Effects of Exogenous 5-Aminolevulinic Acid and 24-Epibrassinolide on Cd Accumulation in Rice from Cd-Contaminated Soil

High grain-C d-accumulating rice variety Yongyou 9 was planted in C d-contaminated farmland in Taizhou City, Zhejiang Province, China to study the effects of 5-aminolevulinic acid (ALA) and 24-epibrassinolide (EBR) on C d accumulation in brown rice. Results showed that the exogenous ALA and EBR had no significant effects on agronomic traits, soil pH and total C d content in soil, but had some effects on the available C d content in soil, and significantly influenced the C d accumulation in the different parts of rice. Results also showed that 100 mg/L exogenous ALA significantly reduced the C d accumulation in brown rice to blow the food safety standard (0.2 mg/kg), and also significantly reduced the C d contents in the roots and culm of rice. However, 200 mg/L exogenous ALA treatment increased the C d content in brown rice remarkably. In addition, 0.15 mg/L EBR treatment increased C d accumulation in roots, culm, leaves and brown rice notably, whereas 0.30 mg/L exogenous EBR treatment reduced the C d accumulation in brown rice properly, but it was not significant Therefore, proper concentration of ALA can effectively reduce the C d accumulation in brown rice, which can be used as an effective technical method for the safe production of rice in C d polluted farmland.