Effect of elevated atmospheric CO2 on cadmium uptake by wheat and sorghum

One of the outcomes of the industrial development has been the increase in CO2 levels in the atmosphere. This study was aimed to investigate the effects of different levels of CO2 and cadmium on growth and cadmium uptake by wheat and sorghum. A greenhouse experiment was carried out with pots contained 3.5 kg soils and in split factorial design. Treatments included four levels of cadmium (0,10, 20 and 40 mgCd kg-1soil) (from Cd(NO3)2) and two levels of CO2 (400 and 900 µL/L ). The results indicated that increasing CO2 levels, enhanced maximum shoot and root dry weight by 26% and 17% for wheat and 18% and 13% for sorghum, respectively. Increasing CO2 levels did not have any effect on Cd uptake by wheat but increased Cd uptake by 37-44% in shoot and 26-37% in root for sorghum. Phytoremediation indices were calculated based on the effect of increasing CO2 level on plant dry matter and Cd uptake. Although, Bio Concentration Factor, Biological Accumulation Coefficient and Tolerance Index were all less than unit, but with increase in CO2 levels these indexes and Remediation Ratio increased for sorghum. Therefore, increasing CO2 levels can decrease the undesirable effects of Cd on wheat, however it should be accounted for in terms of food safety for human and animals in the case of sorghum.