Abstract: Heavy metal in soil is closely related to the quality of agricultural products. In this study, a pot experiment with rice (Oryza sativa L.) under arsenic stress was conducted to examine the effects of different application times and concentrations of complexed iron-bearing material on SPAD value, activities of antioxidant enzymes (SOD, POD, CAT), arsenic uptake and accumulation in rice. The results showed that the activities of SOD, POD and CAT were inhibited in rice under arsenic stress. The addition of complexed iron-bearing material reduced MDA concentration, alleviated the inhibition of arsenic on photosynthesis and activities of SOD, POD and CAT in rice, and decreased the arsenic uptake and accumulation. With respect to adding times, adding complexed ironbearing material before booting stage had better effect than adding before transplanting on controlling arsenic uptake in rice. There was a significant negative correlation between the concentration of arsenic in shoot and the application level of complexed iron-bearing material. Adding complexed iron-bearing material at the level of 0.2 g·kg^-1 before booting stage had the best effect on alleviating arsenic stress, with a 59.22% reduction of arsenic concentration in shoot.

Key words: red soil, vegetation type, pH, exchangeable acidity, profile distribution.