Abstract:Through the pot experiment, four different forms of iron (Fe) were applied to the soil at the jointing stage and grain filling stage to study the effects of cadmium (Cd) uptake and accumulation in rice. The results showed that compared with no Fe application at jointing stage, the content of available Fe in soil increased first and then decreased, and the content of available Cd (DTPA-Cd) in soil showed an overall upward trend, but in the late stage of culture, the contents of iron ethylenediamine o-dihydroxyacetate (EDDHA-Fe) and sodium ethylenediaminetetraacetate (EDTA-Fe) decreased the contents of DTPA-Cd by 35.86% and 27.38%, respectively. EDDHA-Fe significantly reduced the Cd content of iron plaque (IP) and rice Cd by 13.22% and 2.3%, respectively. EDTA-Fe also reduced the Cd content in IP by 14.16%. Ferric citrate and ferrous sulfate increased the Fe/Cd ratio of the IP. Compared with the non-Fe application at the grain filling stage, the DTPA-Cd content increased after Fe application, but the DTPA-Cd content decreased by 13.88% and 13.53% respectively in the late stage of culture. EDDHA-Fe, EDTA-Fe and ferrous sulfate reduced the Cd content in mature IP by 28.64%, 14.83% and 41.25%, respectively. After the application of four Fe species at the filling stage, the content of available Fe in the soil increased slowly. Correlation analysis between soil and plants showed that Fe application at jointing stage mainly affected the content of soil DTPA-Cd, the blocking effect of IP on Cd, and reduced the absorption and transport of Cd in roots, thereby affecting the accumulation of Cd in rice. However, the application of Fe at the grain filling stage mainly reduced the Cd content in the IP and reduced the uptake and transport of Cd by plants. In conclusion, the key growth period and Fe morphology of rice had significant effects on Cd migration, root uptake and shoot transport in the soil-rice system. The application of chelated Fe at the jointing stage and ferrous sulfate at the grain filling stage can help to block Cd through IP and reduce the uptake of Cd by roots, thereby reducing the Cd content of rice.