| With the development of urbanization and industrialization,soil cadmium contamination has become increasingly serious.Taking some artificial intervention to enhance phytoremediation technology is supposed to improve the ability of plants absorbing cadmium,while the single phytoremediation technology has the disadvantages of low efficiency and long cycle.In the thesis,the Sichuan ornamental plant species Althaea rosea with Soil culture potting method was investigate for the effects of Bacillus mucilaginosus and potassium(KCl)on growth,physiological and biochemical characters,nutrient element conditions of various organs as well as the Cadmium absorption capacity and cadmium availability in rhizosphere soil under Cd stress.The purpose of this thesis is to reveal the cadmium uptake capacity of Althaea rosea under cadmium stress with physic potash and biopotassium.The results are as follows:(1)The low and medium Cd concentration(≤50mg/kg)promoted the biomass of Althaea rosea,high cadmium(100mg/kg)concentration significantly inhibited the biomass of Althaea rosea;potassium treatment can increase the biomass of Althaea rosea,but high cadmium and high potassium treatment inhibits Althaea rosea Biomass.Under the condition of Cd treatment,the soluble protein content of the leaves of the Althaea rosea leaves decreased first,then the content of soluble sugar,MDA and proline increased continuously.The potassium treatment reduced the content of MDA,proline,increased soluble protein content and low cadmium level.The content of soluble protein in potassium leaves increased,and the content of soluble protein in potassium decreased at the medium and high cadmium concentration.(2)Under Cd treatment,the absorption of nitrogen(N),calcium(Ca)and magnesium(Mg)in various organs of the Althaea rosea increased,the absorption of phosphorus(P)decreased significantly(P<0.05),and the change of potassium(K)was small.After the application of potassium,the absorption of N and P decreased significantly(P<0.05).The absorption of K and Ca increased significantly(P<0.05),and the change of Mg absorption was not obvious.(3)Under Cd treatment,the cadmium content of various organs of Althaea rosea showed root>stem>leaf,cadmium transport coefficient<1,cadmium enrichment coefficient>1;potassium treatment could increase cadmium uptake in various organs,and potassium fertilizer could increase Althaea rosea under low cadmium level Cadmium transport coefficient,enrichment factor,and potassium application at medium and high cadmium levels increased cadmium enrichment factor in Althaea rosea to reduce cadmium transport coefficient.Potassium fertilizer treatment under Cd can reduce the pH value of rhizosphere soil,increase carbonate bound state,organic matter binding state,and reduce iron and manganese oxidation state cadmium content.(4)Under the medium cadmium treatment(50mg/kg),the biomass of Althaea rosea decreased,and the application of bacterial fertilizer could increase the biomass of various organs of Althaea rosea and increase the ratio of root/crown;cadmium stress significantly promoted the absorption of N and Ca in the roots of Althaea rosea,while P,K,The effect of Mg absorption was not significant.The N absorption of the root of the Althaea rosea was significantly decreased,the absorption of P and K increased significantly,the absorption of Ca increased first and then decreased,and the change of Mg absorption was not significant.(5)Under the treatment of medium cadmium,the cadmium content in the geranium was changed little,but the cadmium accumulation,enrichment coefficient and transport coefficient were significantly improved.The pH value of the rhizosphere soil of the geranium was decreased,and the effective Cd content was increased.Under cadmium treatment,dehydrogenase and polyphenol oxidase activities in the rhizosphere soil of the Althaea rosea were decreased,and the urease,sucrase,activity was improved.The urease,sucrase,dehydrogenase and polyphenol oxidase in the rhizosphere soil of the Althaea rosea were significantly increased after the application of the bacterial fertilizer.In summary,The application of potassium fertilizer under Cd stress can promote the growth of Althaea rosea,activate cadmium in the rhizosphere soil of Althaea rosea and increase the cadmium content in the plant.The application of bacterial fertilizer has little effect on the cadmium uptake capacity of Althaea rosea,but it can improve the nutrient condition of Althaea rosea rhizosphere soil and promote Althaea rosea Increased biomass and increased total cadmium accumulation in various organs. |
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