不同混施钝化剂对水稻吸收累积Cd的影响

将石灰、赤泥和高岭土按不同比例混合(施用总量为4500kg hm-2)施加于Cd污染稻田土壤,根据混合比例不同设置CK(常规种植)、T1(1∶7∶4)、T2(3∶5∶4)、T3(4∶4∶4)和T4(6∶2∶4)共5个处理,探究不同混施钝化剂对水稻吸收累积Cd的影响。结果表明:4种混施处理能够显著降低土壤有效态Cd含量,较CK相比依次降低了28.0%、40.9%、43.4%和57.4%。4种混施处理能够不同程度地降低水稻各部位对Cd的吸收累积,籽粒的Cd含量依次降低47.1%、49.2%、55.5%和81.6%,T2、T3和T4处理水稻籽粒中Cd含量达到了食品安全国家标准(G B27622017,Cd≤0.2mg kg-1)。土壤有效态Cd含量与水稻根、茎、叶和籽粒中Cd含量的Pearson相关系数分别为0.826、0.709、0.778和0.532,均达到显著相关。不同处理根系富集系数依次为5.03、1.83、2.22、1.32和0.90,钝化处理显著降低了水稻根系对Cd的富集能力。各处理水稻产量以及籽粒K、Mg元素含量没有显著差异,T1到T4处理Ca元素含量依次增加。综合分析,T4处理对于降低土壤中有效态Cd含量以及水稻籽粒中Cd含量效果最佳,且没有降低水稻产量和与稻米品质密切相关的K、Mg和Ca元素含量。

Effects of different combined amendments on Cd uptake and accumulation by rice

A field experiment was conducted to study the effect of different combined amendments on Cd uptake and accumulation by rice plants.In this study,lime,red mud,and kaolin were mixed in different proportions(the total application amount was 4500 kg·hm-2)and the mixtures were applied to Cd-contaminated paddy soil.According to the different mixing ratios of the three materials(lime,red mud,and kaolin),five treatments were designed:CK(control treatment),T1(1∶7∶4),T2(3∶5∶4),T3(4∶4∶4),and T4(6∶2∶4).The results showed that the four combined amendment treatments could significantly reduce the available Cd content of the soil and the Cd accumula?tion in different parts of the rice plant.Compared with that of the CK,the available Cd contents in soil were decreased by 28.0%,40.9%,43.4%,and 57.4%,and the Cd contents in rice grain were decreased by 47.1%,49.2%,55.5%,and 81.6%for the four treatments with com?bined amendments,respectively.The Cd contents of rice grain in T2,T3,and T4 treatments met the National Food Safety Standard value(GB 2762—2017,Cd≤0.2 mg·kg-1).The correlation analysis showed that the available Cd content of the soil were significantly related to the Cd contents in various parts of the rice plant(roots,stems,leaves,and grain),and the Pearson correlation coefficient values were 0.826,0.709,0.778,and 0.532,respectively.The root bioaccumulation factors of the five treatments were 5.03,1.83,2.22,1.32 and 0.90,respec?tively;thus,amendment treatments significantly reduced the bioaccumulation capacity of rice roots for Cd.There was no significant differ?ence in the yield of rice or the K and Mg contents of grain in each treatment,and the Ca content of grains was in the order of T1>T2>T3>T4.Based on a comprehensive analysis,the T4 treatment was the best in the five treatments for reducing the available Cd content in soils and the Cd content in rice grains.Furthermore,it did not reduce rice yield or the K,Mg,and Ca contents that are closely related to rice quality.