Objectives
In this research, quinoa plant (Chenopodium quinoa. Willd) was used for cadmium phytoremediation under soil salinity stress in laboratory conditions. To evaluate the interactive effects of cadmium contamination and soil salinity on cadmium uptake and accumulation in different organs of quinoa (Chenopodium quinoa Willd.). To determine the distribution pattern of cadmium within plant organs (root, stem, leaf, and grain) under combined cadmium and salinity stresses. To assess how increasing salinity levels influence cadmium mobility, availability, and extractability in soil. To investigate the extent to which quinoa can reduce soil cadmium concentrations and electrical conductivity (EC) through phytoextraction processes. To examine the tolerance and morphological stability of quinoa when exposed to heavy metal contamination and salinity stress. To evaluate the potential of quinoa as a suitable candidate species for phytoremediation of cadmium-contaminated soils, particularly under saline conditions. The results showed that quinoa plant has a high ability to absorb cadmium. The accumulation of cadmium in the plant organs was the highest in roots, stems, and leaves, and the lowest in the bark of the plant.
Methodology
Hydrometric method was used to determine soil texture (Gee and Or, 2002). Titration method was used to measure calcium carbonate equivalent (CCE) (Klute, 1986). pH was measured in a 1:2:5 soil and distilled water suspension with a pH meter (McLean, 1982). Electrical conductivity (EC) was measured in saturated flower extract (Rhoades, 1996). DTPA extraction method was used to measure absorbable cadmium. The research was conducted as a factorial experiment in the form of a completely randomized design with 2 factors including 4 levels of soil salinity, zero, 4, 8 and 12 dS/m and three levels of cadmium pollution zero, 6 and 12 mg/kg of soil with three replications. The measurement of the concentration of cadmium absorbed in different organs of the plant was done using the method (Ure, 1993). Considering that the research was conducted as a factorial experiment in the form of a completely randomized design with 2 factors including four levels of salinity and three levels of cadmium pollution, at the end, the data obtained were analyzed using MSTATC and SPSS software and the averages were compared. Duncan's multi-range test was performed at the five percent probability level and the results were interpreted. Excel software was also used to draw graphs.
Results
The results showed that quinoa efficiently absorbed and accumulated cadmium in all plant organs, with the extent of accumulation increasing under higher cadmium concentrations and elevated soil salinity. The interaction between cadmium and salinity was significant, leading to greater cadmium uptake as stress levels increased. Cadmium accumulation followed the order root > stem > leaf > grain, indicating the plant’s tendency to retain toxic metals in underground tissues while limiting their transfer to reproductive parts. Soil salinity increased cadmium mobility and availability, resulting in higher plant uptake. After harvest, both soil cadmium levels and electrical conductivity decreased, confirming the active role of quinoa in metal extraction and salt uptake. Overall, the findings highlight quinoa’s strong potential for phytoremediation of cadmium-contaminated saline soils due to its high tolerance and stable morphological performance under stress.
Conclusion
This study demonstrated that quinoa possesses a high capacity for cadmium uptake and accumulation, and that this process is significantly influenced by the simultaneous increase in soil salinity and cadmium concentration. The highest cadmium accumulation occurred in the roots, followed by the stems and leaves, while the lowest concentration was observed in the grains. This distribution pattern indicates the plant’s effective mechanisms for restricting the movement of heavy metals to reproductive organs. Elevated salinity enhanced cadmium mobility and bioavailability in the soil, leading to greater uptake by the plant. The reduction in soil cadmium content and electrical conductivity after harvest further confirmed quinoa’s active role in extracting cadmium and part of the soluble salts from the soil. Overall, the findings indicate that quinoa is a resilient and efficient candidate for phytoremediation of heavy metal–contaminated soils, particularly under saline conditions. |