Paladines-Beltran and colleagues conducted an open-field experiment at the CIMAZ Macagual research center in Florencia, Colombia to evaluate how arbuscular mycorrhizal fungi (AMF) affect cadmium accumulation, oxidative stress, and antioxidant defense in sugarcane (Saccharum officinarum variety CC 01-1940). Plants were grown under four treatment combinations crossing commercial AMF inoculum and cadmium addition (50 mg/kg CdCl2) over 120 days. The study found that AMF colonization reduced cadmium translocation from roots to leaves and activated both enzymatic and non-enzymatic antioxidant mechanisms.
This paper is a plant physiology and phytoremediation study. It does not measure cadmium or any metal in sugarcane juice, molasses, panela, rapadura, or any finished food product. Its findings are contextual evidence for the soil-to-plant cadmium pathway in sugarcane; they cannot be used as food concentration data.
Key numbers
Cadmium concentrations in sugarcane leaves (mg/kg, measured by Energy Dispersive X-Ray Fluorescence Spectroscopy at 120 days, Table 1):
- Without AMF, with cadmium treatment (S-F+Cd): 1.21 +/- 0.10 mg/kg
- With AMF, with cadmium treatment (S+F+Cd): 0.47 +/- 0.10 mg/kg
- Without AMF, without cadmium (S-F-Cd, background): 0.15 +/- 0.10 mg/kg
- With AMF, without cadmium (S+F-Cd, background): 0.15 +/- 0.10 mg/kg
Cadmium concentrations in rhizosphere soil at 120 days (mg/kg, Table 1):
- Without AMF, with cadmium treatment (S-F+Cd): 68.38 +/- 4.55 mg/kg
- With AMF, with cadmium treatment (S+F+Cd): 48.73 +/- 4.55 mg/kg
- Background soil cadmium (without cadmium treatment): 0.18 +/- 4.55 mg/kg
The experimental soil cadmium content in the cadmium-added treatment exceeded the nominal treatment concentration (50 mg/kg), attributed by the authors to initial soil cadmium (0.16 mg/kg) plus residual cadmium from phosphate-based fertilizer pretreatment.
AMF colonization rates: treatments with commercial inoculum achieved 64 percent colonization, versus below 35 percent in uninoculated treatments.
Methods (brief)
Open-field experiment in 5-liter capacity bags. Cadmium was applied as CdCl2.H2O at 50 mg/kg soil. AMF inoculum was SAFER MICORRIZAS M.A commercial product (500 g per plant at planting). Cadmium in soil and leaves was measured by Energy Dispersive X-Ray Fluorescence Spectroscopy (HD XRF, Z-Spec E-max). Foliar tissue was sampled at 0, 3, 6, 9, 12, 24, 48, 96 hours and at 15, 30, and 120 days. No detection limits or certified reference materials are reported for the XRF method. Biochemical markers (chlorophylls, carotenoids, MDA, proline, enzymatic and non-enzymatic antioxidants) were measured using validated spectrophotometric and HPLC methods at multiple time points.
Evidence fitness
This study provides contextual evidence that sugarcane can translocate soil cadmium to leaf tissue, and that AMF inoculation reduces this translocation (from 1.21 to 0.47 mg/kg in leaves under 50 mg/kg soil cadmium treatment). However, the experimental soil cadmium loading (50 mg/kg) is far above typical agricultural soil cadmium concentrations in cane-growing regions (commonly 0.1 to 0.5 mg/kg). Results cannot be extrapolated to leaf or juice cadmium concentrations under normal field conditions. The study does not cover the processing steps (pressing, clarification, evaporation) that convert cane to juice or sugar and that could further alter metal content.
Limitations
The experimental cadmium dose (50 mg/kg soil) is not representative of agricultural conditions. No analytical detection limits or CRM recoveries are reported for the XRF cadmium measurements. Leaf cadmium concentrations are in plant tissue, not in juice or any food product. Only cadmium was measured; no other metals are reported. Sample sizes per treatment group are not stated for the chemical analyses.
Related evidence
- White sugar
- Cadmium
- Inorganic Contaminants in Rapadura from Latin America
- Contamination by Cadmium and Lead in Sugarcane and Its Derived Products in Ecuador
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