Effect of Intercropping and Anion-accompanying Fertilizers on Cd Uptake and Accumulation of Brassica Campestris
|School||Gansu Agricultural University|
|Keywords||Cd soil pollution anion-accompanying fertilizers intercropping oilseed rapes|
The focal and difficult points of using plants to remediate the soil polluted by Cd are todiscover plants that have hyper-accumulating ability and to increase their ability ofaccumulating Cd respectively. Fertilizers are able to affect the absorption, increase theresistance of plants and relieve the poison released by Cd by changing the fractionation ofCd in the soil. Intercropping can also change the phyto-availability of Cd in the soil andinfluence the growth of plants and the plants’ability to absorb Cd by influencing the contentpH, Eh, CEC and organic matter in the soil.A pot culture experiment was conducted to study the impact of anion-accompanyingfertilizers and chickpea intercropping on the phyto-availability of Cd in the soil, Cd uptakeand its mechanism, so as to provide the efficiency of remediating Cd-polluted soil of plantswith scientific evidence. The results of the experiment are as follows:1.Among anion-accompanying fertilizers such as Cl-, SO42-, NO3-, etc., Cl-is better atpromoting the growth of the taproots of oilseed rapes in Cd-polluted soil,12.07%~36.85%exceeding other fertilizer treatments with significant difference, but its effect on thepromotion of the volume of the plants is weaken rapidly with the increase of theconcentration of Cd of the soil. NO3-is good at promoting the root activity of oilseed rapes,3.03%~6.62%exceeding other treatments under Cd pollution and even reaching65.52%~66.87%under the condition of high Cd pollution, with significant differenceamong other treatmenst. SO42-can increase the volume of the roots of oilseed rapes whensoil is seriously polluted by Cd,35.90%~95.41%exceeding other fertilizer treatments. In aword, Cl-, with5.22%~20.82%exceeding other treatments, has a greater effect onpromoting the phyto-availability of Cd in the soil, and this kind of effect increases with theincrease of the concentration of Cl-, which can reach11.23%~23.98%.2.―Siyueman‖Oilseed rapes, whose Enrichment Coefficient (EC) and Translocationfactor (TF) are both greater than one, is a high Cd accumulation species. Though oilseedrapes are planted in soil that contains0.6mg·kg-1of Cd, the upper soil of each processedoilseed rape field contains at least1.15mg·kg-1of Cd, all exceeding0.2mg·kg-1,4.75times exceeding the standard of food security. Therefore, it is not suitable to plant crops on fieldscontains Cd that exceeding0.2mg·kg-1.3.Despite that Cl-can significant increase Cd concentration of the upper part ofoilseeds rapes fields, other fertilizers decrease Cd concentration of the fields. Among thosefertilizers, the impact of treatments non anions (1.15mg·kg-1) or SO42-fertilizer (1.22mg·kg-1) is significant smaller than other treatments, which are27.51%and29.19%of nonprocessed fields (4.18mg·kg-1). To grow oilseed rapes that reach the edible standards in soilcontaining Cd that exceeds the safety standards of the country, we should choose low levelup-taking oilseed rapes and apply urea or fertilizers accompanying SO42-to improve thebiomass of oilseed rapes and decrease the concentration of Cd of the edible parts of it.4.Intercropping chickpea can not only mitigate the stress by Cd pollution, but alsoincrease the efficiency of fertilizers use and the enrichment ratio and transfer ratio of Cd ofoilseed rapes, improve the biomass of oilseed rapes(29.37%and16.18%respectively),secrete organic molecules that can combine with Cd, enhance the phyto-availability ofCd(10.14%and8.47%respectively), increase the Enrichment Coefficient(EC) andTranslocation factor(TF) of oilseed rapes, significant increase the total Cd accumulation ofoilseed rapes(51.22%and39.99%respectively).5.In the two fields with Cd pollution, Cl-and chickpea intercropping treatments havean interaction with the total Cd absorption of oilseed rapes, the total Cd accumulation ofoilseed rapes can reach67.72μg and783.72μg per oilseed rape,5.91and4.82times asmuch as that of11.49μg and198.44μg per oilseed rape of non fertilizer treatments. Theresults show that intercropping chickpeas with fertilizers accompanying Cl-substantiallyincreases the efficiency of remediation for Cd polluted soil of plants.