تأثیر سطوح مختلف شوری بر جذب و توانایی گیاه‌پالایی عنصر کادمیم در گیاه کینوا (Chenopodium quinoa. Willd)

Background and Objectives: Soil contamination with heavy metals, particularly cadmium (Cd), poses serious threats to ecosystem health and food safety. Phytoremediation using salt-tolerant crops offers a sustainable approach for remediating contaminated soils in arid and semi-arid regions where salinization often accompanies metal pollution. Quinoa (Chenopodium quinoa Willd.) has gained attention for its remarkable tolerance to abiotic stresses, including salinity and heavy metals. This study aimed to: (1) evaluate the interactive effects of Cd contamination and soil salinity on Cd uptake and accumulation in different organs of quinoa; (2) determine the distribution pattern of Cd within plant tissues (root, stem, leaf, and grain) under combined stress conditions; (3) assess how increasing salinity levels influence Cd mobility, bioavailability, and extractability in soil; (4) investigate the potential of quinoa to reduce soil Cd concentrations and electrical conductivity (EC) through phytoextraction; and (5) examine the morphological stability and tolerance of quinoa when exposed to concurrent Cd and salinity stress.

 




Materials and Methods: A factorial experiment was conducted under laboratory conditions using a completely randomized design with two factors: four levels of soil salinity (0, 4, 8, and 12 dS/m) and three levels of Cd contamination (0, 6, and 12 mg/kg soil), each with three replications. Soil texture was determined by the hydrometric method. Calcium carbonate equivalent (CCE) was measured using the titration method. Soil pH was determined in a 1:2.5 soil:distilled water suspension using a pH meter. Electrical conductivity (EC) was measured in saturated paste extract. Available Cd concentration in soil was extracted using the DTPA method. Quinoa plants were grown under controlled conditions and harvested after the complete growth period. Cd concentrations in different plant organs (root, stem, leaf, and grain) were measured. Data were analyzed using MSTATC and SPSS software, and means were compared using Duncan's multiple range test at the 5% probability level.
Results: Quinoa demonstrated a high capacity for Cd uptake and accumulation across all plant organs, with accumulation increasing significantly in response to higher Cd concentrations and elevated soil salinity levels. A significant interaction was observed between Cd and salinity stresses, leading to enhanced Cd uptake under combined stress conditions. Cadmium accumulation followed the consistent order: root > stem > leaf > grain, indicating effective retention of toxic metals in belowground tissues and limited translocation to reproductive organs. Increasing soil salinity enhanced Cd mobility and bioavailability, resulting in greater plant uptake. Post-harvest analysis revealed significant reductions in both soil Cd content and electrical conductivity, confirming the active role of quinoa in phytoextraction of Cd and soluble salts. The plant maintained morphological
stability across all treatment combinations, demonstrating remarkable tolerance to both stressors.

 



Conclusion: This study confirms that quinoa possesses exceptional capacity for Cd phytoextraction in saline soils, with the highest accumulation occurring in roots followed by stems and leaves, while grains maintained the lowest Cd concentrations—a desirable trait for food safety. Elevated salinity enhanced Cd bioavailability and subsequent plant uptake, demonstrating a synergistic effect between the two stressors. The significant reduction in soil Cd and EC after harvest underscores quinoa's potential as an effective phytoremediation agent for Cd-contaminated saline soils. These findings support the use of quinoa in sustainable remediation strategies for degraded lands in arid and semi-arid regions, though field-scale validation is recommended to develop practical guidelines for optimal phytoremanagement.