Cadmium (Cd) pollution in soil is becoming increasingly serious due to anthropogenic activities, which not only poses a threat to the ecological environment, but also causes serious damage to human health via the biological chain. Consequently, special concerns should be paid to develop and combine multiple remediation strategies. In this study, different subspecies of oilseed rape, Brassica campestris, Brassica napus and Brassica juncea were applied, combined with three organic acids, acetic acid, oxalic acid and citric acid, in a simulated Cd-contaminated soil. Various physiological and biochemical indexes were monitored in both plant seedling, growth period and mature stage. The results showed that organic acids significantly promoted the growth of Brassica campestris and Brassica juncea under Cd stress. The photosynthesis and antioxidant enzyme activities in Brassica campestris and Brassica juncea were induced at seedling stage, while that in Brassica napus were suppressed and disturbed. The enrichment of Cd in oilseed rape was also obviously increased. Brassica juncea contained relatively high resistance and Cd content in plant but little Cd in seed. Among the three acids, oxalic acids exhibited the most efficient promoting effect on the accumulation of Cd by oilseed rape. Here, a comprehensive study on the combined effects of oilseed rape and organic acids on Cd contaminated soil showed that Brassica juncea and oxalic acid possessed the best effect on phytoremediation of Cd contaminated soil. Our study provides an optimal way of co-utilizing oilseed rape and organic acid in phytoremediation of Cd contaminated soil.
Keywords: antioxidant enzyme; cadmium; combined remediation; oilseed rape; organic acids; phytoremediation; soil pollution.