Contamination of soils with cadmium (Cd) is a serious problem worldwide. Rice (Oryza sativa L.) is reported to accumulate relatively higher Cd contents in consumable parts and is considered a main source of Cd toxicity to humans from rice-derived products. The aim of this pot trial was to investigate the effect of foliar-applied iron (Fe) complexed with lysine on growth, photosynthesis, Cd concentration in plants, oxidative stress, and activities of antioxidants of rice in soil contaminated with Cd. Rice seedlings (30-day-old) were transferred to the soil, and after 2 weeks, different concentrations of Fe-lysine (0, 1.5, 3.0, 4.5, 6.0, and 7.5 mg L-1) were applied as a foliar spray once in a week for 4 weeks and plant samples were taken after 10 weeks of growth in the soil under ambient conditions. Foliar supply of Fe-lysine complex significantly enhanced the plant height, dry weights of plants, concentration of chlorophyll, and gas exchange attributes in Cd-stressed rice. Fe-lysine decreased the Cd concentrations in plants while increasing the Fe concentrations in rice seedlings being maximum with Fe-lysine of 6.0 mg L-1. Electrolyte leakage decreased while activities of key antioxidant enzymes increased with Fe-lysine compared to the control. According to the present results, Fe-lysine complex can effectively be used to reduce Cd concentrations in rice and probably in other crop species.
Keywords: Antioxidant enzymes; Cadmium; Iron-lysine; Photosynthesis; Tolerance.