Organic acids in conjunction with various oilseed sunflower cultivars promote Cd phytoextraction through regulating micro-environment in root zone

Exogenous chelates in conjunction with phytoextraction have been demonstrated as a prominent potential for remediating Cd-contaminated soils. Among bath chelates, low molecular-weight organic acids have the advantages of smaller impact on plant growth and lower negative effects on soil environment. In this research, oilseed sunflowers were selected as the main extraction plants, and the Cd phytoextraction effects of different cultivars, varies organic acid types and concentrations combinations were systematically examined. Results showed that adding exogenous organic acids improved biomass of all issues, but the increase varied with the cultivar. For both cultivars, their biomass increase with acid application concavely, with the acid application rate at which the biomass peaked differed between the two cultivars. Adding exogenous acids boosted Cd concentration in roots and shoots in general, but it reduced the Cd content in seeds as well as the rhizosphere and bulk soil. In addition to its impact on Cd, application of organic acids also reduced nutrient and salinity in the rhizosphere and promoted root uptake of nutrients as a result. Cd content plant an soil was closely related to nutrients in soil and plant. The organic acids reduced soil Cd and nutrients in soil proximal to the roots. It was also found that adding acids reduced Cd content in the top 0–10 cm soil but increased the Cd content in the 10–30 cm soil, alluding a potential leaching. Therefore, adding organic acids to improve phytoremediation of Cd needs to proceed with care. •Remediation effect for Cd of combinations between six organic acid concentration and two species of oil sunflower were investigated.•Cd in various tissues of plant, different soil layers and rhizosphere soil.•Adding exogenous acids boosted Cd concentration in roots and shoots, but reduced the Cd content in seeds as well as the rhizosphere and bulk soil.