Effect Of Different Rice Varieties And Rice-Sesbania Intercropping On The Environmental Behavior Of Cadmium In Flooded Soil

In this paper,the relationship between the formation of rice root iron plaque and the absorption of rice Cd,starting with two angles between different rice varieties and between rice-fields,and by carrying out hydroponic experiments of different rice varieties and potted plants between rice-fields,the mechanism of influence of rice root iron plaque on Cd in soil-plant migration process in flooded environment is studied,with a view to clarifying the influence mechanism of rice root iron plaque on the behavior of rice Cd in the soil.Based on the experimental study,the following conclusions are preliminary:1.In hydroponic tests,under the stress of 24 hours 0.05 mg/L Cd,the total absorption of Shaonuo16-72 Cd without external iron was 1.74 times that of Bing0203,while the accumulation of cadmium was significantly reduced,only 59%of Bing0203.and the Cd content in roots,stems and leaves was significantly lower than Bing0203.Therefore,it was determined that Bing0203 was a low-accumulative species of Cd,while Shaonuo 16-72 was a high-accumulation variety of Cd.2.In rice hydroponics without applying exogenous iron and cadmium,the content of Shaonuo16-72 strains secretion dissolved organic carbon(DOC)was significantly higher than that of Bing0203,while the application of exogenous iron and cadmium increased the root secretion dissolved organic carbon(DOC)content,the content of the root surface iron film and the adsorption of cadmium in the iron membrane,and the increase of Shaonuo6-72 was greater than Bing0203.3.Under the treatment of exogenous iron,the absorption of Cd Shaonuo16-72 has been significantly reduced,indicating that the application of’ exogenous iron can effectively inhibit the absorption of Cd in rice.This is because the application of exogenous iron increased the content of Shaonuo 16-72 surface iron plaque,the root surface iron plaque is an important barrier to prevent Cd migration to rice,thereby reducing the absorption of Cd in rice plants.4.In the rice-field potted plant experiment,there was no significant difference in the biomass between rice-field and rice-to-field monoliths,but the amount of Cd absorbed between the two was significantly greater than the amount of Cd absorbed by the two;5.After planting the field,due to the release of a large number of root secretion strains of the field,the soil cadmium form shows a significant difference:the effective Cd content and the iron manganese combined Cd content,the organic binding Cd,but the residual slag state and the first three forms of Cd no significant difference;6.The formation of the iron plaque of the field and rice root is obviously greater than the amount of the root iron plaque of the rice and the field sheet,and the formation of the iron plaque of the root table is increased.The results of the potted plant test showed that the content of the iron plaque of the root table was positively correlated with the secretion content of the root system of the plant,and the soil pH was negatively correlated,and the iron plaque formation of the plant root table was positively correlated with the Cd absorption content of the plant and the content of the root table adsorption cadmium.Interplay enhances the vitality of the plant root system,forming a certain range of small iron plaque(this content of iron film to promote the absorption of Cd in the plant),while making the soil pH reduced,activated the soil Cd,and ultimately increased the accumulation of Cd.