紫云英还田配施石灰对水稻镉吸收转运的影响

Effect of Chinese milk vetch combined with lime on cadmium uptake and translocation in rice

采用田间小区试验,研究了紫云英(CMV)与石灰(L)单施及两者配施(CMVL)对土壤Cd有效性、水稻根表胶膜及Cd吸收转运的影响.结果表明:L与CMVL处理土壤pH值分别显著提高2.11~2.43和1.68~2.48个单位、二乙烯三胺五乙酸提取态(DTPA-Cd)含量分别显著降低18.88%~40.53%和20.74%~36.85%,而CMV处理对其无显著影响.CMV处理水稻成熟期根表胶膜Cd吸附量(DCB-Cd)显著提高86.72%,根Cd吸收显著增加124.27%,Cd由叶向米的转运系数提高5.58倍,稻米Cd含量显著增加58.54%.L和CMVL处理成熟期DCB-Cd含量分别显著降低34.86%和42.42%,Cd由根表胶膜向根的转运系统分别显著提高170.6%和158.8%、Cd由根向茎的转运系数分别显著降低75.87%和74.71%、Cd由根向米的转运系数分别显著降低74.38%和68.13%,稻米Cd含量分别显著降低54.88%和51.83%.土壤pH值、DTPA-Cd和DCB-Cd含量是影响稻米Cd含量的主要因素.在镉污染稻田施用紫云英时,建议配施石灰可达到显著降低稻米Cd的效果.

A plot experiment was conducted to study the combined effects of Chinese milk vetch(CMV)and lime(L)on the availability of Cd in soil,the concentrations of Cd in Fe-Mn plaque on roots and the uptake and transport of Cd in rice plants.The results showed that soil pH value was significantly increased by 2.11~2.43 and 1.68~2.48 units,and DTPA-Cd concentration decreased by 18.88%~40.53% and 20.74%~36.85% in L and CMVL treatments,respectively,while it had no significant effect on them in CMV treatment.The Cd concentration in Fe-Mn plaque on rice roots at maturity in CMV treatment was significantly increased by 86.72%,that in roots was increased by 124.27% while that of Cd in grains was increased by 58.54%,which the transport coefficient of Cd from leaf to grain was increased by 5.58 times.The Cd concentration in Fe-Mn plaque on rice roots at maturity in L and CMVL treatments were significantly increased by 34.86% and 42.42%,while the transport coefficient of Cd from Fe-Mn plaque on rice root to root significantly increased by 170.6% and 158.8%,respectively.However,the transport coefficient of Cd from root to stem in L and CMVL treatments was significantly decreased by 75.87% and 74.71%,while those of Cd from root to grains decreased by 74.38% and 68.13%,respectively.Cd concentrations of rice grains in L and CMVL treatments were significantly reduced by 54.88% and 51.83%,respectively.Pearson correlations indicated that soil pH,DTPA-Cd and Cd concentration in Fe-Mn plaque on roots were the key factors on the Cd concentration of rice grains.Chinese milk vetch combined lime to Cd-contaminated rice fields can significantly reduce the Cd in rice grains.