Effects of root mycorrhizal colonization and varied phosphorous supply on cadmium accumulation in rice plants

Official URL: https://risc01.sabanciuniv.edu/record=b2767137_(Table of contents)

Cadmium (Cd) is a heavy metal and exerts harmful effects on the environment and humans depending on its concentrations. Rice-based foods are known to be a major dietary source of Cd exposure to human populations. It is therefore important to study the factors affecting Cd accumulation in rice plants. Use of phosphorous (P) fertilizers is often associated with increased Cd accumulation in food crops and suggested that Cd-containing P fertilizers represent an important source of Cd in food crops. However, increases in plant Cd by P fertilizers are not necessarily related to the Cd content of the P fertilizers applied. This counterintuitive finding led us to investigate the factors affecting Cd accumulation in rice plants by paying particular attention to various P fertilizers differing in Cd content and root mycorrhizal activity. It is known that arbuscular mycorrhizal fungi (AMF) are an important barrier against the transfer of Cd from the soil to the shoots of plants. Rice plants (Oryza sativa L. cv. Rekor CL) were cultivated aerobically under greenhouse conditions and treated with increased P fertilization rates v with and without mycorrhizal inoculation and autoclaving the experimental soil. The results obtained showed that increasing the P application caused substantial increases in the shoot Cd concentrations in all of the experimental treatments, irrespective of the Cd content of the P fertilizers. These increases were pronounced when the experimental soil was sterilized. Soil inoculation with AMF significantly decreased the Cd accumulation in rice plants, especially when the experimental soil was sterilized. The results suggested that increase in plant Cd accumulation by P fertilization is related to diminished root mycorrhizal colonization, and root mycorrhizal activity plays a key role in limiting Cd transfer from soils in the above-ground parts of the rice plants.