Comparative study of three Pteris vittata-crop intercropping modes in arsenic accumulation and phytoremediation efficiency

Intercropping of Pteris vittata, an arsenic (As) hyperaccumulator, with crops is a method to realize the "production while remediation"of contaminated farmlands. However, the soil As remediation effects and the related mechanisms of P. vittata intercropping with different crops are rarely reported. In this study, by use of soil microplot experiment and root zone separation technique, the intercropping modes of P. vittata with maize (Zea mays L.), ramie (Boehmeria nivea (L.) Gaudich.) and castor (Ricinus communis L.) were designed to investigate the As and nutrient uptake and accumulation, antioxidant enzyme response, soil As fractionation, and the remediation effects of As contaminated soil by P. vittata-crop intercropping. The results showed that the intercropping increased As content of P. vittata by 3.1-25.3%, decreased As content of maize grains and leaves of ramie and castor by 70.9%-95.6%, 29.2%-32.0% and 18.8%-32.0%, respectively, indicating higher remediation efficiency by P. vittata-crop intercropping. The intercropping increased the total nutrient contents (NPK) of the three crops by 2.0%-91.1%, promoted plant biomass by 3.7%-111.0%, increased the transpiration rate by 4.9%-68.9%, and decreased the malondialdehyde (MDA) content by 7.0%-31.8%. Analysis also showed that the intercropping enhanced soil pH value and available As content in P. vittata rhizosphere. The proportion of iron-bound As was enhanced in P. vittata rhizosphere soil but decreased in three crops rhizosphere soil. The analysis of soil microbial diversity showed that the intercropping decreased the abundance of chloroflexi, increased the abundance of proteobacteria and actinobacteria. In summary, the P. vittata-crop intercropping had a positive significance for improving As remediation effect of P. vittata and reducing the As content in crops. Those modes could be applied in the practice of heavy metal contamination remediation along with crop production in farmland. (C) 2021 Elsevier B.V. All rights reserved.