfalfa W3 under the condition of exogenous cadmium treatment.The main results are as follows:1)There were 25 plants in the study(11 different varieties of highland barley seeds,2 varieties of different varieties of slop seeds,12 different varieties of alfalfa seeds).Low concentration of cadmium(10 mg/L)or less on the germination indexes such as germination percentage,germination potential,germination index and vigor index has a promoting effect,when the concentration of cadmium chloride is 5 mg/L,promotes the most significant(P < 0.05).With the increase of cadmium concentration,cadmium was toxic to seed and the germination index decreased significantly(P < 0.05).Comprehensive,Kunlun 14 gramineous plants of highland barley varieties,memnon,MenYuan bright blue,1 leguminous plant alfalfa varieties WL525H2(9),WL903,six pieces of plant material such as WL243H2 ability of seed germination,seedling growth status and higher resistance to cadmium ability,has the repair as the heavy metal cadmium plants potential,can be further used in salt,low temperature resistance,disease resistance and resistance mechanism research and exogenous cadmium treatment under the condition of different pH and organic acid experimental study on the influence on the ability of resistance to cadmium.2)Applied heavy metal cadmium in plant seeds,seedlings growth inhibitory effect than seed germination inhibition effect is more significant,the seed seedling growth,often more than the seed germination of can reflect the toxicity of cadmium,especially the change of germ and radicle length is an important indicator of the indicator plant by the size of the heavy metal poisoning.When the concentration of cadmium chloride was greater than 30 mg/L,the growth inhibition of seedlings was severe,and its root length,sprout length,root fresh weight and fresh bud weight were significantly reduced.In addition,the applied heavy metal cadmium inhibition effect is greater than the germ of root system,when the concentration of cadmium to 40 mg/L or higher,seriously restrain the growth of the plant seedling radicle,some even appear without growing roots.3)Without cadmium and low concentration of cadmium(5 mg/L)processing condition,the pH of potential heavy metal cadmium repair gramineous plants highland barley varieties Kunlun 14 and leguminosae alfalfa varieties WL525H2(9)of the germination and seedling growth impact of indicators was not significant(P > 0.05),but in the high concentration of cadmium(30 mg/L)or higher processing condition,the pH of 9 alkaline environment can alleviate cadmium stress on potential heavy metal cadmium repair gramineous plants highland barley varieties Kunlun 14 and leguminosae alfalfa varieties WL525H2(9)the toxicity of Cd,significantly promote the seed germination and seedling growth indicators(P < 0.05).4)Without cadmium and cadmium(5 mg/L)processing low concentration under the condition of different concentrations of organic acids(oxalic acid)on heavy metal cadmium potential repair plant gramineous highland barley varieties kunlun 14 and leguminosae alfalfa varieties WL525H2(9)of the germination and seedling growth impact of indicators was not significant(P > 0.05),but in the high concentration of cadmium(30 mg/L)or higher processing conditions,the exerting after 6mmol/L tendency of oxalic acid,the cadmium stresses on potential heavy metal cadmium repair gramineous plants highland barley varieties Kunlun 14 and leguminosae alfalfa varieties WL525H2(9)the toxicity of significantly less than not oxalate and applying 2 mmol/L tendency of oxalic acid treatment,significantly promote seed germination and seedling growth index(P < 0.05). |
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