| Rice is the main food crop in China,the heavy metal pollution area of farmland increases the risk of consuming cadmium rice.There are differences in heavy metal uptake and accumulation among different genotypes(varieties)of rice,Some rice varieties have the characteristics of heavy metal tolerance.At the same time,the uptake of heavy metals by rice is also affected by the availability of heavy metals in soil,the availability of heavy metals in soil is closely related to soil factors,farmland environment may affect the uptake of heavy metals by low heavy metal accumulation varieties in specific environments.Chemical passivators can reduce the available and movable heavy metals by regulating the basic physical and chemical properties of soil.Therefore,the combination of low accumulation rice varieties and passivating agent can effectively improve the efficiency of heavy metal remediation.In this study,a field experiment was carried out for three years in farmland polluted by heavy metals in Tongling.45 rice varieties were used as test materials.In the previous two years,rice varieties were screened in heavily polluted and unpolluted fields of cadmium.In the third year,the low accumulation rice varieties and Lime+biological organic fertilizer+Senmex porous ceramic nanomaterials,were selected to repair Cd heavily polluted farmland and mildly polluted farmland.The Cd content and yield difference of different varieties of rice in different pollution degree and Cd content,yield difference of rice and effect of passivator on available cadmium in soil with combined remediation of low accumulation Rice varieties with Passivator were studied.The results of the study are as follows:1.The higher the degree of Cd pollution in farmland,the higher the accumulation of Cd in rice grain,the lower the rice yield,and there is a very significant negative correlation between rice yield and Cd content in rice grain.2.In the same degree of pollution,Cd accumulation in different grain varieties was significantly different(P<0.05),and the grain accumulation of Japonica rice varieties was lower than that of Japonica varieties.3.The low accumulation rice varieties selected by the low-accumulation rice variety screening test include Xudao 5,Zhendao 11,Xiushui 63,Xudao 7,Jiayou 2,Zhendao 14,Wandao 68,and Yangjing 4227.Nanjing 11,Ningjing 4,Fengliangyouxiang 1,Liangyou6206,Xinliangyou 106,Xinkedao 21,Teqing,Liangyou 766,Zhenzhuai,Zhendao 18,Liangyou 8106,can be used as low Accumulated cadmium rice varieties for further research;and the relatively high accumulation of varieties are Guangliangyou 1128,Liangyouxin 90,II You 838,Xiangliangyou 2,Huiliangyou 898,Shenliangyou 1813,Xinliangyou 4 No.293 and II You 293 are hybrid japonica rice.4.The Cd content of rice grains in the low-accumulation rice varieties that were screened in the lightly contaminated areas of Cd all met the national food safety standards;in the farmlands that were heavily polluted by Cd without the addition of passivators: the Cd content in grain of Zhendao 14,Jiayou 2,Xudao 7,Zhendao 11,Xudao 5,Xiushui 63 and Ningjing 4 reached national food safety standards;Lime + bioorganic fertilizer +porous ceramic nanomaterials can significantly reduce Cd content in rice grains in Cd heavily polluted areas.The percentage of reduction was 1.0%～85.7%,with an average decrease of 52.6%.Six varieties of rice such as Zhenzhuai,Teqing,Xinkedao 21,Xinliangyou 106,Zhendao 18,and Yangjing 4227 could be reduced to national food security standard;5.There was a certain difference in the yield of rice of different varieties on the same pollution level,but the difference was not significant,and the combination of lime +bioorganic fertilizer + ceramic nanomaterials had no significant effect on the yield;6.The application of lime + bioorganic fertilizer + porous ceramic nanomaterials in the Cd heavily polluted area can significantly reduce the available Cd content in soil,the reduction rate is 1.1%-75.8%,with an average of 27.1%;... |
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