Influence of Iron Plaque on Accumulation and Translocation of Cadmium by Rice Seedlings

This study investigated the impact of soil type and rice cultivars on variations in the iron plaque formation and cadmium (Cd) accumulation by different portions of rice seedlings under the influence of Fe amendment. The experiments were performed in pots under glasshouse conditions using two typical paddy soils. Rice seedlings were exposed to three concentrations of Cd (0, 1 and 3 mg kg(-1) soil) and Fe (0, 1.0 and 2.0 g kg(-1) soil). The results revealed that shoot biomass decreased by 12.2-23.2% in Quest and 12.8-30.8% in Langi in the Cd1.0 and Cd3.0 treatments, while shoot biomass increased by 11.2-19.5% in Quest and 26-43.3% in Langi in Fe1.0 and Fe2.0 as compared to the Fe control. The Cd concentration in the roots and shoots of rice seedlings were in the order of Langi cultivar > Quest cultivar, but the Fe concentration in rice tissues showed the reverse order. Fe plaque formations were promoted by Fe application, which was 7.8 and 10.4 times higher at 1 and 2 g kg(-1) Fe applications compared to the control Fe treatment. The Quest cultivar exhibited 13% higher iron plaque formation capacity compared to the Langi cultivar in both soil types. These results indicate that enhanced iron plaque formation on the root surface was crucial to reduce the Cd concentration in rice plants, which could be an effective strategy to regulate grain Cd accumulation in rice plants.