外源有机物料对酸性土壤水稻镉积累的影响

Effects of Exogenous Organic Materials on Cadmium Accumulation in Rice in Acidic Soils

通过盆栽试验,研究了不同初始pH值和有机质含量的土壤在持续淹水下,外源有机物料对水稻植株镉积累的作用效果。得出以下结论:有机物料添加量越多,酸性土壤的初始pH值上升越大,初始Eh值下降越多。在水稻各生育期土壤中有效Cd含量呈现分蘖期>抽穗扬花期>成熟期的规律,持续淹水下添加外源有机物料能够显著降低水稻生育期内酸性泥土中的DTPA-Cd(有效态镉)含量,且外源有机物料的添加量和酸性土壤中的DTPA-Cd含量呈反比。在有机质较多的土壤中(不论酸性还是弱碱性),水稻在各部位中的Cd浓度和周围土壤中的DTPA-Cd浓度均呈极明显正相关的关系。在天然有机质浓度较低的土壤中,水稻在各部位中的Cd浓度和周围土壤的DTPA-Cd浓度均呈极明显负相关关系。水稻各部位Cd的含量从根、茎叶到糙米依次递减,且水稻植株内的Cd主要集中在水稻根部。这说明,添加外源有机物料能够抑制土壤中的Cd向水稻中富集,且添加量越大抑制作用越强。

Through pot experiment,the soil with different initial pH value and organic matter content under continuous flooding,the effects of adding exogenous organic materials on cadmium accumulation in rice under continuous flooding were studied.The results were as follows:with the more the addition of organic materials,the more the initial Eh value decreased,the greater the initial pH value of the acid soils increased.At different growth stages of rice,the content of soil available Cd was tillering stage>heading stage>ripening stage.The content of DTPA-Cd(available Cd)in acid soils was significantly decreased by adding exogenous organic materials under continuous flooding,and was negatively correlated with the amount of exogenous organic materials added.In soils with higher organic matter(whether acidic or alkaline),the content of DTPA-Cd was significantly positively correlated with the content of Cd in rice grains,roots,stems and leaves.However,in soils with low organic matter,DTPA-Cd content in soils was not correlated with the content of Cd in rice grains,but negatively correlated with the content of Cd in roots,stems and leaves of rice.The content of Cd in different parts of rice decreased from root,stem and leaf to brown rice,and Cd in rice plant was mainly concentrated in the root of rice.With continuous flooding,the addition of exogenous organic matter could inhibit the accumulation of Cd from soil into rice,and the higher the addition amount,the stronger the inhibition effect was.